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THE GUIDE TO LOWER EXTREMITY ARTHROLOGY

7/31/2015 Table 8

Madeleine Child, Madison Elliott, Jacob Jensen, Deanna Maurer,

Anthony Purviance, Johanna Schanbacher, Amanda Warren and

Chelsea Zemmin Chief Editor

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TableofContents

The Hip: Regional Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Muscles of the hip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Sacroiliac Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Pubic Symphysis Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Femoroacetabular Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

The Knee: Regional Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Muscles of the knee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Tibiofemoral Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Patellofemoral Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

The Foot and Ankle: Regional Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Muscles of foot and ankle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Proximal Tibiofibular Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Distal Tibiofibular Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Talocrural Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Subtalar Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Talonavicular Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

Calcaneocuboid Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

Cuneonavicular Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90

Cuboideonavicular Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Intercuneiform and Cuneocuboid Complex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98

Tarsometatarsal Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Intermetatarsal Joint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106

Metatarsophalangeal Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Interphalangeal Joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114

Appendix: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A: Gait Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117

B: Citations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119

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THEHIP:REGIONALOVERVIEW

The hip region is composed of three major joints including the pubic symphysis, the paired sacroiliac joints, and the bilateral femoroacetabular joints. The pubic symphysis and the sacroiliac joints are both located within the pelvic girdle. The pelvic girdle is composed of the sacrum and the two innominate bones which are comprised of three fused bones: the ilium, ischium, and pubis. The sacroiliac joint is a modified synarthrodial joint that is formed by the articulation between the sacrum and the ilium and demarcates the transition between the axial and the appendicular skeleton. The primary function of the sacroiliac joints is to provide stability to the pelvic girdle to ensure effective and efficient transfer of loads between the spine and the lower extremities. Due to this relationship, movement occurring at the lumbar spine has a direct influence on the pelvis moving over the femoral heads resulting in a synchronization of movement referred to as lumbopelvic rhythm coordinating the upper portion of the body with the lower extremities.

The pubic symphysis joint is a synarthrodial joint that is comprised of a fibrocartilaginous disc which joins with the articulations of the medial surfaces of the right and left pubic bones. The primary function of this joint is to provide stress relief to the anterior portion of the pelvic girdle. Although very limited motion occurs at both the sacroiliac joints and the pubic symphysis, these joints work together to allow enough flexibility, stress relief, and stability in the pelvic girdle to allow for sufficient attenuation of load and preservation of pelvic structure during daily activities such as walking, standing, and running.

The femoroacetabular joint is closely related to the pelvic girdle as it is formed between the articulating surfaces of the acetabulum of the innominate and the head of the femur. As a result, this joint demarcates the link between the pelvic girdle and the lower extremity. This ball and socket diarthrodial joint allows for a wide range of motion while simultaneously providing a large amount of stability in order to support the weight of the head, arms, and trunk during a multitude of static and dynamic weight bearing activities. Stability at this joint is accomplished by specific anatomical characteristics such as the thick fibrous joint capsule, reinforcing capsular ligaments, and an extensive amount of musculature about the hip. Further details about each of these joints specific form and function will be addressed in the following sections.

Figure 1. Joints of the hip region

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Table 1. Muscles of the hip region

Location Muscle Proximal Attachment

Distal Attachment

Action Segmental Innervation

Peripheral Innervation

Medial Thigh

Adductor Brevis

Body & inferior pubic rami

Pectineal line & proximal part of linea aspera of femur

Adducts hip, weak hip flexor

L2-3-4 Obturator Nerve

Adductor Longus

Body of pubis inferior to pubic crest

Middle third of linea aspera of femur

Adducts and flexes hip

L2-3-4 Obturator Nerve

Adductor Magnus

Inferior pubic ramus, ramus of ischium

Gluteal tuberosity, linea aspera, medial supracondylar line Hamstring Part: adductor tubercle of femur

Adductor part: adducts and flexes hip Hamstring Part: extends hip

Adductor Part: L2-3-4 Hamstring Part: L4-5, S1

Adductor Part: obturator nerve Hamstring Part: tibial division of sciatic nerve

Gracilis Body and inferior ramus of pubis

Superior part of medial surface of tibia

Adducts hip, flexes and medially rotates knee

L2-3-4 Obturator Nerve

Obturator Externus

Margins of obturator foramen, obturator membrane

Trochanteric fossa of femur

Laterally rotates hip, stabilizes head of femur in acetabulum

L3-4 Obturator Nerve

Pectineus Superior ramus of pubis

Pectineal line of femur

Adducts and flexes hip

L2-3-4 Femoral Nerve and occasionally Obturator Nerve

Anterior

Thigh

Iliacus Superior 2/3 of iliac fossa, iliac crest, ala of sacrum, anterior sacroiliac ligaments

Lesser trochanter of femur and shaft inferior, psoas major tendon

Flexes hip and stabilizes hip joint

L2-3-4 [L1] Femoral Nerve

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Anterior Thigh Cont.

Psoas Major Sides of vertebral bodies of T12-L5 & intervening intervertebral discs, transverse processes of L1-5

Lesser trochanter of femur

Flexes hip and trunk , stabilizes hip joint

L1-2-3-4

Femoral Nerve and Ventral Rami of L1

Sartorius Anterior superior iliac spine

Superior part of medial surface of tibia

Abducts, laterally rotates, and flexes hip, flexes and assists medial rotation of knee

L2-3 [4]

Femoral Nerve

Rectus Femoris Anterior inferior iliac spine and ilium superior to acetabulum

Base of patella and tibial tuberosity via patellar ligament

Flexes hip, extends knee

L2-3-4 Femoral Nerve

Posterior Thigh

Biceps Femoris Long head: Ischial tuberosity, sacrotuberous ligament Short head: Linea aspera and lateral supracondylar line of femur

Lateral side of head of fibula

Long head: Extends hip Short and Long head: flexes knee

L5, S1-2-3 L5, S1-2

Long head: Tibial division of the Sciatic Nerve Short head: Common fibular division of the Sciatic Nerve

Semimembranosus Ischial Tuberosity Posterior part of medial condyle of tibia

Extends hip, flexes & medially rotates knee

L4-5, S1-2

Tibial division of Sciatic Nerve

Semitendinosus Ischial Tuberosity Superior part of medial surface of tibia

Extends hip, flex & medially rotate knee

L4-5, S1-2

Tibial division of Sciatic Nerve

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Gluteal Region

Gluteus Minimus Lateral surface of ilium between anterior and inferior gluteal lines

Anterior surface of greater trochanter of femur

Abducts and medially rotates hip, steadies pelvis on leg when opposite leg is raised

L4-5, S1

Superior Gluteal Nerve

Gluteus Medius Lateral surface of the ilium between anterior and posterior gluteal lines

Lateral surface of greater trochanter of femur

Abducts and medially rotates hip, steadies pelvis on leg when opposite leg is raised

L4-5, S1

Superior Gluteal Nerve

Gluteus Maximus Ilium posterior to posterior gluteal line, aponeurosis of erector spinae, dorsal surface of sacrum and coccyx, sacrotuberous ligament

Iliotibial tract that inserts into lateral condyle of tibia, greater trochanter and gluteal tuberosity of femur

Extends and laterally rotates hip

L5, S1-2

Inferior Gluteal Nerve

Obturator Internus Pelvic surface of obturator membrane and surrounding bone

Medial surface of greater trochanter of femur

Extends and laterally rotates hip, abducts flexed thigh at hip

L5, S1-2

Nerve to obturator internus

Superior Gemellus Outer surface of ischial spine

Medial surface of greater trochanter of femur via obturator internus tendon

Laterally rotate and extend hip

L5, S1-2

Nerve to obturator internus

Inferior Gemellus Ischial tuberosity

Medial surface of greater trochanter of femur via obturator internus tendon

Laterally rotate and extend hip

L4-5, S1 [S2]

Nerve to quadratus femoris

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Gluteal Region Cont.

Quadratus Femoris Lateral margin of ischial tuberosity

Quadrate tubercle on inter- trochanteric crest of femur

Laterally rotates hip

L4-5, S1 [S2]

Nerve to quadratus femoris

Piriformis Anterior surface of sacral segments 2-4, posterior superior iliac spine, sacrotuberous ligament

Superior border of greater trochanter of femur

Laterally rotates and abducts hip Extends hip

Ventral rami of L5, S1-2

Branches of lumbo-sacral plexus

Tensor Fasciae Latae

Anterior superior iliac spine and anterior part of iliac crest

Iliotibial tract that attaches to lateral condyle of tibia

Abducts, medially rotates, and flexes hip and assists in maintaining knee extension

L4-5, S1

Superior Gluteal Nerve

Pelvic Floor

Coccygeus Ischial spine, sacrospinous ligament

Inferior sacrum and coccyx

Supports pelvic viscera, draws coccyx forward

S4-5 Ventral rami S4-5

Levator Ani: Puborectalis Pubococcygeus Iliococcygeus

Body of pubis, tendinous arch of obturator fascia, ischial spine

Perineal body, coccyx, ano-coccygeal raphe, walls of prostate or vagina, rectum, anal canal

Supports pelvic viscera, raises pelvic floor

S2-3-4 Pudendal nerve and ventral rami of S4

Back

Lattisimus Dorsi

Spinous processes of T7-L5, thoracolumbar fascia, iliac crest, and last three ribs

Inter-tubercular sulcus of humerus

Extends, abducts, and medially rotates humerus

C6-7-8

Thoraco-dorsal Nerve

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Back Cont.

Erector spinae Posterior sacrum, iliac crest, sacrospinous ligament, supraspinous ligament, spinous processes of lower lumbar and sacral vertebrae

Iliocostalis: angles of lower ribs, cervical transverse processes Longissimus: between tubercles and angles of ribs, transverse processes of thoracic and cervical vertebrae, mastoid process Spinalis: spinous processes of upper thoracic and midcervical vertebrae

Extends and laterally bends vertebral column and head

Dorsal rami of spinal nerves

Dorsal rami of spinal nerves

Multifidus Sacrum, ilium, transverse processes of T1-12, and articular processes of C4-7

Spinous process of vertebrae above spanning 2-4 segments

Stabilizes spine, extension and contra-lateral rotation of spine

Dorsal rami of spinal nerves

Dorsal rami of spinal nerves

Abdominal Wall

Rectus abdominus

Pubic Symphysis, pubic crest

Xiphoid process, costal cartilages 5-7

Flexes trunk, compresses the abdominal viscera

T5-T12 Lower thoracic ventral rami

Internal oblique

Thoracolumbar fascia, anterior 2/3 of iliac crest, lateral half of inguinal ligament

Inferior borders of ribs 10-12, linea alba, pubis via

Compresses and supports abdominal viscera,

T7-12, L1

Lower thoracic ventral rami and first

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Abdominal Wall Cont.

conjoint tendon

flexes and rotates trunk

lumbar nerves: iliohypo-gastric and ilio-inguinal

External oblique

External surface of ribs 5-12

Linea alba, pubic tubercle, anterior half of iliac crest

Compresses and supports abdominal viscera, flexes and rotates trunk

T7-12 (T5-6)

Lower thoracic ventral rami

Transversus abdominus

Internal surfaces of costal cartilages 7-12, thoracolumbar fascia, iliac crest, lateral third of the inguinal ligament

Linea alba with aponeurosis of internal oblique, pubic crest, and pecten pubis via conjoint tendon

Compresses and supports abdominal viscera

T7-12, L1

Lower thoracic ventral rami and first lumbar nerves: iliohypo-gastric and ilio-inguinal

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SacroiliacJoint(SIJoint)

Overview The sacroiliac joints (SI joints) are components of the pelvic girdle that are located anterior to the PSIS of the ilium. These joints demarcate the site of transition between the axial and inferior

appendicular skeleton. Their primary function is to provide structural stability to the pelvic girdle in order to effectively transfer loads of varying magnitudes between the lumbar spine and the lower extremities. Formed between the articulating surfaces of the ala of the sacrum and the ilium of the innominate, the classification of this joint is unique. Throughout life the joint changes from a fairly mobile synovial joint in childhood to a fairly rigid modified synarthrodial joint by the time of adulthood. Due to these structural changes, only a small amount of motion occurs at this joint reportedly measuring at about one to four degrees of rotation and one to 2mm of translation. In addition to this structural boney congruity, motion is restricted at this joint by ligamentous and muscular contributions.

As reported by Ebraheim et al., the SI joint receives its blood supply from a nutrient artery branching off of the iliolumbar artery. Due to the location of these arteries anterior and superior to the SI joint, they are highly susceptible to damage and have the potential to cause large amounts of bleeding as a result of sacral fractures or surgery that requires an anterior approach to the joint (Ebraheim, 1997). The sacroiliac joint receives sensory innervation most commonly reported as contributions from the dorsal rami of L5-S3 spinal nerve roots and less frequently reported as contributions from the ventral rami of L4-S2 spinal nerve roots however reports in the literature remain largely variable.

Tissue Layers (Superficial to Deep) x Integumentary

o Epidermis o Dermis

x Fascia o Superficial Fascia

� Subcutaneous adipose � Cutaneous nerves

x Superior cluneal nerves

x Medial cluneal nerves

x Posterior cutaneous intercostal nerves

x Lateral cutaneous

Figure 2. The sacroiliac joint

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intercostal nerves

x Anterior cutaneous intercostal nerves

� Superficial blood vessels

x Superficial epigastric a/v

x Superficial circumflex iliac a/v

� Lymphatic vessels o Fascia lata of the gluteus

maximus o Thoracolumbar fascia

� Posterior layer � Anterior layer

x Muscles Posterior Approach:

o Gluteus maximus o Gluteus medius o Lattisimus dorsi o External oblique o Internal oblique o Erector spinae o Transversus abdominus o Multifidus

Anterior Approach: o External oblique o Internal oblique o Rectus abdominus o Transversus abdominus o Psoas minor o Psoas major o Iliacus o Quadratus lumborum o Piriformis o Coccygeus o Levator ani (Iliococcygeus)

x Neurovasculature Posterior Approach:

o Inferior gluteal nerve o Superior gluteal nerve o Superior gluteal a/v o Lumbar a/v o Iliohypogastric nerve o Ilioinguinal nerve

Anterior Approach:

o Inferior epigastric a/v o Iliohypogastric nerve o Ilioinguinal nerve o Genitofemoral nerve o Obturator nerve o Femoral nerve o Lateral femoral cutaneous

nerve of the thigh o Common fibular nerve root o Tibial nerve root o External Iliac a/v o Deep circumflex iliac a/v o Internal Iliac a/v o Iliolumbar a/v o Lateral sacral a/v

x Ligaments Posterior Approach:

o Sacrotuberous ligament o Interosseous ligaments o Posterior sacroiliac ligaments

Anterior Approach: o Iliolumbar ligament o Anterior sacroiliac ligament o Sacrospinous ligament

x Joint Capsule x Bone

o Ala of Sacrum o Ilium of Innominate

� Covered in a hyaline cartilage

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Joint Motions and Associated Muscles Table 2. SI joint motions

Motion Associated Muscles Nutation Erector Spinae

Multifidi Recuts Abdominus

Biceps Femoris Counter nutation Rectus Femoris

Latissimus dorsi thoracolumbar fascia

Joint Configuration and Planes of Motion The sacroiliac joint is a modified synarthrodial articulation between the C-shaped auricular surfaces on the lateral aspects of the sacrum and the matching surfaces of the right and left ilia. The opening of the “C” faces the posterior direction. Anteriorly, the joint is classified as a diarthrodial articulation, while the posterior aspect is a fixed synarthrodial connection between congruent elevations and depressions.

The articular surface of the sacrum can be found along the lateral aspect of the sacral foramina of segments S1-S3. This surface is mostly concave, although sexual dimorphism and variation have been reported throughout the literature. The auricular surface of the ilia are found to be mostly convex, although again, with variation. Each articulating surface is covered in a hyaline cartilage layer that thins with aging.

The configuration of the sacroiliac joint changes from birth through adulthood. During childhood, the SI joint has characteristics of being a synovial joint. The articulating surfaces on both the sacrum and the ilia are smooth and flat with a pliable capsule surrounding the joint, allowing for slightly

more mobility. With aging, the articulating surfaces become covered in ridges and grooves that interlock to create movement resistance between the sacrum and the ilium. These coordinating connections create a high amount of friction.

The sacroiliac joint is relatively rigid and immobile. There is a small amount of translation and rotation that takes place in the near-sagittal plane around a near-mediolateral axis. For adults, this can be anywhere between 1-2mm of translation and up to 4 degrees of rotation. Because this mechanism of

Figure 3. Articulating surfaces of the sacroiliac joint

Figure 4. Sacroiliac joint cut along transverse plane

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movement is quite irregular, there are specific terms designated to describe the complex combination of these movements at the SI joint, which will be discussed in the next section.

Biomechanics and Arthrokinematics The biomechanics of the sacroiliac joint are difficult to examine due to the complex nature and location of the joint. The main physiological function of the sacroiliac joint is to provide stability and load transfer between the axial skeleton and the lower extremities. The SI joints also provide stress relief for the pelvic ring. If the pelvic ring were a solid structure, it would fracture under the normal stressors of everyday activity. The SI joints, along with their anterior counterpart the pubic symphysis, provide enough pliancy and force transmission to prevent breakage from occurring.

During ambulation, the lower extremities move in a reciprocal pattern. At the time of right heel strike, the left toes remain in contact with the ground. This causes the muscles and ligaments of the hip to pull on the pelvis and create a torsional force across the right and left innominates. The minimal flexibility found at the SI joints is enough to be able to attenuate these forces and preserve pelvic structure.

As mentioned in the previous section, the sacroiliac joint has a unique combination of translation and rotational movements: nutation and counternutation. Nutation is the relative anterior/inferior tilt of the sacral promontory while the sacral apex and coccyx move posteriorly. This motion is similar to sacral flexion of the ilia. Muscular contributions to this movement are from the erector spinae to rotate the sacrum anteriorly while the rectus abdominis and biceps femoris bring the ilium posteriorly. In addition to muscle dynamics, the downward force of gravity and the ground reaction forces through the lower extremities also provide a nutation torque on the joint during double limb stance. Nutation places the sacrotuberous and interosseous ligaments on tension, creating compression forces which further increase the stability of the joint. For these reasons, full nutation is the close-pack position of the SI joint in which the prominent compression and shear forces at the joint give the most articular congruency and most effective load transfer.

Counternutation is the opposite motion, with the sacral promontory moving posterior/superior while the apex moves in an anterior direction. To make a similar comparison, it would be like sacral extension. Rectus femoris pulls the innominate in the anterior direction, while the thoracolumbar fascia of the latissimus dorsi pulls the sacrum posteriorly. The motions of nutation and counternutation can take place either by the movement of the sacrum on the ilia or of the ilia moving on the sacrum or a combination of the two. The anteroposterior diameter of the pelvic brim and outlet are impacted based on whether the sacrum is in nutation or counternutation. In nutation, the pelvic brim diameter is decreased while the outlet diameter becomes larger. The opposite is true in counternutation. These changes become especially relevant during pregnancy and childbirth.

Figure 5. Movements of the sacroiliac joint

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The sacroiliac joint has some level of bony stability due to the interlocking configuration of the joint itself. Vleeming introduces this concept as form closure in his 1990 article. In perfect form closure,

the articulating surfaces are so well integrated that they provide stability without requiring the assistance of outside forces to maintain the load to the joint. However, this creates a problem of immobility at the joint. Instead, the type of stability found at the SI joint is a combination of form closure and force closure, which is a

dynamic stability supplied by the combination of friction and the compression forces of the surrounding ligamentous and muscular structure.

Muscles associated with providing actions that impact the stability found at this joint are the erector spinae, lumbar multifidi, rectus abdominus, internal oblique, external oblique, transversus abdominus, biceps femoris, gluteus maximus, lattisimus dorsi, Iliacus, and piriformis. The interosseous ligaments along with the long and short posterior sacroiliac ligaments also play a large role in stabilizing the sacroiliac joint region.

Ligaments of the Sacroiliac Joint

Figure 6. Form and force closure of the sacroiliac joint

Figure 7. Posterior view of the sacroiliac joint ligaments

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Table 3. Ligaments of the sacroiliac joint

Ligament Attachments Function Other associated joint constraints

Anterior Sacroiliac Thickening of anterior and inferior portions of SI joint capsule

Primary stabilizer of SI joint reinforcing the anterior portion of the joint

Reinforces anterior portion of joint

Interosseous Sacroiliac Posterior sacral articulating surfaces to iliac tuberosities occupying the space between posterior and superior margins of the joint

Primary Stabilizer of SI joint strongly binding the sacrum and the ilium

Provides multidirectional structural stability of the joint, transfers weight between axial and inferior appendicular skeleton

Short Posterior Sacroiliac Posterolateral side of the sacrum to the ilium near the iliac tuberosity and posterior superior iliac spine mixing with the deeper interosseous sacroiliac ligament

Primary Stabilizer of SI joint reinforcing the posterior portion of the joint

Assists in force closure of the joint

Long Posterior Sacroiliac Lateral crest of the third and fourth sacral segments to posterior superior iliac spine of the ilium mixing with the sacrotuberous ligament

Primary Stabilizer of SI joint reinforcing the posterior portion of the joint

Restrains counternutation of the sacrum, assist in force closure of the joint

Iliolumbar Transverse process of L4-5 to iliac crest of pelvis

Primary Stabilizer of SI joint reinforcing the anterior portion of the joint

Resisting extension, lateral flexion, and axial rotation of L5-S1

Sacrospinous Ischial spine to lateral borders of sacrum and coccyx

Secondary Stabilizer of SI joint

Restrains nutation of the sacrum

Sacrotuberous Ischial tuberosity to posterior superior iliac spine, lateral sacrum, and coccyx mixing with the tendon of the biceps femoris muscle

Secondary Stabilizer of SI joint

Restrains nutation of the sacrum

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Common Pathologies of the Sacroiliac Joint Sacroiliac Joint Dysfunction (Pain):

Sacroiliac Joint Dysfunction is a general term used to describe impaired load transfer and pain perceived in the gluteal, lumbar, abdomen, and lower extremity stemming from pathology in the SI joint. Most pain from the SI region can be attributed to mobility imbalances that arise secondary to trauma, gradual degeneration, or hormonal changes during pregnancy. Examination includes provocation tests to elicit a pain response. These provocation tests include distraction, compression, thigh thrust, Gaenslen’s test, sacral thrust, and motion palpation. Although independently these tests show little validity, when used together, they give a fairly accurate picture of a symptomatic sacroiliac joint.

The dysfunction can be in the form of hyper- or hypomobility and treatment follows a course of focusing on the signs and symptoms present. According to Vanelderen et al., conservative treatment to reduce pain and improve mobility in the sacroiliac joint is best addressed using a combination of exercise therapy and manipulation (Vanelderen, 2010). These methods can be used to address the underlying postural and gait disturbances that are often responsible for SI joint pain. Stabilization exercises work to strengthen the force closure of the joint, targeting the transversus abdominis, abdominal oblique muscles, latissimus dorsi, and gluteal muscles to increase myofascial stability. Active range of motion exercises along with manipulation and mobilizations can be used to improve mobility on the symptomatic side.

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PubicSymphysisJoint

Overview The pubic symphysis joint is a component of the pelvic girdle acting as the anterior link between the pubic bones of the paired innominates. This joint is commonly classified as a synarthrosis joint comprised of a fibrocartilaginous pubic disc that articulates with the medial surfaces of the pubic bones. The primary function of this joint is to provide stress relief to the anterior portion of the pelvic girdle during movement such as walking and during childbirth. In addition to the pubic disc, pubic ligaments strongly bind the joint together allowing only slight motion at the joint measuring at about 2mm of translation and a small amount of rotation.

As reported by Becker et al., the pubic symphysis joint is mainly supplied with blood by a branch of the obturator artery and a branch of the inferior epigastric artery. It has also been suggested that the joint receives additional blood supply from branches of the external and internal pudendal arteries and the medial circumflex femoral artery however this supply is more variable and minimal in amount (Becker, 2010). Also reported by Becker et al., the pubic symphysis is suggested to be innervated by the pudendal and genitofemoral nerves and branches of the iliohypogastric and ilioinguinal nerves (Becker, 2010).

Tissue Layers (Superficial to Deep) x Integumentary

o Epidermis o Dermis

x Fascia o Superficial Fascia

� Camper’s Fascia � Scarpa’s Fascia � Cutaneous nerves

x Anterior cutaneous branch of subcostal nerve

x Anterior cutaneous

branch of iliohypogastric nerve

x Anterior branch of ilioinguinal nerve

x Genital branch of genitofemoral nerve

� Superficial blood vessels

Figure 8. Pubic symphysis joint and associated ligaments

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x Superficial external pudendal a/v

x Superficial epigastric a/v

� Lymphatic vessels � Anterior rectus sheath

x External oblique aponeurosis

x Internal oblique aponeurosis

x Transversus abdominus aponeurosis

� Transversalis fascia � Extraperitoneal fascia � Parietal peritoneum � Linea alba

x Muscles o Pyramidalis o Rectus abdominus o Ischiocavernosus o Bulbospongiosus o Gracilis

o Adductor longus x Neurovasculature

o Ilioinguinal nerve o Genitofemoral nerve o Deep external pudendal a/v o Accessory branches of the

obturator a/v o Pubic branches of inferior

epigastric a/v x Ligaments

o Anterior pubic ligament o Inguinal ligament o Lacunar ligament o Pectineal ligament o Superior pubic ligament o Inferior pubic ligament o Posterior pubic ligament

x Joint o Fibrocartilaginous disc

x Bone o Paired pubic bones of the

innominate � Covered in a hyaline

cartilage

Joint Motions and Associated Muscles Table 4. Motions of the pubic symphysis joint

Joint Motions Associated Muscles Stability Aponeurosis of the Transverse Abdominus,

Rectus Abdominus, Internal Oblique, and Adductor longus

Translation N/A Rotation N/A

Joint Configuration and Planes of Motion The pubic symphysis is typically classified as a synarthrodial articulation and contains a fibrocartilaginous disc joining the articular surfaces of the right and left pubic bones. There is mixed literature regarding the width of the symphysis, although most agree that the anterior portion is wider than the posterior. The interpubic disc has broader superior and inferior edges with a narrow midsection. Within the superior posterior part of the disc is a narrow slit-like cavity known as the cleft.

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The articular surfaces of the pubic bones are oriented obliquely in the sagittal plane and of a slightly convex and oval shape. These ridged articular surfaces are covered in a 1-3mm layer of hyaline cartilage. This cartilage tends to decrease with aging. The bony surfaces below the cartilage are found to be irregular in childhood, smoothing and flattening around age 30 and then progressing with degenerative changes such as joint narrowing and irregularities forming again around the sixth decade of life. The pubic symphysis is a relatively immobile joint, allowing approximately 1-2mm of translation in the transverse and sagittal planes and slight rotation in the frontal and sagittal planes.

Biomechanics and Arthrokinematics Although the pubic symphysis is quite rigid, slight available movements such as translation and rotation do coordinate with those of the SI joint to attenuate load and provide stability to the pelvic ring during everyday activities. There are no muscles associated with these movements as they are a product of the forces acting on the pubic symphysis during various activities. In closed kinetic chain, the movement at either the pubic symphysis or the sacroiliac joints will create and effect movement at the other. This movement provides enough flexibility in the ring in order to prevent pelvic fracture during daily activities.

