PELVIC OSTEOTOMY FOR SPASTIC HIP DISLOCATION
ORTHOPAEDIC DEPARTMENT
THE ALFRED I. DUPONT INSTITUTE
WILMINGTON, DELAWARE
Patients who had not had prior muscle release surgery or whose contracture had reoccurred and limited hip
abduction, first had an open complete release of the adductor longus and brevis, gracilus, and an anterior
branch obturator neurectomy. This was followed with a varus osteotmy using the AO blade plate as
previously described. The chisel was inserted with the goal of creating 90 to 100 degrees varus neck-shaft
angle for non- ambulators and 110 to 120 degree neck-shaft angle for ambulators. After the femoral
osteotomy, care was taken to remove the whole lesser trocanter including the
cartilage cap to provide a complete release of the iliopsoas for marginal or non- ambulators. For community
ambulators, intermusclar lengthening of the Iliopsoas is performed with preservation of the lesser
trocanter on the proximal fragment.
Next, the proximal fragment is abducted and evaluated under
fluoroscopy to document that the femoral head will reduce into the acetabulum . If it does not reduce,
an anterior and medial capsulectomy is performed through the femoral osteotomy. By abducting the proximal
fragment good visualization of the medial capsule is possible and the aspect of the capsule which prevents
reduction can easily be released. If the femoral head does reduce with abduction but continues to be
unstable in the acetabular with superior pressure or had windshield wiper movement with 30 degrees of
abduction in the expected range after fixation of the osteotomy or the sourcil of the acetabulum slopes
superiorly or is diffuse, a pelvic osteotomy was indicated. This was done before fixation of the femoral
osteotomy by packing the femoral site leaving the proximal fragment abducted. An anterior bikini incision
was made just distal to the anterior supior iliaec spine. The iliac apophysis was split and the lateral
aspect of the ileum only was subperiosteally exposed down to the hip capsule. The interval between
sartorius and fascia lata was developed down to the anterior inferior spine. The interval between the
iliac spines was incised and the capsule
was identified from the inferior iliac spine all the way posterior to the triradiate cartilage. The
posterior dissection was performed using a cobb elevator, however the sciatic notch is not entered. The
posterior dissection is all inferior to the sciatic notch. Using a 4- 6 mm wide straight osteotome with
constant fluoroscopic control the initial cut is made directly lateral to medial starting 3- 5 mm above
the osseous corner
of the acetabulum directed medially to the middle of the triradiate cartilage. The cut is than completed
anteriorly with the anterior 1 cm cutting across both tables of the ileum.
The cut is continued
posteriorly by continuing to aim at the center of the triradiate cartilage making sure that all of the
posterior cortex is cut down to the triradiate. With the osteotome in the most posterior aspect of the
osteotomy, the osteotomy should easily open. A tricortical bank bone graft is cut into a triangle 10 - 15
mm tall and long enough to be just short of the triradiate cartilage. The posterior graft is inserted
first trying to get it directed anteriorly so there is more opening posterior. A second smaller anterior
graft is next inserted. The position of the hip is now checked under fluoroscopy to make sure that it
remains stable with movement in the expected range after fixation of the femoral osteotomy.
After this
the femoral osteotomy is reduced and held manually with the hip flexed 90 degrees and the knee fully
extended. The femur is shortened so the osteotomy has no compression force in the straight leg raising
position. This usually requires 2- 6 cm of further femoral shortening. If the patient is a very function
ambulator than distal hamstring lengthening should be done first so less femoral shortening is required.
The femoral osteotomy is next fixed with an AO blade plate.
Careful attention is given to placing the
femur in zero to 15 degrees anteversion so the knee should rest in external rotation with the hip extended
and the hip must come to neutral rotation at 90 degrees of knee and hip flexion for comfort and ease of
sitting. Retroversion must be avoided. If the contra- lateral hip is also subluxated or dislocated the
same procedure is performed at the same setting. If the opposite leg had an abduction contracture or was
more than 2 cm longer, a concurrent varus osteotomy was performed to provide for symmetrical hip motion
and leg length.
An xray at the conclusion of the procedure should show well reduced hips which are symmetrical and well
covered. The windswept position pre-operatively if present must be converted to as symmetrical a position
post-operatively as possible.
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