Complete Anatomical Detail Of Knee Joint

By- Dr. Armaan Singh

Synovial condylar joint

Close pack Full extension Least pack 15 degree flexion

The articular surfaces are the medial and lateral femoral condyles (the intercondylar notch in between)

The medial condyle has a longer articular surface

The superior aspect of the medial and lateral tibial condyles

The posterior aspect of the patella

Average is 17 mm Narrow notch more likely to

tear ACL

Sesamoid bone Thickest articular cartilage

in body Smaller medial facet Q-angle Controlled by Vastus

Medialis Obliquus (VMO) and Vastus Lateralis Obliquus (VLO)

The patella is controlled by the oblique portions of the vastus medialis and vastus lateralis.

The vastus medialis wastes within 24 hours after an effusion of the knee

If the oblique fibers of the vastus medialis are wasted, the patella tends to sublux laterally on extension of the knee. This results in retropatellar pain

Lower most fibres of vastus medialis

Partly arise adductor magnus Straightens the pull on the quads

tendon and patella Controls patella tracking during

flexion extension of the knee Fibres atrophy quickly after knee

injury 10-15 ml of effusion inhibit VMO VMO rehabilitation strength and

timing of contraction

Deficiency of Lateral Condyle

Quadriceps Retinacular fibres Patellar tendon Coronary ligaments Medial and lateral

ligaments Posterior oblique ligament

Quadriceps tendon The patella The patellar ligament Retinacular fibres all form the

anterior part of the capsule The patellar ligament is the insertion

of the quadriceps tendon

Antero-inferiorly is attached to the tuberosity of the tibia

On either side the retinacular fibres pass upwards from the tuberosity in a V-shaped manner to be attached just below the articular margin

The deep infrapatellar bursa and infrapatellar pad of fat lie posterior to it, separating it from the tibia

Laterally, the attachment is just beyond the articular margin

Laterally, it is attached above the groove for the popliteus, below the lateral epicondyle

There is a gap in the capsule to allow the popliteus to emerge

Posterior Superiorly, it is attached just

beyond the articular margin and to the lower border of the popliteal surface of the femur, above the intercondylar notch

Postero-inferiorly, the capsule is attached to the medial condyle of the tibia

By a line running above the groove for the semimembranosus tendon

Below the attachment of the posterior cruciate ligament

Medially, the capsule is attached to the femur just beyond the articular margin of the condyle

Below the medial epicondyle

Netter

Medial ligament Pes anserinus consists

of: Sartorius Gracilis Semitendinosus

Tibial inter-tendinous bursa between them

Is attached superiorly to the medial epicondyle of the femur

It blends with the capsule Attached to the upper third of the

tibia, as far down as the tibial tuberosity

It has a superficial and deep portion

The deep portion, which is short, fuses with the capsule

Attached to the medial meniscusA bursa usually separates the

two parts

The tendons of sartorius, gracilis and semitendinosus cross its tibial attachment where another bursa is situated

The anterior part tightens during the first 70–105°of flexion

Medial ligament, tightens in extension

And at the extremes of medial and lateral rotation

A valgus stress will put a strain on the ligament

If gapping occurs when the knee is extended, this is due to a tear of posterior medial part of capsule

If gapping only occurs at 15º flexion, this is due to tear of medial ligament

Netter

Semimembranosus into the groove on posterior aspect of medial tibial condyle and its extensions

Upwards and lateral is oblique popliteal ligament

Downwards and lateral forms fascia covering popliteus

Downwards and medially fuses with medial ligament

Oblique popliteal ligament passes upwards and laterally

Fuses with the fabella if present

Capsule above lateral femoral condyle

Pierced by middle genicular vessels and nerve

Posterior division of obturator nerve

Popliteal artery lies on it

Oblique Popliteal Ligament

Strengthens the posterior portion of the capsule and prevents extreme lateral rotation

It is an expansion from the semimembranosus tendon close to its insertion to the tibia

Branch from the posterior division of the obturator nerve, pierces the ligament, supplies cruciates and articular twig to knee (referred pain from pelvic peritoneum to knee)

Oblique Popliteal Ligament

Netter

Lateral ligament Iliotibial tract Arcuate complex

• Fabellofibular ligament• Deep portion of capsule• Meniscotibial ligaments

Posterior horn of lateral meniscus

Arcuate complex Popliteus Lateral head of

gastrocnemius

Deep in interval between iliotibial band and biceps

Lateral epicondyle of femur

Midpoint superior surface of fibula and the styloid process of the fibula

It is a cord-like structure that is separated from the capsule by the tendon of the popliteus