During double-limb stance, there are tensile forces acting on the inferior part of the pubic symphysis joint with an equal amount of compression being felt through the superior region. In sitting, there are compression forces in the pubis that are then transmitted along the pubic rami and dispersed about the rest of the innominate bones.

Lateral pelvic tilting that occurs during the single limb stance of gait creates a predominantly shearing force at the pubic symphysis. A typical pubic symphysis joint is able to withstand these forces with barely discernible amounts of translation and rotation. If dislocation occurs at the joint, the pelvis becomes unstable during ambulation and additional stress are placed on the sacroiliac and hip joints.

While there are no muscles acting directly to create movement at the pubic symphysis, there are a number of tendinous attachments from surrounding musculature which provide stability for the anterior innominate. These include the transversus abdominis, rectus abdominis, internal oblique and adductor longus. According to Omar et al, the rectus abdominis and the adductor longus muscle are the most robust players in contributing to the stability of the pubic symphysis, as they are relative antagonists to each other during typical movement patterns (Omar, 2008).

Figure 9. Muscles acting on the pubic symphysis joint

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Ligaments of the Pubic Symphysis Joint Table 5. Ligaments of the pubic symphysis joint

Ligament Attachments Function Other associated joint constraints

Superior Pubic Pubic tubercle and crest spanning superiorly to pubic tubercle and crest of opposite pubic bone, connections with the interpubic disc, pectineal ligament, linea alba, and periosteum of superior pubic rami

Reinforces the superior aspect of the Pubic symphysis joint

N/A

Inferior Pubic (Subpubic or Arcuate

Pubic)

Inferior fibers attach inferior pubic rami of one side to inferior pubic rami of other side Upper fibers mixing with interpubic disc and posterior pubic ligament

Reinforces the inferior aspect of the Pubic symphysis Joint

N/A

Anterior Pubic Periosteum of one pubic bone to periosteum of other pubic bone connecting bones anteriorly Deep fibers mixing with interpubic disc, superficial fibers mixing with tendinous insertions of rectus abdominus and oblique abdominal muscles

Reinforces the anterior aspect of the Pubic symphysis joint

Maintains stability of the Pubic symphysis joint

Posterior Pubic Periosteum of one pubic bone to periosteum of other pubic bone connecting bones posteriorly

Reinforces the posterior aspect of Pubic symphysis joint

N/A

Common Pathologies of the Pubis Symphysis Joint Osteitis Pubis:

Osteitis pubis is an inflammation of the pubic symphysis and surrounding tendons caused by overuse or shear injury often seen in athletes or pregnant women after trauma or surgery to the pelvic region. According to Dr. Rob Johnson (2003), in his article about Osteitis pubis, patients with this disorder often present with a gradual onset of pain in the groin and possibly the lower abdomen, hip, thigh or perineum. Because there is a lengthy list of differential diagnosis, the testing clinician must be

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aware of the vague signs and symptoms associated with Osteitis pubis and should keep the pathology on his or her radar. Specific examination often shows point tenderness to palpation and a positive pubic spring test, in which the clinician presses the right and left superior pubic rami to elicit a pain response. Groin pain can also be exacerbated by resisted hip abduction or passive stretch to the hip adductors (Johnson, 2003). Some loss of hip internal rotation range of motion may occur and there is often an antalgic gait pattern. Imaging is often used to confirm a diagnosis of Osteitis pubis.

Osteitis pubis is a self-limiting pathology and so treatment often involves modification of activity and typical exercise therapy. Exercise therapy for this condition should include hip range of motion and strengthening program for the hip, lumbar and abdominal regions. Prognosis for this disorder is excellent as 90 - 95% of patients attain full recovery, although that process can take up to 1 year.

Symphysis Pubis Dysfunction (specifically in pregnancy): Symphysis Pubis Dysfunction, also referred to as symphyseal pain, is a condition that is

commonly characterized by a decrease in pelvic girdle stability resulting in the development of mild to severe pain (Depledge, 2005). This condition has been reported to affect athletes and patients who experienced a traumatic pelvic injury. However, due to the high prevalence of this condition reported in pregnant women, further discussion of this condition will focus specifically on this patient population (Becker, 2010). One suggested reason for the development of this condition during pregnancy is attributed to the hormonal changes that occur during this time. These hormonal changes, specifically the increase of the hormone Relaxin, have been found to be responsible for promoting connective tissue modifications which result in a more pliable pubic symphysis joint and more relaxed and lengthened ligaments surrounding the joints of the pelvic girdle (Depledge, 2005; Leadbetter 2004) . While these hormonal changes do decrease stability in the pelvis, recent literature has reported that Relaxin is not a significant factor in causing the development of symphyseal pain. As a result, the etiology of this common condition remains unclear and warrants further investigation into additional factors including mechanics, metabolism, trauma, and degenerative changes (Aldabe, 2012).

Pain associated with this condition is located in the region of the pubic symphysis with common referral patterns to the lower abdomen, thigh, back, groin, perineum, and leg and has been reported as being worst during weight bearing activities (Becker, 2010). Other signs and symptoms include an audible or palpable clicking or grinding in the joint, atypical waddling gait, tenderness over the pubic symphysis, and difficulty with daily activities (Depledge, 2005). In an effort to try and diagnose this condition a couple different sets of diagnostic criteria have been reported. For example, one set of criteria includes answering “yes” to two of the following inquiries including pain when turning in bed, walking, lifting a light load, getting up from a chair, or climbing stairs and positive examination findings suggestive of pain and pelvic dysfunction (Leadbetter, 2004). Conservative management through physical therapy intervention has been studied to measure its effectiveness in reducing pain and increasing function for women with this condition. As reported by Depledge et al., exercises targeting the abdominal stabilizers, pelvic floor, gluteus maximus, lattisimus dorsi muscle, and hip adductor muscles in addition to patient education, and activity modifications were effective in both (Depledge, 2005).

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FemoroacetabularJoints(HipJoints)

Overview The femoroacetabular joints demarcate the link between the pelvic girdle and the lower extremities. The commonly classified ball and socket synovial joints are formed by the articulation between the head of the femur and the acetabulum of the innominate. Due to its anatomical features, the femoroacetabular joint is a highly mobile joint that allows for three degrees of freedom. Even so, its primary function is to provide a great amount of stability during a variety of static and dynamic weight-bearing activities such as ambulation and standing. For this reason, in addition to its thick and fibrous joint capsule, the joint is also reinforced by ligaments and a large amount of musculature in order to maintain stability and perform a wide array of movements.

The femoroacetabular joint receives its main blood supply from the retinacular arteries branching off of the medial and lateral circumflex femoral arteries which originate from the deep artery of the thigh or less commonly from the femoral artery. The joint also receives its blood supply from the artery to the head of the femur which branches off of the obturator artery and passes through the ligament of the head of the femur.

The femoroacetabular joint is innervated by the same nerves that are responsible for innervating adjacent muscles acting on or crossing over the joint. For this reason, the anterior portion of the capsule is innervated femoral nerve, posterior capsule by the nerve to the quadratus femoris, inferior capsule by the obturator nerve, and superior capsule by the superior gluteal nerve.

Tissue Layers (Superficial to Deep) x Integumentary

o Epidermis o Dermis

x Fascia o Superficial fascia

� Subcutaneous adipose � Cutaneous nerves

x Superior cuneal nerves

x Middle cuneal nerves

x Inferior cuneal nerves

x Lateral femoral cutaneous nerve of the thigh

x Anterior femoral

Figure 10. Blood supply to the femoroacetabular joint

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cutaneous nerve of the thigh

� Superficial blood vessels

x Superficial circumflex iliac a/v

x Superficial epigastric a/v

x Superficial external pudendal a/v

x Great saphenous v

x Accessory saphenous v

� Lymphatic vessels � Fascia lata of thigh and

gluteus maximus x Muscles (by Compartments)

Anterior Compartment o Sartorius o Rectus femoris o Psoas major o Iliacus Medial Compartment o Gracilis o Adductor longus o Adductor magnus o Adductor brevis o Pectineus o Obturator externus Gluteal Region o Tensor fasciae latae o Gluteus maximus o Gluteus medius o Gluteus minimus o Piriformis o Superior gemellus o Obturator internus

o Inferior gemellus o Quadratus femoris Posterior Compartment o Biceps Femoris (Long head) o Semitendinosus o Semimembranosus

x Neurovasculature Anterior Approach:

o Femoral a/v o Femoral nerve o Profunda femoris o Lateral circumflex femoral a/v

x Ascending x Transverse x Descending

o Medial circumflex femoral a/v o Anterior and posterior branch

of obturator nerve Posterior Approach:

o Superior gluteal a/v o Superior gluteal nerve o Inferior gluteal a/v o Inferior gluteal nerve o Sciatic nerve o Posterior cutaneous nerve of

the thigh o Pudendal nerve o Nerve to the obturator internus o Nerve to the quadratus femoris

x Bursa o Trochanteric o Iliopectineal o Ischial

x Ligaments o Iliofemoral o Pubofemoral o Ischiofemoral

x Joint o Joint capsule o Synovial membrane o Transverse acetabular ligament

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o Acetabular Labrum o Ligament of the head of the

femur x Bone

o Head of the femur o Acetabulum of the innominate

x Covered in a layer of hyaline cartilage

Joint Motions and Associated Muscles Table 6. Muscles of the femoroacetabular joint

Joint Motion Primary Movers Stabilizing and Helping Movers Flexion Iliopsoas, Sartorius, Tensor

fasciae latae, Rectus femoris, Adductor longus, Pectineus

Adductor brevis, Gracilis, Gluteus minimus (anterior fibers)

Extension Gluteus maximus, Biceps femoris (long head), Semitendinosus, Semimembranosus, Adductor magnus (posterior head)

Gluteus medius (posterior fibers), Adductor magnus (anterior head)

Abduction Gluteus medius, Gluteus minimus, Tensor fasciae latae

Piriformis, Sartorius

Adduction Pectineus, Adductor longus, Gracilis, Adductor brevis, Adductor magnus

Biceps femoris (long head), Gluteus maximus (lower fibers), Quadratus femoris

Internal Rotation N/A Gluteus minimus (anterior fibers), Gluteus medius (anterior fibers), Tensor fasciae latae, Adductor longus, Adductor brevis, Pectineus

External Rotation Gluteus maximus, Piriformis, Obturator internus, Superior Gemellus, Inferior Gemellus, Quadratus femoris

Gluteus medius (posterior fibers), Gluteus minimus (posterior fibers), Obturator externus, Sartorius, Biceps Femoris (long head)

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Joint Configuration and Planes of Motion The femoroacetabular joint is a classic ball and socket synovial articulation between the convex head of the femur and the ipsilateral concave acetabulum of the pelvis. The head of the femur is a spherical shape located at the proximal end of the femur bone. The surface is almost entirely covered with a layer of hyaline cartilage, save for the area over the fovea, which is a small surface cavity located slightly posterior to the center. The acetabulum is a deep socket formed from contributions of all three pelvic bones and is orientated in a lateral, anterior, and inferior position. The lunate surface of the acetabulum is a horseshoe shaped area of the rim covered in hyaline cartilage which contacts directly with the femoral head. The missing inferior segment of the rim is the acetabular notch which is spanned by the transverse acetabular ligament, connecting the two ends of the lunate surface. The fibrocartilaginous acetabular labrum surrounds the periphery and deepens the socket, increasing the concavity of the acetabulum and creating better congruency for the femoral head. The labrum creates a seal around the joint which maintains a negative intra-articular pressure and helps encase the synovial fluid.

The entire joint is enclosed within a strong joint capsule, formed by an external fibrous layer and internal synovial membrane. Thickened segments of the fibrous structure are formed from contributions of the iliofemoral, pubofemoral, and ischiofemoral ligaments. Most of the capsule fibers spiral from the hip to the intertrochanteric line of the femur. The capsule is reinforced anterosuperiorly where the joint sustains the most stresses. Some of the deeper fibers of the ischiofemoral ligament circle around the neck of the femur forming the orbicular zone. Inside the capsule, synovial fluid is present, allowing for reduced friction and fluidity of movement with hip joint mobility in multiple directions.

Variations can be noted in the angles created between the head and neck of the femur. The angle of inclination occurs in the frontal plane between the femoral neck and the medial side of the femoral shaft. At birth this angle is between 140-150 degrees but changes with weight bearing to about

Figure 11. Femoroacetabular joint configuration

Figure 12. Ligaments of the femoroacetabular joint

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125 degrees in a normal adult, optimizing the alignment of the joint. This angle coincides with the greater trochanter being level with the center of the femoral head. Malalignment of this angle creates altered mechanics down the chain of the lower extremity, influencing the knee, ankle and foot posturing. Coxa vara is a decreased angle of inclination which leads to increased genus valgus at the knee and pronation at the foot. This pathological reduction causes an increased moment arm for greater force production of hip abductor muscles but also simultaneously decreases their functional length. Thus, this negates the benefits of the longer moment arm. Shear force across the superior portion of the femoral neck is also amplified. In children, this condition can lead to slipped capital femoral epiphysis (SCFE). Coxa valga is an increased angle of inclination leading to genu varus at the knee and supination at the foot. This enlarged angle has the opposite effect on the muscles responsible for hip abduction. While functional length of the muscles is increased, the moment arm for torque production is diminished. In more extreme cases of coxa valga, the head of the femur may be positioned in such a way as to favor joint dislocation.

The angle of torsion refers to relative rotation of the femoral head and shaft as viewed from above. A normal angle is one in which a transverse axis through the femoral head and neck lies about 15 degrees anterior to the mediolateral axis through the femoral condyles. Infants are born with about 30-40 degrees of anteversion, which normalizes to adult values with continued bone growth and weight bearing activities. Excessive anteversion is when this angle remains greater than 30 degrees into

adulthood and is associated with an increased likelihood of anterior hip dislocation, incongruences of the joint, and excessive wear on acetabular cartilage, all of which can predispose an individual to developing osteoarthritis of the hip. Range of motion into external rotation is decreased while internal rotation ranges are above average. Pathological levels of femoral anteversion in children are often seen in conjunction with a compensatory in-toeing gait pattern which self-corrects over time with the structural changes of

Figure 13. Femoral angle of inclination

Figure 14. Femoral anteversion and retroversion

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the lower extremities. This is not true of children with cerebral palsy who tend to maintain the extreme 60-80 degrees of anteversion and the in-toeing gait pattern.

Retroversion is when the angle of torsion is significantly less than 15 degrees. The availability of internal rotation at the hip is diminished, while external rotation is excessive of normal values. Individuals with retroverted femurs may walk with a larger foot progression angle, indicative of a toe out compensatory posture during gait.

Biomechanics and Arthrokinematics Arthrokinematics:

As mentioned above, the femoroacetabular joint is formed by the articulation between the convex head of the femur and the concave surface of the acetabulum. Due to this anatomical structure, arthrokinematics that occur in the hip joint follow the convex on concave principle when applied to open chain femur on pelvis motion from a neutral position. This principle states that the intra-articular motions of roll and glide happen in opposing directions. During abduction, the convex head of the femur rolls superiorly on the surface of the acetabulum while simultaneously gliding inferiorly, and during adduction the head of the femur rolls inferiorly and glides superiorly. During external rotation, the head of the femur rolls posteriorly while the glide occurs anteriorly, and during internal rotation the femur rolls anteriorly and glides posteriorly. In the case of flexion and extension however, the femur does not exhibit the same roll and glide motions, but instead the head of the femur spins around a focal point on the surface of the acetabulum.

Osteokinematics: Femoroacetabular osteokinematic motion occurs in all three major planes of motion around an

axis of rotation located in the center of the femur. Motion at the hip can be described as either femur on pelvis motion or pelvis on femur motion. Femur on pelvis motion occurs during open chain activity where the femur moves freely on a relatively stationary pelvis. Pelvic on femur motion occurs during closed chain activity where the pelvis moves over relatively stationary femurs. Regardless of which segment is moving, the osteokinematics that occur at the hip joint are as follows referenced from anatomical position. Hip flexion and extension occur in the sagittal plane about a medial-lateral axis of rotation. Average passive range of motion in this plane is 120 degrees of flexion and approximately 20 degrees into extension. Hip abduction and adduction occur in the frontal plane about an anterior-posterior axis with normal ranges being about 40 degrees of abduction and 25 degrees of adduction. Hip internal and external rotation occurs in the transverse plane about a longitudinal axis. Normal internal rotation is about 35 degrees while external rotation reaches approximately 45 degrees.

Open-packed/ Closed-packed position: The closed pack position of the hip joint is full extension, slight abduction and internal rotation. In this stable position, the capsular ligaments are taut and pulling the femoral head tightly into the acetabulum, minimizing the amount of accessory motion that can occur at the joint. This is unique from other joints in the fact that the closed pack position of the hip is not also the most congruent position between the articulating surfaces. The position which provides the most congruency is in 90

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degrees of flexion with abduction and external rotation. It is in this position that a distraction manipulation would be performed, prior to moving into more limited positions of the joint capsule.

Ligaments/function: The three principal ligaments associated with femoroacetabular joint capsule are the iliofemoral and pubofemoral anteriorly, and the ischiofemoral posteriorly. The iliofemoral, also known as the Y-ligament, is the strongest ligament in the hip. All three ligaments contribute fibers to reinforce the joint capsule but also provide resistance to prevent the hip from moving into excessive extension. This ligamentous structure is able to withstand the extension moment created by double limb stance, in which the body’s natural line of gravity is posterior to the axis of the hip joint. Because of this passive tension on the ligaments, erect bipedal posture with a slight hyperextension allows for the body weight to be supported without recruiting muscular activation from the muscles of the hip. This has applicable value as lower extremity weakness may be detected if this “hanging” stance is observed during standing posture analysis.

Primary Movers: The musculature responsible for producing particular movements at the hip is highly dependent on the hip joint position. It is also important to note here that femoroacetabular joint motion may be regarded in the context of either the femur moving on the pelvis or vice-versa. Because of the complexity associated with discussing specific muscle contribution at various hip joint positions, this section will detail the primary and secondary movers of each available motion when starting from anatomical position and assuming femoral-on-pelvic motion. Primary movers are designated based on multiple factors including cross-sectional area of the muscle, line of pull, and moment arm. Stabilizing muscles are helper muscles supporting the primary movers in accomplishing the movement but those which would be unable to complete the motion independently.

The primary movers of the hip into flexion are the iliopsoas, sartorius, rectus femoris, tensor fascia latae, adductor longus and pectineus. Helpers of hip flexion include adductor brevis, gracilis and the anterior fibers of gluteus minimus. The iliopsoas is comprised of two separate muscles. The iliacus originates from the iliac fossa and the lateral edge of the sacrum. The psoas major originates from the transverse processes of T12-L5. These two muscles come together to insert via a common tendon which diverts posteriorly as it crosses the superior pubic ramus to insert at the lesser trochanter of the femur. The large cross sectional area, combined with the increased leverage created by the tendon diversion, make the iliopsoas muscle arguably the most significant of all the hip flexors. Sartorius is a long, thin muscle originating on the ASIS and crosses over the anterior thigh to insert on the medial side of the

Figure 15. Musculature of the femoroacetabular joint

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proximal tibia. Sartorius has a role in hip flexion, as well as external rotation and abduction. Because it crosses the knee as well, it is thought that the role of sartorius in hip flexion may be more impactful when the hip and knee are flexing simultaneously. Rectus femoris attaches to the AIIS and along the superior portion of the acetabulum. Although the rectus femoris is best known as a primary knee extensor, its direct line of pull also allows contribution to hip flexion. Tensor fascia latae (TFL) is a small muscle that originates on the ASIS and anterior part of the iliac crest and extends to join the fibers of the iliotibial tract, which inserts at the lateral condyle of the tibia. The TFL best flexes the hip in conjunction with an abduction motion. Finally, adductor longus and pectineus, while involved with hip flexion are predominantly known for their role in adduction of the hip and so will be discussed further in a later section.

Extension at the hip is accomplished by the primary contributions of gluteus maximus, biceps femoris (long head), semitendinosus, semimembranosus and adductor magnus (posterior head). This motion is helped by the actions of the posterior fibers of gluteus medius along with anterior head of adductor magnus. The gluteus maximus has a vast origination from the posterior sacrum, coccyx, ilium and the sacroiliac and sacrotuberous ligaments. This powerful muscle inserts the superior fibers into the iliotibial tract and the inferior fibers to the gluteal tuberosity of the femur. The gluteus maximus has the largest cross sectional area of all the lower extremity muscles and a considerable moment arm in anatomical position, making it the principal hip extensor muscle. The long head of the biceps femoris, semitendinosus and semimembranosus are lumped together under the name “hamstrings”. This cluster of muscles collectively originate on the ischial tuberosity and cross the knee joint to insert on either the lateral side of the fibular head (biceps femoris) or the medial surface of the tibia (semitendinosus and semimembranosus). The moment arm of the hamstrings group changes as the hip changes position and it never reaches the extent of the moment arm of the gluteus maximus. The hamstrings serve as primary knee flexors and their role in hip extension is greatly affected by the position of the knee. As before, adductor magnus will be discussed in the next paragraph.

The primary movers for hip adduction are adductor longus, adductor brevis, adductor magnus, pectineus and gracilis. Secondary muscles that assist with this motion are biceps femoris (long head), gluteus maximus (inferior fibers) and quadratus femoris. The adductor muscles are located on the medial thigh. The magnus, longus and brevis originate from the body and inferior pubic ramus and attach at various points along the linea aspera on the posterior femur. Adductor magnus is made up of the anterior head, which runs with the other adductor muscles, and the posterior head, which attach to the adductor tubercle on the medial side of the distal femur and acts more as a hip extensor along with the hamstring group. The pectineus is a small muscle from the superior ramus of the pubis to the pectineal line of the femur. Gracilis a two-joint muscle that originates with the rest of the adductor group and courses down to cross the knee and insert medially on the proximal shaft of the tibia.

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Pectineus and gracilis are in the most superficial layer of adductors. The bilateral adductors work together to balance each other out during frontal plane motion in weight bearing. When adductors on the right side are working to bring the femur into adduction, the contralateral adductors are contracting to bring the pelvis into adduction on the femur and stabilize the pelvis over the single limb.

The muscles primarily responsible for abduction at the hip are gluteus medius, gluteus minimus and tensor fasciae latae. These are assisted by actions of the piriformis and sartorius muscles. Gluteus medius is the largest abductor, originating on the lateral surface of the ilium between the anterior and posterior gluteal lines with its distal attachment on the greater trochanter of the femur, giving this muscle the longest of the abductor moment arms. The gluteus medius is divided into three components, each contributing to abduction as well as additional movements of the hip. From a neutral anatomic position, the anterior and middle fibers are active during internal rotation while posterior fibers assist with external rotation and extension. Gluteus minimus is a smaller muscle located deep to the gluteus medius and originates between the anterior and posterior gluteal lines on the ilium to insert at the greater trochanter and the superior portion of the joint capsule. It’s hypothesized that this capsular attachment allows gluteus minimus to retract the capsule to avoid impingement and stabilize the femoral head in the acetabulum. TFL, discussed earlier, also contributes some abductor torque.

The primary movers of external rotation at the hip are gluteus maximus and the group of short lateral rotators, which consists of piriformis, obturator internus, superior gemellus, inferior gemellus and quadratus femoris. Associated helper muscles are the posterior fibers of gluteus medius and minimus, obturator externus, sartorius, and the long head of biceps femoris. The short lateral rotators are positioned perpendicularly to the vertical axis of the femoral shaft, giving them an effective line of pull to execute their primary movement. These muscles also provide a compressive force that gives a great amount of stability to the posterior side of the joint during weight bearing and non-weight bearing activity at the hip. Obturator externus, although considered one of the six “short external rotators” is classified as a secondary muscle due to its slightly posterior line of pull from anatomical position.

While there are no primary movers responsible for internal hip rotation, many muscles previously discussed have anterior segments that work in the horizontal plane to create medial rotation of the hip. These include gluteus minimus, gluteus medius, TFL, adductor longus, adductor brevis and pectineus. The torque produced by these muscles into internal rotation is influenced dramatically with reference to the amount of flexion at the hip. As hip flexion increases, so does the push of these muscles into their actions as internal rotators of the hip.

Gait: In analyzing the hip joint motion during ambulation, it is beneficial to reference a single limb as

Figure 16. Adductor coupling

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it moves through the gait cycle. Magnitude of movements at the hip change quite dramatically based on walking speed, so for the sake of this brief description, joint angles are approximated in relation to average gait speed of 1.4m/s. Starting at the moment of initial heel contact, the hip is in approximately 20 degrees of flexion with the extensor muscles engaged in anticipation of accepting the body weight. It is during this transition from initial contact through loading response that the highest level of activity is seen from the hip extensors to counter the maximal flexion torque created by the combination of the large ground reaction force with a long moment arm. From mid-stance through terminal stance, the hip moves through a neutral position and into roughly 20-30 degrees of extension. The center of mass moves up and over the base of support during this fairly passive weight transfer, involving very little muscle activity in the sagittal plane. The abductors are active in the frontal plane to address the peak adduction force during this phase of single limb stance. At the conclusion of terminal stance is when hip extension demand is at its height, stabilizing the hip joint in preparation of swing phase. The maximal contribution of the hip flexors takes place during pre- and initial swing. Extension torque diminishes as the swinging limb creates a flexion demand, bringing the hip into its most flexed position of 30 degrees during mid-swing. The hamstrings begin to fire during mid-swing and reach their highest activation during terminal swing, slowing the leading leg as it approaches the ground. Contraction of the hip stabilizers occurs as the joint prepares for the succeeding cycle.

