Atypical Femur Fracture in the Setting of Long-Term Bisphosphonate use for Osteogenesis Imperfecta: A Case Report

Parker J Prusick ,Nathan Donaldson,Jesse Roberts,Steven Jones

doi:10.31579/2690-1897/094

Abstract

Bisphosphonate (BP) therapy for moderate to severe osteogenesis imperfecta (OI) has become a mainstay of treatment in the last three decades. Given the significant improvements in bone mineral density and theoretical reductions in fracture risk, many patients are treated with bisphosphonates for prolonged periods of time. There currently lacks consensus in the optimal duration of BP therapy for patients with OI, and patients are often treated on a case-by-case basis. Long-term BP therapy has been associated with atypical femur fractures in adult patients treated for osteoporosis. The American Society for Bone and Mineral Research concluded that the median duration of BP therapy in patients with atypical femur fractures was 7 years. The role of long-term BP therapy in OI patients with atypical femur fractures remains unclear. Here, a case report is presented of an adolescent patient with type V OI that sustained a subtrochanteric femur fracture with features of an atypical pattern following treatment with intravenous pamidronate for 10.5 years. At the time of injury, the contralateral femur was also found to have atypical features suggestive of an impending fracture. The completed fracture was treated with closed reduction and cephalomedullary nail fixation. The impending fracture was prophylactically stabilized using the same technique. Prior to the injury, limb-length radiographs obtained to evaluate lower extremity alignment demonstrated features of an impending fracture but went unnoticed. Further studies are needed to clarify the role of long-term BP therapy in patients with OI suffering from atypical femur fractures.

Highlights

Osteogenesis imperfecta (OI) is a genetic condition that leads to bone fragility and an increased risk for fractures
The etiology of OI consists of a mutation of type I collagen that precipitates poor bone mineral density and an abnormal formation of the osseous matrix [1]
Bisphosphonate therapy for moderate to severe osteogenesis imperfecta has become a mainstay of treatment in the last three decades

Summary

Introduction

Osteogenesis imperfecta (OI) is a genetic condition that leads to bone fragility and an increased risk for fractures. The left proximal femur had an area of lucency in the lateral cortex suggestive of a stress fracture These findings went unnoticed by the treating providers at the time the study was performed. Three months after this study was obtained, the patient sustained a left subtrochanteric femur fracture through this area of lucency This was one month prior to the patient’s 14th birthday. Radiographs were obtained, which showed a lateral cortical lucency in the right proximal femur similar to the previously demonstrated lucency on the left (Figure 7). This finding led to the discussion of prophylactic cephalomedullary nail fixation, as the patient was still quite active in ballet and dancing.

Discussion

Conclusion