OUTCOME OF REVISION OF METAL ON METAL HIP RESURFACING

Introduction: A proposed benefit of hip resurfacing is straightforward revision. This study assesses the outcome of revision in a large series of failed resurfacings. Methods: A consecutive series of 84 revisions of metal-on-metal hip resurfacings was analysed. The cohort consisted of 51 (61%) women and 33 (39%) men with a mean age of 48.0 years (range: 15.1–75.3 years) at primary resurfacing. The underlying diagnosis was primary osteoarthritis in 40 (48%) patients, developmental dysplasia of the hip in 13 (15%), avascular necrosis in 9 (11%) and slipped upper femoral epiphysis in 7 (8%). Mean patient age at first revision was 50.8 years (range: 18.4–75.9 years), at a median of 1.8 years (25 th percentile 0.03 years, 75 th percentile 4.6 years) after the primary operation. 29 (35%) resurfacings were revised for aseptic loosening, 23 (27%) for periprosthetic fracture, 8 (10%) for component malalignment, 8 (10%) for pain alone, 4 (5%) for infection, 4 (5%) for avascular necrosis and 4 (5%) for instability. Results: At a mean follow-up of 4.6 years (range: 1.0–8.2 years) after the first revision, 10 (12%) of the revised hips had undergone a second revision procedure. 6 men and 3 women required re-revision (data not available for 1 patient). The reasons for the first revision were acetabular malalignment (n=2), femoral neck fracture (n=2), aseptic loosening (n=2), avascular necrosis (n=1), instability (n=1) and pain alone (n=1). The second revision was required at a mean of 3.4 years (range: 0.4–6.3 years) after the first. Discussion: This study suggests that revisions of hip resurfacing for acetabular malalignment may be at increased risk of subsequent re-revision (2 of 7 patients, 29%). Revision for other causes appears to have better survival in the short to medium term.