Treatment response evaluation using Yttrium-90 in patients with rheumatoid arthritis of knee joint

For radiosynovectomy, we have measured the retention time of yttrium-90 ( 90 Y) hydroxyapatite (particle size 1–10 μm) within the knee joint space and evaluated the treatment responses in knees with rheumatoid arthritis. Radioactive measurements in the region of knee after injection of 90 Y hydroxyapatite into the joint space were made with a single prove system designed to monitor radioactivity and showed retention of 90 Y in the knee ranged 76.6% ±5.4% after 4 days of injection. The clinical improvements in rheumatoid arthritis of knee joint with steinbroker Stages I and II were increased as time goes by, the improvement ratio is in 72% at 6 th months and 76% at 12 th months after injection of 90 Y 185 MBq (5 mCi) per joint.