Ligaments of the Femoroacetabular Joint Table 7. Ligaments of the femoroacetabular joint

Ligament Attachments Function Other associated joint constraints

Iliofemoral (Y-ligament)

Near the anterior inferior iliac spine and adjacent margin of the acetabulum to the intertrochanteric line of the femur

Stabilizing and strengthening the anterior aspect of the joint capsule

Resist excessive motion into hip extension and external rotation

Pubofemoral Anterior and inferior rim of the acetabulum and adjacent portions of superior pubic ramus and obturator membrane to mix with the Iliofemoral ligament on the intertrochanteric line of the femur

Stabilizing and strengthening the anterior aspect of the joint capsule

Resist excessive motion into hip abduction, extension, and lesser amount into external rotation

Ischiofemoral Posterior, inferior aspect of the acetabulum to the greater trochanter and femoral neck

Stabilizing and strengthening the posterior aspect of the joint capsule

Resist excessive motion into internal rotation, extension, and adduction

Transverse Acetabular Continuation of the acetabular labrum

Join the ends of the acetabular labrum

N/A

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passing over the acetabular notch

Ligamentum Teres (Ligament of the head

of femur)

Both sides of the outer edge of the acetabular notch to fovea of the femur and slight mixing with transverse acetabular ligament

Passageway for the obturator neurovasculature

Taut in semi-flexion and adduction

Common Pathologies of the Femoroacetabular Joint Hip Osteoarthritis (OA):

Hip osteoarthritis is a chronic disease in which the hip joint undergoes progressive degeneration of the articular cartilage in addition to the manifestation of osteophytes. The etiology of this disease can be classified as either primary or secondary. Primary OA has no known cause however common risk factors include increase in age, physical stresses, and genetics. Secondary osteoarthritis occurs when there has been an identifiable disturbance to the joint such as trauma, overuse, or congenital abnormalities altering typical joint biomechanics such as slipped capital femoral epiphysis, leg length differences, avascular necrosis, coxa vara, femoroacetabular impingement, and repetitive dislocation. Common signs and symptoms of osteoarthritis include anterior groin pain, morning stiffness, weakened or atrophied hip musculature, atypical gait pattern, and inflammation. In order to diagnosis hip OA, the American College of Rheumatology has recommended a set of guidelines known as Altman’s Criteria for Hip OA. These include hip pain, less than 115 degrees of hip flexion, and less than 15 degrees of hip internal rotation. In the instance that hip internal rotation is greater than 15 degrees an alternative set of criteria exists which includes painful hip internal rotation, greater than 50 years old, and morning hip stiffness that lasts less than 60 minutes. In order for a patient to be diagnosed while using these sets of criteria, all three factors must be present. With the progression of the disease, many activities of daily living can become challenging including difficulties with squatting, bathing, stair climbing and rising from sitting to standing. Conservative management through physical therapy intervention can be used to address these changes and usually includes patient education, activity modification, manual therapy, therapeutic exercise, and assistive device training. However, if conservative management is not effective hip OA is an indication for a total hip arthroplasty and post-operative rehabilitation.

Hip Fracture: A hip fracture is most commonly a break that occurs at the neck, intertrochanteric line, or

subtrochanteric area of the femur. This fracture can occur in younger populations with an aggressive force of impact through the hip joint while the lower limb is in an extended position. However, this diagnosis is most common in individuals over the age of 60, due to the weakening bones often corresponding with osteoporosis and the increased incidence of falls. Hip fracture is associated with a high rate of mortality in elderly due to secondary complications, such as soft tissue damage and hemorrhage that arise status post injury. When the fracture is intracapsular, the potential damage to circumflex arterial blood supply to the proximal end of the femur increases the risk of avascular necrosis. With the severity of potential associated complications, along with the aging baby boomer

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population, hip fractures are considered to be a geriatric epidemic, costing over $6 billion a year with expected rise in the next few decades.

The mechanism of injury is most often a compression trauma with direct impact to the lateral aspect of the hip. As stated above, this is commonly the result of a fall or high speed impact. Symptoms include pain with weight bearing and lateral rotation of the affected limb.

Treatment options include open reduction internal fixation (ORIF), external fixation, total hip arthroplasty, or hemiarthroplasty. Immediately following surgery, it is important for the clinician to monitor the surgical site and educate patients on the precautions associated with their procedure. During this time, patients are instructed to utilize the appropriate assistive devices to best follow the surgeon’s protocols regarding the need for immobilization and/or weight bearing status. Once able, a treatment program often includes improving range of motion and strength, in conjunction with gait, balance and functional training. Prognosis is poor for the elderly, with a significant decrease in quality of life and functional decline following hip fracture. Hip fracture and its associated complications are indirectly responsible for the greatest number of deaths in the geriatric population.

Femoroacetabular Impingement: Femoroacetabular impingement (FAI) is a diagnosis common in younger patient presenting with hip pain stemming from slight variation of bony morphology. Pincer type FAI is an abnormality of the acetabulum in which there is an over coverage of the femoral head. In this case, extreme hip flexion may

cause the anterior sides of the femoral and neck to push against the anterior acetabular rim and labrum, tearing the cartilage. This form of FAI tends to be more prevalent in women. In Cam FAI, there is an abnormal growth of the head or neck of the femur, which then jams into the acetabulum during extreme flexion leading to shear forces on labrum and diffuse articular damage.

Examination reveals sharp groin pain with flexion and internal rotation of the hip. Patients are usually limited in range for these movements and a FADIR test will be positive for impingement at 90 degrees of flexion with internal rotation. There is posterior and/or lateral hip pain with external rotation or prolonged sitting and stair climbing. Pain or asymmetry is present with the FADER. Anterior-posterior and lateral imaging of the pelvis can be used for further diagnosis by showing a femoral head deformity and the acetabular shape. MRI will highlight labral tears and damage to the cartilage.

Conservative treatment of femoroacetabular impingement may include NSAIDs and limitation of impingement inducing activities, like those involving extreme hip flexion and excessive compression of

Figure 17. Femoroacetabular impingement classifications

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the anterior hip joint. Distractions and inferior/lateral glides can decrease pain and are a practical addition for a self-managed home program. If conservative treatment fails, surgical intervention may be necessary. Prognosis is good for arthroscopic osteoplasty and most patients are able to return to sports and activity with good to excellent results.

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TheKnee:RegionalOverview The knee joint is a modified hinge joint and contains two separate joints within the joint capsule. The first joint is comprised of the articulation between the femoral condyles and the tibial plateau, the tibiofemoral joint. The second joint, the patellofemoral joint, is made between the articulation between the posterior articular surface of the patella and the intercondylar groove of the femur. It acts to increase the moment arm for the quadriceps muscle and increasing the force it is able to exert.

The primary motions of the knee are flexion and extension that are integral to the motion necessary for gait. These motions are controlled by the hamstring and quadriceps muscle groups respectively. During the swing phase of gait the knee flexes in order to allow for toe clearance from the floor. The knee also remains in flexion during the stance phase for shock absorption to minimize wear on soft tissue structures. Although knee flexion is initially passive, due to rapid ankle plantar flexion and hip flexion in terminal stance, the hamstrings act eccentrically to slow the rate of passive knee extension during terminal swing.

The knee is necessary for stability as well as mobility during gait as it resides between the hip and foot and ankle (discussed in other sections), which are very mobile segments of the lower extremity. This stability is reliant upon the soft tissue structures of the knee which include ligaments, tendons, joint capsule, and the meniscus. The knee joint is one of the most commonly injured joints in the body due to its reliance on soft tissue structures for stability. The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) resist anterior and posterior translation, respectively, of the tibia on the femur in closed chain. The medial collateral and lateral collateral ligaments resist valgus and varus stress to the knee joint respectively. All of these ligaments are subject to injury with trauma. Furthermore, unique to the knee joint is the meniscus that increases the congruent surface area between the femoral condyles and the tibial plateau allowing for reduced friction and stability of the joint. This structure is subject to wear and tear with over use as well as damage due to trauma.

Blood supply to the knee comes from the popliteal artery named for the popliteal fossa that it passes through on the posterior aspect of the knee. The popliteal artery emerges from the adductor hiatus on the medial aspect of the thigh before which is the femoral artery that supplies blood to the thigh musculature. From the popliteal artery emerges four branches of genicular arteries; superior medial, superior lateral, inferior medial and inferior lateral. The descending genicular artery branching from the femoral artery

Figure 18. Knee blood supply

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anastomoses along with the genicular arteries to allow adequate blood supply to the knee despite occlusion to flow through the popliteal artery.

The knee is innervated by nerves arising from the lumbar and sacral plexi. These nerves include the femoral, obturator, sciatic and tibial nerves which provide afferent sensory fibers from the joint capsule and supporting structures. Furthermore, these nerves also provide motor and sensory innervation to the musculature that control motion of the knee. In general, each nerve supplies a different compartment of the thigh where the obturator nerve supplies the medial compartment, the femoral nerve supplies the anterior compartment and the sciatic and tibial nerves innervate the posterior compartment. Cutaneous innervation of the skin overlying the joint is performed by the anterior cutaneous branches of the femoral nerve, from the lumbar plexus L2-L3, and the posterior femoral cutaneous nerve, from the sacral plexus S1-S3.

Table 8. Muscles of the knee joint

Muscle Proximal Attachment

Distal Attachment Action Innervation

Quadriceps femoris:

x Rectus Femoris Anterior inferior iliac spine and ilium superior to acetabulum

Via common tendinous (quadriceps tendon) and independent attachments to base of patella; indirectly via patellar ligament to tibial tuberosity

Extend leg at knee joint

Femoral nerve (L2, L3, L4)

x Vastus lateralis Greater trochanter and lateral lip of linea aspera of femur

x Vastus medialis Intertrochanteric line and medial lip of linea aspera of femur

x Vastus intermedius

Anterior and lateral surfaces of shaft of femur

Hamstrings:

x Semitendinosus Ishchial tuberosity

Medial surface of superior part of tibia

Extend thigh; flex leg and rotate it medially when knee is flexed; when thigh and leg are flexed, these muscles

Tibial division of sciatic nerve part of tibia (L5, S1, S2)

x Semimembranosus Posterior part of medial condyle of tibia; reflected attachment forms oblique popliteal ligament (to

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lateral femoral condyle)

can extend trunk

x Biceps femoris Long head: ischial tuberosity Short head: linea aspera and lateral supracondylar line of femur

Lateral side of head of fibula; tendon is split at this site by fibular collateral ligament of knee

Flexes leg and rotates it laterally when knee is flexed; extends thigh

Long head: tibial division of sciatic nerve (L5, S1, S2) Short head: common fibular division of sciatic nerve (L5, S1, S2)

Sartorius Anterior superior iliac spine

Medial aspect of proximal tibia

Flexion and medial rotation of knee

Femoral nerve (L2, L3, L4)

Gracilis Body of the pubis and inferior pubic ramus

Medial surface of tibia distal to condyle, proximal to insertion of semitendinosus, lateral to insertion of sartorius

Flexion and medial rotation of knee

Obturator nerve (L2, L3, L4)

Gastrocnemius Posterior aspect of femoral condyles and joint capsule

Posterior calcaneal surface

Flexion of knee

Tibial nerve (S1, S2)

Plantaris Lateral supracondylar line

Posterior calcaneal surface

Flexion of knee

Tibial nerve (L4, L5, S1, S2)

Popliteus Lateral femoral condyle and oblique popliteal ligament

Soleal line of tibia NWB: medial rotation of tibia and knee flexion WB: lateral rotation of femur and knee flexion

Tibial nerve (L4, L5, S1)

Tensor fasciae latae Anterior superior illiac spine and external lip iliac crest

Iliotibial tract Assists in maintaining knee extension

Superior gluteal nerve (L4, L5, S1)

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TibiofemoralJoint Overview The tibiofemoral joint is formed by the articulation of the proximal tibia and distal femur. The joint is contained within a thick fibrous capsule that provides lubrication and structure. Much of the stability of the joint comes from the soft tissue structures that will be discussed in later sections.

The tibiofemoral joint is a synovial classification modified hinge joint with 2 degrees of freedom with motion available in the sagittal and transverse planes. The primary motion of this joint is for flexion and extension during gait and other functional activities. However, due to the orientation of this joint, rotation also occurs. Normal range of motion in the healthy adult knee can range between 130-150 degrees of flexion and between 5-10 degrees of extension past 0 degrees. Rotation of this joint varies by the amount of flexion/extension. At 90 degrees of tibiofemoral flexion, 40-45 degrees of rotation is available.

Please refer to The Knee: Regional Overview in the previous section for neurovascular supply of the tibiofemoral joint as it is shared with the patellofemoral joint, within the same joint capsule.

Tissue Layers (Superficial to Deep) x Integumentary

o Epidermis o Dermis o Hypodermis

x Subcutaneous o Superficial Fascia o Adipose tissue

x Deep Fascia of the leg/ Fascia lata o Iliotibial tract o Intermuscular septa x3 o Patellar Retinaculum (Medial

and Lateral) x Muscles and Tendons

o See table below x Bursa / Fat Pads

o Infrapatellar Fat Pad o Prepatellar o Infrapatellar o Deep Infrapatellar o Suprapatellar o Subpopliteal o Pes Anserine

x Neuro Vasculature o Nerves

� Tibial N. � Sural N. � Common Fibular N. � Medial input from

obturator & saphenous NN.

o Arteries: Genicular anastomoses

� Femoral A. � Popliteal A. � Anterior/ posterior

recurrent A. x Extracapsular and capsular ligaments

o MCL (superficial and deep) o LCL o Joint capsule o ACL o PCL o Menisci

x Synovial Joint

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o Joint Capsule o Synovial membrane o Joint space

o Articular Cartilage o Osseous joint surface

Joint Motions and Associated Muscles Table 9. Motions and muscles of the knee joint

Motion Primary Mover Stabilizing and Helping Synergists

Extension Quadriceps Femoris Popliteus

Flexion Hamstring (Semitendinosus, Semimembranosus, Biceps Femoris)

Gastrocnemius, Popliteus

Internal Rotation

Flexed knee: Semimembranosis and Semitendinosis. Knee extended: Popliteus

Sartortius, Gracilis

External Rotation

Biceps femoris N/A

Joint Configuration and Planes of Motion The tibiofemoral joint is a bi-condyloid joint that allows for flexion and extension in the sagittal plane and internal and external rotation in the transverse plane. The joint itself has medial and lateral compartments each of which contain a femoral condyle, meniscus and tibial plateau. As the name implies, the tibiofemoral joint is made from the articulation of the femur and tibia.

The distal end of the femur is comprised of medial and lateral femoral condyles containing the articular cartilage that contacts the articular cartilage of the proximal tibia, known as the tibial plateau. The femur itself is not anatomically vertical, rather it lies on an oblique angle from the hip joint to the knee. This angle necessitates the medial femoral condyle to protrude more inferiorly than the lateral condyle for maximal congruency of the joint. Conversely, the lateral condyle protrudes more anterior. Between the two condyles is the intercondylar notch where the cruciate ligaments cross. The anterior-superior aspect of the condyles is the patellar groove containing

the articular cartilage that contacts the patella (to be discussed later). Superior to the femoral condyles are medial and lateral epicondyles that serve as attachment points for the collateral ligaments.

Figure 19. Tibial plateau and femoral condyles

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The articular surfaces of the proximal tibia lie on a structure known as the tibial plateau. These surfaces are quite shallow when compared to their femoral counterparts, necessitating the meniscus to increase congruence between the articular surfaces. The medial and lateral tibial plateaus are separated by intercondylar tubercles. Just inferior to the tibial plateau is the tibial tuberosity that serves as the attachment point for the patellar tendon and the quadriceps femoris muscle group.

As previously mentioned, the tibiofemoral joint relies heavily on soft tissue structures for stability. There are four primary ligaments that act to support the structure of the knee joint. Two paired collateral ligaments lie on the medial and lateral aspects of the knee coursing from distal femur to proximal tibia. Within the joint capsule are two cruciate ligaments that course from the tibial plateau to the medial aspects of the femoral condyles.

The paired collateral ligaments, medial collateral (MCL) and lateral collateral (LCL) serve to protect the knee from excessive coronal plane motion. The MCL is a relatively wide and thin structure on the medial aspect of the knee spanning from the medial femoral epicondyle to the medial surface of the proximal tibia and resists valgus forces. Due to the thin, paper-like structure of this ligament, it is commonly injured and will be discussed further in subsequent sections. The LCL is a narrower, cord-like structure on the lateral aspect of the knee coursing from the lateral epicondyle of the femur to the head of the fibula resisting varus forces.

More internal to the joint are two cruciate ligaments, anterior cruciate (ACL) and posterior cruciate (PCL), which cross each other and are named based on their attachment to the tibia. These ligaments primarily resist sagittal plane motion, however, due to the obliquity of their course through the knee, they resist almost all motions of the knee. The ACL courses from the medial part of the anterior intercondylar area of the tibia to the posterior part of the medial surface of the lateral condyle of the femur. This ligament has two bundles, anterior-medial and posterior-lateral, which are named for their relative attachment points on the tibia. The anterior-medial bundle The ACL acts to resist tibiofemoral extension as well as anterior displacement of the tibia on the femur or posterior glide of the femur on the tibia. The PCL runs from the posterior intercondylar area of the tibia to the lateral surface of the medial condyle of the femur. This ligament acts to resist posterior translation of the tibia on the femur or anterior translation of the femur on the tibia. All of the ligaments of the knee are tight in extension.

Figure 20. Cruciate ligaments

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The meniscus is a supporting structure that is unique to the tibiofemoral joint. It is a fibrocartilaginous structure on the tibial plateau that allows for shock absorption, lubrication, and increased congruency of the joint. The meniscus itself is composed of medial and lateral portions that are shaped differently in order to accommodate the dissimilar shapes of the medial and lateral femoral condyles. Comparatively, the medial meniscus is more oval shaped while the lateral meniscus is more circular shaped. Each meniscus is anchored to the tibial intercondylar region by way of their anterior and posterior horns. They are further anchored to the joint capsule via the coronary ligaments. Finally, the two menisci are connected together with a transverse ligament on the anterior side.

The meniscus has three vascular zones, from superficial to deep they are red-red, red-white and white-white. These zones correlate with the amount of blood supply that is received by that region. The most superficial zone, red-red, has the most blood supply, where the deep zone, white-white, has no vascular supply. This has implications on the healing of meniscal injuries, to be discussed later.

The tibiofemoral joint would not be complete without the joint capsule. The capsule is fairly lax to allow for the necessary amount of range of motion. The capsule has two layers that differ functionally. The outer layer is fibrous and gives support to the joint and the inner layer is a synovial membrane, as this joint is a synovial joint, this membrane acts to produce the lubricating synovial encased within the joint itself.

Biomechanics and Arthrokinematics The tibiofemoral joint allows for two degrees of freedom. In the sagittal plane, flexion and

extension occur about the medio-lateral axis that runs through the medial and lateral femoral condyles. The greatest range of motion for this joint occurs on this plane and is therefore the most important for function, namely gait. In the transverse plane, internal and external rotation occur about the longitudinal axis. There is limited range of motion available on this plane. The motion of this joint can be discussed in either closed chain, where the femur moves on a stationary tibia, or in open chain, where the tibial moves on a stationary femur. Closed chain motion is considered more functional when discussing the lower extremity as most functional activities are performed in weight bearing.

Tibiofemoral flexion occurs when the angle between the tibia and femur is decreased when measured from the posterior direction. In order for this motion to occur, in closed chain, the convex articular surface of the distal femur rolls posterior upon the concave articular surface of the proximal tibia. Therefore, in order to maintain congruency of the joint and allow for the greatest range of motion,

Figure 21. Tibiofemoral soft tissue structures

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the femur must also glide anterior on the tibia. Conversely, in open chain, the concave surface of the tibia rolls posterior on the convex condyles of the femur and also must glide posterior to maintain congruency.

The hamstring muscle group, containing semitendinosus, semimembranosus and biceps femoris, are the primary movers for tibiofemoral flexion. This muscle group resides on the posterior thigh and is innervated by the sciatic nerve. The semitendinosus and semimembranosus occupy the medial hamstring and the biceps femoris occupies the lateral hamstring. As these muscles share their proximal

attachment on the ischial tuberosity, therefore crossing the hip joint as well, this indicates that they also function in hip extension (see femoroacetabular joint). The distal attachment of the semitendinosus and semimembranosus is on the medial aspect of the proximal tibia where the distal attachment for the biceps femoris is on the fibular head oriented laterally to the proximal tibia (details in table 1).

Extension of the tibiofemoral joint occurs when the angle between the femur and tibia is increased. In closed chain, the convex femur rolls

anteriorly and glides posteriorly upon the concave tibia (seen in the right picture in Figure 22). The opposite is true in open chain where the concave tibia rolls anterior and glides anteriorly on the convex femur. In both of these cases, the meniscus is pulled anteriorly by the quadriceps muscle.

The primary mover for extension of the tibiofemoral joint is the quadriceps femoris group containing the vastus muscles (vastus lateralis, vastus intermedius and vastus medialis) and the rectus femoris muscle. These muscles have variable proximal attachments, however, they share their distal attachment at the quadriceps tendon at the base of the patella and ultimately the tibial tuberosity via the patellar tendon. The rectus femoris muscle originates at the anterior inferior iliac spine (AIIS) and courses on the middle anterior superficial thigh. The vastus lateralis originates from the greater trochanter and linea aspera of the femur and course along the lateral thigh. It is the vastus lateralis that has the largest cross-sectional area of the knee extensors, making it the primary mover in this direction. The vastus intermedius lies deep to the rectus femoris and originates from the anterior and lateral shaft of the femur. Finally, the vastus medialis originates from the intertrochanteric line and linea aspera and courses along the medial thigh. Due to their positions on the thigh, these muscles have variable lines of pull acting at the tibiofemoral joint, however, when acting together, the summed force creates the

Figure 22. Tibiofemoral arthrokinematics

Figure 23. Quadriceps pull on patella

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optimal line of pull for knee extension. The vastus lateralis and medialis also counteract each other to stabilize the patella (discussed in detail later).

Axial rotation of the tibiofemoral joint involves primarily spin at the joint surface. As the joint is most congruent in extension, due to the stability provided by the soft tissue structures mentioned earlier, very little, if any rotation occurs when the knee is fully extended. More rotation is available as the tibiofemoral joint is flexed towards 90 degrees. It is at 90 degrees that greatest amount of rotation is available.

Primary movers for axial rotation are the hamstrings. Although their proximal attachments are on the ischial tuberosity, giving them function at the hip as well, internal rotation is primarily provided by the semitendinosus and semimembranosus when the knee is flexed. When the knee is extended, however, the popliteus acts to internally rotate the knee to unlock the knee joint and allow flexion to occur. As its distal attachment is on the lateral side of the tibia, the biceps femoris muscle acts to externally rotate the tibiofemoral joint. The short head of the biceps femoris is in the most optimal position for this due to its proximal attachment on the posterior femur itself. The proximal attachment of the long head arises from the ischial tuberosity allowing it to function as a hip extensor as well.

Much of the orientation and function of the knee joint is due to the shape of the femoral condyles. Although flexion and extension occur about a medial-lateral axis, the axis is not fixed because the condyles of the femur have an eccentric curvature that causes the axis of rotation to migrate, known as the evolute. Functionally the evolute causes the moment arm of the quadriceps and hamstrings to change with varying degrees of flexion/extension. Another consequence of the shape of the condyles is the screw-home mechanism. This is the conjunct motion of external rotation of the tibia on the femur during tibiofemoral extension (roughly the last 30 degrees). This motion allows for maximal bony congruency of the tibiofemoral joint when the knee is extended.

Medial and lateral rotation, also known as axial rotation, are also available occurring on the transverse plane about the longitudinal axis. The amount of rotation at this joint is variable depending on the degree of knee flexion. With the knee flexed to 90 degrees, roughly 40-45 degrees of rotation is available. There is typically twice as much external rotation as internal rotation.

Mobilization of the tibiofemoral joint is an effective intervention to increase the range of motion when range is limited. Considering the arthrokinematics is an effective way to remember which glides to perform and improve each motion. To improve tibiofemoral flexion, perform an anterior to posterior

Figure 24. Evolute

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glide mobilization of the tibia on the femur. Conversely, to improve tibiofemoral extension, performing a posterior to anterior glide of the tibia on the femur is effective.

Ligaments of the Tibiofemoral Joint Table 10. Ligaments of the tibiofemoral joint

Ligament Proximal Attachment

Distal Attachment Function Other associated joint constraints

Anterior Cruciate Ligament

medial part of the anterior intercodylar area

posterior part of medial surface of lateral condyle of femur

prevent posterior displacement of femur on tibia and hyperextension of knee

Also resists rotation RA

Posterior Cruciate Ligament

posterior intercondylar area of tibia

lateral surface of medial condyle of femur

prevents anterior displacement of the femur on the tibia and hyperflexion of the knee

Also resistes rotation

Medial Collateral Ligament

medial femoral epicondyle

Medial condyle and shaft of tibia

Stabilizes medial aspect of joint

Prevents genu valgum, abduction of knee

Lateral Collateral Ligament

Lateral femoral epicondyle

Head of fibula Stabilizes lateral aspect of joint

Resists genu varum, adduction of knee

Common Pathologies of Tibiofemoral Joint ACL Tear/Rupture:

The ACL is the most frequently ruptured ligament of the knee. Injury to this ligament typically occurs with trauma. Due to the oblique angle by which the ACL courses through the knee, it is at high risk for injury because it resists many different directions of movement. Injury to the ACL leads to impaired joint mechanics and stability. A common mechanism of injury is rupture or tear during rapid deceleration, cutting, or landing from a jump. Others can include severe rotation of the knee with the foot planted and severe tibiofemoral hyperextension. The anterior drawer test is specific for testing the amount of laxity in the ACL. Although conservative treatment can be effective, common intervention for ACL injury is reconstructive surgery in which the surgeon grafts a new ligament from either the hamstring or patellar ligament of the patient.

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MCL Tear: Due to its broad and thin structure, the MCL is another ligament that is commonly injured in the

knee. Injury to this ligament commonly occurs with ACL injuries. Like the ACL, trauma is typically involved with MCL tears. A common mechanism of injury is contact to the lateral side and placing a valgus force on the knee with the foot planted. Also, damage can occur with severe hyperextension of the knee. Injury to this ligament can be detected with valgus force to the knee joint when compared bilaterally.

Meniscal Tear: The meniscus is another commonly injured

structure of the tibiofemoral joint. Approximately 49% of sports related ACL tears also involve a tear to the meniscus. There are four different types of meniscal tears including bucket handle, flap, transverse, and horn tear. Of these, the bucket handle tear has the worst prognosis as it is completely within the avascular zone. Treatment of a meniscal tear is difficult as much of the structure is avascular. With a peripheral injury, surgical repair can be successful. However, if concurrent with an ACL injury, surgery to the meniscus can have implications on the healing of the ACL because with a post meniscal repair is necessary to remain non weight bearing for a period of time. Apley’s and McMurray tests are specific for a meniscal injury.

Figure 25. Meniscal instability

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PatellofemoralJoint Overview

The patellofemoral joint is characterized by the articulation of the patella and the intercondylar (trochlear) groove of the femur. The function of the patella is to increase the torque output created by the quadriceps femoris muscles at the knee joint and to decrease friction forces in the anterior knee that are associated with knee flexion and extension. The patella is an inverted-triangle shaped sesamoid bone that is imbedded within the quadriceps femoris tendon. Superiorly, at its base, is the insertion of the quadriceps tendon, and inferiorly, at its apex, is the proximal attachment of the patellar ligament which attaches distally to the tibial tuberosity. The patella has 2 main facets on its posterior surface which is covered in smooth articular cartilage (thickest in the body). These facets interact with their corresponding medial and lateral femoral condyle to promote proper patellar tracking as it moves

superiorly and inferiorly in relation the femur, demonstrated in Figure 26. It is important to note that the patella remains relatively motionless in relation to the tibia and they act as a unit during flexion and extension due to their solid attachment via the patellar ligament.