Surrounded by bicepsFabbriciani & Oransky, 1992

Lateral Ligament

Deep to lateral collateral ligament

Popliteus Inferolateral genicular

vessels and nerve

Taut in extension 20°flexion, lateral ligament

complex more lax than medial

Primary lateral restraint to varus loading

Arcuate ligament is the edge of capsule that arches above the popliteus

Passes from the tip of the styloid process

Just posterior to the lateral ligament

Blends origin of the lateral head of gastrocnemius and oblique popliteal ligament

Edge of capsule arches over popliteus and may give partial origin to popliteus

Fabella lies at point on the poster lateral side of knee

Where multidirectional collagenous tensile stress meet

8% - 10% osseous 90% - 92%

cartilagenousFabbricani & Oransky, 1992

Connects the periphery of the menisci to the tibia

They are the portion of the capsule that is stressed in rotary movements of the knee

Origin inferior, popliteal surface of tibia, above the soleal line, fascia of semimembranosus

Deep to arcuate popliteal ligament

Enters capsule Crosses lateral surface of

lateral meniscus Attached by popliteal-

meniscal fibres which bound hiatus

Enters hiatus Crosses femoral

condyle Deep to lateral

collateral ligament Inserts into anterior

part of groove Superior popliteal

recess communicates joint

Femoral condyles rotate medially around taut ACL during the locking mechanism of the knee

Popliteus laterally rotates the femur to unlock the knee so flexion can occur

The iliotibial tract is a thickening of the deep fascia of the thigh, fascia lata

The tract is attached to Gerdy’s tubercle on the anterolateral aspect of the lateral tibial condyle

The superficial three quarters of the gluteus maximus end in a thick tendinous lamina which is inserted into the iliotibial tract

The tensor fascia lata is also inserted into the tract

Gives origin to the oblique fibres of the vastus lateralis that help to stabilise the patella

In full knee extension the tract lies anteriorly to the line of flexion of the knee,

As it is free of bony attachments between the lateral femoral epicondyle and Gerdy’s tubercle

It is free to move posteriorly to this axis on flexion of the knee

Standish & Wood, 1996.

As the tract crosses the lateral epicondyle of the femur a bursitis may develop as the result of a ‘long-leg syndrome’

The iliotibial band acts as an extensor of the knee when the knee is flexed from 0°to 30°and as a flexor when the knee is flexed more than 40°, due to the change in the transverse axis which occurs at 30–40°flexion.

The pelvic tilt is a mechanism for tightening the iliotibial band. The pull of the band stabilises the knee in extension, as well as helping to resist extension and adduction of the hip of the weight-bearing leg

Flexion and extension take place between the femoral condyles and the upper surface of the menisci

Rotation occurs between lower surface of the menisci and upper surface of the tibia

Contraction of the quadriceps results in extension

The anterior cruciate becomes taut

And medial rotation of the femur occurs around the taut anterior cruciate to accommodate the longer surface of the medial condyle

Femoral condyles rotate medially around taut ACL during the locking mechanism of the knee

Popliteus laterally rotates the femur to unlock the knee

So flexion can occur Then the hamstrings flex

the knee

Anatomically named by their tibial attachments

Clinically femoral are called origin

Covered by synovial membrane on anterior and on both sides which is reflected from capsule,

I.e. oblique popliteal ligament

Bursa between them on lateral aspect

anterior

lateral

Synovial membrane covers the anterior and sides of the cruciates

Not covered on posterior aspect

Anterior and Posterior Cruciates Ligament

Anterior cruciate is attached to anterior aspect of the superior surface of the tibia behind

Anterior horn of medial meniscus in front of the anterior horn of the lateral meniscus

Passes upwards and laterally to the posterior aspect of medial surface of lateral femoral condyle

Anterior Cruciate

PCL

Anterior cruciate ligament

Posterior meniscofemoral ligament

Superior Aspect of Tibial Plateau Menisci

Three dimensional fan shaped

Multiple non-parallel interlacing collagenous fascicles

Anterior Cruciate Ligament (ACL)

anterior

Anterior Cruciate Ligament

Tibial attachment is in antero-posterior axis of tibia

Femoral attachment is in longitudinal axis of femur

Forms 40°with its long axis

90°twist of fibres from extension to flexion

Anterior Cruciate Ligament

Anteromedial fibres have the most proximal femoral attachment

Contribute to anteromedial stability

Intermediate to straight and anteromedial

Posterolateral aids in anteromedial stability

Anterior Cruciate Ligament

ACL are vertical in extension

90°flexion are horizontal

PCL are more vertical in 90°flexion

Anterior Cruciate Ligament

At 0°of flexion the fibres of the ACL are more vertical

At 90°flexion they are in the horizontal plane

Fibres of the PCL are more vertical with flexion and increasing flexion, > 90°becomes pivot

