Personalized Medicine for Metal on Metal Hip Resurfacing: Predictors for the 10 Years Success of the Birmingham Hip Resurfacing

Background: Metal-on-metal hip resurfacing arthroplasty was introduced to preserve patients’ bone and facilitate revision surgery. This prospective cohort study aims to determine a prognostic model (OsBHR) to predict which patient and surgeon related factors predict better long term implant survival for the Birmingham Hip Resurfacing (BHR). Methods: Between 1997 and 2002, details of 4490 patients (4945 hips) treated by hip resurfacing arthroplasty using the BHR prosthesis were entered in a prospective international registry and available for analysis. Implant survival was determined using the Kaplan-Meier estimator and a shared frailty proportional hazard model was used to determine predictors of implant revision. Results: prognostic equation suggested a minimum diameter of 50 mm should be used for male and 52 mm for female patients to ensure a minimum 10-year survival rate of 95% for in procedures performed by an average surgeon. Conclusion: Implant survival at ten years and beyond strongly depends on component size and gender, varies between surgeons but is little affected by patient age. The OsBHR predictor allows a personalized estimated survival at ten years based on pre-operative variables.