The patellofemoral joint is part of the greater knee joint complex sharing its synovial structure and neurovascular supply with the tibiofibular joint (see in The Knee: Regional Overview). It is one of the most incongruent joints in the body due to the nature of its function and

mobility. Due to this incongruence, the patella is dependent on local structures and forces to provide stability. The stability is provided by both active and passive stabilization, and joint surface interaction. The patellofemoral joint is an arthrodial/plane joint which functions in a multiplanar space and is non-axial. Movement at this joint is guided by the intercondylar groove of the femur. This joint is often compared to a train on the track, with the patella moving within the intercondylar groove. The patella is more mobile when restricted only by passive restraints such as the surrounding retinacular fibers and the joint capsule. However, during active range of motion the patella receives dynamic stability from the quadriceps femoris approximating it into the trochlear groove. This increases stability while the patella glides superiorly and inferiorly and limits its mobility especially, in side to side motion. Major deviations from its normal tracking motion can and often do lead to patellofemoral joint pathology.

Tissue Layers (Superficial to Deep) x Integumentary

o Epidermis o Dermis o Hypodermis

x Subcutaneous o Superficial Fascia o Adipose tissue

x Deep Fascia of the leg/ Fascia lata

Figure 26. Patellar motion

46

o Iliotibial tract o Intermuscular septa x3 o Patellar Retinaculum (Medial

and Lateral) x Muscles and Tendons

o See table below x Bursa / Fat Pads

o Infrapatellar Fat Pad o Prepatellar o Infrapatellar o Deep Infrapatellar o Suprapatellar o Subpopliteal o Pes Anserine

x Neuro Vasculature o Nerves

� Tibial N. � Sural N. � Common Fibular N. � Medial input from

obturator & saphenous NN.

o Arteries: Genicular anastomoses

� Femoral A. � Popliteal A. � Anterior/ posterior

recurrent A. x Extracapsular and capsular ligaments

o MCL (superficial and deep) o LCL o Joint capsule o ACL o PCL o Menisci

x Synovial Joint o Joint Capsule o Synovial membrane o Joint space o Articular Cartilage o Osseous joint surface

Patellofemoral Joint Motions and Associated Muscles Table 11. Patellofemoral muscles and motions

Motion Primary Mover Stabilizing and Helping Synergists

Superior glide of the patella on a fixed femur (associated with knee extension) OKC

Quadriceps femoris: Rectus femoris, Vastus lateralis, Vastus medialis, Vastus intermedius

Tensor fasciae latae via the Iliotibial band

Inferior glide of the patella on a fixed femur (associated with knee flexion) OKC

Quadriceps femoris Hamstrings: Biceps femoris, Semitendinosus, Semimembranosus

Superior glide of the femur on a fixed patella CKC

Quadriceps femoris Gluteus maximus, Gluteus medius, Gluteus minimus

Inferior glide of the femur on a fixed patella CKC

Quadriceps femoris Gluteus maximus, Gluteus medius, Gluteus minimus

Joint Configuration and Planes of Motion The medial and lateral femoral condyles are separated by the anterior intercondylar groove that

articulates with the posterior aspect of the patella. The intercondylar groove is concave from side to side and slightly convex in the sagittal plane. The intercondylar groove of the femur includes a medial and

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lateral facet that is positioned more proximally and anteriorly. The lateral facet is characterized by a steeper slope that aids in patellar stability within the intercondylar groove.

The patella is the largest sesamoid bone in the body. It is located within the quadriceps femoris tendon and is relatively flat and triangular in shape. The apex (point) of the triangle is pointed inferiorly and the base superiorly. The quadriceps tendon inserts at its base and is continued inferiorly at the apex by the patellar ligament as it courses to its distal attachment at the tibial tuberosity. Anteriorly, the broad surface of the patella is convex and boney, while posteriorly there are five facets: superior, inferior, medial, lateral, and odd which are covered in thick hyaline cartilage. During the movement from flexion to extension, different facets articulate with the femoral condyles as they glide over the femur.

The patellofemoral joint is a sliding/plane joint which functions in gliding, tilting, and rotating motions without a permanent axis of motion. However there are motions defined for this joint as it tracks on the femur. Patellar flexion is when the patella tracks down the femoral condyles while patellar extensions is tracking more proximally. Rotation about the longitudinal axis is termed medial or lateral patellar tilt and is named for the direction in which the anterior surface of the patella is moving. Finally, there is medial and lateral shift and rotation which occurs around an anterior posterior axis. The patellofemoral joint relies upon the congruence between the patellar facets and the trochlear groove/ femoral condyles to provide stability both statically and dynamically. In addition, compressive forces from the contracting quadriceps femoris muscle help approximate the patella into the intercondylar groove and passive structures of the medial and lateral retinaculum passively restrict patellar motion. Due to its design the patellofemoral joint is inherently unstable, much like the tibiofemoral joint, and requires ligamentous and muscular support to limit excessive range of motion.

Biomechanics and Arthrokinematics of the Patellofemoral Joint Flexion and extension of the knee joint are the primary motions of the tibiofemoral joint,

however, the patellofemoral joint is directly affected by these motions. When considering the patellofemoral joint, it is important to remember that the inferior pole of the patella is directly connected to the tibia via the patellar ligament. The tibia and patella therefore move together as a unit and the patella moves in relation to the femur below it or vice versa. During open chain knee flexion, a sliding motion occurs between the patella and the fixed intercondylar groove of the femur. During closed chain knee flexion, the intercondylar groove of the femur slides on the fixed patella, which is held in place by the patellar tendon.

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Functional Role of the Patella:

The patella is a spacer between the femur and the quadriceps muscle and increases the moment arm of the knee extensor mechanism. The internal moment arm of the knee extensor is the distance between medial-lateral axis of rotation (evolute) and the line of force of the quadriceps muscle. Torque is the product of this force and the moment arm. Therefore, the patella increases knee extension moment. This torque varies due to three factors which affect the length of the knee extensor moment arm. These factors include: the shape and position of the patella, shape of the distal femur and depth of the intercondylar groove, and the “evolute” as discussed with the tibiofemoral

joint configuration section. Most researchers agree that the knee extension moment arm is highest between 20-60 degrees of knee flexion. This explains why knee extension torque is highest in this range of motion. In addition, the patella reduces the friction between the femoral condyles and the hyaline cartilage covering the posterior surface of the patella. The ability of the patella to perform its functions without restricting knee motion depends on its mobility.

At full extension, the patella is typically situated slightly lateral in the femoral sulcus above the femoral condyles. As knee flexion is initiated, the patella shifts medially as it is pushed by the larger lateral femoral condyle and as the tibia medially rotates with unlocking of the knee. As knee flexion proceeds past 30 degrees, the patella may shift slightly lateral or remain fairly stable due to the patella being firmly engaged within the femoral condyles. Different degrees of knee flexion correspond with different points of articulation at the patellofemoral joint. At 135 degrees of flexion the patella contacts the femur near its superior pole (picture A in Figure 28) and rests in the intercondylar notch below the trochlear groove. In this position the odd facet and the lateral fact both contact the femur. As the knee extends to 90 degrees of flexion the point of contact moves medially and inferiorly on the patella (Figure B in Figure 28). As the patella proceeds from 90 to 60 degrees the patella moves into the condylar groove and has the greatest area of contact with the femur. However this only amounts to a third of the

Figure 27. Patellar moment arm

Figure 28. Patella and femoral contact

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total surface of the patella in contact. This can lead to large compressive forces at the joint. As the knee continues to extend to 60 degrees the contact area is located centrally (Figure E), and finally in the last 20-30 degrees, the main point of contact is located medially on the inferior pole of the patella. When the knee is extended, the patella rests above the groove against the suprapatellar fat pad. In this position the patella loses its mechanical engagement with the femur and can be moved freely without active contraction of the quadriceps femoris.

Joint Compression/ Stability and Patellar Tracking:

When the force vectors transmitted through the quadriceps tendon and patellar ligament within the extensor mechanism are added, they form a sizable joint compression force (see Figure). Although these forces are produced by the pull of the quadriceps, their amplitude is strongly related to the degree of knee flexion. As a result, the patellofemoral joint is constantly exposed to high levels of compression between its components. A few examples include 1.3 times body weight during walking, 2.6 times body weight during straight leg raise, 3.3 times body weight during stair climbing, 7.8 times body weight during deep knee bends and 14 times body weight during power lifting. To better understand this stress you must consider that both the compressive forces and contact area increase with knee flexion maxing out somewhere between 60 and 90 degrees of flexion. However, this relation is disproportionate and the compressive forces increase more in relation to contact area which leads to a peak in compressive stress (force/area). However in normal knee mechanics this inequity is not enough to create pathological cartilage damage as long as the patella is tracking properly. This compressive force is paramount in the stability of the patellofemoral joint as they retract the patella deep into the trochlear groove which increases both force and form closure effects to prevent dislocation of the patella.

Factors Associated with PF Joint Compression Stress Force of quadriceps muscle Knee flexion angle Contact area

Figure 29. Compression forces on the patella

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Among the most important factors affecting patellar tracking is the magnitude and direction of the overlying quadriceps muscle. As the quadriceps contracts, it doesn’t only pull the patella superiorly, but also slightly lateral and posterior. This is due in part to the larger cross sectional area of the vastus lateralis muscle. A measure of the superior lateral line of pull of the quadriceps is called the Q angle (quadriceps angle). This angle is measured by drawing a line between the ASIS and the center of the

patella and a second line between the center of the patella and the tibial tuberosity. The resulting angle superior to where these lines intersect is the Q angle (see Figure 30). The average angle in the healthy adult population is 13-15 degrees with females having roughly 4 more degrees. While the Q angle is popular clinically when evaluating patients with lateral patellar tracking and anterior knee pain, it has been criticized for its low association with pathology at the patellofemoral joint. There are many factors that naturally oppose the lateral pull of the quadriceps in relation to the patellofemoral joint. These factors are necessary to promote optimal tracking. Optimal tracking is defined as the movement between the patella and femur across the greatest possible area of articular surface with the least possible stress (Neuman, 2010). The literature describes both local and global factors that affect tracking. Local factors are those which act directly on the joint and global factors are related to the bones and joints of the lower extremity.

Local factors:

The Q angle represents the net lateral pull of the quadriceps creating a bowstring force at the patella. A large bow stringing force tends to pull the patella laterally over a region of reduced contact area. As seen in the Figure 31, increased tension of the IT band can create tension on the lateral retinaculum of the patella and add to the natural lateral pull of the patella. Tight or adhered lateral patellar retinacular fibers can increase this lateral pull as well. The main structure designed to oppose this lateral bowstringing is the steep lateral facet of the intercondylar groove of the femur. This steep slope naturally blocks the lateral progression of the patella as is tracks superiorly and inferiorly in the groove. The vastus medialis oblique muscle also is naturally oriented to help balance the lateral pull of the quadriceps as a whole. Although the VMO is in alignment to oppose the vastus lateralis, clinically you cannot differentiate their activation with

Figure 30. Q-angle

Figure 31. Forces acting on the patella

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exercises due to the common innervation. Finally, the medial patellar retinacular fibers limit the lateral tracking of the patella. The medial patellofemoral ligament is the thickest part of this structure and is attached between the medial patella and the femur, tibia, medial meniscus, and VMO. This ligament is often ruptured with complete lateral patellar dislocations. The MPFL is most taught at 20 degrees of flexion.

Global Factors:

The lateral bowstringing force is strongly influenced by the bony alignment of the lower extremity. As a general rule, factors that resist excessive valgus forces and extremes of axial rotation favor optimal tracking of the patellofemoral joint. These factors are global factors because they are associated with joints above and below the knee. Excessive genu valgum increases the Q angle and lateral bowstringing. This can occur due to laxity of the MCL of the knee, weak hip external rotator/ abductor

musculature, coxa vara, femoral anteversion, femoral or tibial torsion, and over pronation of the subtalar joint in weight bearing (See Figure 32). These factors increase external rotation at the knee and/or excessive genu valgum and can lead to joint dysfunction (see Table 12). Excessive knee rotation is often found in conjunction genu valgum, and can lead to an increase Q angle and lateral bowstringing forces. It is important to note that in weight bearing external rotation of the knee is expresses as internal rotation of a mobile femur on a fixed tibia. As a clinician, dynamical tests of hip abductor and external rotator strength, such as the single leg squat, can give a good look at the neuromuscular control and strength of the hip musculature.

Figure 32. Bowstringing

Table 12. Patellar maltracking

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Ligaments of Patellofemoral Joint Table 13. Ligaments of the patellofemoral joint

Ligament Attachments Function Other associated joint constraints

Medial patellar retinacular fibers & medial patellofemoral ligament (MPFL)

Extensions of connective tissue over the vastus lateralis, vastus medialis and iliotibial band that connect to the femur, tibia, patella, quadriceps and patellar tendons, collateral ligaments and menisci

Connective tissue reinforcement for the anterior and medial knee capsule, and aiding in passive patellar stability

Taut in the last 20 degrees of extension to limit lateral patellar motion on the femur

Lateral patellar retinacular fibers

Extensions of connective tissue over the vastus lateralis, vastus medialis and iliotibial band that connect to the femur, tibia, patella, quadriceps and patellar tendons, collateral ligaments and menisci

Connective tissue reinforcement for the anterior and medial knee capsule, and aiding in passive patellar stability

Laterally directed force on the patella; Resists a medial glide of the patella

Patellar Ligament Apex of the patella (inferior) to the tibial tuberosity

Connective tissue reinforcement for the anterior knee capsule; Guides the motions of the patella during open chain knee flexion by attaching the patella to the tibial tuberosity; Included in the knee extensor mechanism; Transmits forces up and down the lower extremity; Transmits axial rotation of the tibia as transmitted

Holds the patella in place during closed chain knee flexion through the pull on the patellar tendon

Iliotibial Band Blending of the tensor fasciae latae and gluteus maximus muscles at the outer lip of the anterior border of the ilium and anterior superior iliac spine to the lateral tibial condyle at Gerdy’s tubercle

Connective tissue reinforcement of the lateral knee capsule; Creates an extension demand at the knee with the help of gluteus maximus and tensor fasciae latae

Restrains patella laterally; Resists medial glide of the patella

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Common Pathologies of the Patellofemoral Joint Patellofemoral Pain Syndrome (PFPS):

PFPS is one of the most common dysfunctions of the knee joint. One in four people will experience anterior knee pain with a higher incidence in athletes. PFPS is defined as “pain, inflammation, imbalance and instability of any component of the extensor mechanism of the knee from congenital, traumatic, or mechanical stress” (James, 2015). All of the factors above that are associated with patellar maltracking can predispose a patient to PFPS, but is no clear consensus on a definitive cause. The typical patient demographic for this disorder is the young female athlete. They are more likely to have static and dynamic alignment problems than males. The pain is usually of insidious onset and increases with activity. General guidelines for treatment are to assess above and below the knee at the hip and foot for abnormal biomechanics or other impairments. Research shows that strengthening the hip is often the best course of action if hip abductor and external rotator weakness is present. There is no research showing specific VMO strengthening exercises to be more effective than general quad strengthening. Knee taping and foot orthotics may also help the patient compensate until impairments have been resolved. It also is beneficial to have patients avoid or modify exacerbating factors until remediation techniques have allowed for a reduction in symptoms.

Patellar Dislocation: The patella dislocates laterally in 90% of incidents. With patellar hypermobility, lax medial

structures, and a flattened lateral femoral condyle, the risk of lateral patellar subluxation or dislocation increases. This dislocation typically occurs at 20-30 degrees of flexion before the patella is fully seated into the intercondylar groove. The steep lateral facet of this groove provides 55% of the stability that resists lateral patellar tracking. As a result, if this structure is not as pronounced, lateral dislocations become more likely. Patella alta also increases the likelihood of dislocation due to the delayed initiation of contact with the intercondylar groove as compression forces increase with knee flexion. This paired with the bowstringing effect of the quadriceps results in a net lateral line of pull that can cause the patella to dislocate. Females are more prone to this than males, and the occurrence of recurrent lateral dislocations of the patella in females is

approximately 58% of all joint dislocations and is nearly 14% in men. Patellar dislocation is treated very similarly to patellofemoral pain syndrome with hip and quad strengthening and ROM. If instability persists, braces can be used.

Figure 33. Patellar dislocation

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FootandAnkleOverview The foot and ankle complex is composed of 28 bones and 25 component joints. In general, this

complex can be thought of as a single functional unit when considering its role in both locomotion and stabilization. As a functional unit, the foot and ankle are involved primarily in stance and gait. During these activities, proper arthrokinematics of the foot and ankle influence the ability of the lower limb to attenuate forces. When working correctly, the foot and ankle help to allow forces to be distributed in such a way so as to avoid injurious impact or misalignment of the foot, ankle, knee, hip, and essentially all joints up the kinetic chain.

The ankle joint is composed of the proximal tibiofibular joint, distal tibiofibular joint, and the talocrural joint. Importantly, the talocrural joint is the primary provider for functional mobility and stability at the ankle while the proximal and distal tibiofibular joints function to permit and control motion occurring at that joint. The foot consists of many joints between the calcaneus, navicular, cuboid, cuneiform, tarsal, metatarsal, and phalangeal bones, all of which will be discussed in more detail in the following sections of this guide.

The foot can be broken down into three regions: the rearfoot, midfoot, and forefoot. These regions of the foot work conjunctly with one another and with the ankle to produce and transmit the motions of pronation and supination. Pronation is the conjunct motion of foot abduction, dorsiflexion, and eversion. Conversely, foot supination includes the conjunct motions of foot adduction, plantarflexion, and inversion. Supination and pronation are uniplanar movements. The motions occur in a single plane that is oriented obliquely to all three planes of the body. Therefore, though motion occurs in all planes, it is uniplanar in the sense that it is occurring in this single obliquely oriented plane. In order for the foot to fully pronate and supinate, all regions of the foot and ankle must work together. The motion is generated predominantly at the talocrural and subtalar joints. Each joint’s specific function and contribution will be discussed in upcoming sections.

Along with the complex motions produced at the foot and ankle, this region plays a pivotal role in stabilization within the context of motion of the lower extremities during gait; a role achieved through bony and soft tissue structures. While some joints within the foot contribute to foot pronation and supination, other joints stay relatively immobile. For example, a slight amount of glide may occur within joints of the midfoot. This region of the foot, however, is generally stable during locomotion. Rotational forces can be transmitted from the rearfoot to the forefoot through the relatively stable midfoot region. Ligaments span from bone to bone to create stability in the midfoot as well as in the other regions of the foot and ankle. Also, muscles act to stabilize certain parts of the foot while creating motion at other parts of the foot and ankle. It is a constant interplay between motion and stability, as with any region in the human body.

It is important to consider how the foot and ankle function differently depending on their position. During gait, the ankle and foot move between pronation and supination to create more of a

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supple landing surface for weight acceptance and then a more rigid lever for push-off. Pronation puts the foot and ankle in a relatively supple position, whereas supination makes for a relatively stiff lever for push-off. Refer to the phases of gait chart (refer to Appendix A) for more information on the gait cycle. The foot and ankle also function differently depending on whether they are in an open or closed kinetic chain position. In a closed kinetic chain, the more proximal aspect of joints move on the more distal aspect and the foot remains planted while the body shifts over it. In an open kinetic chain, more freedom of movement is permitted as the foot moves through space. Thus, each joint of the foot and ankle acts differently depending on whether the foot is in an open or closed kinetic chain.

This section will discuss the specific configurations of the joints of the foot and ankle, anatomy of the joint region, muscles acting on these joints, ligaments stabilizing these joints, and their overall functions as part of the foot and ankle complex. Common pathologies and treatment options related to each joint will also be discussed. This will provide a deeper understanding of this intricate and fascinating region of the human body and shed some light on the combined function of the joints making up this region, specifically during gait.

Table 14. Muscles acting on the foot and ankle

Muscles Origin Insertion Action Segmental Innervation

Peripheral Innervation

Tibialis Anterior

Lateral condyle & proximal 2/3rds of lateral tibia & interosseous membrane

Medial cuneiform & adjacent 1st metatarsal

dorsiflexes ankle inverts foot

L4-5, S1 Deep Fibular Nerve

Extensor Digitorum Longus

Lateral tibial condyle, proximal 3/4th of fibula & interosseous membrane

Dorsal digital expansions of digits 2-5

dorsiflexes ankle extends D2-5 (MP & IP) &MP)

L4-5, S1 Deep Fibular Nerve

Extensor Hallucis Longus

Middle ½ of anterior fibula & interosseous membrane

Distal phalangeal base of 1st toe

dorsiflexes ankle extends great toe (MP & IP)

L4-5, S1 Deep Fibular Nerve

Peroneus Tertius

Distal fibula & interosseous membrane

Base of 5th metatarsal

dorsiflexes ankle and everts foot

L4-5, S1 Deep Fibular Nerve

Peroneus Longus

Fibular head & proximal 2/3rd of fibula

Lateral aspects of 1st metatarsal & medial cuneiform

everts foot, plantar flexes ankle, depresses 1st MT head

L4-5, S1 Superficial Fibular Nerve

Peroneus Brevis

distal 2/3 of the fibula

lateral base of the 5th MT

everts foots, plantar flexes ankle

L4-5, S1 Superficial Fibular Nerve

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Flexor Digitorm Longus

posterior tibia distal to soleal line

plantar surfaces of the distal phalangeal bases

plantar flexes ankle and flexes digits 2-5 (MP & IP)

L5, S1-2 Tibial Nerve

Flexor Hallucis Longus

distal 2/3 of the posterior fibular surface and interosseous membrane

plantar surfaces of the distal phalangeal base of 1st toe

plantar flexes ankle and flexes great toe (MP & IP)

L5, S1-2 Tibial Nerve

Gastrocnemius posterior aspect of the femoral condyles and joint capsule

post calcaneal surface

flexes knee and plantar flexes ankle

S1-2 Tibial Nerve

Plantaris Lateral suprcondylar line

post calcaneal surface

flexes knee and plantar flexes ankle

L5, S1-2 Tibial Nerve

Soleus posterior aspect of the head and prox 1/4 of fibula & tibial soleal line

post calcaneal surface

plantar flexes ankle

L5, S1-2 Tibial Nerve

Tibialis Posterior

interosseous membrane, lateral tibial surface & medial fibular surface

navicular, intermediate cuneiform and bases of MT 2-4

inverts foot and plantar flexes ankle

L4-5. S1 Tibial Nerve

Popliteus lateral femoral condyle and oblique popliteal lig

soleal line of the tibia

NWB-med rot of tibia and knee flexion. WB (insertion is fixed)-lat rot of femur and knee flexion. Unlocks knee from extension into early flexion

L4-5, S1 Tibial Nerve

Flexor Digiti Minimi

Base of 5th metatarsal

Proximal phalangeal base

Flexes 5th digit (MP)

S1-2 Lateral plantar nerve

Abductor Digiti Minimi

Calcaneal tuberosity

Lateral side of proximal phalangeal base of 5th digit

Abducts and flexes 5th digit

S1-2 Lateral plantar nerve

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Quadratus Plantae

Medial surface of calcaneus & lateral process of calcaneal tuberosity

Flexor digitorum longus tendon

Assists flexor digitorum longus

S1-2 Lateral plantar nerve

Plantar Interossei

Plantar surface of base of Metatarsals

Dorsal digital expansions of digits 3-5

Adducts and flexes digits 3-5 (MP)

S1-2 Lateral plantar nerve

Dorsal Interossei

Metatarsal shafts Proximal phalangeal bases & dorsal digital expansions of digits 2-4

Abducts and flexes digits 2-4 (MP)

S1-2 Lateral plantar nerve

Adductor Hallucis

Base metatarsals 2-4 & distal ends of metatarsals 3-5

Lateral base of proximal phalanx of great toe

Adducts great toe

S1-2 Lateral plantar nerve

Abductor Hallucis

Medial calcaneal tuberosity

Medial side of proximal phalangeal base of great toe

Flexes & abducts great toe

L4-5, S1 Medial plantar nerve

Flexor Hallucis Brevis

Cuboid & tendon of tibialis posterior

Base of proximal phalanx of great toe

Flexes great toe (MP)

L4-5, S1 Medial plantar nerve

Flexor Digitorum Brevis

Medial process of calcaneal tuberosity

Sides of intermediate phalanges of digits 2-5

Flexes toes (proximal IP)

L4-5, S1 Medial plantar nerve

Extensor Hallucis Brevis

Middle half of medial fibula

Dorsal aspect of base of distal phalanx of hallux

Extension of great toe (MP&IP)

L4-5, S1 Deep fibular nerve

Extensor Digitorum Brevis

Anterolateral calcaneus

Dorsal aspect of bas of proximal phalanx (1) or

Extension of digits 2-5 (MP&IP)

L4-5, S1 Deep fibular nerve

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lateral side of tendons of EDL (2-4)

Lumbricals

Tendons of flexor digitorum longus

Medial sides of dorsal expansions of digits 2-5

Flexes proximal phalanges (MP) & extend IP joints

L4-5, S1 S1-2

1st lumbrical: medial plantar nerve 2-4: lateral plantar nerve

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ProximalTibiofibularJoint

Overview The proximal tibiofibular joint (PTFJ) is located lateral, and immediately inferior to the knee and is formed by the head of the fibula articulating with the posterolateral facet of the tibia. These two bones are further connected at the shafts by an interosseous membrane. The classification of this joint is a plane synovial joint. Although in close proximity and often considered part of the knee, the proximal tibiofibular joint provides motion at the ankle. Movement here is minimal and will be discussed further in the talocrural joint section. This joint is important in order to provide stability and dissipate forces between the leg and thigh. It is believed that the tibia bears 90-100% of the body weight being transmitted through the femur.

Blood supply to the joint originates from the popliteal artery that branches at the popliteal muscle. Branches of the popliteal artery supplying the PTFJ include the inferior lateral genicular artery and anterior tibial recurrent artery. Deep venous drainage passing through the interosseous membrane near the joint is the anterior tibial vein which drains into the popliteal vein. Innervation to the proximal tibiofibular joint primarily comes from a branch of the tibial nerve called the nerve to the popliteus, and the common fibular nerve. The common fibular nerve winds around the neck of the fibula before dividing into the deep and superficial fibular nerves. Piercing the interosseous membrane, the deep fibular nerve runs alongside the anterior tibial artery and vein.

Tissue Layers x Integumentary

o Epidermis o Dermis

x Subcutaneous Tissue o Adipose tissue o Cutaneous nerves

� Medial and lateral Sural cutaneous nerves

� Superficial fibular nerve � Sural nerve

o Superficial veins o Lymphatic vessels o Lymph nodes

x Deep fascia of the leg (crural fascia) o Anterior intermuscular septum o Posterior intermuscular septum o Interosseous membrane

x Muscles and tendons o Anterior compartment

� Tibialis Anterior � Extensor hallucis longus � Extensor digitorum

longus � Peroneus tertius

o Lateral compartment � Peroneus longus � Peroneus brevis

o Posterior compartment � Gastrocnemius � Soleus � Plantaris � Flexor digitorum longus � Flexor hallucis longus � Tibialis posterior � Popliteus

x Neurovasculature o Inferior lateral genicular artery o Anterior tibial artery o Anterior recurrent tibial artery

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o Posterior tibial artery o Great saphenous vein o Small saphenous vein

x Ligaments o Patellar ligament o Lateral collateral ligament o Anterior superior tibiofibular

ligament o Posterior superior tibiofibular

ligament

x Joint capsule o Synovial membrane o Synovial fluid o Articular cartilage o Periosteum

x Bones o Tibia o Fibula

Table 1: Joint Motions and Associated Muscles Table 15. Proximal tibiofibular muscles and motions

Proximal Tibiofibular Motion Primary mover Stabilizing and helping synergists Anterior-posterior glide N/A* Ankle dorsiflexors Superior-Inferior glide N/A Ankle plantar flexors Fibular rotation N/A Ankle plantar flexors and dorsiflexors

*Very little motion occurs at this joint. It is important there is a firm articulation in order to effectively transfer forces within the lateral knee from the fibula to the tibia. No single muscle is termed a primary mover of this joint.

