Gentamicin and tobramycin penetration into synovial fluid.

The penetration of gentamicin and tobramycin into the synovial fluid of 12 patients with nontraumatic joint effusions was studied. Simultaneous serum and synovial fluid specimens taken after the intramuscular or intravenous administration of an antimicrobial agent were assayed. Synovial fluid levels of antibiotic were >50% of serum levels in all subjects studied. In five patients, synovial fluid levels were equal to or exceeded simultaneous serum values. These results suggest that intra-articular injection of aminoglycoside antibiotics is not necessary in the treatment of infectious arthritis.