Early diagnosis of impending femoral insufficiency fractures by use of MRI: case report and review of the literature

Bisphosphonate (BSP) therapy has been widely used for management of osteoporosis, and has been shown to reduce the risk of vertebral and femoral neck fractures in postmenopausal osteoporotic patients [1, 2]. BSPs inhibit osteoclast function and induce osteoclast apoptosis, and, thus, increase bone mineral density and suppress bone turnover. However, previous studies have suggested that chronic suppression of bone turnover may produce hypermineralized bone that is more brittle, and therefore more susceptible to low-energy or stress fractures [3, 4]. Longterm BSP therapy has recently been reported to be associated with low-energy subtrochanteric and diaphyseal femoral fractures, and a peculiar, consistent fracture configuration has been described for these insufficiency fractures [5]. Radiological findings of stress reactions before the fracture have also been described [6]. Therefore, to prevent fractures, patients on long-term BSP therapy may require close monitoring. In a recent study, prophylactic fixation was performed on the basis of symptoms and radiographic findings. However, radiographic findings alone may not be sufficient to support the decision to adopt a preventive procedure. To the best of our knowledge, no study has yet been undertaken to determine whether magnetic resonance imaging (MRI) can detect cortical damage or predict an impending fracture in patients on long-term BSP therapy. In this study we used MRI to identify evidence of impending fractures in patients on long-term BSP therapy with thigh pain and a suspicious radiographic femoral lesion.