Rapid osteolysis of the femoral neck: consequence of an insufficiency fracture of the hip?

PURPOSE: To describe the imaging and clinical features of rapid osteolysis of the femoral neck in an attempt to better understand this uncommon pathology.
MATERIALS AND METHODS: We retrospectively reviewed the files of 11 patients (six women and five men) aged 53-78 years diagnosed with rapid osteolysis of the femoral neck. Available imaging studies included radiographs, CT, MRI, and bone scintigraphy. Histopathological evaluations were available for seven cases.
RESULTS: All patients presented with complaints of hip pain, six of whom had acute symptoms, while the rest had progressive symptoms and impairment. All but one case were found to have bone deposition in adjacent hip muscles. CT confirmed bone deposition in adjacent tissues and true osteolysis of the femoral neck with relative sparing of the articular surfaces. Bone scintigraphy and MRI were useful to exclude underlying neoplastic disease.
CONCLUSIONS: Rapid osteolysis of the femoral neck tends to occur in patients with underlying comorbidities leading to bone fragility and may actually represent a peculiar form of spontaneous insufficiency fracture. Recognition of its imaging features and clinical risk factors may help distinguish this process from other more concerning disorders such as infection or neoplasm.