Hip resurfacing is the safer and more effective choice

Hip resurfacing arthroplasty (HRA) remains controversial because of concerns surrounding metal-on-metal bearings, pseudotumours and metallosis. Yet a 2013 propensity-matched analysis of more than 30,000 English patients reported that metal-on-metal HRA carried a lower all-cause mortality than both cemented and uncemented total hip arthroplasty (THA), with a survival advantage that widened over ten years. This narrative review examines that paradox and proposes a coherent mechanistic explanation: that resurfacing confers its survival benefit by restoring normal physical activity.

The argument is built by synthesising evidence across several domains. Large cohort and meta-analytic data confirm a dose-response relationship between habitual physical activity and reduced all-cause, cardiovascular and cancer mortality. Gait laboratory studies, wearable step-count data and 24-hour activity monitoring consistently show that, although THA reliably relieves pain, it does not restore activity to healthy levels; stride length, hip extension and walking speed remain reduced and asymmetric. By contrast, HRA preserves the native femoral head and restores a normal flexion-extension arc, stride length and symmetrical gait indistinguishable from healthy controls. Newly completed UK Biobank accelerometry confirms this in real life: THA patients take significantly fewer steps than matched controls, whereas resurfaced patients do not differ from controls and walk approximately 9% more than THA patients.

Imaging corroborates these functional findings. Following THA, progressive proximal femoral stress shielding and bone loss occur irrespective of stem design, whereas intertrochanteric bone density is preserved or improved after resurfacing.

For patients with adequate bone quality and a life expectancy of at least ten years—particularly younger, active individuals—resurfacing may therefore represent the safer and more effective choice. Although modern resurfacings and THA show comparable revision rates, the salvage of a failed resurfacing is a well-functioning THA, whereas revision of a failed THA typically leaves patients with lifelong pain and inferior function. Emerging ceramic-on-ceramic devices promise comparable functional restoration while avoiding the complications of metal ions, with important implications for patient selection and shared decision-making.