HEMIARTHROPLASTY UNIPOLAR

AND BIPOLAR INDICATIONS

APPROACH AND PROCEDURE

Moderator :Prof.Dr A .E Manoharan D.Ortho,M.S Ortho.

Presentor :Dr.Thouseef A Majeed

M S Ortho PG

VMKVMCH Salem

Hemiarthroplasty

• Half joint replacement

• Hemiarthroplasty involves replacing the

femoral head with a prosthesis, while retaining

the natural acetabulum (endoprosthesis)

• Fractures of the neck of femur is the commonest

fracture in old aged individuals because of severe

osteoporosis and advancing age causing more

brittleness of the bone

• Non union and avascular necrosis are the two

principal complications of this fracture

• Almost 45yrs ago prosthetic replacement was

introduced for solving the unsolved problems of

fracture Neck Of Femur

• Vitallium intramedullary prosthesis had definite role

in its treatment.

History

• 1932: Hey Grooves replaced a femoral head with

Ivory

• 1938: Smith Peterson first used Vitallium mould

arthroplasty in the hip in case of ankylosis as a

result of Rheumatoid Arthritis

• 1944: Judet brothers introduced Acrylic femoral

head for the treatment of Osteoarthritis.

• 1948: Mc Bride introduced Threaded stem.

• 1950: Moore introduced a self locking Cobalt

chrome alloy prosthesis

• 1952 : Thompson worked on a prosthesis at the

same time as Moore

• In 1947: The Bipolar prosthesis first introduced by

James E.Bateman and Gilberty

• 1983 : Charnley-Hastings used Bipolar prosthesis

• Prosthesis should not be used for fresh

fractures in preferance to internal

fixation unless there are definite

indications

TYPES OF PROSTHESIS• Two types of prosthesis

–STEM PROSTHESIS

–MEDULLARY PROSTHESIS

STEM PROSTHESIS• It has a head and a stem

• Stem is inserted into the neck and

anchored in the cortex of the shaft

• They are no more used

• E.g– JUDET brothers,

R.E.M.THOMSON

MEDULLARY PROSTHESIS• It has a head and a stem

• Anchored in medullary canal

• It is either fixed by press fit (inference fit) or

by bone cement

• Austin Moore 1957 devised intramedullary

self locking prosthesisfenestrstion to facilitate

bone growth and to increase blood supply

DIFFERENT PARTS OF UNIPOLAR PROSTHESIS

• HEAD: (37mm to 59mm)

• NECK

• STEM: triangular in shape thin and

becomes easy for insertion but chances of

breakage of the tip

• COLLAR

• Fenestrations

• Collar is transverse in Moores & in

Thompsons is acutely angled and wide

• FENESTRATION

–Moores prosthesis is fenestrated

– Bone grows through the fenestrations

&

– Anchor the prosthesis inside the shaft

AUSTIN MOORE PROSTHESIS

• INDICATIONS

– Failure of closed reduction of a

displaced intracapsular fracture in an

elderly patient >60yrs

– Patient with rhematoid disease with

minimal arthritis of hip

– Neglected fractures (>1wk) and when there is no acetabular

damage

– Fracture associated with pagets disease when there is

minimal acetabular damage

• Fractures secondary to malignancy

• Acute displaced intracapsular Fracture

• RELATIVE INDICATIONS:

• Advanced physiological age

• Femoral neck fracture that loose fixation several

weeks after operation

• Old undiagnosed fractures of femoral neck (3wks)

• Pre existing diseases of hip

• CONTRA INDICATIONS

• Pre existing sepsis

• Active young patient

• Pre existing disese of acetabular cartilage-

o Rheumatoid Arthritis

o Osteoarthritis

PREQUESITIES

• Traction internal rotation view should be taken

• Presence of neck with Calcar femorale

ADVANTAGES

• Allows immediate weight bearing to return the

patients to pre-fracture level of activity.

• It eliminates Avascular Necrosis and non union.

