Pelvic fractures associated with long-term bisphosphonate therapy - case report

Long term bisphosphonate use has been associated with "atypical" subtrochanteric and diaphyseal fractures of the femoral shaft. We are reporting a case of pelvic fractures in addition to atypical long bone fractures, in a patient with osteopenia treated with bisphosphonate for 8 years, and teriparatide for 2 years. After 5 years of bisphosphonate therapy the patient suffered an atraumatic fracture of the femoral shaft. With an additional 3 years of bisphosphonate use she fractured both the upper and lower pubic rami on the left side. Bone histomorphometry performed on a biopsy of right iliac crest was negative for malignancy and calcification defects. It showed normal to low/normal bone turnover which correlated well with a low NTX level. Post-surgical X-rays revealed cortical thickening of the femur and beaking at the femoral shaft fracture, the classic findings associated with alendronate-related fractures. The pelvic fractures also reveal beaking at the fracture sites. Spontaneous fracture of the pelvis with unusual characteristics, in a patient with an atypical fracture of the femur suggests that the pelvic fracture may be related to long term bisphosphonate therapy.