METAL-ON-METAL HIP RESURFACING COMPARES FAVORABLY TO TOTAL HIP ARTHROPLASTY IN THE US: UPDATE ON A PROSPECTIVE SINGLE INSTITUTION US STUDY WITH 1-YEAR FOLLOW-UP

Abstract

In May 2006, the US FDA approved the first type of metal-on-metal hip resurfacing (MOMHR) for distribution in the US because of promising survivorship achieved in Europe for patients with a diagnosis of primary osteoarthritis. No long-term US survivorship data currently exists for the Birmingham Hip Resurfacing (BHR) implant. The purpose of this study was to demonstrate early efficacy with validated outcome measures and survivorship comparable to total hip arthroplasty (THA).

A cohort of 79 consecutive MOMHR patients was compared to a similar cohort of 71 THA patients, controlling for age, gender and comorbidities. Mean f/u was 14.1±5 mos (range 12–24 mos). The mean age for the MOMHR group was 50±9 yrs, and mean body mass index (BMI) was 29±5. The THA group had a mean age of 52±9 yrs and a mean BMI of 30±6. Outcomes were prospectively assessed with the SF-12 and WOMAC.

For both groups, pre-op pain and function scores were similar. At 1 yr f/u, MOMHR showed significantly more improvement (p< 0.05) in stiffness, pain and physical function compared to the THA. The overall complication rate was 7% in the MOMHR group and 9% in the THA group. There were no instances of displaced femoral neck fracture, component loosening, dislocation or chronic deep infection in any patient in the MOMHR cohort.

These early results are promising, but longer-term follow-up is needed to properly compare MOMHR to THA which remains the current gold standard.