PCL is least affective at 30°flexion

Hunziker et al 1992, Covey 2001

Cruciate

PCL Provides 94% of

restraint to posterior displacement

ACL Provides 86% of

restraint to anterior displacement

Anterior and Posterior Cruciate

Middle genicular artery

Inferior medial genicular

Inferior lateral genicular arteries via infrapatellar fat pad

Only one main artery

Middle genicular enters upper third

Anterior Cruciate LigamentBlood Supply

Strongest ligament Shorter More vertical Less oblique Twice as strong as

ACL Posterior

Posterior Cruciate

PCL is the strongest ligament of the knee

It is shorter More vertical Less oblique Twice as strong as

ACL Closely applied to the

centre of rotation of knee

It is the principal stabiliser

Hunziker et al.,1992

Posterior Cruciate

The tibial attachment of the PCL was on the sloping posterior portion of the tibial intercondylar area

Anterior to tibial articular margin

Blends with periosteum and capsule

Extended 11.5-17.3 mm distal to the tibial plateau

Javadpour & O’Brien, 1992

Frazer, 1965

Tibial Attachment of the PCL

Anatomically the fibres pass anteriorly and medially and proximally

It is attached on the antero-inferior part of the lateral surface of the medial femoral condyle

The area for the PCL is larger than the ACL

It expands, more on the apex of the intercondylar notch than on the inner wall

Hunziker et al.1992

.

Posterior Cruciate

Three functional bands Names vary Anterior or anterolateral is

larger Central Taut in flexion Posterior or posteromedial

taut in extension Posterior oblique bundleHunziker et al 1992

Posterior Cruciate Ligament

Insertions of the PCL Passes through four

zones Ligament Fibrocartilage Tidemark of mineralised

fibrocartilage Bone in less than 1 mm Cooper & Misol, 1970; Fabbriciani & Oransky, 1992

Attachment of PCL

Posterior oblique bundle Most posterior fibres Attached to

posterosuperior part of femur

Posterior medial part on intercondylar area of tibia

Longest fibres Tense in full extensionFredrick & O’Brien, 1992; Hunziker et al.,1992

Posterior Cruciate Ligament

Proximal fibres on femur Posterior fibres on the tibia

are longest Undergo least change

Posterior Cruciate

The PCL is located near the longitudinal axis of the knee

Medial to the centre of the knee

Vertical in frontal plane

30°to 35°in sagittal More horizontal in

sagittal with increased flexion

Posterior Cruciate

PCL provides 94% of restraint to posterior displacement of the tibia

Prevents external rotation of tibia more at 90°than at 30°

ACL 86% of restraint to anterior displacement

Posterior Cruciate

Blood Supply of Cruciates

Posterior cruciate is supplied by four branches

Distributed fairly evenly over its course

Subcortical vascular network at bony attachments

Don’t contribute much to ligaments

Sick & Koritke, 1960

Blood Supply of Cruciates

Main is middle genicular artery enters upper third of PCL

Synovium surrounding PCL also supplies the PCL

Contributions inferior medial, inferior lateral genicular arteries via infrapatellar fat pad

Periligamentous and intra-ligamentous plexus

Very little from bony attachmentArnoczky 1987

Blood Supply of PCL

Branches of tibial and obturator nerves

Mechanoreceptors Proprioceptive

action

Posterior Cruciate Ligament Nerve Supply

Branches of tibial nerve

Middle genicular nerve Obturator nerve (post) Branches of the tibial

nerve enter via the femoral attachment of each ligament

Nerve fibres are found with the vessels in the intravascular spaces

Nerve Supply of Cruciates

Three types Found near the femoral

attachment Around periphery Superficially, but well below the

synovial lining. Where maximum bending

occurs Ruffini endings And ones resemble golgi

tendon organs Paccinian Proprioceptive function

Mechanoreceptors resembling golgi tendons

Running parallel to the long axis of the ligament

Found near the femoral attachment

Around the periphery, where maximum bending occurs

Posterior division of obturator nerve

There is a gradual change in stiffness between the flexible ligamentous tissue and bone

There is a transitional zone of fibrocartilage between collagen and bone

This helps to prevent the concentration of stress at the attachment site

Beynnon, 2000; Hunziker et al.,1992

Posterior Cruciate LigamentBony Attachment

Menisci are made of fibro cartilage

Wedge shaped on cross section

Medial is comma shaped with the wide portion posteriorly

Lateral is smaller, two horns closer together round

They are intracapsular and intra synovial

anterior

Anterior to posterior Medial, anterior horn is

attached to the intercondylar area in front of the ACL and the anterior horn of the lateral meniscus

Posterior horn of lateral, posterior horn of medial and PCL

Medial is more fixed Lateral more mobile

anterior

Medial is attached to the deep portion of medial collateral ligament

Lateral is separated from lateral ligament by the inferolateral genicular vessels and nerve

The popliteus, which is attached to lateral meniscus

Posterior horn gives origin to meniscofemoral ligament

Coronary ligaments are the portion of the capsule attached to the periphery of meniscus, which connects it to the tibia