Joint Configuration and Planes of Motion The proximal tibiofibular joint (Figure 34) is classified as a synovial plane joint. The tibial articulation aspect has a lateral, dorsal, and inferior orientation while the fibular orientation is medial, ventral, and superior. Although subtle, motion is described as the fibular concave surface on the tibial convex surface. According to Loudin, Manske, and Reiman (2013), three movements occur at this joint including: rotation of the fibula on the tibia, gliding in the anteroposterior plane, and gliding in the mediolateral plane. Motion is very small and occurs while being dependent on knee and foot position.

Biomechanics and Arthrokinematics The proximal tibiofibular joint does not have extensive biomechanical properties. Rather, the joint functions to primarily dissipate torsional forces, lateral tibial bending force, and tensile stresses (Loudin, Manske, and Reiman, 2013). More specifically, torsional forces are those arising from the ankle joint, and tensile stresses, rather than the compressive forces of weight bearing, affect the proximal tibiofibular joint (Loudin, Manske, and Reiman, 2013). Functioning to primarily stabilize and control the motion at the talocrural joint, this joint acts as an extreme dorsiflexion limiter (refer to Table 14 for specific dorsiflexors). During maximal dorsiflexion, the force derived at the talocrural joint translates up to the

Figure 34. Proximal tibiofibular joint

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proximal tibiofibular joint. In doing so, the fibula must translate superiorly resulting in the slight and synchronous gliding motions discussed above.

Clinically, this joint is important because even though minimal, movement at the PTFJ is critical to achieve functional dorsiflexion and plantarflexion. These movements as components of gait will be discussed later in the talocrural joint section. For now, the important thing is that there are many reasons for the ankle to have limited dorsiflexion, one being casting at the ankle for an extended amount of time. With limited dorsiflexion, the clinician must remember to look up the chain for attributing issues to be addressed in interventions. The proximal tibiofibular joint is prone to becoming less mobile and can directly correlate with available dorsiflexion and plantar flexion. If this occurs, fibular head mobilizations or manipulation is indicated. For such interventions, open-packed position of the joint is at 25 degrees of knee flexion with 10 degrees of plantar flexion; a position pertinent to be effective in joint mobilizations and manipulations.

Ligaments of the Proximal Tibiofibular Joint Table 16. Proximal tibiofibular ligaments

Ligament Proximal Attachment

Distal Attachment Function Other associated joint constraints

anterior superior tibiofibular

Anterior tibia Anterior fibula Maintain proximal integrity between the tibia and fibula

N/A

posterior superior tibiofibular

Posterior tibia Posterior fibula Maintain proximal integrity between the tibia and fibula

N/A

Common Pathologies of the Proximal Tibiofibular Joint Common pathologies of the proximal tibiofibular joint are limited. According to Radakovich

(1982), it is important to be aware of the direct and indirect pathologies that do exist for differential diagnoses. Indirect injury includes severe ankle stress of the weight bearing extremity. This injury is due to the tibial rotation motion being blocked when in weight bearing and results in the rotational forces to be translated through the joint to the proximal fibula.

Direct trauma can occur when a flexed knee in weight bearing sustains a forceful lateral blow. Direct injuries include dislocation, subluxation, or a sprain. Sprains to this joint are often overlooked and should be evaluated thoroughly before ruling out. Complaints of pain will be in the lateral knee or the posterolateral calf. Palpation and ROM assessment may or may not elicit exacerbated symptoms. Symptoms will present as more mild and irritating than debilitating. While there are no standardized tests and measures, Radokovich discusses a test of going into knee flexion without support from the contralateral limb (1982). The test is indicative of being positive if the patient is unable to stabilize. Treatment can range from cautious neglect to a less often surgical intervention. Conservative treatment is often sufficient with the use of non-steroidal anti-inflammatory agents, ice, compression, or a partial weight-bearing status if need.

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DistalTibiofibularJoint(DTFJ)

Overview The distal tibiofibular joint (DTFJ) consists of the inferior articulation between the concave

surface of the distal tibia, known as the fibular notch, and the convex surface of the distal fibula. The distal tibiofibular joint is classified as a syndesmosis synarthrodial joint. According to Levangie and Norkin (2005), a syndesmosis joint is when the two bones are directly connected by a fibroadipose tissue, such as an interosseous membrane. Its main role is to create a tight hold between the distal tibia and fibula to maintain stability of the ankle joint, permitting very little movement to occur. Movement of the fibula will occur during plantarflexion of the ankle and dorsiflexion of the ankle to accommodate the wider anterior portion of the trochlea of the talus.

The distal tibiofibular joint is supplied with blood from the medial malleolar branches of the anterior and posterior tibial arteries plus blood from the perforating branch of the fibular artery. The joint is innervated by the deep fibular neve, tibial nerve and saphenous nerve.

Tissue Layers x Integumentary

o Epidermis o Dermis o Hypodermis

x Subcutaneous fat x Subcutaneous fascia x Superior Extensor Retinaculum x Muscle tendons of anterior

compartment of the leg: o Tibialis Anterior o Extensor Hallicus Longus o Extensor Digitorum Longus

x Interosseous membrane

x Muscle tendon of deep compartment of the leg:

o Flexor Hallicus Longus o Flexor Digitorum Longus

x Calcaneal Tendon x Flexor retinaculum x Subcutaneous fascia x Subcutaneous fat x Integumentary:

o Hypodermis o Dermis o Epidermis

Figure 35. Distal tibiofibular joint

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Joint Motions and Associated Muscles Table 17. Distal tibiofibular muscles and motions

Motion Primary Mover Secondary Movers

Superior translation and lateral rotation of fibula during ankle dorsiflexion

N/A Tibialis Anterior Extensor digitorum longus Extensor Hallucis longus Peroneus Tertius

Inferior translation and medial rotation of fibula during ankle plantarflexion

N/A Gastronemius Soleus Tibialis Posterior Flexor Digitorum Longus Flexor Hallucis Longus Peroneus Longus Perneus Brevis

*The motion that takes place at this joint occurs from the muscles that dorsiflex and plantar flex the ankle. There is no primary mover of this joint.

Joint Configuration and Planes of Motion The distal

tibiofibular joint is made up of the convex surface of the medial fibula and the concave surface of the lateral tibia. There is very little movement occurring at the distal tibiofibular joint. When movement does occur, the fibula will rotate in the fibular groove of the tibia to accommodate ankle motion at the talocrural joint. According to Norkus (2001), the fibula laterally rotates 3-5 degrees during dorsiflexion to create more room for the talus and will medially rotate 3-5 degrees during ankle plantarflexion. There is also slight fibular elevation during ankle dorsflexion and fibular lowering during ankle plantarflexion.

Biomechanics and Arthrokinematics The distal tibiofibular joint will change position depending on whether the ankle is in an open or

closed-chain position. During weight bearing, the fibula moves inferiorly about 2.4 mm, deepening the ankle mortise and tightening the interosseous membrane. This adds more stability and lateral support to the ankle during the stance phase and push-off mechanism in gait.

Figure 36. Ligaments and joint structure of the distal tibiofibular joint

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The distal tibiofibular joint is very important for proper mobility occurring at the talocrural joint. The talocrural joint is dependent on the tight junction between the tibia and fibula, which makes up the ankle mortise. During ankle motion, the mortise needs a firm grasp on the talus for smooth mobility and stability. The ligaments of the distal tibiofibular joint are responsible for the tight junction and for maintaining ankle stability. There is slight movement at the distal tibiofibular joint during ankle dorsiflexion and plantar flexion to accommodate the superior aspect of the talus. During dorsiflexion of the ankle, the tibia and fibula need to separate and expand the ankle mortise to allow the wider superior-anterior portion of the talus to roll posteriorly. The distal tibiofibular joint accomplishes this by laterally rotating and translating the fibula superiorly. During plantarflexion, the ankle mortise narrows by the fibula moving inferiorly and medially rotating. Together, the distal tibiofibular joint and the talocural joint work in unison to accomplish ankle dorsiflexion and plantarflexion during gait. Further gait mechanics of the ankle is discussed in more detail in the talocrural section.

Ligaments of Distal Tibiofibular Joint Table 18. Ligaments of the distal tibiofibular joint

Ligament Proximal Attachment

Distal Attachment

Function Other associated joint constraints

Interosseous Tibiofibular ligament

Lateral surface of distal tibia

Anteroinferior triangular segment of the medial aspect of distal fibular shaft

Allows for slight separation between malleoli during dorsiflexion of talocrural joint Stablizes joint during weight bearing

Anterior inferior Tibiofibular

Anterolateral tubercle of the tibia

Longitudinal tubercle on anterior aspect of lateral malleolus

Stability and tight hold of fibula to tibia

Prevents excessive fibular motion External talar rotation

Posterior Inferior Tibiofibular

Posterior tubercle of tibia

Posterior lateral malleolus

Stability and tight hold of fibula to tibia

Prevents excessive fibular motoin

Transverse tibiofibular ligament (deep component of posterior inferior tibiofibularligament)

Posterior tibial margin

Osteocondral junction on the posterior and medial margins of distal fibula

Deepens articular surface of distal tibia Deepens the mortise to increase joint stability

Prevent talar translation

Common Pathologies of the Distal Tibiofibular Joint: A common pathology that occurs at the distal tibiofibular joint is a distal tibiofibular

syndesmosis ankle sprain, also known as a high ankle sprain. During a high ankle sprain, the anterior tibiofibular ligament is jeopardized. The anterior tibiofibular ligament is a broad, strong ligament whose role is to connect the distal fibula and distal tibia. The two most common mechanisms of injuries are

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hyperdorsiflexion or a combination of rotation and plantarflexion at the ankle. The incidence is reported to be 1-11% of all reported ankle injuries. Recovery from a syndesmosis sprain is longer than a common ankle sprain due to the need to be non-weight bearing for some time. If the ATF is not fully healed, weight bearing will allow the distal tibiofibular joint to spread and re-irritate the ligament, delaying healing and recovery.

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Talocruraljoint

Overview The talocrural joint is formed by the articulations of the distal tibia, distal fibula, and superior talus. This unique joint is classified as a hinge-type synovial joint. The main function of the talocrural joint is to link the leg and foot, and is responsible for accepting and passing forces between each. Primary motions occurring at this joint are pronation and supination. Pronation includes instantaneous dorsiflexion, eversion, and abduction, and supination includes instantaneous plantar flexion, inversion, and adduction.

The talocrural joint is supplied with blood by two popliteal artery branches, the anterior and posterior tibial arteries, as well as the fibular artery; all give off malleolar branches. The anterior tibial artery supplies anterior structures and proceeds to the dorsum of the foot where it becomes the dorsalis pedis artery. Posterior to the medial ankle is the posterior tibial artery which divides into the medial and lateral plantar arteries. The fibular artery is a branch of the posterior tibial artery that descends the leg, pierces the interosseous membrane, and passes to the dorsum of the foot. Venous drainage is primarily done through the long and short saphenous veins. These then drain into the great saphenous vein that courses the medial ankle anterior to the malleolus. Innervation of the talocrural joint is provided by the tibial nerve which specifically innervates the posterior compartment of the leg; a compartment mostly responsible for plantar flexion. The tibial nerve eventually passes posterior and inferior to the medial malleolus and then divides into the lateral and medial plantar nerves that go to the foot. The talocrural joint also receives innervation from the deep fibular, posterior tibial, saphenous, and sural nerves. Innervation to the anterior compartment of the leg is supplied by the deep fibular nerve, while the lateral compartment and anterior skin receives innervation from the superficial fibular nerve.

Tissue Layers x Integumentary

o Epidermis o Dermis

x Subcutaneous Tissue o Adipose tissue o Cutaneous nerves

� Saphenous nerve � Sural nerve

o Superficial arteries/veins � Dorsalis pedis artery � Long and short

saphenous veins o Lymphatic vessels o Lymph nodes

x Deep fascia: o Inferior extensor retinaculum o Flexor retinaculum

x Muscles and tendons o Anterior compartment

� Tibialis Anterior � Extensor hallucis longus � Extensor digitorum

longus � Peroneus tertius

o Lateral compartment � Peroneus longus

tendon � Peroneus brevis

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o Posterior compartment � Gastrocnemius � Soleus � Plantaris � Flexor digitorum longus

muscle � Flexor hallucis longus

muscle/tendon x Neurovasculature

o Superficial fibular nerve o Anterior tibial artery o Deep fibular nerve o Anterior medial malleolar

artery o Posterior Tibial artery o Small saphenous vein

x Bursa/fat pad o Tendo calcaneus bursa o Tendo calcaneus tendon

x Ligaments

o Deltoid (medial ligament) � Tibiotalar fibers � Tibionavicular fibers � Tibiocalcaneal fibers

o Lateral Ligament � Anterior talofibular

ligament � Posterior talofibular

ligament � Calcaneofibular

ligament x Anterior Joint capsule x Posterior joint capsule x Bone

o Tibia � Medial malleolus

o Fibula � Lateral malleolus

o Talus

Joint Motions and Associated Muscles* Table 19. Talocrural muscles and motions

Talocrural Motion Primary Mover Stabilizing and helping synergists Abduction Peroneus longus Peroneus tertius, extensor digitorum

longus, Peroneus brevis Adduction Tibialis posterior Tibialis anterior , Flexor hallucis longus,

flexor digitorum longus Dorsiflexion Tibialis anterior Extensor hallusis longus, Extensor

digitorum longus, Peroneus tertius, Plantarflexion Gastrocnemius/Soleus Peroneus longus, Flexor hallucis longus,

flexor digitorum longus, Peroneus brevis, tibialis posterior, plantaris

Eversion Peroneus longus Peroneus tertius, extensor digitorum longus, Peroneus brevis

Inversion Tibialis Posterior Tibialis anterior, Flexor hallucis longus, flexor digitorum longus

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Joint Configuration and Planes of Motion The talocrural joint is comprised of three junctions that overall form a rectangular concavity resembling a mortise (Figure 37); often it is referred to as the mortise joint. This shape provides natural stability that is critical to the ankle’s function. The lateral aspect of the mortise is formed by the lateral malleolus of the distal fibula articulating with the lateral talus. Medially, the articulation consists of the distal tibia’s medial malleolus with the medial talus. Together with the distal tibial expansion, a concave, rectangle shape is formed (Figure 38). This concave formation articulates with the superior (dorsal) talus, also called the trochlea of the talus for its dome shape. The trochlear surface is convex when going in the anteroposterior direction, and concave when going in the mediolateral direction. The talus has a prominent head that goes toward the navicular by projecting forward and slightly medial.

The neck of the talus has a long axis that positions the head of the talus about 30 degrees medial to the anteroposterior plane. In young children, this position is about 40-50 degrees medial to the plane and can explain why children often have an appearance of inverted feet. Above the mortise, the fibular notch of the lateral tibia has a concave formation that articulates with the slightly convex distal and medial fibula, providing a structural component to the joint.

The lateral malleolus of the fibula extends more distally than the medial malleolus, providing a bony block to the motion of eversion. This explains why ankle sprain injuries occur more often in inversion as

opposed to eversion. More on this will be discussed below.

The talocrural joint has an anterior joint capsule and a posterior joint capsule; both are relatively thin. The integrity of the joint is therefore comprised of strong collateral ligaments. Medially is the large deltoid ligament which is triangular in shape, and laterally are three distinct ligaments (see Table 2). 70% of the joint’s surface is covered with articular cartilage that is 3 millimeters thick where the joint translates weight bearing forces. It is said that 90-95% of compressive forces translate through the tibiotalar articulation. The thickness of the articular cartilage allows the joint to compress 30-40% when subduing peak physiological forces. This characteristic of the joint has a large role in force translation between the leg and foot during gait and will be discussed below.

The talocrural joint has one degree of freedom that permits uniaxial motion in multiple planes. This unique movement is due to an oblique axis. Motions therefore occur as elements of a larger movement. For example, when the talocrural joint is pronating, every 1 degree of adduction will co-occur with every 1 degree of inversion. This oblique axis goes through both malleolar tips and the body of the talus. When thinking of the position of the lateral malleolus being posterior and inferior to the

Figure 37. Carpenter’s mortise

Figure 38. Proximal aspect of the talocrural joint

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medial malleolus, one can visualize the obliquity of that axis (Figure 39). Specifically, the axis is deviated 10-25 degrees from a true axis about the mediolateral plane, and 6-15 degrees among the transverse plane axis of rotation. The varying amount of degree depends on the source. The end result is that dorsiflexion and plantar flexion are the predominant movements at the talocrural joint.

In discussion of range of motion, the neutral position of the joint is 0 degrees and when the foot is at 90 degrees to the

leg. In reference to this position, the talocrural joint is capable of 15 to 25 degrees of dorsiflexion, and 40 to 55 degrees of plantar flexion. The greater amount of range of motion in plantar flexion can be explained by looking at the medial and lateral facets of the talus (Figure 40). The lateral facet is longer and provides a larger linear displacement. Because of this, as the joint rotates, there is more room available when going into plantar flexion than in dorsiflexion. It is also important to keep in mind that less dorsiflexion is obtained when the knee is straight. This is due to the gastrocnemius being a two-joint muscle, meaning it crosses both the ankle and the knee. Further, when the knee is in extension the gastrocnemius is taut proximally and allows less range distally at the ankle. To assess true dorsiflexion, assure the knee is bent.

Before discussing biomechanics and arthrokinematics related to the talocrural joint, it is important to first understand the terminology and multi-planar movements about the axis of interest. When considered as individual components of pronation and supination, the following can be said fundamentally: dorsiflexion and plantar flexion transpire in the anteroposterior plane, eversion and inversion in the mediolateral plane, and abduction and adduction in the horizontal plane. These movements would then be about the mediolateral axis, anteroposterior axis, and transverse axis, respectively. However, it is known that this description is inadequate due to the movements rotating about an oblique axis. Movements occurring perpendicular to the oblique axis are now termed pronation and supination, of which include the elements described above. This then explains why movements at the ankle are in fact uniplanar, and not triplanar.

Figure 39. Oblique axis of talocrural joint

Figure 40. Talar facet

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Biomechanics and Arthrokinematics In discussion of dorsiflexion and plantar flexion, it is critical to recognize that the trochlea is

narrower posteriorly than anteriorly. For dorsiflexion to occur, the mortise of the joint must therefore expand to compensate for the widened anterior talus. Important to note, this movement is dependent on the permissible movements of the proximal and distal tibiofibular joints. The expansion that occurs permits the anterior talus to wedge in the mortise of the joint and providing increased surface area contact; the ankle is now very stable. In fact, this position is considered the joint’s close-packed position and best sets up the joint to accept forces up to 4 times the body weight. In contrast, when in plantar flexion combined with inversion, the talocrural joint is the least stable, or in loose pack position. For this reason, it is easily understood why inversion ankle sprains tend to occur when the foot is in relative plantarflexion.

When the foot is off the ground and movement about the talocrural joint is open chain, dorsiflexion consists of convex on concave motion. More specifically, the talus must roll forward in relation to the leg while simultaneously sliding posteriorly (Figure 41). Anterior translation is therefore kept minimal. Importantly, the calcaneofibular ligament becomes taut with the posterior glide which is synonymous with dorsiflexion. This can be stated as a general rule for collateral ligaments attaching to the talus. In closed chain kinematics, or in weight bearing, the concave mortise will move over the convex, planted talus. This concave on convex relationship provides movements in the same direction. In other words, the distal tibia and fibula will both roll and glide anteriorly relative to the talus. At end range dorsiflexion, the structures elongated include the posterior capsule and all tissues that participate in plantar flexion. The primary mover of dorsiflexion at this joint due to cross sectional area and line of pull is the tibialis anterior (see Table 14 for attachments).

In open chain plantar flexion, the talus will roll posteriorly while gliding anteriorly. The same collateral ligament rule applies here, only with plantar flexion. In a closed chain movement of plantar flexion, the talus will be the bone rolling and gliding anteriorly relative to the tibia and fibula. At end range plantar flexion, the anterior capsule of the joint is stretched along with all tissues participating in dorsiflexion. The gastrocnemius and soleus (together termed the triceps surae) are predominantly responsible for plantar flexing the ankle. Cross sectional area of these muscles and their line of pull contribute to their dominant function.

Open and closed chain dorsiflexion and plantar flexion play a critical element to the gait cycle (see Figure 42), and because these are the two primary motions about the talocrural joint, they will be

Figure 41. Open chain dorsiflexion of talocrural joint

Figure 42. Ankle motion during gait

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discussed here. The first critical event of gait is achieving heel contact during the initial contact phase. For this to happen, the ankle must be able to dorsiflex to at least neutral during swing phase in order to clear the toes of the ground and obtain a heel-strike. Further, closed chain dorsiflexion of 10 degrees is necessary during single limb support, specifically at terminal stance to create a maximal torque demand of dorsiflexion that subsequently achieves optimal muscle position for push off. At this transitional moment of the gait cycle from terminal stance to pre-swing, the plantar flexor muscles are producing peak activity. The critical event here is rapid plantar flexion, an event necessary to propel the lower extremity into swing phase with enough momentum to properly clear the foot of the ground. About 15 to 20 degrees of plantar flexion is necessary for this phase of gait.

Ligaments of the Talocrural Joint Table 20. Talocrural Ligaments

Ligament Proximal Attachment

Distal Attachment Function Other associated joint constraints

Deltoid ligament - 4 parts: 1.Tibionavicular 2.tibiocalcaneal 3.Anterior tibiotalar 4.Posterior tibiotalar

Medial malleolus 1. Navicular (near the tuberosity)

2. Sustentaculum talus

3,4. Medial tubercle and adjacent part of talus

Limits eversion Limits dorsiflexion limits anterior-to-posterior translation of the talus within the mortise 4.Limits plantar flexion

Anterior talofibular ligament

Anterior aspect of the lateral malleolus

Neck of talus Gives lateral stability to the ankle, primarily limiting inversion

Plantar flexion, adduction

Posterior talofibular ligament

Posterior-medial side of lateral malleolus

Lateral tubercle of the talus

Gives stability to the talus within the mortise

Limits excessive abduction of the talus, especially in dorsiflexion

Calcaneofibular ligament

Apex of the lateral malleolus

Lateral surface of the calcaneus

Resists inversion across the talocrural joint, especially when dorsiflexed

dorsiflexion

Inferior transverse ligament

Posterior talofibular ligament

Posterior aspect of the medial malleolus

Forms part of the posterior wall of the talocrural joint

N/A

*Lateral ligament is comprised of anterior talofibular ligament, posterior talofibular ligament, and calcaneofibular the ligament. Deltoid ligament is also called the Medial ligament.

Common Pathologies of the Talocrural Joint Pathologies related to the ankle are extensive. In this section, only the most common pathologies related specifically to the talocrural joint will be discussed. To begin, ankle sprains are the

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most common athletic injury. As mentioned above, inversion ankle sprains out-number eversion ankle sprains. The inversion ankle sprain damages the lateral supporting ligaments, most often in this order of progression of tissue damage and severity: anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), and lastly, the posterior talofibular ligament (PTFL) (see Figure 43). The most common special tests associated with this injury is the Anterior Drawer test and Inversion Talar Tilt test. For grades 1 and 2 sprains, intervention includes PRICE, range of motion exercises, and weight bearing as tolerated.

The less common sprain of the ankle, accounting for 5-10% of ankle sprains, is the medial ankle sprain of the deltoid ligament. Mechanism of injury includes forced eversion. A special test used to assess this injury is the Eversion Talar Tilt test. Management includes the same course of treatment as inversion ankle sprains but healing may take longer due to the severity of injury.

Although medial ankle sprains are less common than lateral, 75% of ankle fractures occur on the medial side. Avulsion of the medial malleolus is common in addition to a more serious one called, Pott’s fracture. Pott’s fracture includes dislocation of the ankle as the foot is forcibly everted causing tearing off of the medial malleolus due to the pull by the deltoid ligament. Subsequently, the talus moves laterally shearing off the lateral malleolus, or more commonly, breaking the fibula superior to the tibiofibular syndesmosis. The Ottawa Ankle Rules should be applied when assessing any ankle injury to rule out a fracture. Ankle fractures are significant due to the inability of the patient to achieve anatomical alignment with the injury due to pain and healing. Any injury affecting alignment can lead to long term morbidity, and proper diagnosis and treatment can prevent this.

Neurological pathology includes, but is not limited to, tibial nerve entrapment (tarsal tunnel syndrome) and happens when the posterior tibial nerve is entrapped or compressed. This nerve runs under the flexor retinaculum and behind the medial malleolus. Reasons for this may be edema, tightness of the posterior compartment, including the synovial sheaths of the tendons, and other soft tissue restrictions. Over-pronation of the foot is a common cause to all of these factors. Pain is often reported in the heel and medial ankle. The Tinel’s sign is a common test for this pathology. Correcting biomechanics, assuring proper foot wear use, and using anti-inflammatories are the primary treatments for this pathology.

As in any joint, post-traumatic osteoarthritis (OA) is quite common in the talocrural joint. Following trauma, the joint is left with incongruences which permits intra-articular stress that leads to damage. According to Bloch, Srinivasan, and Mangwani (2015), ankle OA develops 78% of the time after trauma. Still, ankle OA is less common than hip and knee OA and therefore has lacking literature on evidence-based interventions. Non-surgical and surgical interventions exist for this pathology including

Figure 43. Lateral ligaments

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the sparingly used total ankle replacement procedure. Overall the standard of care for appropriate patients remains to be arthrodesis, and the more minimally invasive procedure – arthroscopy (Bloch, Srinivasan, and Mangwan. 2015).

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SubtalarJoint

Overview The subtalar joint consists of articulation between the inferior talus and the superior calcaneus.

It is located just inferior to the talocrural joint. The talus and calcaneus articulate on three different surfaces, creating three separate facets: anterior, middle and posterior. The posterior facet has its own separate capsule and is sometimes known as the talocalcaneal joint. The anterior and middle facets share a joint capsule and together form the talocalcaneonavicular joint. The tarsal canal divides the two joint capsules. The subtalar is a synovial joint, classified as a plane joint. Due to the different positions and surfaces of the facets, the subtalar functions as a key component for the triplanar twisting motions of supination and pronation. The subtalar joint is very important in walking and balancing on uneven surfaces.

The plantar aspect of the joint is innervated by the medial or lateral plantar nerve. The dorsal aspect of the joint is innervated by the deep fibular nerve. The arterial supply is from branches of the posterior tibial and fibular arteries.

