Review Question - QID 219821

Total hip arthroplasty in patients with hip dysplasia requires unique considerations to optimize outcomes and limit complications. In the setting of a Crowe-IV hip joint, a femoral shortening osteotomy should be performed to prevent sciatic nerve palsy (Answer 1).

Adult dysplasia of the hip results in a shallow acetabulum and with femoral head subluxation or dislocation, depending on severity. The Crowe classification was formulated to characterize the severity of dysplasia. To improve hip biomechanics and improve durability, the acetabular component should be placed in the true acetabulum. However, this requires the femoral head to be reduced back into the native acetabular location. While the exact amount of acute limb lengthening that will result in a neural injury is unknown, an increase of 2-4 cm has been associated with sciatic nerve palsy. Femoral shortening can be done with either sequential resection of the proximal femur or by a subtrochanteric osteotomy. A subtrochanteric osteotomy is generally preferred due to its ability to correct angular deformity, which obviates the need for greater trochanter osteotomy. A sub-trochanteric shortening osteotomy would have lowered the risk of sciatic nerve palsy in this patient.

Sanchez-Sotel et al. published a thorough review of the surgical treatment options for developmental dysplasia of the hip in adults. The authors review treatment options for hip dysplasia, depending on the severity as classified by the Crowe classification. For a Crowe type IV hip, the authors recommend anatomic placement of the acetabular component. To prevent sciatic nerve palsy, the authors recommend a femoral shortening osteotomy. They report that a greater trochanteric osteotomy and sequential proximal femoral resection may be technically easier but has several disadvantages. Therefore, they recommend a subtrochanteric femoral osteotomy with an uncemented stem.

Ollivier et al. published the results of a retrospective review of 20 patients who underwent cementless total hip arthroplasty with shortening subtrochanteric osteotomy at a mean follow-up of 10 years. Although derived from a small sample size, the 10-year survivorship free from revision for aseptic loosening was 89%. The authors conclude that femoral shortening osteotomy with cementless total hip arthroplasty results in a high rate of successful implant fixation and stable clinical improvement.

Figure 1 shows the AP right hip film of a patient with Crowe type IV hip dysplasia, showing a high dislocation.

Incorrect answers:
Answer 2: Anterior acetabular retractor placement should not affect sciatic nerve function and would more likely injure the femoral nerve.
Answer 3: Although navigation may assist in difficult cases, there is no reported decrease in sciatic palsy with its use.
Answer 4: There is no reported decrease in sciatic palsy when using an anterior approach in patients with hip dysplasia.
Answer 5: Although acetabular and medialization can improve the coverage of the acetabular component, this is unlikely to cause sciatic nerve lengthening.