Purpose: Osteogenesis imperfecta (OI) has been treated with bisphosphonates for many years, with some clear clinical benefits. In adults, there are reports of a new pattern of atraumatic subtrochanteric fractures with bisphosphonate treatment. This study assesses if bisphosphonate treatment leads to an altered pattern of femoral fractures.
Methods: Retrospective review of imaging for a cohort of 176 bisphosphonate-treated OI patients to identify the locations of femoral fractures over a two-year period, as compared to a historical control group managed pre-bisphosphonates.
Results: Sixteen femoral fractures were identified in this time period in the bisphosphonate-treated group. All but two were within the subtrochanteric region. In comparison, the historical group-composed of 26 femoral fractures-had a more widespread fracture pattern, with the most frequent location being the mid-diaphysis. Many of the subtrochanteric fractures in the treatment group occurred with minimal trauma.
Conclusions: It appears that concerns over the treatment of the adult osteoporotic population with bisphosphonates are amplified and mirrored in OI. It is possible that the high bending moments in the proximal femur together with altered mechanical properties of cortical bone secondary to the use of this group of drugs increase the risk of this type of injury, which warrants further modification of surgical management of the femur.
Keywords: Bisphosphonates; Osteogenesis imperfecta.