Tissue Layers (dorsal to plantar) x Integumentary

o Epidermis o Dermis o Hypodermis

x Subcutaneous fat x Dorsal fascia of the foot x Inferior Extensor Retinaculum and

Flexor Retinaculum x Tendons:

o Peroneus Tertius tendon o Extensor Digitorum Longus

tendon

o Extensor Hallucis Longus tendon

o Tibialis Anterior tendon o Flexor Hallucis longus tendon o Flexor Digitorum longus tendon o Tibialis Posterior tendon o Peroneus Longus tendon o Peroneus Brevis tendon

x Muscles: o Extensor digitorum brevis

muscle o Extensor hallicus brevis muscle

x Neurovasculatture

Figure 44. Subtalor joint

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o Tibialis Anterior artery with medial and lateral tarsal artery branch

o Deep fibular nerve x Talus bone x Joint capsule

o Synovial membrane o Synovial Fluid o Articular cartilage

x Calcaneal bone x Quadratus Plantae Muscle x Neurovasculature

o Posterior Tibial Artery and Lateral and Medial Plantar branches

o Tibial Nerve and Lateral and Medial Plantar branches

x Muscles and Tendons: o Abductor Hallucis Muscle o Flexor Digitorum Brevis Muscle o Abductor Digiti Minimi Muscle

x Plantar fascia of the foot x Plantar Aponeurosis x Subcutaneous fat x Integumentary

o Hypoepidermis o Dermis o Epidermis

Joint Motions and Associated Muscles Table 21. Subtalor muscles and motions

Motion Primary Mover Secondary Movers Inversion Tibialis Posterior Tibialis Anterior

Eversion Peroneus Longus Peroneus brevis Peroneus Tertius

Abduction Tibialis Posterior Adduction Peroneus Longus Dorsiflexion Tibialis Anterior Extensor digitorum longus

Extensor Hallucis longus Peroneus tertius

Plantarflexion Gastrocnemius, Soleus Tibialis Posterior Flexor Digitorum Longus Flexor Hallucis Longus Peroneus Longus Perneus Brevis

Joint Configuration and Planes of Motion The subtalar joint consists of the talus and calcaneus. The talus is the most superior bone in the

foot and has three facets that articulate with the calcaneus, the largest of the tarsal bones. The anterior and middle facets of the talus are convex and are typically continuous with each other. They articulate with the slightly concave middle and anterior facets of the calcaneus. The posterior facet is the largest facet, occupying about 70% of the total articular surface between the two bones. It consists of a convex calcaneal surface and a concave talus surface. According to Norkin and Lenangie (2005), the concavity and convexity between the two joint capsules are reversed, limiting the potential mobility of the subtalar joint. Motion at the subtalar joint will occur simultaneously at the joint articulations, but in

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opposite directions. For example, when the talus moves on the calcaneus, the anterior and middle facets are convex, so roll and glide occur in opposite directions, but the posterior facet of the talus is concave, where roll and glide should occur in the same direction (447).

Due to the position and articulation of the facets, the subtalar joint moves in a curvilinear arc around a single axis. The axis of rotation is 42 degrees superior from horizontal and 16 degrees medially from the sagittal plane. The axis of rotation is oblique, piercing the lateral-posterior heel and coursing anterior, medial and superior through the subtalar joint.

This oblique axis allows the subtalar joint to move in 3 degrees of freedom. The 42 degrees of upward rotation allows for the subtalar joint to mainly move through eversion and inversion in the frontal plane and adduction and abduction in the transverse plane. The slight medial axis also allows ankle dorsiflexion and plantarflexion to occur in the sagittal plane, yet the motion is very slight. Ankle eversion is when the foot is laterally rotated away from midline whereas inversion consists of medially rotating the foot towards midline. The subtalar joint moves through 20-30 degrees of inversion and 5-15 degrees of eversion. Abduction of the foot occurs around a vertical axis, where the foot moves directly outward, and away from the midline of the body. Adduction is the exact opposite motion, with the foot moving towards the midline. Due to the difficulty of isolating abduction/adduction at the subtalar joint, it is usually not measured. Dorsiflexion is when the angle between the dorsum of the foot and the leg decreases while plantarflexion is when this angle increases. The range of motion at the subtalar joint for dorsiflexion and plantarflexion is very minimal and therefore not typically measured.

Biomechanics and Arthrokinematics The three articular surfaces allow the subtalar joint to move in 3 degrees of freedom, creating

the tri-planar coupled motion of pronation and supination. When inversion, adduction and plantarflexion are combined, the motion is named supination. When eversion, abduction and dorsiflexion occur, the motion is called pronation. The motion occurring at the joint will change depending whether the foot is in open or closed chain. In open chain, the distal calcaneus moves while the talus is fixed. During closed chain, the talus moves while the calcaneus is stationary. According to Levangie and Norkin (2005), the calcaneus is still able to move around the longitudinal axis and will complete the motions of inversion/eversion. Abduction/adduction and dorsiflexion/plantaflexion will occur at the freely moving talus. The table below describes the motion occurring when the foot is non-weight bearing and weight bearing:

Table 22. Pronation and supination conjunct motions

Pronation: Supination: Non-weight

bearing: Calcaneal Eversion Calcaneal Abduction Calcaneal dorsiflexion

Calcaneal Inversion Calcaneal Adduction Calcaneal Plantarflexion

Weight bearing: Calcaneal Eversion Talar Adduction Talar Plantarflexion

Calancaeal Inversion Talar Abduction Talar Dorsiflexion

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According to Rockar (1995), the orientation of the muscle tendons with respect to the subtalar axis will determine what motion they will produce. The muscles medial to the subtalar joint will supinate the foot while the lateral muscles will create pronation. Tibialis posterior, soleus, gastrocnemius, tibialis anterior, flexor hallucis longus and flexor digitorum longus work to supinate the foot. Tibialis posterior is a primary supinator due to its significant lever arm and advantageous line of pull. Soleus and gastrocnemius’s distal attachment passes the subtalar joint medially, making them supinators of the ankle. Due to their cross-sectional area and lever arm, they also create a strong supination force. Tibialis anterior supinates the foot, but due to its proximity to the joint, it does not have an effective line of pull. On the other side, peroneus longus and peroneus brevis act as pronators of the ankle due to their lateral insertion. Both muscles have long lever arms due to the distance between their attachment and the subtalar axis, making them strong pronators. Similarly, extensor digitorum longus also has a long lever arm lateral to the subtalar axis, which makes it a strong pronator of the ankle as well.

The subtalar joint is needed for proper gait mechanics. When walking, the subtalar joint works in junction with the transverse tarsal joints (talonavicular and calcaneocuboid joints) to supinate and pronate the ankle. During initial contact, the subtalar joint is in a slightly supinated position. Immediately after heel contact, the subtalar joint moves into pronation, as the talocrural joint is plantarflexed. The pronation occurs from the ground pushing the joint into slight eversion, while the impact of the heel contact pushes the joint into abduction and dorsiflexion. This pronation acts as a shock absorber by placing the foot in a more open-packed position to allow flexibility at the midfoot and increase contact between the foot and the ground. The flexibility of the midfoot is important because it allows the foot to contour when walking over uneven terrain. The subtalar joint maintains on average 5 degrees of pronation during early-mid stance phases of gait. The ankle pronation also allows for internal rotation to occur up the chain at the tibia and fibula. At mid-late stance, the subtalar joint starts to reverse motion and moves into supinated position while the leg externally rotates. Supination places the foot in a closed-packed position, creating a more stable ankle and a rigid midfoot. The rigidity prepares the foot for a powerful push off during the pre-swing phase of gait. During swing phase, the calcaneus stays in a slightly inverted position to prepare the next heel contact.

Figure 45. Supination and pronation at the subtalor joint (A) closed Kinematic chain and (B) open kinematic joint

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Ligaments of Subtalar Joint Table 23. Subtalor ligaments

Ligament Proximal Attachment

Distal Attachment

Function Other associated joint constraints

Interosseous (Talocalcaneal) ligament

Talar Sulcus Calcaneal Sulcus Binds talus and calcaneus together

Limit extremes of all motions, especially inversion

Cervical ligament

Inferior-lateral surface of the neck of the talus

Lateral surface of calcaneal sulcus

Binds talus and calcaneus

Limit extremes of all motions, especially inversion

Medial Talocalcaneal ligaments

Medial tubercle of the talus

Posterior sustentaculum tali

Reinforce posterior capsule, secondary stabilizers of the joint

Lateral Talocalcaneal ligament

Lateral surface of the talus

Lateral surface of the calcaneus

Reinforce posterior capsule, secondary stabilizers of the joint

Posterior Talocalcaneal ligament

Lateral tubercle of the talus

Superior surface of the calcaneus

Reinforce posterior capsule, secondary stabilizers of the joint

Calcaneofibular Anterior part of lateral malleolus

Posterior region of lateral calcaneus

Limits excessive inversion in neutral ankle position or dorsiflexion

Ankle inversion

Tibiocalcaneal fibers of deltoid ligament

medial malleolus Sustentaculum talus

Limits excessive eversion

Ankle eversion

Posterior talofibular

Malleolar fossa on the medial surface of the lateral malleolus

Posterolateral talus

Limits excessive inversion and rotary subluxation of the talus

Common Pathologies of the Subtalar Joint According to the American Academy of Orthopaedic Surgery (2014), a common pathology

around the subtalar joint is a talar fracture. A talar fracture usually occurs at the neck of talus during high impact events. Fractures can also occur at the lateral process of the talus, usually during forced eversion. If a fracture is stable, meaning the break has not been displaced, it can usually be treated

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without surgery. A cast is typically placed over the foot for 6-8 weeks while the bones heal. Afterwards, a patient usually goes through a rehabilitation process to build strength and stability. If the bones have been displaced, which is more typical, surgery usually occurs.

Another common pathology is a fracture to the calcaneus. Calcaneal fractures account for 60% of all tarsal bone fractures. The calcaneus is typically fractured in a high-collision event, such as a fall or motor vehicle accident. Treatment usually consists of immobilization and non-weight-bearing to allow the bone to heal, followed by physical therapy. For more severe cases, surgery may be needed.

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TalonavicularJoint

Overview The talonavicular joint is the junction between the talus and the navicular bone. This junction is

often classified as either an ovoid or ball and socket joint and is located on the dorsal-medial aspect of the foot, just distal to the talocrural joint. The talonavicular joint and the calcaneocuboid joint make up the transverse tarsal joint of the midfoot. The transverse tarsal joint allows for the motions of supination

and pronation to occur in the foot. This is especially advantageous when walking over uneven surfaces.

The talonavicular joint receives its blood supply from the lateral tarsal artery, dorsalis pedis, and the lateral and medial plantar arteries. The lateral tarsal artery is a branch off of the dorsalis pedis artery. This is a primary terminal branch of the anterior tibial artery. The lateral and medial plantar arteries are terminal braches from the posterior tibial artery and supply blood to the plantar aspect of the foot.

The plantar surface of the talonavicular joint is innervated by the medial or lateral plantar nerve while the dorsal aspect is innervated by the deep fibular nerve which branches off the common fibular nerve proximal to the knee joint.

Tissue Layers [dorsal to plantar] x Integumentary

o Epidermis o Dermis o Hypodermis

x Dorsal Fascia o Subcutaneous tissue: cutaneous

and sensory nerves and blood vessels, subcutaneous fat stores, other loose connective tissue

o Inferior Extensor Retinaculum x Dorsal Extrinsic Muscle Tendons

o Extensor Digitorum Longus o Fibularis terticus

x Dorsal Muscle Layer o Extensor Digitorum Brevis

o Extensor Hallucis Brevis x Dorsal Neurovascular

o Lateral tarsal artery and dorsalis pedis artery

o Deep fibular nerve x Dorsal Ligaments

o Dorsal Talonavicular Ligament o Bifurcated Ligament o Fibers of the Deltoid Ligament

x Talonavicular Joint Capsule o Synovial membrane o Synovial fluid o Articular cartilage o Periosteum o Bone [talus and navicular]

x Plantar Ligaments

Figure 46. Locatin of transverse tarsal joint

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o Plantar Calcaneonavicular (Spring) Ligament

x Plantar Neurovasculature o Lateral and medial plantar

arteries o Lateral and medial plantar

nerves x Plantar Muscles and Tendons

o Tibialis posterior tendon o Flexor hallucis brevis o Flexor digiti minimi o Quadratus plantae o Flexor hallucis longus tendon

o Flexor digitorum longus tendon o Flexor digitorum brevis

x Plantar fascia and aponeurosis o Subcutaneous fascia: cutaneous

and sensory nerves and blood vessels, subcutaneous fat stores, other loose connective tissue

x Integumentary o Hypodermis o Dermis o Epidermis

Joint Motions and Associated Muscles Table 24. Talonavicular muscles and motions

Talonavicular Motion Primary Mover Stabilizing and Helping Synergists Inversion (aspect of supination)

Tibialis posterior Flexor digitorum longus, flexor hallucis longus, tibialis anterior

Eversion (aspect of pronation)

Fibularis longus Fibularis brevis, fibularis tertius

Dorsiflexion (aspect of pronation)

Tibialis Anterior Fibularis tertius, Extensor halluces longus, extensor digitorum longus

Plantarflexion (aspect of supination)

Gastrocnemius, Soleus Tibialis posterior, fibularis brevis, fibularis longus

*It is important to note that many of these muscles do not cross the talonavicular joint but instead work through the other joints in the foot to convey the movement and allow for motion to be achieved at the talonavicular joint.

Joint Configuration and Planes of Motion The talonavicular joint is comprised of the concave

proximal edge of the navicular bone and the convex distal edge of the talus. The talonavicular joint is difficult because it can be classified as either a diarthrodial ovoid joint or a ball and socket joint depending on the mechanism of motion occurring at the joint and on the weight bearing status. A ball and socket joint allows for more freedom of movement which can be seen while the navicular bone rotates around an axis. This rotation of the navicular bone about its axis allows for more motion. This joint configuration is primarily seen during non-weight bearing. As an ovoid joint, the talonavicular joint has two major planes of motion around the longitudinal and oblique axes. The longitudinal axis is Figure 47. Axes of the foot

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positioned 15 degrees superior to the anterior-posterior axis when rotated around the vertical axis of the foot. It is also 9 degrees medial to the anterior-posterior axis when rotated around the medial-lateral axis. The primary motions that occur around this axis are the eversion and inversion components of pronation and supination respectively. The oblique axis is positioned 52 degrees above and 57 degrees medial to the anterior-posterior axis. The primary motions around this axis are the dorsiflexion and abduction motions associated with pronation and the plantar flexion and adduction motions for supination. Most motions that occur at the talonavicular joint occur simultaneously on both axes.

Talonavicular motion can also occur while in a closed pack position, such as during the stance phases of gait. It is especially important to consider the movement of other joints surrounding the talonavicular joint while it is in this position during gait. Movements at other joints, such as the calcaneus, can allow for more inversion and eversion movement to occur at the talonavicular joint. Heel contact is the first of the stance phases of gait. When the heel strikes the ground, two degrees of plantarflexion occur in the foot in order to accommodate the weight of the body. This movement is caused by eversion of the calcaneus and the moment arm of the bodyweight pushing the talus into slight abduction and dorsiflexion. These motions combine and result in pronation. As the weight of the body is accepted and moves over the foot during the ankle rocker phase of gait, the joints of the foot are pushed further into eversion and dorsiflexion (components of pronation). It is when the weight of the body begins to be accepted by the other leg that the foot starts to move into supination. This is during rapid ankle plantarflexion and allows propulsion of the leg forward. Even though there is movement throughout the foot into eversion and back to inversion, it is only about five degrees of total movement.

Many of the muscles that were designated as primary movers in Table 24 do not directly cross the talonavicular joint. The only one that crosses the joint is the posterior tibialis, which is the primary inverter. It is the primary inverter due to the line of pull as it wraps around the posterior aspect of the medial malleoli and that it has the greatest cross sectional area of the muscles that perform inversion. The gastrocnemius and soleus do not cross the talonavicular joint but due to the influence of motion at other joints in the foot, they are the primary plantarflexors due to cross sectional area and line of pull at the posterior aspect of the calcaneus. Dorsiflexion is primarily done by tibialis anterior due to cross sectional area and line of pull as its distal attachment is the medial cuneiform and first metatarsal head. It does not cross the talonavicular joint but works by conjunct motion. Eversion is primarily performed by the peroneus/fibularis longus. This has the greatest cross sectional area, as it is the largest of the fibularss, and line of pull as it wraps around the lateral malleoli.

Biomechanics and Arthrokinematics The talonavicular joint works in conjunction with the calcaneocuboid joint to form the

transverse tarsal joint. This is the junction of the rear and mid foot regions. The talonavicular joint is primarily involved in the composite motions of pronation and supination. Pronation consists of dorsiflexion, eversion, and abduction. Supination consists of plantarflexion, inversion, and adduction. Even though these motions are more generally described as pertaining to the transverse tarsal joint, there is more motion at the talonavicular joint as compared to the calcaneocuboid joint. In order to observe the isolated motion of transverse tarsal joint, it is necessary to stabilize the subtalar joint, as

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this is one joint that works with the talonavicular joint to provide the maximal amount of supination and pronation motion during weight bearing. Once the subtalar joint is stabilized, it can be observed that at the talonavicular articulation the navicular bone spins during supination/pronation motion.

It is difficult to isolate the specific motions in order to determine the range of motion available at each individual joint. Due to this, range of motion will be discussed as it pertains to the foot as a whole. There are about 20-25 degrees of inversion and 10-15 degrees of eversion available in a typical foot. The increased motion available for inversion indicates that there is more motion available for supination as compared to pronation. A normal foot also has 10-20 degrees of dorsiflexion and 50-60 degrees of plantarflexion. A lot of this motion originates in the region of the talocrural joint.

When performing open kinetic chain supination, the navicular bone spins to allow for the motion to occur. This is primarily done by the posterior tibialis which has an attachment on the navicular bone and is a primary mover for supination. During the motion of supination, the posterior tibialis spins the navicular and pulls the foot into inversion resulting in the lateral column of the foot to be pulled inferior to the medial column of the foot. The navicular bone is the key pivoting point for this motion.

Closed kinetic chain supination and pronation also occur at the talonavicular joint. This motion is important during stance phases of gait and is especially important to maintain balance and footing on uneven surfaces. This is discussed in greater depth in the biomechanics section of the calcaneocuboid joint.

In order to understand the importance of pronation and supination during gait, it is essential to discuss the medial longitudinal arch of the foot. The foot utilizes the truss mechanism to aid in gait and other weight bearing activities. The medial longitudinal arch is located in the “instep” of the foot. It is

comprised of the calcaneus, talus, navicular, cuneiforms, and three of the metatarsal bones. It is also comprised of soft tissue structures such as the plantar fat pads, superficial plantar fascia, spring ligament, and sesamoid bones. This can be seen in Figure 48.The talonavicular joint is key as it is one of the major structures involved in maintaining the height of the medial longitudinal arch.

If weight bearing were to occur without the presence of the medial longitudinal arch conveying the forces of the body into the truss system, all the weight of the body would be transmitted through one area. This could cause excessive stress, which could result in pathologies such as fracturing and

Figure 48. Medial longitudinal arch

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overuse syndromes. Due to the presence of the medial longitudinal arch, the force of the body weight can be distributed throughout the joints of the foot. The talonavicular joint acts as the major hinge of the truss and allows for the acceptance and distribution of these forces to other joints, but especially to the spring ligament and plantar fascia of the foot. As body weight is accepted, the arch flattens (seen in the lower picture in Figure 49), allowing for the acceptance and storage of energy and forces via the intrinsic muscles of the foot, plantar fascia, and spring ligament. This is depicted as the black arrow in the lower picture in Figure 49. As a weight shift occurs to decrease the amount of force/pressure coming through the joint, the plantar structures act as a spring to transmit energy for movement. They also allow for the medial longitudinal arch to return to its original shape. This mechanism in reference to gait will be discussed further in the calcaneocuboid biomechanics section.

Ligaments of the Talonavicular Joint Table 25. Talonavicular ligaments

Ligament Proximal Attachment

Distal Attachment Function Other associated joint constraints

Interosseous Calcaneal sulcus Talar sulcus and adjacent area

Gives posterior stability to the talonavicular joint

Inversion

Dorsal talonavicular

Neck of talus Dorsal surface of navicular bone

Gives dorsal stability to the talonavicular joint

Eversion

Bifurcated

Anterior process of calcaneus

Superior and lateral aspect of navicular bone

Gives lateral stability to the talonavicular joint

Inversion

Anterior fibers of deltoid

Medial malleolus Navicular tuberosity Gives medial stability to the talonavicular joint

Eversion and abduction

Plantar Calcaneonavicular (Spring )

Anterior aspect of sustentaculum tali of calcaneus

Plantar aspect of navicular bone

Forms the floor of the talonavicular joint; supports head of talus and medial longitudinal arch

Abduction

Figure 49. Truss mechanism

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Common Pathologies of Talonavicular Joint There are a few common pathologies that can affect the talonavicular joint. One pathology is a medial eversion ankle sprain. This is the least common of ankle sprains and can be caused by instability further up the kinematic chain, weakness in muscles that invert such as the posterior tibialis, or by an accident that forces the collapse of the ankle medially. This can damage the deltoid ligament and cause pain and swelling in the surrounding tissues. Since the deltoid ligament is a part of the ligaments that give stability to the talonavicular joint, stress to this ligament can cause dysfunction at the joint. Medial eversion ankle sprains are treated initially with ice, compression, elevation, and activity modification. After the initial swelling and pain are manageable, strengthening of the inverters in the leg and muscles further up the chain occurs to help recover and prevent future injuries.

Another common pathology is tibialis posterior tendinitis or strain. This can be caused by overuse leading to damage and inflammation or by a motion that puts too much stress on the tendon, causing it to tear or stretch beyond its elastic abilities. This pathology is often accompanied by tenderness upon palpation in the area of the tendon or by pain while contracting the muscle belly. This is treated with modification of activity until healing occurs and then strengthening and stretching for recovery and prevention of future injury.

The talonavicular joint is a key joint for maintaining the structure of the arch of the foot. Due to this, any weakness in talonavicular joint can result in deformity of the arch and foot pain. A pathology associated with this is valgus flat foot or pes planus. This is one example where it is important to acknowledge that the entire lower extremity works as a chain; a weakness at one point can result in pathology at another location. It can be caused by weakness at the hip, specifically the gluteals. This may be a cause pain at the foot or anywhere up the chain, specifically at the knees or low back. It is treated by strengthening of the intrinsic muscles of the foot and inverters. If the deformity is debilitating enough, orthotics can be used to maintain a more neutral arch and decreased the strain on the tissues.

Rheumatoid Arthritis (RA) often results as a secondary pathology to deformities of the feet, especially valgus flat foot. Deformities of the foot can cause irregular wearing on the joints, which increases the risk and prevalence of RA. This can greatly affect ADLs, especially walking, and can have a great influence on daily life. Strengthening can help alleviate some of the pain but due to the progressive and degenerative nature of the condition, it is unlikely to be pain free (Miyamoto, 2004).

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CalcaneocuboidJoint

Overview The calcaneocuboid joint is found on the lateral side of the foot, just distal to the subtalar joint and the lateral malleoli. It consists of the distal surface of the lateral calcaneus and the proximal surface of the cuboid. It is combined with the talonavicular joint to form the transverse tarsal joint of the midfoot (see Figure 46). The calcaneocuboid plays a more prominent role in stabilization when compared to the talonavicular joint which demonstrates much more motion.

The calcaneocuboid receives its blood supply from the lateral tarsal artery and the lateral plantar artery. The lateral tarsal artery is a branch off of the dorsalis pedis artery and helps to supply blood to the tarsals and the lateral aspect of the dorsum of the foot. The lateral plantar artery is a branch off of the posterior tibialis artery and supplies the lateral aspect of the plantar surface of the foot with blood.

The calcaneocuboid joint is innervated by the deep fibular nerve and by the lateral plantar nerve. The deep fibular nerve runs down the anterior lateral aspect of the leg and innervates a good portion of the dorsal aspect of the foot. The lateral plantar nerve is a branch off the tibial nerve which innervates the lateral aspect of the plantar surface of the foot.

Tissue Layers [dorsal to plantar] x Integumentary

o Epidermis o Dermis o Hypodermis

x Dorsal Fascia o Subcutaneous tissue: cutaneous

and sensory nerves and blood vessels, subcutaneous fat stores, other loose connective tissue

o Inferior Extensor Retinaculum x Dorsal Extrinsic Muscle Tendons

o Extensor Digitorum Longus o Tibialis Anterior

x Dorsal Muscle Layer o Extensor Digitorum Brevis o Extensor Hallucis Brevis

x Dorsal Neurovascular o Lateral tarsal artery o Deep fibular nerve

x Dorsal Ligaments

o Dorsal calcaneocuboid ligament o Bifurcated ligament

x Calcaneocuboid Joint Capsule o Synovial membrane o Synovial fluid o Articular cartilage o Periosteum o Bone [calcaneus and cuboid]

x Plantar Ligaments o Long plantar ligament o Plantar calcaneocuboid [short

plantar] ligament x Plantar Neurovasculature

o Lateral plantar artery o Lateral plantar nerve

x Plantar Muscles and Tendons o Tibialis posterior tendon o Fibularis brevis and longus

tendons o Flexor hallucis brevis o Flexor digiti minimi

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o Quadratus plantae o Flexor digitorum longus tendon o Flexor digitorum brevis o Abductor digiti minimi

x Plantar fascia and aponeurosis o Subcutaneous fascia: cutaneous

and sensory nerves and blood

vessels, subcutaneous fat stores, other loose connective tissue

x Integumentary o Hypodermis o Dermis o Epidermis

Joint Motions and Associated Muscles Table 26. Calcaneocuboid muscles and motions

Motion Primary Mover Stabilizing and Helping Synergists Inversion (aspect of supination) Tibialis posterior Flexor digitorum longus, flexor

hallucis longus, tibialis anterior Eversion (aspect of pronation) Fibularis longus Fibularis brevis, fibularis tertius Dorsiflexion (aspect of pronation)

Tibialis Anterior Fibularis tertius, Extensor halluces longus, extensor digitorum longus

Plantarflexion (aspect of supination)

Gastrocnemius, Soleus Tibialis posterior, fibularis brevis, fibularis longus

*Many of these muscles do not directly cross the calcaneocuboid joint but instead work through the other joints in the foot to convey the movement and allow for motion to be achieved at the calcaneocuboid joint.

Joint Configuration and Planes of Motion The calcaneocuboid joint is a sellar joint, indicating that distal surface of the calcaneus and proximal surface of the cuboid have convex and concave surfaces. The interaction of the bone surfaces prevents the normal gliding motion at the joint and acts more like a wedge. This decreases the motion allowed at the calcaneocuboid joint, increasing the stability and increasing the motion at the talonavicular joint in order to compensate.

Similar to the talonavicular joint, the calcaneocuboid joint allows for pronation and supination to occur at the mid foot but to a much lesser degree. Due to the nature of the joint, the main function of the calcaneocuboid joint is stability. Thus, not much motion is observed at this joint. The little motion that does occur at this joint is observed on the longitudinal and oblique axes that were described in the talonavicular joint configuration section. There is 20-25 degrees of inversion and 10- 15 degrees of eversion observed at the transverse tarsal joint, but this includes the motion at the talonavicular joint as well.

