Long-term clinical results from 10 years follow-up after radiosynoviorthesis: a prospective observational study.

Background: The aim of this study was to assess the long-term anti-inflammatory effect and safety of 90-Yttrium and 166-Holmium radiosynoviorthesis (RSO) for treating chronic knee synovitis of various origins.
Methods: A total of 820 patients were included in this study and were followed up to 10 years after the procedure for objective and subjective changes in signs and symptoms of inflammation.
Results: Five years after RSO, excellent and good results were seen in 71% (95% CI 67-74%) of patients. Six, seven, eight and nine years following RSO, efficacy did not decrease significantly. Ten years after RSO, the effectiveness of the therapy fell to 65% (95% CI 59-71%). Overall, 64% of patients did not need another joint puncture ten years after RSO. We achieved excellent to good results at 5 years in 79% of patients with rheumatoid arthritis, 59% with ankylosing spondylitis, and 62% with osteoarthritis. Efficacy was mainly affected by the local X-ray stage of the knee joint. A significant association was also found between the diagnosis of the underlying disease and the success of radiosynoviorthesis. Efficacy, however, was not substantially affected by any of the following factors: the duration of synovitis, the number of punctures before radiosynoviorthesis, the number of intraarticular steroid injections before the procedure, or the number of interventions before radiosynoviorthesis (radiotherapy, surgery).
Conclusions: Radiosynoviorthesis is an effective long-term method of treating chronic synovitis. The treatment showed the most favorable effects in patients with rheumatoid arthritis and those with mild to moderate degenerative osseous changes.