• Hospital stay is cut short by about 30%

DISADVANTAGES

• Salvage procedures are complicated when there is sepsis or

mechanical failure

• At least 2/3rd of patients treated by internal fixation have

functional hips that last the remainder of lifetime, a fact

ignored by prosthetic replacement

• More extensive surgery

THOMPSONS PROSTHESIS• Designed for non union of fracture

neck of femur when there is no neck

available

• Designed to rest on the

intertrochanteric line

INDICATION

• Absence of neck

• Non union fracture neck of

femur

• Malignancies

• Bony Secondaries- Pathological

fracture

• Osteoporotic fracture with neck

• Although designed for use without bone cement.

• Now frequently used with bone cement due to

o Small stem

o Difficult to achieve stability within femur

SELECTION

• Not simple because of radiological

magnifications in preoperative assessment

• Overgrowth of articular cartilage adopts the

acetabulam to the size of metal head

FEMORAL HEAD

• Always select the size of femoral head which is removed

• If correct size not available, 1 size smaller size is

preferred to bigger size

• If too large head , equatorial contact occurs, resulting

in a tight joint with a decreased motion and pain.

• If head is too small, polar contact occurs with

increased stress over reduced area; leads to erosion,

superomedial prosthetic migration & pain.

FEMORAL NECK LENGTH

• If the neck is left excessively long, reduction

may be difficult and pressure on acetabular

cartilage is increased.

• Prostheses should be inserted so that the distance

between the greater trochanter and center of the

femoral head is restored.

• Alternatively, attempt to restore the distance

between the lesser trochanter and the acetabulum.

• This will restore the length of the abductor

mechanism and thereby help to prevent

postoperative limp.

FIXATION

• Classical fixation is called as Interfernce fit

• Obtained by reaming and driving the prosthesis into the

shaft of the femur

POSITION• Fixed in neutral or slightvalgus,

• Avoid varus, anteversion or retroversion.

• Excessive retroversion causes external

rotational deformity and increased risk of

dislocation with internal rotation.

• Excessive anteversion can lead to in-toeing

• 10degree of anteversion is ideal to prevent

dislocations.

BIPOLAR PROSTHESIS

Gilberty & Bateman in 1974, reported use of

bipolar prosthesis.

Erosion and protrusion of acetabulum would

be less because motion is present between metal

head & polyethylene socket (inner bearing).

Motion between metallic cup & acetabulum

(outer bearing), since cup is not fixed in bone.

• Because of compound bearing surface, bipolar

designs provide greater overall range of motion than

either unipolar designs or conventional THR.

• Made available with a 22 or 32 mm diameter head

Recent modifications

Axis of metallic and polyethylene cups are now

eccentric so that with loading of hip.

Metallic cup rotates laterally than medially, and thus

avoids fixation in varus position and avoids

impingement of head on edge of cup.

• WIDE RANGE OF MOVEMENTS

• STABILITY WILL BE IMPROVED

• PREVENTS THE COMPLICATIONS

• INCREASED LIFE SPAN OF PROSTHESIS

• CAN DO A TOTAL HIP LATER

ADVANTAGES

• WIDE RANGE OF MOVEMENTS

– It is due to size and geometry of inner bearing

– After a certain arc of abduction-adduction movements

and then the further movement occurs between

acetabulam and outer metallic cup of prosthesis

• STABILITY WILL BE IMPROVED

– At the degree of movement of the inner

bearing, when the joint tends to dislocate, it is

prevented by movement of outer bearing in

opposite direction.

• PREVENTS THE COMPLICATIONS LIKE

– Acetabular erosion and protrusio acetabulii

– Loosening of stem

• INCREASED LIFE SPAN OF PROSTHESIS

– As it is a low friction arthroplasty, the wear and tear is

minimal in both implant and the acetabulam

– Hence the life span is more when compared to other

universal endo prosthesis

• CAN DO A TOTAL HIP LATER

o Bipolar design affords the advantage of low friction

arthroplasty without implanting a separate acetabular

component.

o As absence of fixed acetabular cup eliminates the

potential complications use of methyl methacrylate for

fixation of one acetabular cup, which increases the duration

of surgery and complications associated with fixing the cup

with cement.

