[The modified Dunn procedure to treat severe slipped capital femoral epiphysis].

The modified Dunn procedure enables restoration of the proximal femoral anatomy and normal hip function in patients with slipped capital femoral epiphysis (SCFE). Surgery is indicated in severe SCFE and in hips with a moderate slip angle and impaired function. To prevent further dislocation of the femoral head, the authors recommend non-weightbearing until surgery, since an accurate evaluation of slip stability is not possible in the clinical setting. Only a well-trained orthopedic surgeon with a high level of expertise in hip preservation surgery should perform this procedure. Precise knowledge of the vascular anatomy of the proximal femur is essential to perform successful surgery with low rates of complications such as avascular necrosis of the femoral head. Surgical hip dislocation with osteotomy of the greater trochanter is the approach used. After arthrotomy, stability of the physis is checked. To prevent rupture of the retinacular vessels in hips with an unstable physis, these heads are prophylactically pinned before dislocation out of the socket. Blood supply to the femoral head as well as intraarticular damage can be judged in the dislocated position of the femoral head. The retinacular flap preserves epiphyseal perfusion while the femoral head is dislocated from the femoral neck. Resection of posteromedial callous formation from the femoral neck as well as removal of the remaining physis from the femoral head prevent stress on the retinacular vessels after reduction of the femoral head (epiphysis) on the neck.