Metal-on-Metal Hip Resurfacing: Radiographic Evaluation Techniques☆

Hip resurfacing devices require a new radiographic evaluation technique owing to femoral components with short or no stems. Fourteen US surgeons implanted 1148 metal-on-metal hip resurfacing (HR) devices in a US-FDA-IDE clinical trial, which began in 2001. In this multi-center, prospective study, 337 patients (mean age, 50.1 years) were enrolled as a study group of unilateral HR arthroplasties. Radiographs of 292 HR arthroplasties at a minimum 2-year follow-up (maximum 3 years) were reviewed. There were 10 patients with radiographic evidence of femoral component instability beyond 2 years, as evidenced by subsidence ≥ 5mm. Of these, 7 did not have clinical symptoms associated with femoral component instability. In the study group, 24 revisions were reported, of which 8 were due to femoral neck fractures, 4 were due to acetabular component loosening, 11 were due to femoral component loosening, and 1 due to dislocation.