DISADVANTAGES

• INCREASED INCIDENCE OF DISLOCATION

REQUIRED IN OPEN REDUCTION

• INCREASED COST

MODULAR PROSTHESIS• Implant of choice for displaced

femoral neck of femur fractures

• In most cases, inserted as a

cemented femoral stem with

neck length, offset, and

acetabular adjustment

• This theoretically decreases the

stress on the acetabular cartilage

• Can be used with a fixed femoral

head (unipolar) or bipolar head and

provides a relatively easy conversion

to a THA, if required in future

INSERTION OF PROSTHESIS

• When an uncemented prosthesis used, it is essential to

achieve a firm fit within femoral canal and good seating of

the neck of the prosthesis on the calcar.

• Prosthesis should be tapped into place fairly gently. If

stronger hammer blows used fracture of femur may occur

• Valgus rather than a varus position should be borne in mind

• Reduction of prosthesis is achieved by applying

longitudinal traction at the same time gently abducting and

externally rotate the leg.

• Simultaneously pressure is applied to the femoral head so

as to push it distally and medially into the acetabulam.

• Confirmation of the reduction is achieved by assessing that

the hip has full range of movements.

Hemiarthroplasty Issues:Unipolar vs. Bipolar

• Unipolar– Lower cost– Simpler

• Bipolar– Less wear– More modular – More expensive– Can dissociate– Can convert to total hip

arthroplasty

Cement Vs Press fit

• Cement (PMMA)

– Improved mobility, function,

walking aids

– Sudden Intra-op cardiac

death risk slightly increased:

• Non-cemented (Press-fit)– Pain / Loosening higher– Intra-op fracture

(theoretical)

• Patients with a "stove pipe" type of femur (with no

tapering of medullary canal) are the best candidates

for cemented stems.

• Since there will be a higher risk of fracture with press fit

stems in these patients.

• Risks of cement in hip fractures: methylmethacrylate

embolism (leading to death).

Arthroplasty Issues:Hemiarthroplasty versus THA

• Hemi–More revisions• 6-18%

–Smaller operation• Less blood loss

–More stable• 2-3% dislocation

• Total Hip–Fewer revisions• 4%

–Better functional outcome–More dislocations• 11% early • 2.5% recurrent

[Cabanela, Orthop 1999]

[JBJS 1994]

Approaches

POSTERIOR APPROACHES

Gibsons approach(postero lateral approach)

Southern or Mores approach

LATERAL APPROACHES

Anterolateral approach (Watson Jones approach)

Harris lateral approach

McFarland & Osborne lateral approach

Posterior approach(Southern Mores approach

POSITION• Lateral decubitus with an axillary roll• All bony prominences are padded

LANDMARK: Greater trochanter

INCISION:10-15cm curved centered

on posterior aspect of Greater

trochanter

• Begin proximally 6-8cms

posterosuperior to posterior aspect

of Greater trochanter

• Continue to Greater trochanter

• Curve the incision in line with fibers of Greater

trochanter

• Continue along shaft of femur

INTERNERVOUS PLANE: No true plane

SUPERFICIAL DISSECTION:

Incise the fascia lata to

expose the Vastus lateralis.

Superiorly split the fibers

of GM(very important)

gently.

Gluteus Maximus split in line with its fibres

Gluteus medius released from crest of trochanter →short rotators exposed

DEEP DISSECTION:

Internally rotate the lower extremity at the hip to aid exposure of external rotator tendons

Posterior joint Capsule incised to expose head & neck

DANGERS • NERVES SCIATIC NERVE – from direct injury or retraction or duing

repair of external rotators and capsule when closing

FEMORAL NERVE – from retraction and displacement of

proximal femur during reaming of the acetabulum or

retractor placement

OBTURATOR NERVE. – Retractors

VESSELS INFERIOR GLUTEAL ARTERY – direct injury or

retraction

MEDIAL FEMORAL CIRCUMFLEX – during takedown

of external rotators from bone of posterior proximal femur

OBTURATOR ARTERY – retractor in inferior aspect of

acetabulum.

Closure is extremly important with posterior exposure to lessen possibility of dislocation

Short rotators are retrieved and are then reattached through bone holes in the posterior margin of trochanter in the region of anatomic attachment

Gibsons approach (1953)

POSITION

• Place the patient in lateral position

INCISION:

• The proximal limb of incision is begin

at a point 6-8 cm anterior to posterior

superior iliac spine & just distal to

iliac crest overlying the anterior

border of gluteus maximus muscle.