Synovial membrane, stops at the upper border of the meniscus

Lines the deep aspect of the coronary ligament

Blood supply at the periphery only

Flexion and extension takes place at the upper surface of the menisci

Rotation occurs between the lower surface of the menisci and the tibia anterior

Shock absorption Redistributes forces Spread synovial fluid Minimal effect on stability On rotation menisci move with

femur Lateral moves 20 - 24 mm Medial less mobile 10 -15 mm Lateral meniscus bears more

load

Function of Menisci

Anterior and posterior arise from posterior horn of lateral meniscus

Anterior attached to femur anterior to PCL

Posterior attached posterior to PCL

More variations in posterior

The Anterior meniscofemoral (Humphrey) is attached to lateral aspect of the medial femoral condyle in front of the PCL

The posterior (Wrisberg) is attached posterior to the PCL

The posterior meniscofemoral ligament is usually present

Vary in size

Increase with age Compact lobules With fibro-elastic

interlobular septa Septa well vascularised Provide firmness,

deformability and elastic recoil

Williams & Warick,1980

Superiorly Fills the space between the

inferior pole of the patella The ligamentum patella and

deep infrapatella bursa Attached to intercondylar

notch via ligamentum mucosum

Williams & Warick,1980

Posteriorly Covered by synovial

membrane Forms alar folds Femoral condyles Intercondylar notch

by ligamentum mucosum

Attached to anterior horns of menisci

Proximal tibiaWilliams & Warick,1980

Blood supply inferior genicular arteries

Also supply the lower part of the ACL from network of synovial membrane of fat pad

Centre of fat pad limited blood supply

Lateral arthroscopic approach to avoid injury

Kohn et al., 1995; Eriksson et al., 1980

Can only expand anteriorly Inflammation of IFP Bulges on either side of

patellar tendon Synovial membrane is

compressed by femoral condyles

Pain and inflammation

• Intrinsic• Hoffa’s disease• Intracapsular chondroma• Localised nodular synovitis• Post-arthroscopy / post-surgery fibrosis• Shear injury• Torsion

Hyperextension injury Genu recurvatum and

tilted inferior pole of patella Tenderness distal to

patella Beyond margins of the

patellaBrukner & Khan, 2000; Garret et al., 2000

Anterior extra capsular disorders

Patellar fracture Patellar tendon

rupture Deep infrapatellar

bursitis Patellar tendonosis

Osgood-Schlatter Disease Sinding-Larsen Johanssen Disease

ACL repair with patellar tendon may result in fibrosis of fat pad and pain

Delays rehabilitation Inflammation of IFP may be

process leading to fibrosisMurakami et al., 1995

The synovial membrane is very extensive

It lines the inner aspect of the capsule and the non-articular structures inside the capsule, except posteriorly where it is carried forwards to cover the anterior and sides of the cruciate ligaments

It covers the infrapatellar pad of fat, forming the alar folds

The ligamentum mucosum is attached to the intercondylar notch at the apex of the alar fold

The alar folds increase the surface area of the synovial membrane via the infrapatellar pad of fat,

Which fill the changing spaces during movement of the joint and help to redistribute the synovial fluid

The synovial membrane is continuous with:

The suprapatellar bursa which extends a hand’s breadth above the patella. This bursa always appears distended when there is a haemarthrosis or traumatic synovitis in the knee joint

Many other bursae, e.g. around the popliteus and under the medial head of the gastrocnemius

A suprapatellar plica may separate the suprapatellar bursa from the synovial membrane of the knee joint

Plicae folds may also be found on either side of the patella

Patellar Tendinitis / SLJ

Fat pad impingement

Infrapatellar Bursitis

Traction Apophysitis

Fractures & Instability

Patellofemoral syndrome

Prepatellar bursitis

Synovial plica

Anatomical anomalies

Femoral torsion Genu valgum Increased Q-

angle High (alta)

patella Tibial torsion Overpronation

Q Angles

Males 140 Females 170

> 200 greater problems

Anterior cruciate tear Bone bruising Posterior cruciate tear Osteochondritis Synovial plica

Traumatic Meniscal tears Ligament tears Cruciates Collaterals Patellar dislocations Fractures Patella Tibial plateau Articular cartilage damage

Atraumatic Patellofemoral syndrome Malalignment Dislocations Subluxations Iliotibial band syndrome Popliteus tendinopathy Patellar tendinitis Osgood-Schlatter’s Fat pad impingement

• Medial ligament tear• Anterior cruciate tear• Torn medial meniscus

Valgus / External rotation Posterior horn of medial

meniscus trapped by posterior condyles

• Medial meniscus has higher incidence but less morbidity

• Traumatic tears• Twisting on a planted, flexed knee• Atraumatic tears• Degenerative wear and tear