Subtrochanteric Femoral Insufficiency Fracture in Woman on Bisphosphonate Therapy for Glucocorticoid-Induced Osteoporosis

We present the case of an 85-year-old woman who sustained a subtrochanteric femoral shaft insufficiency fracture after receiving bisphosphonate therapy for osteoporosis. After more than 6 years of taking risedronate sodium (Actonel) and daily supplemental calcium carbonate and vitamin D, the patient developed right anterior thigh pain that was worse with weight-bearing. A small, pyramidal ridge of cortical bone was demonstrated by radiographs and CT along the antero-lateral subtrochanteric region of the right femoral shaft. On MRI, there was focally increased T2 signal in the adjacent bone marrow. Radionuclide bone scan showed moderately-intense, focally-increased uptake. The lesion was recognized as a potential stress riser for fracture; however, before a prophylactic intramedullary rod could be placed, the patient suffered a low-energy insufficiency fracture through the lesion. In the setting of bisphosphonate therapy for osteoporosis, a painful pyramidal projection of cortical bone in the subtrochanteric femoral shaft should be recognized as an impending insufficiency fracture and treated expeditiously.