METALLOSIS IN CONTEMPORARY METAL-ON-METAL HIP ARTHROPALSTY : 5 TO 9-YEAR FOLLOW-UP

Abstract

Background: Recent studies have reported early periprosthetic osteolysis in patients who have been treated with a contemporary metal-on-metal total hip arthroplasty and suggested that metal hypersensitivity associated with an immunologic response to metal may be of etiologic importance. We evaluated the results and histologic findings in patients who underwent revision surgery for a failed contemporary metal-on-metal total hip arthroplasty.

Material and Methods: Two hundred and seventeen total hip arthroplasties (SL-Plus stem and Bicon-Plus cup) with a Sikomet metal-on-metal articulation were implanted in one hundred and ninety four consecutive patients and retrospectively reviewed at mean of 77 months postoperatively. Clinical follow up was performed with the Harris hip score and plain radiographic evaluation was performed. Histologic analysis was performed on the periprosthetic tissues of 14 hips that underwent revision arthroplasty.

Results: The mean Harris hip score improved from 45 preoperatively to 96 at final evaluation. Fourteen (6.4%) hips were revised: 9 for aseptic loosening, 2 for technical failure and three for septic failure. Histologic examination of the retrieved periprosthetic tissues from the eleven patients who underwent revision for aseptic loosening or technical failure showed microscopic metallosis and extensive lymphocytic and plasma cell infiltration around the metal debris. With an endpoint of removal of a component with aseptic loosening, endpoint survivorship was 93% for the stem and 98% for the cup respectively.

Conclusions: Our findings are in agreement with recent publications and support the possibility that periprosthetic osteolysis and aseptic loosening in hips with metal-on-metal articulation are possibly associated with hypersensitivity to metal debris. Prospective, comparative randomized long-term studies are necessary to determine the cause(s) of loosening of this particular articulation.