Urinary cobalt levels in patients with porous Austin-Moore prostheses.

Austin-Moore prostheses with a porous surface have been used recently to improve stabilization in total joint arthroplasty. However, these prostheses expose tissue directly to greater metallic surface area than previous nonporous designs. Cobalt levels were measured in the urine of patients who had received porous and nonporous prostheses, to assess any increased risk of metal toxicity posed by the porous design. Although a higher mean urinary cobalt concentration was found for patients with porous prostheses, the absolute levels were comparable with those of patients with nonporous prostheses. The prostheses with a porous surface appear to pose no significant added risk of metal toxicity as compared with the nonporous design.