Objective: The aim of this study was to assess the treatment results of 90Y radiation synovectomy for chronic exudative synovitis of knee joints.
Methods: The retrospective data consist of 394 consecutive knee radiation synovectomies performed using 6 mCi (222 MBq) of 90Y. The assessment included 3-point custom pain and joint mobility scale, evaluation of joint's circumference, binary joint's temperature evaluation, patellar ballottement test, indications for puncture and its volume in applicable cases. 21 cases had to be forfeited due to missing data regarding follow-up.
Results: The final analysis of 373 treatment procedures performed in 253 patients yielded following results-at 6 months after treatment, 80.9% of the patients reported at least partial pain relief (including 33.3% with complete pain relief), which increased to 86.7% at one year. The pain intensity decreased over time, however, the outcomes were worse in older patients. The probability of pain recurrence was 15% at 6 months, and 28% at one year. It was highest in post-traumatic synovitis, and lowest in pigmented villonodular synovitis. The circumference of the treated knee joints decreased over the course of follow-up, however, the decrease was significantly lower in older patients. The fraction of patients with full knee joint mobility increased from 34.6 to 40.6% at 6 months and 49.2% at one year. The percentage of patients that required articular puncture decreased from 62.8% at baseline to about 35.6% at 6 months, and 32.8% at one year. Positive patellar ballottement was found in 68.5% before treatment and remained at about 40-50% during the course of follow-up. The increased temperature of the joint was reported in 51.2% at baseline and decreased to 33% at 6 months and 28.3% at one year.
Conclusions: (1) Radiation synovectomy is a safe and effective method of treatment in patients with exudative synovitis, however, the pain recurrence rate is significantly higher in post-traumatic exudative synovitis compared to pigmented villonodular, undifferentiated, and rheumatoid arthritis. (2) Our results suggest that older patients have worse treatment results with radiation synovectomy compared to younger patients.
Keywords: Hypertrophic-exudative synovitis; Knee joint; Radiation synovectomy; Radiosynovectomy; Radiosynoviorthesis; Yttrium-90.