• It is extended distally to

anterior border of greater

trochanter & further distally

in line of femur for 15-18

cm.

SUPERFICIAL DISSECTION

• Iliotibial tract is incised in

line with direction of its

fibres.

• Next, gluteus minimus and medius are divided at their insertion to expose the capsule.

ANTEROIOR -LATERAL APPROACH(Watson Jones approach)

POSITION

• SUPINE – CLOSE TO EDGE – BUTTOCK HANGS OVER – TILTING THE TABLE TO OPPOSITE SIDE

INCISION

FIGUREOF 4 (FLEX AND ADDUCT SO THAT THE LEG LIES OVER OPPOSITE KNEE) →8-15 cms INCISION CENTERING ACROSS THE POSTERIOR THIRD OF GREATER TROCHANTER

INTERNERVOUS PLANE

NO TRUE INTERNERVOUS PLANE AS BOTH TENSOR FASCIAE

LATAE AND GLUTEUS MEDIUS SUPPLIED BY SUPERIOR

GLUTEAL NERVE

Anterior flap consisting of gluteus medius, minimus & vastus lateralis; alternatively this can be done by osteotomy

Anterior Capsule exposed & capsulotomy performed release from femoral attachment and a ‘T’ into acetabular rim.

Deep dissection

FEMORAL NERVE

o Most laterally placed in femoral triangle.

o Not flexing the hip after dissecting up to anterior rim of acetabulum

o Placing retractors into substance of iliopsoas Or over exuberant

retraction can damage it.

VESSELS –FEMORAL ARTERY & VEIN – damaged by acetabular

retractors that penetrate iliopsoas substance.

DANGERS

Harris lateral approach

Position o Place the patient on unaffected hip,elevate

the affected one to 60 degrees and

maintain this with a sand bag.

Incision o Make a U’shaped incision ,

o Base at the posterior border of greater

trochanter.

• Begin the incision 5cm

proximal to the anterior

superior iliac spine.

• Curve it distally and

posteriorly to the posterio

superior corner of the greater

trochanter

• Distally divide the ilio tibial band in line with the skin

incision

• At the greater trochanter , place a finger deep to the band

and feel for gluteus maximus on gluteal tuberosity and

guide the incision on fascia latae posteriorly.

• Make a short oblique incision at

the deep surface of the

posteriorly reflected fascia latae

• Begin the incision at the middle

of the greater trochanter extend it

medially and proximally into the

gluteus maximus muscle

• Free the abductor muscles

by osteotomizing the

greater trochanter

Risks due to trochanteric osteotomy• Trochanteric non-union

• Trochanteric bursitis

• Heterotopic ossification

Position:

o Lateral with affected hip is

above

Incision

o Mid lateral incision centering

greater trochanter.

McFarland & Osborne lateral approach

• Gluteal fascia and

iliotibial band are divided

in mid lateral line

• Incision is made to bone

obliquely across the

trochanter and distally in

vastus lateralis

• Combined mass of

gluteus medius & vastus

lateralis with their

tendinous junction is

elevated & retracted

anteriorly.

oTendon of gluteus minimus is split and divided before

retraction proximally

oCapsule opened to expose joint.

Preoperative planning

Radiographic examination• X ray of pelvis with both hip AP

view

• Anteroposterior and cross –table

lateral view of the involved proximal

femur.

Templating

• Preoperative templating

to determine the

appropriate femoral stem

and unipolar or bipolar

head size.

• The normal hip is used as a template to

duplicate normal leg length and hip

offset.

• Proper hip offset helps to maintain proper

soft tissue tension.

• Templating begins anterior posterior view

of pelvis that includes proximal femur.

• Pelvis should not be rotated

• 15 degree internal rotation of normal hip eliminates the

normal anteversion.

• The centre of the head is marked in non injured hip.

• A line is drawn down the centre of femoral shaft.

• The distance from this lines to the centre of the femoral

head is the hip offset

• Using templates a stem of appropriate size is choosen.

• It is also important to check that stem also matches both

anteroposterior and lateral views of the injured hip before

templating on the normal hip.

