Radioactive yttrium in the treatment of rheumatoid knee effusions. Preliminary evaluation.

Irradiation of the synovium for the treatment of chronic knee effusions associated with rheumatoid arthritis and allied conditions is being increasingly used as an alternative to surgical synovectomy. Intraarticular injections of a colloidal solution of radioactive gold (19"8Au) has been tried with some success (Ansell, Crook, Mallard, and Bywaters, 1963; Virkkunen, Krusius, and Heiskanen, 1967; Makin and Robin, 1968; Grahame, Ramsey, and Scott, 1970). However, as 198Au has a beta-particle maximum range in tissue of only 4 mm. and as the synovium in these chronic knee effusions can attain a thickness of greater than 1 cm., a complete synovial ablation is not produced. A serious disadvantage of intraarticular 198Au is that there may be marked leakage from the joint to the regional lymph nodes, the liver, and spleen in as many as 36 per cent. of patients so treated (Virkkunnen and others, 1967). Moreover, radioactive gold possesses a significant gamma-ray component and this gives an unwanted whole body radiation to the patient. Because of these disadvantages it has been suggested that radioactive yttrium (90Y) may be a more suitable agent (Ansell and others, 1963; Grahame and others, 1970). 90Y is a pure beta-emitter with a maximum range in tissue of 10 mm. It has a higher maximum energy than gold, 2 26 MeV compared with 0 9 MeV, and it has a half-life of 2-7 days. The whole body distribution of 90Y silicate and 90Y resin after intraarticular injections has been compared (Prichard, Bridgman, and Bleehen, 1970). It was found that silicate preparations were associated with an appreciable leakage from the joint, but that the resin remained localized. It has also been shown that the 90Y resin was taken up more or less evenly in both normal and inflamed rabbit synovia (Webb, Lowe, and Bluestone, 1969). We have therefore undertaken a controlled double-blind trial, using intra-articular 90Y resin in the treatment of chronic knee effusions. The preliminary results after assessment of all cases 6 months after the intra-articular injections are presented.