Femoral head stress fracture: an unknown complication following Sugioka's transtrochanteric rotational osteotomy.

Sugioka's transtrochanteric rotational osteotomy, as a treatment of osteonecrosis of the femoral head, has variable success rates. Its known complications include: progressive varus deformity, femoral neck fracture, and femoral head collapse. However, femoral head stress fracture has not been described as a complication of Sugioka's transtrochanteric rotational osteotomy. This article presents cases of 2 of 64 patients who underwent Sugioka's transtrochanteric rotational osteotomy between 1994 and 2006 and experienced femoral head stress fractures. Both patients were young and active. They presented with acute inability to bear weight and pain on the operated hip after mountain climbing 1 and a half to 3 years following the index surgery. Diagnosis of femoral head stress fracture was established by the presence of an inferolaterally-directed vertical fracture line from the superolateral aspect of the femoral head on computed tomography scans for both patients. One patient was successfully managed with conservative measures, whereas the other underwent total hip replacement after failed conservative treatment. We hypothesize that the direction alteration of the trabecular system due to proximal femoral segment rotation, varus positioning of the proximal femur, and inadequate placement of the screw into the necrotic femoral head may have caused the femoral head stress fractures after transtrochanteric rotational osteotomies. Stress fracture of the femoral head is a potential complication following Sugioka's transtrochanteric rotational osteotomy for osteonecrosis of the femoral head, which may be prevented by avoiding heavy exercises such as mountain climbing, until adequate remodeling of the trabecular system is gained and screws can be inserted into the femoral head subchondral bone as deeply as possible with avoidance of the necrotic area.