Effect of a second joint arthroplasty on metal ion levels after primary total hip arthroplasty.

Serum metal ion levels increase after primary total hip arthroplasty (THA) regardless of bearing surface. We conducted a study to determine the effect of a second joint arthroplasty on existing serum metal ion levels at long-term followup. Twelve patients underwent primary THA and then either another THA (8 patients) or total knee arthroplasty (TKA) (4 patients). The secondary procedures were performed a mean of 102.7 months (range, 36-144 months) after the index surgeries. The secondary THA group had significantly elevated levels of cobalt ion at 36 and 48 months, chromium ion at 12 and 24 months, and titanium ion at 48 and 72 months. The TKA group had no significant differences in cobalt, chromium, or titanium ion levels up to 72 months after surgery. Overall, when metal-polyethylene THA was performed after primary THA, there was a trend toward elevated serum metal ion levels at all follow-up intervals. This trend should be investigated with larger clinical trials.