Radiosynoviorthesis with [90Y] Yttrium citrate in refractory synovitis of the knee: Experience of 2 reference hospitals.

Introduction: To describe the therapeutic efficacy of radiosynoviorthesis with [⁹⁰Y]Yttrium citrate (⁹⁰Y), in patients with chronic knee synovitis refractory to systemic treatments and/or infiltrations, correlating the results with the different etiologies and degenerative changes that they showed, in order to optimize the indication of the technique.

Material and methods: Observational retrospective study with 32 patients (22 men and 10 women) and 34 knees, with refractory chronic knee synovitis, who underwent radiosynoviorthesis between January 2013 and December 2022. Its efficacy was described and analyzed by the subjective improvement referred by the patients and its relationship with the existing etiologies and radiological degenerative changes, expressed by the Kellgren-Lawrence (K-L) scale.

Results: A statistically significant subjective improvement was observed in 70.6% of the cases (p < 0.001). There were 92.3% of cases with absent, doubtful or mild degenerative changes (K-L 0-2) who improved, while only 50% with moderate or severe changes (K-L 3-4) improved, showing statistically significant differences (p = 0.03). Among patients with chronic inflammatory origin of synovitis (spondyloarthropathies and rheumatoid arthritis), 80% improved, while in those with osteoarthritis (degenerative) origin, only 25% improved with statistically significant differences (p = 0.006).

Conclusions: Radiosynoviorthesis with ⁹⁰Y is an effective treatment in patients with knee refractory chronic synovitis, especially in the presence of mil degenerative joint changes and chronic inflammatory origin. We must ensure the appropiate selection of patients according to these criteria.