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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)
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