Subchondral stress fracture of the femoral head is a rare condition that usually occurs as an insufficiency fracture in people with poor bone quality. This study evaluated the clinical and radiographic aspects of the subchondral stress fracture of the femoral head that occurred in the form of an insufficiency or a fatigue fracture.

Between January 1998 and April 2003, 10 cases of the subchondral stress fracture of the femoral head in 8 patients were treated. The characteristics of this condition were determined by assessing the clinical course and findings of the radiographs, bone scintigram and MR images.

A fatigue fracture developed in 6 young healthy conscripts within 5 months after recruitment. An insufficiency fracture developed in one senile patient and in one known osteogenesis imperfecta patient. All patients except for one did not have any predisposing factors for osteonecrosis and antecedent trauma. On the initial radiographs, femoral head collapse was observed in 4 hips. Bone scintigraphs showed increased radionuclide uptake in the femoral head. The MR images demonstrated an subchondral abnormal signal intensity line (MR crescent sign) and a bone marrow edema pattern.

A subchondral stress fracture of the femoral head can occur as a fatigue fracture as well as an insufficiency fracture. Bone scintigraphy is a valuable tool for screening patients suspected of having a subchondral stress fracture.