The immediate effects of intra-articular injections of osmic acid.

One hundred mg of osmic acid (with corticosteroid and lidocaine) was injected for therapeutic purposes into the knee in 10 patients suffering from various types of recalcitrant synovitis (mostly rheumatoid arthritis). The effects of this injection were followed by examination of synovial fluid, blood, and urine of these patients, collected at various intervals after intra-articular injection. As a control, a group of 3 patients (5 knees) received corticosteroid and lidocaine intra-articularly, and another group (6 patients, 7 knees) was injected with lidocaine only, both with the same total volume as the first group. Blood and urine examinations revealed essentially no effects of osmic acid, whereas in synovial fluid a strong inflammatory reaction was observed up to the second day after the injection, though the effusion soon disappeared. In a group treated with lidocaine + corticosteroid, a mild, early inflammatory reaction was noted, while lidocaine alone produced only a dilution effect, and the exudate remained relatively longer. Thus, the early local inflammatory reaction due to osmic acid is an expression of the necessary drastic effect of this beneficial therapeutic agent.