POS1403 RADIOSYNOVECTOMY IN A CLINICAL SETTING: AN UNDEREXPLOITED TOOL AT OUR DISPOSAL
Authors: L. R. Caballero Motta, A. M. Anzola Alfaro, J. Molina Collada, I. Janta, Y. K. Henao, R. Perez Pascual, F. J. López-Longo, J. M. Alvaro Gracia, J. C. Nieto González
Journal: Annals of the Rheumatic Diseases (2021)

Background: Radiosynovectomy (RS) is a useful for treating inflammatory arthritis that fail conventional treatments. The main isotope used is Yttrium-90 on large joints as knees, whereas Erbium-169 and Renium-186 are more common in small and medium sized joints respectively. RS is a safe procedure since the isotopes cannot escape the synovial capsule or be absorbed into circulation. It is, however, lethal against cells within the inflamed joint. The most common rheumatic disease treated with RS is rheumatoid arthritis (RA), followed by axial spondyloarthritis (SpA) and idiopathic juvenile arthritis (JIA). It has also been used on persistent synovitis after joint replacements, pigmented villonodular synovitis (PVNS) and undifferentiated arthritis. Objectives: To describe the experience in RS of a tertiary rheumatology center and compare patients with and without clinical response to treatment in the following 12 months. Methods: Observational retrospective study between May 31st 2013 and October 31st 2019. We collected demographic variables, data about the disease of the patient, the joints affected, isotope utilized, presence of Baker’s cyst, systemic treatment received, need of additional infiltrations (before and after), complications and any changes in medication up to a year after the procedure. All the RS were performed ambulatory and the radioisotope infiltration was guided by ultrasound, with 40mg of triamcinolone infiltrated after. SPSS v23 was used for statistical analysis; with Chi2 for qualitative variables and Student’s T distribution for quantitative variables. Results: We evaluated 67 joints in 49 patients in total. All of them were refractory to conventional treatment. 44 patients (65.7%) were women, median of 53.4 years of age (IQ 43.4-67.1). The median disease duration was 12.5 years and RS seemed to fare better the longer the patient had the disease (median of 13.5 years vs 6.5 years p&lt;0.001). The joints infiltrated where 46 (68.6%) knees, 14 (20.9%) wrists and 7 (15.2%) elbows. Out of the knees, 16 (34.8%) belonged to RA patients with effective response in 14 (87,5%). 100% of elbows had an effective response, of them 6 (85.7%) had RA. However, even when 9 (64.2%) wrists also had RA as diagnosis, only 3 (21.4%) were effective. Of the PVNS, 6 out of 8 (75%) had no clinical response, as shown in Table 1. Table 1. RS response compared to clinical diagnosis. TOTAL EFFECTIVE INEFFECTIVE p 67 (100%) 46 (68.6%) 21 (31.3%) Inflammatory Arthritides (RA + PsA + SpA + sJIA), (% ) 52 (77.6) 39 (75% ) 13 (25%) &lt;0.0001 RA (% ) 30 (44.7) 22 (73.3 ) 8 (26.6) &lt;0.001 RA positive ACPA/FR 21 (70) 15 (71.4 ) 6 (28.6) &lt;0.0001 Psoriasic arthritis (PsA) (% ) 6 (9) 4 (66.6) 2 (33.3) 0.42 SpA (% ) 10 (14.9) 8 (80) 2 (20) 0.45 sJIA (% ) 6 (9) 5 (83.3) 1 (16.6) 0.55 PVNS (% ) 8 (11.9) 2 (25) 6 (75 ) &lt;0.001 Inespecific monoarthritis (% ) 3 (4.4) 3 (100) 0 (0) 0.23 OA + Calcium Pyrophosphate Deposition (CPPD) (% ) 4 (5.9) 2 (50) 2 (50) 0.33 Intra articular corticosteroids were needed before RS, with no differences in effective and ineffective joints; however after RS it was significantly lower in effective joints in the first six months (0% vs 43% p&lt;0.0001) and remained so in the following 6 months (0% vs 19% p&lt;0.0001) Only 13 (28%) patients with effective RS needed to change systemic treatment compared to 10 (43%) of those ineffective (p&lt;0.0001). None of the patients with RS had any complication after the procedure during follow up. Conclusion: Our study showed that knees were the main joint infiltrated and they had an overall good response to treatment, especially if the diagnosis was RA. Patients with effective procedures needed leest treatment changes and significantly less corticosteroids infiltrations. In our study, RS in PVNS was significantly less effective than in inflammatory arthritis (25% vs 75% p&lt;0.0001) and RA seemed to have the best response overall. References: [1]Liepe K. Efficacy of radiosynovectomy in rheumatoid arthritis. Rheumatol Int. 2012 Oct; 32(10):3219-24. [2]Ćwikła JB, Żbikowski P, Kwiatkowska B, Buscombe JR, Sudoł-Szopińska I. Radiosynovectomy in rheumatic diseases. J Ultrason. 2014 Sep; 14(58):241-51. Disclosure of Interests: None declared