LAUSR

Background Calcium pyrophosphate deposition disease (CPPD) and Osteoarthritis (OA) are often associated (1). However, is still controversial how calcium pyrophosphate (CPP) deposits coul d affect OA features (1) and, eventually, the response to the OA treatments. Objectives To evaluate the efficacy and the safety of Ultrasound (US)-guided injections of the knees with Hyaluronic Acid (HA) in patients with OA and CPPD, compared to OA. Methods Consecutive patients, referred to the outpatient clinic with a clinical and radiological knee OA required intra-articular (IA) treatment with high molecular weight (HMW) HA and without any clinical inflammatory signs, were enrolled. No limits about OA score [Kellgreen-Lawrence (K-L) score] were used. Patients with diagnosis or suspicion of other chronic inflammatory rheumatic diseases were excluded. For each patients, were recorded age, sex, Body Mass Index (BMI) and K-L score. The presence of CPP deposits were evaluated by US at level of menisci and knee hyaline cartilage, using the OMERACT criteria (2). All the patients were submitted to three IA injections with HA, performed every week. Before each injection, the synovial fluid (SF) was aspirated and its amount recorded. All SF aspiration and injections were US-guided. At baseline and before each injection, the Western Ontario and Mc Master Universities Osteoarthrits Index (WOMAC) was submitted to the patients. The data were analyzed using a Wilcoxon test for independent samples and a regressive logistic model, including age, sex, BMI, K-L, SF and CPPD presence. Results We enrolled 23 patients (12 woman [52,17%]) with a mean age of 67,65 yo (SD±11,93), a mean BMI of 27,43 (SD±4,82) and a median K-L score of 3 (range 2-3). 10/23 (43,88%) patients were identified as affected by CPPD at US [6 woman, mean age 67,39 yo (SD±12,1), BMI 27,14 (SD±4,4), median K-L of 3 (range 2,75-3,25)]. No differences about age, BMI and K-L score were observed. Regard the baseline WOMAC, the CPPD group mean [955,89 (SD±416,5)] was significantly higher (p<0,01) than OA [379,5 (SD±225,21)]. Considering the short term effect, the WOMAC score improved in both groups after the first injection, but it was significantly higher in the CPPD group (p<0,01) and the regressive model analysis, showed that only the CPPD is correlate to the WOMAC change. After the second injection, the improvement continues but without differences. The regressive model showed that no variables correlate with WOMAC. The data from the long term follow up are not still available. Regarding the SF amount, no differences statistically significant were observed between the two groups at every time. Conclusion The US-guided injections with HMWHA at knees appear effective and safe in patients with OA associated to CPPD. Particularly the presence of CPP does not appear a risk factor for the development of inflammation. However, these results are preliminary and should be confirmed in a larger cohort and for a longer follow-up. References [1] Abhishek A, et al. Evidence of a systemic predisposition to CC and association between CC and OA at distant joints: a cross-sectional study. Arthritis Care Res (Hoboken). 2013Jul;65(7):1052-8. [2] Filippou G, et al. Definition and Reliability Assessment of Elementary US Findings in CPPD: A Study by the OMERACT CPPD Ultrasound Subtask Force. J Rheumatol. 2017Nov;44(11):1744-1749 Disclosure of Interests Antonella Adinolfi: None declared, Federica Rumi: None declared, Greta Carrara: None declared, Marcello Govoni: None declared, Bruno Frediani: None declared, Carlo Alberto Scirè: None declared, Georgios Filippou Speakers bureau: Laborest, Abbvie, BMS, Sanofi