Radiation synovectomy (RS) is one of many therapeutic options used for recurrent joint synovitis. Our aim was to analyze the effect of the surgical synovectomy combined with yttrium 90 (Y-90) in the treatment for recurrent joint synovitis. A surgical combined RS procedure was used on 32 knees of 30 patients. They were divided into two groups. Group 1 consisted of 7 knees of 7 patients (5 women and 2 men) with a mean age of 40.7 years in whom RS was combined with the open synovectomy. Group 2 consisted of 25 knees of 23 patients (21 men and 2 women) with a mean age of 45.5 years in whom RS was combined with the arthroscopic synovectomy. Arthroscopic synovectomy or open surgery biopsy was carried out for all cases who diagnosed of having synovitis. A scintigraphic examination was conducted within 24 h after the RS procedure to investigate the systemic leakage of Y-90 in all patients. The outcome of treatment was assessed based on self-reporting using the visual analogue scale (VAS) of night pain, rest pain, activity pain, effusion, and satisfactory scores. The average follow-up period was 4.15 years. There was a significant difference between before and after treatment in terms of outcome parameters' VAS scores in both groups (p < 0.05). But there was no statistically significant difference between open and arthroscopic synovectomy groups in terms of outcome parameters (p > 0.05). Satisfactory outcome was excellent in 3 patients (42.8 %) in group 1 and 8 patients (32 %) in group 2. Surgical synovectomy with combined Y-90 could treat recurrent joint synovitis successfully. There was no statistically significant difference between open and arthroscopic synovectomy techniques combined with RS procedure.