Review Question - QID 8538

It has been demonstrated on a cadaver model that screw fixation of moderate and severe slipped capital femoral epiphyses may result in screw impingement upon the acetabulum and labrum. This is likely when the screw head on the anteroposterior view is seen to lie medial to the intertrochanteric line. Femoral artery pseudoaneurysm has been reported when the screws are left long (projecting far from the bone) to ease removal. Chondrolysis is associated with persistent penetration into the hip joint; both screws stop well short of the articular surface. Many in vitro studies of slip models have demonstrated increased strength of construct of two screws compared to one, although the clinical relevance can be questioned. The radiographs show the screw heads firmly in the femoral head, with loss of fixation in the femoral neck. Sanders and associates reported a series of 7 such failures and hypothesized that acute-on-chronic slips may develop osteopenia of the femoral neck. All patients reported continued pain postoperatively rather than the relief typically seen following surgical stabilization of the epiphysis. There is no radiographic evidence of osteonecrosis or chondrolysis.