Serum ion level after metal-on-metal THA in patients with renal failure.

We retrospectively reviewed cementless THAs with metal-on-metal bearings in five patients with chronic renal failure and investigated the relations between renal failure and elevated serum cobalt and chromium levels and the side effects of these elevations. Serum cobalt and chromium levels were measured by atomic absorption spectrophotometry at a minimum followup of 2.7 years (mean, 3.9 years; range, 2.7-6.2 years) in five patients with chronic renal failure and in six patients with normal renal function after THA. Mean serum cobalt concentration was 12.5 microg/L in patients with chronic renal failure; this was more than 100-fold higher than in patients with the same prosthesis type and similar followup period, but with no known renal disease. However, the mean serum chromium concentration was 5.1 microg/L, which was within the normal range in all 11 study patients. Side effects related to elevation of serum cobalt or serum chromium concentration were not identified and overall clinical results were good 4 years after surgery. The serum cobalt level was higher in patients with chronic renal failure. Longer followup is necessary to determine any clinical effects.