Seasonality of Periprosthetic Femur Fractures in 12,700 Primary and Revision Total Hip Arthroplasties.

BACKGROUND: Periprosthetic femur fractures after primary and revision total hip arthroplasty (THA) are one of the most common long-term reasons for reoperation after THA. Previous investigations have analyzed the incidence and risk factors of these fractures. No previous study, however, has analyzed a variation in periprosthetic femur fractures between meteorologic seasons. The aim of this study was to compare the incidence of periprosthetic femur fractures after primary and revision THAs depending on the meteorologic season. METHODS: We identified 8920 patients (10,672 hips) who underwent primary THAs and 1830 patients (1998 hips) who underwent revision THAs at our institution between 1995 and 2011. All patients resided in the Upper Midwest at the time of surgery. Patients who experienced periprosthetic femur fractures were identified and categorized based on the meteorologic season. A Cox model was used to assess the association of seasonality with the risk of fracture. RESULTS: During the study period, 165 primary THAs and 80 revision THAs sustained a periprosthetic femur fracture. Using winter as a reference, the risk of a periprosthetic femur fracture after primary THA was not statistically higher in the spring (hazard ratio [HR] = 1.3; P = .2), autumn (HR = 1.4; P = .2), and summer (HR = 1.415; P = .1). Similarly, the risk of periprosthetic femur fracture after revision THA was not statistically higher in the spring (HR = 0.9; P = .6), autumn (HR = 0.6; P = .1), and summer (HR = 0.9; P = 1.0). CONCLUSION: The risk of periprosthetic femur fracture after primary and revision THA does not significantly differ between meteorologic seasons.