Preoperative assessment for intertrochanteric femoral osteotomies in severe chronic slipped capital femoral epiphysis using computed tomography.

We propose here to focus on preoperative assessment for intertrochanteric femoral osteotomies in severe slipped capital femoral epiphysis (SCFE) using computed tomography. This intertrochanteric osteotomy was preoperatively customized for each chronic SCFE patient treated, and has been performed on 22 patients with an average posterior slip angle of 55 degrees. The osteotomy is planned with images from computed tomography as follows. The angle between a provisional axis on one image and the axis of the lateral aspect of the femur on the other image is defined as alpha. When the alpha angle varies from 20 to 30 degrees, a simple flexion osteotomy is selected for correction along the axis of the lateral femur; when the alpha angle is more than 30 degrees, a flexion osteotomy along with some valgus correction should be considered; when the alpha angle is less than 20 degrees, varus correction should be added. The postoperative posterior slip angle, head-shaft angle (P < 0.05) and epiphyseal height ratio (P < 0.005) in the group using our method were superior to the Southwick group. Postoperative hip motion was nearly the same as the unaffected side. The average leg length discrepancy was 0.9 cm (range, from 0 to 2.0 cm). Reduced blood loss (P < 0.001) and shorter operation time (P < 0.001) were also noted, compared with the Southwick group. We concluded that the intertrochanteric femoral osteotomy based on this strategy minimizes the surgical complexity, resulting in a more anatomic reduction of the capital femoral epiphysis.