Supination occurs at the calcaneocuboid joint due to the pull of the posterior tibialis. This muscle acts on the joint indirectly through the pull of the talonavicular joint. The motion at the talonavicular joint allows for consequential motion at the calcaneocuboid into supination. Pronation occurs due to the pull of anterior tibialis and fibularis brevis and longus muscles which act mostly indirectly on the calcaneocuboid to pull the entire foot into eversion and dorsiflexion.

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Similar to many of the other joints in the foot, many of the movements that occur at the calcaneocuboid joint are performed primarily by muscles and tendons that do not directly cross the joint. There is not much motion at the calcaneocuboid motion but the little that occurs is performed by the same muscles that influence the talonavicular joint.

Biomechanics and Arthrokinematics The calcaneocuboid joint works with the talonavicular joint to form the transverse tarsal joint of the midfoot. This joint is essential during gait to accept the weight of the body and transmit forces through the medial longitudinal arch and the truss mechanism to the rest of the foot (discussed in the biomechanics section of the talonavicular joint). This joint is also important in the formation of the rigid lever that allows for forces to be generated during the push off phase of gait.

The initial phase of gait is heel contact. Prior to this phase, the foot is primarily in supination as it swings through. The contact with the ground causes the foot to go into pronation in order to absorb the forces from the weight of the body. It is again important to note that the movements at the transverse tarsal joint influence and are reflected in movements of the forefoot. Some of the energy of these forces is stored in the soft tissue of the plantar region, such as the spring ligament and plantar fascia. As the gait progresses into mid stance, the foot continues to pronate to absorb the additional forces, especially during the transition to single leg stance. Then as the gait cycle progresses towards the rapid plantarflexion and push off phase, the foot moves more into supination in order to form the rigid lever needed for push off (Figure 50).

The rigid lever is formed when the joints of the foot are rigid or locked into place. This allows the transmission of forces and the propulsion of the foot forward during gait. In order to understand the rigid lever, it is important to be able to picture the axes of each of the joints (Figure 51). When the axes are parallel to each other, the joint surfaces are able to move and glide on one another. This is seen in most of the foot but is being looked at specifically at the transverse tarsal joint and the joints of the calcaneus. The parallel axes are important during pronation to be able to transmit loads and forces and store energy during the weight acceptance phases of gait. The axes can also be in positions where they are not parallel to each other. This is what forms the rigid lever. The further from parallel that the axes are, the less congruent the surfaces and the less they are able to

Figure 50. Rigid lever during supination

Figure 51. Axes of the transverse tarsal joint during gait

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move against each other. The decreased motion means that all forces are transferred and allow the foot to push off. The axes are less congruent during supination, which occurs towards the late stages of stance. This allows the foot to become a rigid lever to allow the force of the gastrocnemius and soleus to be fully transferred to allow push off from the ground and to aid in limb advancement.

Ligaments of the Calcaneocuboid Joint Table 27. Calcaneocuboid ligaments

Ligament Proximal Attachment

Distal Attachment Function Other associated joint constraints

Dorsal calcaneocuboid

Dorsal calcaneus surface

Dorsal cuboid surface

Gives dorsal-lateral stability to the calcaneocuboid joint

Dorsal and lateral displacement of cuboid

Bifurcated ligament

Distal calcaneus Cuboid and navicular bone

Gives dorsal stability to the calcaneocuboid joint

Dorsal displacement of cuboid

Long plantar ligaments

Plantar surface of the calcaneus and cuboid

Plantar surface of the bases of the metatarsals

Gives plantar stability to the calcaneocuboid joint

Plantar displacement of the bones in the foot

Plantar calcaneocuboid (Short plantar)

Anterior and deep to the long planar ligament

Plantar surface of cuboid bone

Gives plantar stability to the calcaneocuboid joint

Plantar displacement of the bones in the foot

Common Pathologies of Calcaneocuboid Joint A cuboid fracture is a common pathology of the calcaneocuboid joint. There are two types of

fractures that can occur: stress or trauma. Stress fractures can be caused by overuse or issues with bone integrity. Trauma fractures can occur from crushing, MVA, accidents or related to sports. Similar to other fractures in the foot, when there is a fracture, it is often accompanied by pain and inability or difficulty while weight bearing. Fractures are diagnosed with imaging, usually x-ray, and are treated with casting and activity modification.

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The Cuneonavicular Joint

Overview The cuneonavicular joint of the midfoot consists of the three cuneiform bones and their

articulations with the more proximal navicular bone. The medial, intermediate, and lateral cuneiform bones each articulate with the anterior aspect of the navicular bone, which has three separate facets for each corresponding cuneiform. Though these joints can be broken down into three separate sub-joints (medial, middle and lateral cuneonavicular joints) they are usually thought of as only one. There is only a small degree of motion at each of the cuneonavicular joints but all of the separate joint motions are correlated with one another and with the motions occurring throughout the entire foot. The motions play an important role in contributing to foot pronation and supination and therefore motion at these joints impacts the foot’s function as a unit. The motion at this joint effects the biomechanics of gait and other weight-bearing activities.

The dorsal and plantar surfaces of this joint have their own respective nerve innervations. The deep peroneal (or fibular) nerve innervates the dorsal aspect of the entire joint. The plantar surface, on the other hand, is innervated by multiple nerves depending on which joint segment is being referenced. On the plantar surface, the medial and intermediate cuneonavicular joints are innervated by the medial plantar nerve, whereas the lateral cuneonavicular joint is innervated by the lateral plantar nerve. The plantar aspect of this joint receives its blood supply from the medial and lateral plantar arteries (terminal branches of the posterior tibial artery), as well as from the deep plantar arch, which is formed by the lateral plantar artery and the deep plantar artery. The dorsal aspect of the joint is supplied by the medial and lateral tarsal arteries, which branch off of the dorsalis pedis artery.

Tissue Layers x Integumentary

o Epidermis o Dermis o Hypodermis

x Subcutaneous o Adipose tissue o Fascia layers

� Superficial fascial layer � Deep fascial layer � Plantar aponeurosis � Medial and lateral

plantar fascial layers x Muscles and Tendons

o Extensor digitorum longus tendon

o Extensor digitorum brevis o Extensor hallucis longus tendon o Extensor hallucis brevis o Quadratus plantae

o Flexor hallucis brevis tendon o Flexor hallucis longus tendon o Tibialis posterior tendon o Flexor digitorum longus tendon o Flexor digitorum brevis o Tibialis posterior tendon

x Neurovasculature o Subcutaneous

� Superficial fibular nerve � Dorsal digital nerves � Dorsal venous network

o Deep � Deep fibular nerve � Dorsalis pedis artery � Medial and lateral

tarsal arteries � Medial plantar artery &

nerve

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� Lateral plantar artery & nerve

x Ligaments o Dorsal cuneonavicular ligament o Plantar cuneonavicular

ligament x Joint Capsule

o Synovial membrane o Synovial fluid o Articular cartilage o Bones

� Navicular � Median Cuneiform � Intermediate cuneiform � Lateral cuneiform

Joint Motions and Associated Muscles Table 28. Cuneonavicular joint muscles and motions

Motion Primary Mover Stabilizing and Helping Synergists Dorsiflexion Tibialis Anterior Extensor hallucis longus and brevis

Fibularis tertius Plantarflexion Tibialis Posterior Gastrocnemius, soleus, flexor

digitorum longus Flexor hallucis longus

Eversion Fibularis longus Fibularis brevis and tertius Inversion Tibialis posterior Tibialis anterior, flexor hallucis

longus, flexor digitorum longus *All motions are accomplished by slight gliding of the cuneonavicular joint as a result of muscle actions on joints proximal to the cuneonavicular joint itself. These motions are components of supination (inversion, plantarflexion, adduction) and pronation (eversion, dorsiflexion, abduction) of the midfoot.

Joint Configuration and Planes of Motion The anterior surface of the navicular bone is slightly convex transversely. Posterior surfaces of

each cuneiform bone are slightly concave. Gliding motions of this synovial plane joint occur in the sagittal, transverse, and frontal planes in order to achieve conjunct motions translated from the hindfoot to the midfoot. The small degree of glide at this joint therefore contributes to supination and pronation of the foot and ankle complex.

The cuneonavicular joint is classified as a synovial plane joint. Motion accomplished at the cuneonavicular joint is a result of the three ellipsoidal navicular surfaces and three concave cuneiform surfaces gliding in opposite directions from one another. This allows for a small amount of motion, but not much, because the foot must remain fairly rigid during walking, running, and other weight-bearing activities to support the rest of the body. Though the exact amount of motion available at this joint is variable depending on the source referenced, it is generally about five to ten degrees of motion. This motion is occurring in an oblique plane of motion which means that there is some motion occurring in each plane of the body.

Biomechanics and Arthrokinematics The main function of this joint is to help transfer pronation and supination motions distally

towards the hindfoot from the forefoot. This transferring of motion is essential during gait. The foot and ankle move conjunctly to supinate and create a rigid lever during the push-off phase of gait and then move into pronation during initiation of stance phase in order to absorb the load of the body during

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weight acceptance and adapt to variations in terrain. The cuneonavicular joint allows only a slight amount of motion, which is enough to allow the mid-foot and forefoot to move in conjunction with the rear-foot.

Another way that stability of the foot is achieved is via the medial and lateral longitudinal arches of the foot (Figure 52). These arches work in conjunction with the transverse arch to absorb forces during weight bearing. The cuneonavicular joint is an essential component of the medial longitudinal arch of the foot, along with the calcaneus, talus, and three medial metatarsals. This arch is lowered towards the ground during weight-being in order to help attenuate loads on the nearby joints. Further information can be found in the biomechanics section of the talonavicular joint.

When considering the primary movers of the cuneonavicular joint, it is important to note that all the muscles act indirectly on this joint. No muscles truly cross the joint and therefore all motions are a result of motion being translated through the joint indirectly. Two primary movers will be considered, one for each of the composite motions. First, supination is accomplished primarily by the tibialis posterior muscle. Second, pronation is accomplished primarily by the fibularis longus muscle. These are considered the two primary movers, though other muscles contribute to the motions of pronation and supination as well.

The tibialis posterior contributes to both inversion and plantarflexion, as seen in Table 1. It has the most ideal line of pull and a substantial cross sectional area to make it the primary supinator at the midfoot. The fibularis longus is the primary muscle responsible for pronation due to its attachment to the medial plantar aspect of the foot and its resultant line of pull. The fibularis longus contributes to eversion of the foot. Both the tibialis posterior and fibularis longus muscles are essential in keeping the foot in correct alignment for gait. They work as primary movers in conjunction with other extrinsic muscles of the foot to allow for pronation and supination during gait.

Ligaments of the Cuneonavicular Joint Table 29. Cuneonavicular ligaments

Ligament Proximal Attachment

Distal Attachment

Function Other associated joint constraints

Dorsal cuneonavicular (three small ligaments)

Navicular bone (dorsal surface)

One attached to each dorsal cuneiform bone

Stabilizes dorsal surface of the joint

Resists excessive gliding

Figure 52. Arches of the foot

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*Plantarcuneonavicuar (three small ligaments)

Navicular bone (plantar surface)

One attached each plantar cuneiform bone

Stabilizes plantar surface of the joint

Resists excessive gliding

*Tibialis posterior tendon: contributes plantar stability to the plantar cuneonavicular ligaments.

Common Pathologies of the Cuneonavicular Joint There are no commonly occurring pathologies of the cuneonavicular joint. However, pathologies

that occur relatively uncommonly to the joint and surrounding areas include dislocation of the first ray, midtarsal pes planus, and Mueller-Weiss syndrome. In the case of dislocation of the first ray, the first ray is comprised most proximally at the medial cuneonavicular joint. This dislocation is not very commonly seen. It can be treated with relocation and immobilization of the affected lower extremity. (Toullec, 2015).

Midtarsal pes planus can also occur predominately due to cuneonavicular and talonavicular joint dysfunction. Pes planus, or “flat foot,” has been seen in multiple case reports and has been successfully treated via early reduction. People with pes planus often times are asymptomatic. However, in more serious cases, symptoms of pes planus include foot pain and instability as well as issues further up the chain such as knee pain (Figure 53). Symptoms may be provoked by changes in work environment

and/or activity level resulting in long hours spent standing. (Bourdet, 2013).

Finally, Mueller-Weiss Syndrome refers to spontaneous osteonecrosis of the navicular bone. It is more common in females and is associated with navicular fractures. It can be progressive and lead to severe and chronic midfoot pain. In multiple studies examining Mueller-Weiss Syndrome, radiographs have shown a dorsomedial dislocation of the navicular bone along with the collapse of the lateral navicular bone, resulting in a comma-shaped configuration. (Nguyen, 2014). Treatment for Mueller-Weiss Syndrome involves immobilization and often surgery.

Figure 53. Pes planus

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TheCuboideonavicularJoint Overview

The cuboideonavicular joint is comprised of the cuboid and navicular bones of the midfoot. The lateral surface of the navicular bone articulates with the medial aspect of the posterior surface of the cuboid bone to form this joint. Both of these surfaces are quite flat, as seen in (Figure 54). This joint is often a fibrous articulation, meaning that little to no motion is occurring between the two joint surfaces. However, it can also be a synovial plane joint with a slight amount of glide occurring. When this is the case, it is considered to be a part of the cuneonavicular joint capsule (consisting of articulations between the three cuneiform bones and the navicular bone).

The cuboideonavicular joint is within the midfoot, and therefore plays an integral role in transferring motion throughout the foot. It has a role in load absorption and transfer and contributes to the composite motions of supination and pronation of the foot and ankle complex which are key components of gait and other weight bearing activities.

The cuboideonavicular joint receives its nerve innervation and vascular supply from different sources on the plantar and dorsal joint surfaces. The plantar surface receives nerve innervation from articular branches of the medial and lateral plantar nerves and blood supply from branches of the lateral plantar artery. The dorsal surface of the joint is innervated by the deep fibular nerve. Its blood supply comes from the lateral tarsal artery, which is a branch of the dorsalis pedis.

Tissue Layers x Cutaneous

o Epidermis o Dermis o Hypodermis

x Subcutaneous o Adipose tissue o Fascia layers

� Superficial fascia � Deep fascia � Plantar aponeurosis � Medial and lateral

plantar fascia x Muscles and Tendons

o Extensor digitorum longus tendon

o Extensor digitorum brevis o Extensor hallucis longus tendon o Tibialis anterior tendon o Tibialis posterior tendon o Quadratus plantae o Flexor digitorum brevis o Flexor hallucis longus o Flexor hallucis brevis

x Neurovasculature o Superficial fibular nerve o Deep fibular nerve o Dorsal digital nerves

Figure 54. Cuboideonavicular joint

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o Dorsal pedis artery o Lateral tarsal artery o Lateral branch of fibular nerve o Lateral plantar artery o Medial and lateral plantar

nerves x Ligaments

o Dorsal cuboideonavicular o Interosseous cuboideonavicular o Plantar cuboideonavicular

x Joint Capsule o Synovial membrane o Synovial fluid o Articular acrtilage o Bones

� Lateral surface of navicular bone

� Posteriomedial surface of cuboid bone

Joint Motions and Associated Muscles Table 30. Cuboideonavicular muscles and motions

Motion Primary Mover Stabilizing and Helping Synergists Dorsiflexion Tibialis Anterior Extensor hallucis longus and brevis

Fibularis tertius Plantarflexion Tibialis Posterior Gastrocnemius, soleus, flexor

digitorum longus Flexor hallucis longus

Eversion Fibularis longus Fibularis brevis and tertius Inversion Tibialis posterior Tibialis anterior, flexor hallucis

longus, flexor digitorum longus *These motions result from muscles acting on other joints of the foot and ankle, causing indirect motion at the cuboideonavicular joint. This joint is in some cases synarthroidial, or fibrous, in which case close to no motion will occur. In other cases, the joint is considered to be a plane joint, in which case the joint has s light amounts of glide that contribute to the above motions in conjunction with the cuneionavicular joint.

Joint Configuration and Planes of Motion There are two possible configurations of the cuboideonavicular joint. The more common

presentation seen in the foot is a fibrous cuboideonavicular joint. In this case, little motion occurs between the two joint surfaces. The less common presentation is a synovial plane joint. In this case, a slight amount of gliding occurs between the cuboid and navicular bones in all three planes of the body (transverse, sagittal, and frontal). The joint surfaces are both relatively flat. Motion at this joint is a result of muscles acting on all the joints of the forefoot, rearfoot, and ankle. No muscles cause direct motion, seeing as no muscles directly cross this joint. As with all midtarsal joints of the midfoot, this joint contributes to pronation and supination of the foot/ankle complex when movement is seen at the joint.

Most often, the cuboideonavicular joint is a fibrous joint. When this is the case, very limited to no motion occurs between the navicular and cuboid bones. The articulation acts more as an immobile region of the midfoot. Conversely, at times the cuboideonavicular joint is a synovial plane joint. This is a less common presentation. The two articular surfaces are both flat and allow for a slight degree of gliding within the synovial capsule which is continuous with the capsule of the cuneonavicular joint. There still exists only a slight amount of gliding between the two bones and a slight degree of motion in

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the sagittal, transverse, and frontal planes. In both presentations of this joint, it plays a role similar to that of all joints of the midfoot; transferring motion between the rearfoot to forefoot, while maintaining stability of the midfoot.

Biomechanics and Arthrokinematics Whether the joint is fibrous or synovial, this region has an integral function during gait, and

allows the foot to function as a lever and a shock absorber depending on the phase of gait. This is related closely to the rearfoot (subtalar joint), which is where most of the motion during gait is occurring. Gait mechanics are achieved by the composite motions of pronation and supination. Upon heel strike and continuing through the weight acceptance phase of gait, the foot pronates in response to loading. This requires eversion and dorsiflexion. The cuboideonavicular joint functions as part of the midfoot to transfer the “twisting” motion between the fore- and hind-foot, allowing the foot to pronate and therefore become a more malleable complex to accept weight and adapt to the terrain. The navicular and cuboid bones are more parallel to one another when the foot is placed in a more pronated position, which produces a more supple forefoot.

As the gait cycle continues through midstance and into push-off, the orientation of joints in the foot change in order to create a more rigid lever. During late stance phase in preparation for push-off and swing phases of gait, the foot moves into supination. The movement involves plantarflexion and inversion. These motions are also translated through the midfoot, including the cuboideonavicular joint. The whole foot must function as a unit, including the orientation of the cuboid and navicular bones to become less parallel to one another. This causes the forefoot to be less mobile. The rigid “lever” is created when the foot supinates, propelling the body forward to continue the gait cycle. The interplay between pronation and supination is essential for gait mechanics and the midfoot, which includes the cuboideonavicular joint, allows these motions to occur.

The primary mover for pronation is the fibularis longus due primarily to its line of pull as well as its cross sectional area. The fibularis longus has an optimal line of pull because it originates on the lateral aspect of the fibula and inserts on the plantar surface of the first metatarsal and medial cuneiform bones. Thus, it pulls the foot into eversion and dorsiflexion. It also has the greatest cross-sectional area of the ankle everters. The primary mover into supination is the tibialis anterior muscle. Its line of pull and cross sectional area qualify it as the primary mover. These and all other muscles that act on this joint are acting indirectly, as they do not actually cross the joint itself.

Ligaments of the Cuboideonavicular Joint Table 31. Cuboideonavicular ligaments

Ligament Proximal Attachment

Distal Attachment

Function Other associated joint constraints

Dorsal Cuboideonavicular Ligament

Dorsum of distal cuboid

Dorsum of navicular

Stabilization of cuboideonavicular joint

Restricts excessive glide at the joint

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Plantar Cuboideonavicular Ligament

Plantar surface of medial cuboid

Plantar surface of navicular

Stabilization of cuboideonavicular joint

Restricts excessive glide at the joint

Interosseous Cuboideonavicular Ligament

Dorsal and lateral aspects of distal phalanx

Plantar and lateral aspects of distal phalanx

Prevents excessive varus stresses on phalanges

Restricts excessive glide at the joint

Common Pathologies of the Cuboideonavicular Joint There are rarely pathologies seen at the cuboideonavicular joint. However, any disruption of the

midfoot, rearfoot, or forefoot can cause dysfunction at this joint. Notably, a fracture of the cuboid bone can lead to disruption of this and other joints associated with the cuboid bone. This injury can occur as a result of compressive and tensile forces, with plantar fascia dysfunction being a contributing factor. Cuboid fractures often times will heal conservatively but can require surgical fixation if severe (Yu, 2013). Physical therapy interventions may include patient education on activity modifications to assist in healing of the fractured cuboid bone, as well as addressing pain.

Cuboid syndrome is another pathology that occurs due to laxity in the ligaments of the cuboid bone. Cuboid syndrome is described as lateral midfoot pain, isolated to the area of the cuboid bone. It can occur due to misalignment of the cuboid bone as a result of ligament laxity. Manual therapy has been shown to decrease symptoms associated with cuboid syndrome, specifically a manipulation of the cuboid bone commonly called a “cuboid whip” (Matthews, 2014).

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TheIntercuneiformandCuneocuboidComplex Overview

The intercuneiform and cuneocuboid complex (abbreviated as IC-CC) is composed of the articulations between the three cuneiform bones as well as the articulation of the cuneiform bones and cuboid bone of the midfoot. The medial cuneiform bone articulates with the intermediate cuneiform bone. The intermediate cuneiform articulates with both the medial and lateral cuneiforms. The lateral cuneiform articulates with the intermediate cuneiform and with the cuboid bone. The medial aspect of the cuboid bone has an oval facet which forms its articulation with the lateral cuneiform. The cuneiform bones have an essential structural role in contributing to the transverse arch of the foot. The orientation of these bones account, in part, for the transverse convexity of the dorsal aspect of the midfoot.

The blood supply of the IC-CC comes from the lateral and medial plantar arteries. Nerve innervation of the planter aspect of the joint comes from the medial and lateral plantar nerves, whereas the dorsal aspect is innervated by the deep fibular nerve.

Tissue Layers x Cutaneous

o Epidermis o Dermis o Hypodermis

x Subcutaneous o Adipose tissue o Fascia layers

� Superficial � Deep � Plantar Aponeurosis � Medial and Leteral

Plantar x Muscles and Tendons

o Extensor digitorum longus tendon

o Extensor digitorum brevis o Extensor hallucis longus tendon o Tibialis posterior tendon o Quadratus plantae o Flexor hallucis longus o Flexor hallucis brevis o Flexor digitorum brevis

x Neurovasculature o Superficial fibular nerve

o Deep fibular nerve o Dorsal digital nerves o Dorsal pedis artery o Lateral tarsal artery o Medial and lateral branches of

deep fibular nerve o Lateral and medial plantar

arteries o Medial and lateral plantar

nerves x Ligaments

o Dorsal IC-CC ligaments o Plantar IC-CC ligaments o Interosseous ligaments o Long plantar ligment

x Joint Capsule o Synovial membrane o Synovial fluid o Articular acrtilage o Bones

� Lateral surface of navicular bone

� Posteriomedial surface of cuboid bon

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Joint Motions and Associated Muscles Table 32. IC-CC muscles and motions

Motion Primary Mover Stabilizing and Helping Synergists Dorsiflexion Tibialis Anterior Extensor hallucis longus and brevis

Fibularis tertius Plantarflexion Tibialis Posterior Gastrocnemius, soleus, flexor

digitorum longus Flexor hallucis longus

Eversion Fibularis longus Fibularis brevis and tertius Inversion Tibialis posterior Tibialis anterior, fexor hallucis

longus, flexor digitorum longus *Note that these are the same motions, primary movers, and helping muscles as the two previously discussed joints. Much like the other joints of the midfoot, all muscles act indirectly on the IC-CC. No muscles directly cross the joints of this complex.

Joint Configuration and Planes of Motion The IC-CC consists of the three cuneiforms and the cuboid bone and their articulations with one

another. There are a total of three articulations: two between the three cuneiform bones and one between the lateral cuneiform and cuboid bones. All joint surfaces are flat, creating synovial plane joints. Therefore, relatively no concavity or convexity exists in this joint complex. A small amount of glide occurs at each of the joints of the IC-CC, contributing to midfoot motion and essentially the translation of motion between the forefoot and rearfoot. The joints between the cuneiforms and cuboid are oriented parallel to the long axis of the metatarsals. The motion at these joints occurs in the transverse, frontal, and sagittal planes of the body. This is due to the fact that the joint surface is not aligned with a single plane of the body, which indicates that a small gliding motion in only one joint plane results in even smaller gliding motions in all three planes of the body.

Biomechanics and Arthrokinematics As with all joints of the midfoot, the IC-CC has an important role in providing stability to the

midfoot. It also allows for small amounts of motion (gliding and rolling) in order to contribute a small amount of motion to foot supination and pronation. This is essential during gait and other weight bearing activities, as the whole foot must function as a unit to allow for propulsion, weight bearing, and overall functioning of the foot/ankle complex, thus affecting the whole kinetic chain of the body. The biomechanics of gait in relation to the midfoot and foot as a whole have been discussed in the cuboideonavicular and cuneonavicular joint overviews, including the importance of supination and pronation during the gait cycle. Reference the previous two sections for more information on this topic. The IC-CC’s role in stability will be discussed here, seeing as stability via the transverse arch is a unique biomechanical role of this joint complex.

The cuneiform bones are shaped so that the plantar aspects are narrower than the dorsal aspects. This creates an arch shaped transversely across the distal midfoot. Thus, these bones, along with the metatrasal heads, are the main contribution making up the transverse arch of the foot (see

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Figure 55). The arch is reinforced by ligaments, muscles and their tendons. Ligaments contributing to the transverse arch include the interosseous ligaments and plantar and dorsal ligaments. For more information

on the longitudinal arches of the foot, refer to the biomechanics section of the talonavicular joint.

The interosseous, plantar, and dorsal ligaments of the foot aid in reinforcing the transverse arch. The arch is also stabilized by muscles including the fibularis longus, tibialis posterior, and intrinsic muscles of the foot. Both the fibularis longus and tibialis posterior tendons span across the plantar surface of the foot, aiding in support of the transverse arch as well as the medial and lateral longitudinal arches. The transverse arch or the midfoot allows the midfoot to absorb load. In weight bearing, the arch distributes the load placed on the foot over a broader area.

As with all intertarsal joints comprising the midfoot region, no muscles act directly on the IC-CC. However, motions can occur due to muscles acting indirectly on the complex. The main motions of the midfoot are pronation and supination. Pronation can be broken down into the planar movements of eversion and dorsiflexion, and supination can be broken down into inversion and plantarflexion. When considering cross-sectional area and lines of pull as well as moment arms of all muscles creating these composite motions, the primary movers into supination and pronation are the tibialis posterior muscle and the fibularis longus muscle, respectively.

