Atypical Femoral Fractures and Bisphosphonates Treatment: Is it a Risk Factor?

Introduction: Bisphosphonates are effective in preventing osteoporotic fracture, however atypical femoral fractures with a well-defined radiological pattern have been described in association with prolonged treatment with bisphosphonates. Our objectives in this study were to characterize patients >= 65 years old with femoral fractures (subtrochanteric/diaphyseal) considered typical and atypical and the relationship between the occurrence of atypical fractures and bisphosphonate use. Material and Methods: We conducted a case-control study with patients admitted in our hospital with subtrochanteric or diaphyseal femur fracture in a period of five and a half years. After applying the exclusion criteria, the 92 fractures (91 patients) were classified as typical or atypical. The determination of prior bisphosphonate treatment was obtained through consultation of the individual medical history. Results: We found 11 atypical fractures (10 patients) and 81 typical fractures (81 patients). The median age of both groups was statistically different (72 years -atypical vs. 80 years - typical, p < 0.01). The reason for the use of bisphosphonates was 0.60 in atypical fractures and 0.01 in typical, and an odds ratio of 101.1 was obtained (p < 0.01). Discussion: Our results are supported and are in agreement with published studies relating to the occurrence of atypical femoral fractures associated with treatment with bisphosphonates. Conclusion: Despite the small number of cases it was possible to demonstrate a statistically significant relation between atypical femoral fractures and treatment with bisphosphonates. One should note that these atypical fractures occurred in patients significantly younger than patients with typical fractures.