Effects of gentamicin and monomer on bone. An in vitro study.

Gentamicin-loaded bone cement is used with increasing frequency in primary and revision arthroplasty. Considering the high local concentration and the well-known toxic effect of gentamicin on the kidney, a similar inhibiting effect on bone tissue might be expected. In a series of in vitro studies using paired mouse calvaries cultured for 2 days, the authors found a dose-dependent decrease in the release of previously incorporated calcium-45 (45Ca) or tritiated proline and a decrease in alkaline phosphatase activity. In combination with methylmethacrylate, a small additional reduction in 45Ca release and a marked decrease in alkaline phosphatase activity were recorded. These results indicate that released gentamicin and monomer from antibiotic-supplemented bone cement depresses bone turnover and might thus play an important part in the pathogenesis of loosening.