TRANSIENT BONE MARROW EDEMA SYNDROME AND SUBCHONDRAL INSUFFICIENCY FRACTURE

Subchondral Fatigue Fracture of the Femoral Head in Young Healthy People
HJ Kim, WS Song, JJ Yoo, KH Koo, YM Kim
Department of Orthopaedic Surgery, Seoul National University College of Medicine, Seoul, Korea

Introduction: Stress fracture of the femoral head is a rare condition and usually occurs in people with poor bone quality as an insufficiency fracture. We evaluated the clinical aspects of the subchondral fatigue fracture of the femoral head (SFFFH) that occurred in young healthy people.

Patients and Methods: Between January 1998 and November 2001, 7 cases of SFFFH in 5 patients were treated. The characteristics of this condition were ascertained by assessing the clinical course and findings of radiographs, bone scintigram and MR images.

Results: All patients were male military recruits in early twenties. Pain developed within 6 months after recruitment. On initial radiographs, definite abnormal findings were observed in 3 hips of 2 patients. In 2 of them, the femoral head was collapsed markedly. In the other 4 hips, no definite abnormal findings were noticed. The bone scintigram showed increased radionuclide uptake in the femoral head. MR images demonstrated localized abnormal signal intensity (bone marrow edema pattern) area in the femoral head. In all cases, MR crescent sign was observed. In the cases without collapse of the femoral head, the pain decreased gradually and disappeared completely in 6 months with improving findings on follow-up MR images. The collapsed cases needed surgical treatment; THA and strut iliac bone graft.

Conclusions: When a military recruit or an athlete is complaining of hip pain, a high index of suspicion for SFFFH is necessary to prevent the collapse of the femoral head. Bone scintigram is of great value as a screening tool. Osteonecrosis of the femoral head can be differentiated by the findings on MR images.