Anterior Approach Subtrochanteric Osteotomy

An interesting case that perfectly illustrates how the anterior approach and its facilitating technologies are well suited to complex hip surgeries. Here we undertake a subtrochanteric osteotomy and total hip arthroplasty to address an iatrogenic deformity created below the lesser trochanter.

Overview:

This case perfectly illustrates how the anterior approach and its facilitating technologies really does lend itself to complex primary hip arthroplasty. A

It relates to a very active 39-year-old male. He was born in Russia and had a diagnosis of Legg-Calve Perthes disease at age six. This was managed conservatively until age 15 at which point he underwent an Ilizarov type subtrochanteric lengthening procedure presumably to manage a leg length inequality.

Hi AP radiograph demonstrates a very large area of regenerate bone. Interestingly, on clinical exam, you would expect him to have a short, somewhat externally rotated right hip as a consequence of his Perthes disease, you find that actually his leg lengths are symmetrical. This prompted me to get a standing 51 inch cassette film leg length assessment. This revealed that while his clinical leg lengths were equal, there was about a two and a half centimeter area of regenerate bone which meant that if a total hip arthroplasty was performed in the usual fashion we would end up with a leg length inequality.

My thoughts in the form of a problem list.
the Perthes deformity which classically leads to challenges with soft tissue mobilization
challenges relating to getting the neck cut right
challenges in terms of lengthening and offset recreation in a somewhat deformed proximal femur
we are also dealing with acetabular dysplasia which creates problems of hip center and raises the question of whether to use a graft or an augment or consider a high hip center as an alternative
a sub trochanteric deformity which has not only length but potentially angular or rotational deformities.

On calibrating from the AP pelvis we move on to the proximal femur to plan our neck resection – which is performed under fluoroscopy. We mark the level with an osteotome and upon removal of the femoral head neck segment a reamer is introduced to prepare the acetabulum. In this case, we know we were dealing with acetabular dysplasia. We anticipated a large defect above the acetabular component and we were prepared to graft this under AP fluoroscopic imagery.

The acetabular component is placed and checked using the Velys system. Once we were comfortable with the position of the acetabular component, screws were placed in the usual manner using oblique radiographs to confirm positioning and to assess the defect for preparation of our acetabular graft.

Upon completion of the acetabulum, we turn our attention to the femur. Using an awl from the Synthes flexible reamer set we were able to pass
through the regenerate and at this point we recognized we also had an angular deformity which would necessitate correction. By positioning the deformity in its maximal plane we were e able to assess the angular deformity to guide our intraoperative correction.

Our next step was to prepare the medullary canal. We used flexible reamers to prepare the canal to accept our SRom implant. This implant was selected to enable us to correct axial plane deformity as well as to perform the subtrochanteric osteotomy.

At this point a separate lateral approach was then made - a typical lateral subvastus approach. Femur pins were used to guide our resection and the final resection was performed under direct fluoroscopic control using a saw and eventually a bone hook to guide the femoral component across the osteotomy site. An oblique osteotomy was selected to control for axial rotational stability.

In our final montage at six weeks post-op his early recovery was excellent. He was able to mobilize fully weight bearing on the operative extremity. He had no dislocation precautions in place and a testament to his early functional recovery was that at two weeks post-op he was able to ride in on his motorcycle for his wound check.

This patient now has over a year of follow-up. Radiographically he has complete osteointegration of his super-acetabular graft. He has healing of his sub-trochanteric osteotomy and stable fixation of his acetabular and femoral components. He seems to be as pleased as I am about his result and I look forward to continued follow-up of this patient.