Medium term follow up of the Biodynamic neck sparing prosthesis

Hip resurfacing (HR) and neck sparing prostheses (NSP) have been advocated for the treatment of arthritis in younger patients. Some complications following HR have been documented in the recent literature, but NSP are not yet supported by clinical follow-up studies of sufficient duration. We present an assessment of the neck sparing "Biodynamic" prosthesis. 153 patients were evaluated in a longitudinal cohort prospective study, with survival analysis, clinical score and radiographic assessment of stability and osteointegration at 41.8 months average follow up. Survival and clinical outcome were similar to most traditional prostheses in the literature. On radiographic analysis we recorded good neck preservation and osteointegration. Only two stem failures were recorded. Poor clinical outcome was related to misalignment of prostheses implanted during the 'learning curve'. The NSP system described may be a good alternative to HR for younger patients. The system is characterized by good survival and clinical and radiographic outcome combined with bone stock preservation.