Intra-articular radiation synovectomy.

Fifty-three knees in 44 patients with severe, chronic rheumatoid arthritis (RA) were treated by the instillation of an intra-articular radionuclide (dysprosium-165; 165Dy) coupled with a large, relatively inert carrier (ferric hydroxide macroaggregate). The extremely low leakage rates found in earlier animal experiments were confirmed in the human, with a mean leakage rate of 0.3% of the injected dose. This leakage corresponds to a total body dose of 0.4 rad and a liver dose of 2.5 rad, equivalent to a lumbosacral series of diagnostic radiographs. Eighty percent of the treated knees showed improvement, which was maintained as long as one year after treatment. There was a direct correlation between the preoperative radiographic stage and the response to treatment, with patients in Stages I and II more likely to have a good or excellent response at one year. There was also good correlation between clinical improvement and improvement in technetium-99m (99mTc)-pertechnetate flow scintigraphy. Chemical synovectomy by the instillation of appropriate radionuclides can be recommended as an effective means of reducing inflammation, effusion, and pain in patients with RA. The duration of favorable results cannot be predicted, but the results to date suggest that longevity should be comparable with that of surgical synovectomy. Like surgical synovectomy, radiation synovectomy is most effective in the early stages of the disease process, before there is extensive destruction of cartilage and bone.