The intra-articular distribution of 90yttrium does not influence the clinical outcome of radiation synovectomy of the knee

Objectives: To assess the impact of the intra-articular distribution of 90yttrium-citrate (90Y) on the clinical effect of radiosynoviorthesis (RSO) of the knee and on 90Y leakage from this joint. Methods: Patients with arthritis of the knee received 185 MBq 90Y combined with a glucocorticoid, followed by clinical bed rest. Intra-articular 90Y distribution, measured with a dual-head gamma camera immediately or after 24 hours, was scored as mainly diffuse or mainly focal. Leakage to regional lymph nodes, the liver and spleen was assessed with a dual-head gamma camera after 24 hours. Clinical effect was scored after 6 months by a composite change index (CCI), range 0–12; responders were defined as having a CCI ⩾6. Results: Seventy-eight knees of 69 patients, mostly suffering from undifferentiated arthritis (42%) or RA (28%), were treated. 90Y distribution was mainly diffuse in 54% and mainly focal in 46% with clinical response rates of 40% versus 56%, respectively, p = 0.3. CCI was not correlated with distribution. 90Y leakage was found only to the liver and the spleen (mean leakage 0.4% and 1.1%, respectively). Leakage was significantly less in case of diffuse intra-articular 90Y distribution, whereas leakage to the liver was correlated with distribution (r = 0.68, p