Background: Authors of recent studies have reported early
periprosthetic osteolysis in patients who have been treated with a
contemporary metal-on-metal total hip arthroplasty and have 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 had undergone revision of a failed contemporary metal-on-metal
total hip arthroplasty.
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 194 consecutive patients, and the results were retrospectively
reviewed at a mean of seventy-seven months postoperatively. Clinical follow-up
with the Harris hip score and plain radiographic evaluation were performed.
Periprosthetic tissues from fourteen hips that had undergone revision
arthroplasty were subjected to histologic analysis.
Results: The mean Harris hip score improved from 45 points
preoperatively to 88 points at the final evaluation. Fourteen hips (6.5%) were
revised: nine because of aseptic loosening, two because of technical failure,
and three because of septic failure. Histologic examination of the retrieved
periprosthetic tissues from the eleven patients who had undergone revision
because of aseptic loosening or technical failure showed metallosis and
extensive lymphocytic and plasma-cell infiltration around the metal debris.
With removal of the component because of aseptic loosening as the end point,
survivorship was 93% for the stem and 98% for the cup.
Conclusions: Our findings are in agreement with those in recent
publications and support the possibility that periprosthetic osteolysis and
aseptic loosening in hips with a 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 prostheses with this particular articulation.
Level of Evidence: Therapeutic Level IV. See Instructions
to Authors for a complete description of levels of evidence.