In the name of GOD THA & DDH

By : paisoudeh karim MD Firoozgar hospital Iran university of medicine

Classification of DDH/CHD in adults : CROWE (Crowe JBJS 1979) HARTOFILAKIDIS

In addition to the proximal migration of the femur, several deformities of the bone and soft tissues Femoral head  small , deformed Femoral neck  narrow and short marked anteversion The greater trochanter usually is small and often located posteriorly The femoral canal is narrow

The acetabulum is oblong and its roof is eroded.

In high and intermediate  false acetabulum is not deep or wide enough for containment of the cup

The thickest bone available usually is in the true acetabulum

Extensive capsulectomy( tenotomy of the psoas, rectus femoris, and adductors) Anteroposterior radiographs of the pelvis and proximal femur and a lateral view of the femur must be studied carefully No more than 3 to 4 cm of lengthening should be planned

The shallow dysplastic acetabulum may require a very small acetabular component ( ≤40 mm) A 22-mm femoral head No more than 5 mm of the cup should protrude Most authors recommend placement of the acetabular component within the true acetabulum

Crowe type I , there is relatively little bony deformity and the acetabular component can be placed in the true acetabulum without difficulty Crowe type II and type III, when the socket is placed within the true acetabulum, a large superior segmental deficit remains with a lack of superior coverage of the component

In most patients, grafting is not required if the acetabular component is placed in a slightly high location as long as it is not also lateralized(15%) The screws should be oriented in parallel and along lines of weight-bearing forces(lag)

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High dislocation, as in Crowe type IV, the acetabulum is hypoplastic, but its superior rim has not been eroded by the femoral head.

The bone is often very soft, and the final reamers may be used in reverse to enlarge the acetabulum by impaction rather than removal of bone Transacetabular screw fixation of the acetabular component usually is required because of rim deficiencies and osteopenia.

The femoral component must be placed in neutral or slight anteversion in relation to the axis of the knee joint For Crowe type III and type IV hips, femoral length is more problematic

The architecture of the proximal femoral metaphysis is preserved and the orientations of the greater trochanter and abductors are corrected to restore hip mechanics and prevent instability and limp.

A standard stem design also can be used.

The osteotomy is made just distal to the lesser trochanter, A short oblique or step-cut osteotomy fixed with cerclage wires also provides greater rotational stability than a transverse osteotomy but adds a degree of technical difficulty.

In most cases, total hip arthroplasty can be performed without osteotomy of the trochanter, but if at the end of trial reduction the trochanter impinges on the pelvis