• For cemented insertion,adequate space must be maintained

around the stem to accommodate the cement mantel

(usually 2mm)

• The template is placed over the anterioposterior pelvis

film ,dierectly in line with the femoral canal.

• It is then slid down the canal until one of the neck length

markings matches the offset of normal hip.

• The distance from this marking down to the lesser

trochanter is measured using the magnified ruler markings

on the template.

• This distance is recorded and later measured

intraoperatively to mark the level of desired neck cut.

• The distance from the lesser trochanter to the centre of the

femoral head is also measured ,to recreate this distance

intraoperatively.

• The neck length marking on the template that most

closely matches the offset of the normal is the neck

length that will be used first when performing an

intra-operative trial & assuming intra-operative

stability for the prosthesis itself.

• Some patients have hips with larger offset than available on

the templates.

• These patients usally needs a prosthesis of high offset

geometry.

• If high offset stem is not used ,the soft tissue tension of the

hip abducters will be subnormal.

• These muscles may function sub optimally and hip stability

may be compromised.

PROCEDURE

• Position: according to the approach selected for hemi-

arthroplasty

• Through selected approach hip joint is exposed.

• In osteoarthritis hip is dislocated by flexion adduction and

inernal rotation and neck is ostetomised in posterior

approach

• In lateral approach dislocate the hip anteriorly .

• The neck should be osteotomised approximately 1cm

proximal to the lesser trochanter.

• Shortening of the limb by excessive femoral neck resection

and short femoral neck component may lead to prosthetic

dislocation due to soft tissue laxity.

• Lengthening of the limb will result in increased pressure on

the acetabular cartilage and acetabular erosion.

• In fracture neck of femur ,head is removed by using cork

screw by incising the ligamentum teres.

• Femoral head size should be measured by using caliper or

template.

–Head in smaller diameter will result in assymetric

load in acetabulum and lead to protrusio acetabuli.

–Head in larger diameter will not fully seat with in

acetabulum and leads to increse risk of prosthetic

dislocation

• If pulvinar is excessively large should be trimmed.

• Soft tissues from the posterior and lateral aspect of femoral

neck to the lesser trochanter is excised.

• Box osteotome is used to open the femoral canal.

• Sequential reaming done with rasp (reamer) until the

appropriate size (2size smaller to the template) in

appropriate anteversion.

Anteversion

• Orientation of the femoral neck in

relation to the femoral condyles at

the level of the knee.

• In most cases, the femoral neck is

oriented anteriorly as compared to

the femoral condyles.

• Femoral anteversion averages

between 30-40° at birth,

and between 8-14° in adults 

• Males having a slightly less

femoral anteversion than

females 

• In the case of posterior orientation, the term femoral

retroversion is also applied.• Excessive anteversion result in internal rotation

deformity and increased risk of anterior hip dislocation.

• Retroversion result in external rotation deformity and

increased risk of posterior hip dislocation.

• Trial femoral component neck and head is placed.

• Reduce the hip by traction and external rotation.

• Hip stability is assessed through range of motion.

– External rotation with hip in full extension.

– Flexion and adduction.

– Hip in neutral ,straight pull from the foot

• Trial implant replaced with appropriate prosthesis.

• If cementing , the bone plug is inserted and vaccum is

created by suction.

• Cementing is done through retrograde fashion using a

cement gun and good pressurisation technique.(hand

packed)

• Prosthesis is inserted using manual force and light taps with mallet

until the fully seated to the level of calcar cut .

• Excess cement is removed.

• Head is reduced.

• Stability is reasessed.

• Short external rotators and underlying capsule are repaired.

• Suturing done by layers.

• Shift the patient in abduction by keeping a pillow between legs.

OPERATIVE COMPLICATIONS

• Erosion of acetabulum

• Fracture of stem of prosthesis

• Dislocation of Prosthesis

• Fracture of femur

• Retroversion and anteversion of prosthesis

• Varus angulation

• Neck length variation

• Possibility of the sciatic nerve injury

POST OPERATIVE MANAGEMENT

• In case of cemented hemiarthroplasty mobilization will be

started on the second day & in uncemented will be after

2weeks

• Use of walker

• Avoidance of stairs and prevention of excessive hip flexion

or adduction

• Avoid squatting & sitting cross legged