Ligaments of IC-CC Table 33. IC-CC ligaments

Ligament Proximal Attachment

Distal Attachment

Function Other associated joint constraints

Dorsal IC-CC Ligamnets

Dorsal aspect of cuneiform bones (medial, intermediate, lateral)

Dorsal aspect of adjacent cuneiform bones (intermediate, lateral) or cuboid bone

Stabilizes the IC-CC joints, reinforces transverse arch

Resists gliding of the IC-CC joints

Plantar IC-CC Ligaments

Plantar aspect of cuneiform bones (medial,

Plantar aspect of adjacent cuineform bones (intermediate,

Stabilizes the IC-CC joints, reinforces transverse arch

Resists gliding of the IC-CC joints

Figure 55. Transverse arch

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intermediate, lateral)

lateral) or cuboid bone

Interosseous Ligaments

Articular surfaces between the medial, intermediate, and lateral cuneiform bones

Articular surface of the adjacent cuneiform bones (intermediate, lateral) or cuboid bone

Stabilization of the IC-CC joints, reinforces transverse arch

Resists gliding of the IC-CC joints

Common Pathologies of the Intercuneaform and Cuneocuboid Complex The cuneiform and cuboid bones are subject to both dislocation and fracture upon high impact,

though these bones are rarely dislocated or fractured. The midtarsal region of the foot is highly reinforced by ligaments, tendons, and muscles and is designed to sustain high forces. However, if the stability of the transverse tarsal region is compromised, instability and even fracture or dislocation can occur in this area. The Lisfranc ligament is injured at times and can eventuate into intercuneiform instability. Injury to any of the surrounding ligaments of the midfoot, can predispose IC-CC to instability and injury. This is rarely observed but if it is observed, the Lisfranc ligament is more often the compromised ligament. (Kadel, 2005)

In addition, the cuboid bone can be dislocated or fractured, compromising its articulation with the lateral cuneiform. As discussed in pathology of the cuboideonavicular joint arthrology section, the cuboid bone can be therapeutically manipulated back into place if it is incorrectly aligned. If fractured, it may heal with conservative treatment or require surgical fixation.

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TarsometatarsalJoint

Overview The tarsometatarsal (TMT) joints are a group of 5 joints that separate the midfoot from the

forefoot. The TMT joints are formed by the distal tarsal bones (cuneiforms and cuboid), and the base of the metatarsals. They are plane synovial joints that glide and slide through their range of motion. Most of this motion occurs at the 1st and 5th TMT joints. The TMTs are often called the Lisfranc joints after Jacques Lisfranc, a French field surgeon in Napoleon’s army. Jacques described this self-titled injury, which involves a fracture of the forefoot (typically the 2nd metatarsal) and corresponding displacement of the lateral four metatarsal bones. This injury typically occurred when a mounted soldier fell from his horse with his foot trapped in the stirrup. To return the soldier to battle more quickly an amputation along this junction was performed, severing the forefoot from the midfoot (Lisfranc’s amputation).

The blood supply to the TMT joints is provided by the anterior tibial artery via the lateral tarsal artery, a branch of the dorsalis pedis. The medial two TMT joints are innervated by the medial plantar nerve, while the remaining three joints are innervated by the lateral plantar nerve.

Tissue Layers [Superficial to deep]

x Integumentary o Epidermis o Dermis o Hypodermis

x Subcutaneous o Plantar surface:

� Superficial fascia

� Subcutaneous adiopose � Plantar aponeurosis

o Dorsal surface: � Superficial fascia � Subcutaneous adipose

x Muscles/ tendons o Plantar Surface

Figure 56. Tarsometatarsal joints and bones

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� Flexor digitorum brevis � Abductor halluces � Abductor digiti minimi � Flexor halluces longus

tendon � Flexor digit minimi

brevis � Quadratus plantae � Flexor digitorum longus

tendon � Adductor halluces � Fibularis longus tendon � Tibialis posterior

tendon � Tibialis anterior tendon

o Dorsal Surface � Extensor digitorum

longus tendon � Extensor hallucis long

tendon � Extensor digitorum

brevis

� Extensor halluces brevis x Neuro Vasculature

o Nerves � Medial plantar nerve � Lateral plantar nerve

o Arteries � Lateral tarsal artery � Dorsalis Pedis

x Ligaments o Long plantar ligament o Plantar Ligaments o Interosseous Ligaments o Dorsal ligaments

x Synovial Joint o Joint Capsule o Synovial membrane o Joint space o Articular Cartilage o Osseous joint surface

Joint Motions and Associated Muscles

Table 34. Tarsometatarsal muscles and motions

Joint Motion Primary Movers Secondary Movers Stabilization of the medial longitudinal arch

Fibularis longus Tibialis anterior, Tibialis posterior, Adductor hallucis

Eversion of 1st tasometataral joint

Fibularis Longus

Inversion and abduction of first tarsometatarsal joint

Occurs passively with dorsiflexion

See Doriflexion

Plantar Flexion Flexor digitorum longus Flexor digitorum brevis, Flexor hallucis longus, Flexor hallucis brevis, Fibularis longus

Dorsiflexion Extensor digitorum longus Extensor digitorum brevis, Extensor hallucis longus, Extensory hallucis brevis

Joint Configuration and Planes of Motion

As mentioned earlier the first through third metatarsals each articulate with their respective cuneiform bone, and the 4th and 5th metatarsals articulate with the cuboid. The first TMT joint is composed of the articulation with the medial cuneiform bone and has its own join capsule. The second TMT joint articulates with the intermediate cuneiform bone and the mortise formed from the imposing medial and lateral cuneiform bones to either side. Due to this design the 2nd ray is more posterior in its

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deeply seated, stable position. This joint shares its capsule with the third TMT joint, which is defined by the articulation of the 3rd MT and lateral cuneiform bones. The fourth and fifth metatarsal joints also share a capsule and are the articulation between their corresponding metatarsal joint and the distal surface of the cuboid bone. Finally there are small articular surfaces between adjacent metatarsals to permit free motion where they interact with one another.

To stabilize these shallow joints, a multiplicity of ligaments are needed to limit motion due to the lack of bony form closure. As listed below in Table 35, these joints are spanned by the dorsal, plantar and interosseous ligaments which help reinforce the joint capsules. Moreover, there is a deep transverse metatarsal ligament that spans the heads of the metatarsals on the plantar surface. This ligament isn’t part of the TMT joints but it contributes to their stability by limiting motion down the

chain. Finally, there is the Lisfranc ligament that runs obliquely from the medial cuneiform to the second metatarsal, and further limits the motion at the relatively immobile second tarsometatarsal joint.

The tarasometatarsal joints each have their own axis of motion. However these motions are somewhat dependent on the joints around them. For example some researchers associate the motion at the cuneonavicular joint to the motion of the TMTs due to the small motion available at this joint. Therefore it is easier to place it in a “ray” with the corresponding cuneiform and make them a functional unit. The vast majority of the tarsometatarsal motion comes from the first and fifth rays. As shown in the Figure 57 these two joints have an oblique axis of motion that is perpendicular to one another. The first TMT joint has the most motion about its axis which is inclined so as dorsiflexion also results in inversion and adduction.

The fifth TMT joint produces motions that are in opposition of the first when it is dorsiflexed; namely inversion and adduction. The third TMT joint primarily functions in dorsiflexion and plantar flexion, and the second and fourth TMT joints act as intermediaries between them all.

Ligaments of the Tarsometatarsal Joint

Table 35. Tarsometatarsal ligaments

Ligament Attachments Function Other associated constraints

Dorsal ligaments The 2nd metatarsal receives attachments from each cuneiform.

Maintain congruency of the cuneiforms,

Resists plantar flexion and dorsiflexion of associated joints

Figure 57. Axes of the tarsometatarsal joints

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Lateral cuneiform to 3rd metatarsal metatarsals. Lateral cuneiform to 4thmetatarsal, Cuboid to 4th metatarsal Cuboid to 5th metatarsal

cuboid and metatarsals

Plantar ligaments Medial cuneiform to 1st and 2nd metatarsalsMedial cuneiform to 2nd and 3rd metatarsals via oblique bands Cuboid to the 4th and 5th metatarsals

Maintain congruency of the cuneiforms, cuboid and metatarsals.

Resists plantar flexion and dorsiflexion of associated joints.

Interosseous ligaments

Lateral surface of the medial cuneiform to the adjacent angle of the 2nd metatarsal (Lisfranc’s ligament)Lateral cuneiform to the adjacent angle of the 2nd metatarsalLateral angle of the lateral cuneiform to the adjacent 4th metatarsal base.

Maintain congruency of the cuneiforms and metatarsals.

Limits overall mobility of associated joints.

Lisfranc’s ligament Lateral surface of the medial cuneiform to the adjacent angle of the 2nd metatarsal

Maintain congruency of the 2nd metatarsal with the cuneiform bones.

Assists in maintain transverse arch

Stabilizes the tarsometatarsal joint complex.

Strongest of the interosseous ligaments.

Common Pathologies of Talonavicular Joint The Tarsometarsal joints are relatively stable and have limited pathology. It is important

however to consider a lack of ligamentous connection between the 1st and 2nd metatarsal bases. One pathology that can happen and is well known is an avulsion of the 2nd MT base. As described in the overview, this injury has been named the Lisfranc fracture. Significantly, this injury is often missed and can cause long-term disability. Palpation is a key way to assess and diagnose this injury. Often time intervention requires modification of activity or surgical reduction and fixation.

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IntermetatarsalJoints

Overview The foot contains four intermetatarsal joints that lie between the proximal ends, or bases, of metatarsals one through five. These joints are considered plane synovial joints and allow very little movement between them other than a slight gliding motion when movement occurs at the metatarsals. Each of these four joints contains its own joint capsule. Vascular supply travels to the intermetatarsal joints by way of the lateral metatarsal artery which is a branch of the dorsal artery of the foot. Digital nerves innervate these joints as they do much of the forefoot.

Tissue layers x Integumentary

o Epidermis o Dermis o Hypodermis

x Subcutaneous o Plantar Surface:

� Superficial Fascia � Subcutaneous adipose � Plantar aponeurosis

o Dorsal Surface � Superficial fascia � Subcutaneous adipose

x Muscles/tendons o Plantar Surface:

� Flexor digitorum brevis � abductor halluces � abductor digiti minimi � flexor halluces longus

tendon � Flexor digiti minimi

brevis � Quadratus plantae � Flexor digitorum longus

tendon � Adductor halluces � Fibularis longus tendon � Tibialis posterior

tendon

� Tibialis anterior tendon o Dorsal Surface

� Extensor digitorum longus tendon

� Extensor halluces longus tendon

� Extensor digitorum brevis

� Extensor halluces brevis x Neuro Vasculature

o Nerves � Digital nerves

o Arteries � Dorsal artery of the

foot x Ligaments

o Dorsal/plantar intermetatarsal ligaments

o Dorsal/plantar tarsometatarsal ligaments

x Synovial Joint o Joint capsule o Synovial membrane o Joint space o Articular cartilage o Osseous joint surface

Joint Motions and Associated Muscles The intermetatarsal joints are small and tightly joined by ligaments and therefore very little motion occurs between them. The little amount of gliding that is available occurs mostly due to passive motion during weight bearing and gait. Although no muscles act directly to create motion at these

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joints, the gliding motion that occurs here can be created by muscles that act on the tarsometatarsal joints.

Joint Motions and Associated Muscles

Table 36. Intermetatarsal muscles and motions

Joint Motion

Primary Muscles, Stabilizing and Helping Synergist

Gliding Flexor digitorum longus, flexor digitorum brevis, extensor digitorum longus, extensor digitorum brevis, tibialis anterior, fibularis longus, quadratus plantae

Joint Configuration and Planes of Motion The four intermetatarsal joints are plane joints that form between the bases of metatarsals one through five. Each joint has its own capsule with a fibrous outer layer that provides support and an inner

synovial membrane that produces lubricating synovial fluid. Between each metatarsal are dorsal and plantar intermetatarsal ligaments that give stability to the joints (see Figure 58). Furthermore, tarsometatarsal ligaments provide stability to these joints as they often cross diagonally to metatarsals one or even two joints away. These joints are categorized as synovial plane joints indicating their articular surfaces are flat. Due to the shape of these joints, they only allow for one degree of freedom. Dorsal and plantar glides occur in the sagittal plane at these joints.

Biomechanics and Arthrokinematics Intermetatarsal joints allow for very limited motion as they only allow one degree of freedom. The primary function of these joints is to augment the motion at the tarsometatarsal joints. Although movement at these joints is seldom isolated, gliding can occur between them with active or passive

movement of the tarsometatarsal joints. This gliding can occur in a dorsal or plantar motion. Gliding occurs when the planar articular surfaces of the joints slide past each other.

Figure 58. Intermetatarsal ligaments

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Ligaments of the Intermetatarsal Joint Table 37. Intermetatarsal ligaments

Ligament Proximal Attachment

Distal Attachment

Ligament Function

Joint Constraints

Dorsal/plantar intermetatarsal ligaments

Dorsal and plantar proximal metatarsal

Dorsal and plantar proximal metatarsal

Stabilizes joint

Resists dorsal and plantar intermetatarsal glide

Dorsal/plantar tarsometatarsal ligaments

Dorsal and plantar tarsals

Dorsal and plantar proximal metatarsal

Stabilizes joint

Resists dorsal and plantar intermetatarsal glide

Common Pathologies of Intermetatarsal Joints Isolated injuries of the intermetatarsal joints does not typically occur. They are however, subject to injury with traumatic injuries of the tarsometatarsal joints. Please refer to the tarsometatarsal section for information about these injuries.

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MetatarsophalangealJoints

Overview The metatarsophalangeal joints are located in the distal region of the foot, in the fore foot. They are located just proximal to the webbed space between the toes and can be found by going on tip-toes. The joint that bends is the metatarsophalangeal joint. The metatarsophalangeal joints are condyloid synovial joints.

The metatarsophalangeal joints are supplied blood from the dorsal metatarsal arteries and the common plantar digital arteries. The dorsal metatarsal arteries are branches off the dorsalis pedis artery. This is a branch off the anterior tibial artery that pierces the interosseous membrane of the leg just distal to the knee. There is one metatarsal artery that runs between each of the metatarsal bones just distal to the metatarsophalangeal joints and then they branch again. The common plantar digital arteries are branches off the deep plantar arch that is found near the tarsal-metatarsal joints on the plantar surface of the foot.

The metatarsophalangeal joints are innervated by the deep fibular nerve which branches off the common fibular nerve. The deep fibular nerve branches off around the location of the fibular head and then runs along the anterio-lateral surface of the tibia until it branches near the ankle in order to innervate different aspects of the dorsal aspect of the foot. The metatarsophalangeal joints are also innervated by the medial and lateral plantar nerves from the plantar side.

Tissue Layers [dorsal to plantar] x Integumentary

o Epidermis o Dermis o Hypodermis

x Dorsal Fascia o Subcutaneous tissue: cutaneous

and sensory nerves and blood vessels, subcutaneous fat stores, other loose connective tissue

o Inferior Extensor Retinaculum x Dorsal Extrinsic Tendons

o Extensor digitorum longus tendons

o Extensor hallucis longus tendons

o Extensor digitorum brevis tendons

o Dorsal Interossei muscles and tendons

x Dorsal Neurovascular o Dorsal metatarsal arteries o Deep fibular nerve

x Dorsal Ligaments o Medial and lateral collateral

Figure 59. Location of metatarsophalangeal joints

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x Metatarsophalangeal Joint Capsule o Synovial membrane o Synovial fluid o Articular cartilage o Periosteum o Bone [metatarsals 1-5 and

proximal phalanges] x Plantar Ligaments

o Plantar plate o Deep transverse metatarsal o Plantar fascia

x Plantar Neurovasculature o Common plantar digital arteries o Medial and lateral plantar nerve

x Plantar Muscles and Tendons o Plantar interossei

o Adductor hallucis o Flexor digiti minimi o Flexor hallucis brevis o Lumbricals o Abductor hallucis o Abductor digiti minimi o Flexor digitorum brevis

x Plantar fascia and aponeurosis o Subcutaneous fascia: cutaneous

and sensory nerves and blood vessels, subcutaneous fat stores, other loose connective tissue

x Integumentary o Hypodermis o Dermis o Epidermis

Joint Motions and Associated Muscles Table 38. Metatarsophalangeal muscles and motions

Motion Primary Mover Stabilizing and Helping Synergists Flexion Flexor digitorum brevis,

Flexor hallucis brevis Flexor digitorum longus, Flexor hallucis longus, lumbricals, flexor digiti minimi

Extension Extensor digitorum brevis, Extensor hallucis brevis

Extensor digitorum longus, Extensor hallucis longus

Abduction Dorsal interossei, Abductor hallucis

Abductor digiti minimi

Adduction Plantar interossei, Adductor hallucis

n/a

*There are multiple primary movers due to different muscles that allow for motion at the great toe, digits 2-4, and digiti minimi.

Joint Configuration and Planes of Motion The metatarsophalangeal joints are condyloid synovial joints. This means that they have two degrees for freedom to allow for movement into flexion and extension and abduction and adduction. The motion of the extension at the metatarsophalangeal can be observed when going on tip-toes while weight bearing.

The distal metatarsal surface that corresponds with the phalangeal joint is a concave surface. The proximal phalangeal joint is a convex surface. This indicates that when the metatarsals are stabilized and immobile, the convex surface of the phalangeal joints is moving. The convex on concave motion is

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that the roll and glide are in opposite directions. For example, during flexion the phalange is rolling into flexion but the glide is into extension in order to maintain contact with the metatarsal joint.

The metatarsophalangeal joints can achieve 65 degrees of extension. This can be fully seen when the toes are extended while on tip-toes. The great toe can achieve greater range to about 85 degrees of extension. The metatarsophalangeal joints can achieve 30-40 degrees of flexion.

There is a plantar plate that can be found on the plantar aspect of the metatarsal joints and links them together. This is especially important when considering push off of gait and the stress that the longer toes (first and second digits) would endure during gait. Without the plantar plate, the first and second digits would bear the majority, if not all of the stress of push off during gait. With the plantar plate, the stresses of push off are distributed laterally to the other metatarsophalangeal joints and decreasing the wear on the first two digits.

Another important configuration of the joint is the inclusion of sesamoid bones on the plantar aspect of the first metatarsophalangeal joint. They are embedded in the flexor hallucis brevis and extend the moment arm of the flexor hallucis longus tendon to allow the muscle a more ideal line of pull to flex the great toe. The inclusion of the sesamoid bones increases the length of the moment arm that would normally be much shorter as it would be running directly along the plantar side of the first metatarsal and the proximal phalange. Even though it does not have the greatest cross sectional area of the muscles that cross this joint, it is the primary mover due to line of pull. This also applies to the flexor digitorum brevis, extensor digitorum brevis, and extensor hallucis brevis muscles. They all attach more proximal than their longus counterparts, allowing them a more ideal line of pull for movement at the metatarsointerphalangeal joint.

Biomechanics and Arthrokinematics Movement at the metatarsophalangeal joint during gait is often into extension during push off. There is a plantar aponeurosis that runs from the calcaneus to the proximal phalanx and attaches to the plantar plate. When the toes are extended during push off, the plantar aponeurosis is stretched and the attachment to the plantar plate causes a lateral pull. This causes supination which aids the foot in the

Figure 60. Plantar plate

Figure 61. Sesamoid bone of the great toe

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formation of the rigid lever to transmit forces for the push off phase during gait. This is often referred to as the windlass effect.

Ligaments of Metatarsalphalangeal Joint Table 39. Metatarsophalangeal ligaments

Ligament Proximal Attachment

Distal Attachment

Function Other associated joint constraints

Medial and Lateral collateral

Dorsal aspect of metatarsal head

Plantar aspect of proximal phalanx and plantar plate

Prevents excessive adduction and abduction; gives additional stability

Adduction, abduction

Plantar Plate Plantar aspect of metatarsal head

Plantar aspect of proximal phalanx

Prevents excessive extension

Extension

Deep transverse metatarsal

Plantar Plate 1-4 Plantar plate 2-5 Prevents excessive abduction of metatarsals

Abduction

Plantar fascia Calcaneal tuberosity

Proximal phalanx Supports and gives additional stability to the medial longitudinal arch of the foot

Flattening of medial long-itudinal arch

Common Pathologies of Metatarsophalangeal Joints Pathologies seen in this joint region include metatarsalgia and stress fractures as well as pathologies of the first ray such as halux valgus and rigidus. Metatarsalgia and stress fractures are caused by overuse, tight shoes, or a high impact event. Over pronation can also increase the stress and increase the risk of metatarsophalangeal fractures. Both of these pathologies can be treated with ice, rest and anti-inflammatories. A walking boot can be helpful to rest and reduce the stresses on the bones and joints. Surgery is rare and only used in the most extreme of cases.

Hallux valgus is also known as bunions. There are many possible causes for bunions including a family history, tight shoes or wear and irritation at the joint associated with over pronation. Regardless of the reason, irritation at the first metatarsophalangeal joint occurs, causing inflammation in the area. This eventually leads to a lateral push of the proximal phalange and a bump forms as a result of the irritation. Surgery is a possible treatment option for extreme cases. For more conservative treatment, ice can be used and patient education on proper foot-wear. A hallux valgus manipulation can also be performed to reset and realign the system to allow for more motion.

Hallux limitus or rigidus is a reduction of movement due to a trauma or sprain of the great toe at the location of

Figure 62. Bunion

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the metatarsophalangeal joints. When the trauma is forced hyperextension, this is called turf toe. This can be seen when someone stops quickly at high speeds, forcing the toe under the foot during weight bearing. The degree of severity can range from a mild sprain to torn tears of the plantar joint structures. There is associated pain and often difficulty with gait due to the limited amount of motion available at the joint as compared to that which is required during gait. Surgery is an option for the most severe of cases. More conservative treatments can include increasing range of motion via manipulations and mobilizations at the great toe which include sesamoid mobilization and manipulation of hallux rigidus. Taping can also be used for temporary relief of pain and other symptoms while walking and weight bearing.

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InterphalangealJoints

Overview There are nine interphalangeal joints located within the toes of a foot (refer to Figure 59). There are five proximal interphalangeal joints (PIP) and four distal (DIP). The great toe only contains a proximal interphalangeal joint. Due to the nature of the hinge joint, only flexion and extension are seen at these joints.

The dorsal digital arteries supply blood to the dorsal aspect of the joints. The dorsal digital arteries are supplied by the dorsal metatarsals, branches off the arcuate artery of the foot. The proper plantar digital arteries supply the plantar aspect of the interphalangeal joints with blood. They are branches off the lateral plantar arch which is a branch off the posterior tibial artery.

The interphalangeal joints are innervated by the deep fibular nerve and the medial and lateral plantar nerves. The deep fibular nerve is a branch off the common fibular nerve and supplies most of the dorsal foot with innervation. The medial and lateral plantar nerves are branches off the tibial nerve that runs along the posterior aspect of the leg and branches around the region of the lateral malleoli.

Tissue Layers [dorsal to plantar] x Integumentary

o Epidermis o Dermis o Hypodermis

x Dorsal Fascia o Subcutaneous tissue: cutaneous

and sensory nerves and blood vessels, subcutaneous fat stores, other loose connective tissue

o Inferior Extensor Retinaculum x Dorsal Extrinsic Tendons

o Extensor digitorum longus tendons

o Extensor hallucis longus tendons

o Extensor digitorum brevis tendons

x Dorsal Neurovascular o Dorsal digital arteries o Deep fibular nerve

x Dorsal Ligaments o Medial and lateral collateral

x Metatarsophalangeal Joint Capsule o Synovial membrane o Synovial fluid o Articular cartilage o Periosteum o Bone [phalanges]

x Plantar Ligaments o Plantar plate o Medial and lateral collateral

x Plantar Neurovasculature o Proper plantar digital arteries o Medial and lateral plantar nerve

x Plantar Tendons o Flexor digiti minimi tendon o Flexor hallucis brevis tendon o Flexor digitorum brevis tendons

x Plantar fascia and aponeurosis o Subcutaneous fascia: cutaneous

and sensory nerves and blood vessels, subcutaneous fat stores, other loose connective tissue

x Integumentary

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o Hypodermis o Dermis

o Epidermis

Joint Motions and Associated Muscles Table 40. Interphalangeal muscles and motions

Motion Primary Mover Stabilizing and Helping Synergists Flexion Flexor digitorum longus, flexor

hallucis longus Flexor digitorum brevis, flexor digiti minimi, flexor hallucis brevis

Extension Extensor digitorum longus, extensor hallucis longus

Extensor digitorum brevis, extensor digiti minimi, extensor hallucis brevis

*There are multiple primary movers due to different muscles that allow for motion at the great toe, digits 2-4, and digiti minimi.

Joint Configuration and Planes of Motion The interphalangeal joints are hinge joints that have one degree of freedom for movement. This allows for motion into extension and flexion. There are five proximal interphalangeal joints and four distal interphalangeal joints. This takes into account that the great toe does not have a third phalanx bone.

The more proximal phalanx bone is convex and the more distal bone is concave. The direction of the glide and spin depends on the motion and the weight bearing status. If the proximal phalanx is moving on the more distal phalanx, the glide and spin will occur in opposite directions. If it is the distal phalanx moving on the more proximal phalanx, the glide and spin will occur in the same direction.

There are multiple primary movers due to the fact that the interphalangeal joints account for nine different joints on five different toes. The great toe is not included as an attachment for the flexor or extensor digitorum longus. It has its own set of muscles that have a more ideal line of pull to move the interphalangeal joint into either extension or flexion. These are the extensor hallucis longus or the flexor hallucis longus.

Biomechanics and Arthrokinematics The primary role of the interphalangeal joints during gait is to continue the transmission of forces during push off. The role of the medial longitudinal arch in the transmission of forces was discussed in previous biomechanical sections. The interphalangeal joints work to continue the transmission of forces through the medial longitudinal arch to the distal end of the phalanges where it is converted to motion during push off. This is often considered to be an extension of the windlass mechanism which was discussed in the metatarsophalangeal joint biomechanics section.

The interphalangeal joints also work for stabilization. This is especially seen during the push off phase of gait when only the

Figure 63. Interphalangeal joints during push off

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forefoot is in contact with the ground. The interphalangeal joints allow for motion that maintains balance while forces are transmitted through the forefoot and to the ground. Minor movements at the interphalangeal joints allow for adjustments to maintain balance, especially over uneven surfaces.

Ligaments of Interphalangeal Joints Table 41. Interphalangeal joint muscles and motions

Ligament Proximal Attachment

Distal Attachment

Function Other associated joint constraints

Plantar Plate Distal aspect of proximal phalanx

Proximal aspect of distal phalanx

Prevents excessive extension of phalanges

Extension

Medial Collateral Dorsal and medial aspects of distal phalanx

Plantar and medial aspects of distal phalanx

Prevents excessive valgus stresses on phalanges

Valgus stress, abduction of more distal segment

Lateral Collateral Dorsal and lateral aspects of distal phalans

Plantar and lateral aspects of distal phalanx

Prevents excessive varus stresses on phalanges

Varus stress, adduction of more distal segment

Common Pathologies of the Interphalangeal Joints Phalangeal fractures can occur due to trauma or overuse causing an issue with the integrity of the phalangeal bones. Common symptoms are pain and bruising in the area. The patient will most likely not be able to take steps on the injured foot. Treatment includes ice for any swelling that may occur and rest while the bone is allowed time to heal. Range of motion can be added when tolerated in order to maintain motion at the joint and to prepare for return to function.

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AppendixA:Gait

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