What this Trial Is About

Knee osteoarthritis (OA) is an heterogeneous disease, both symptomatically and structurally, with very different evolving profiles. Although several serum, urinary or synovial biomarkers have been developed in knee OA, their interest as potential predictive factors of clinical and structural progression remains poorly known. Similarly, to date, no biological predictive markers of response to OA treatments have been validated, particularly for intra-articular treatments \[corticosteroids (CTC), hyaluronic acid (HA), platelet-rich plasma (PRP)\]. Finally, although cohorts of OA patients have already been established in the past, none of them has made it possible to establish a biobank of serum and synovial fluid obtained from the same patient at inclusion but also during the follow-up of the OA disease, up to the joint replacement. The investigators hypothesize that some biomarkers in serum, PRP and synovial fluid in knee OA: * are be correlated with the clinical symptoms and radiological lesions, thus allowing to define distinct clusters of patients whose clinical and radiological evolving profile could be different * are correlated with the clinical evolution (pain and functional limitation) * can predict the radiographic progression but also in the long term the necessity of joint replacement * could constitute predictive factors of response to intra-articular treatments (CTC, HA and PRP). To validate theses hypothesis, investigators will conduct a longitudinal cohort study with long term follow-up until joint replacement in patients with knee OA. In parallel to this longitudinal study, a cross-sectional ancillary study will be conducted to compare the levels of different serum and synovial biomarkers between subjects with knee OA and subjects with chronic inflammatory rheumatism (rheumatoid arthritis, spondylarthritis) A/ Main objectives: \- Longitudinal study To study the correlations between changes in clinical symptoms (pain, function, quality of life, effusion, flare-up) / radiographic progression during the follow-up on the one hand, and the levels of biomarkers in serum, PRP and synovial fluid at inclusion / their variations at different times of the study on the other hand. B/ Secondary objectives * Longitudinal study 1. To study the correlations between clinical (pain, function, quality of life, effusion, congestive flare) / radiographic phenotype on the one hand, and serum, PRP, and synovial biomarker values at each follow-up visit. 2. To assess the prognostic value of clinical, biological or clinico-biological clusters on the ultimate outcome of OA defined by joint replacement. 3. To assess the prognostic value of different serum and synovial biomarkers on the structural progression during the follow-up. 4. To assess the prognostic value of different serum and synovial biomarkers on the efficacy of different intra-articular treatments (CTC, HA, PRP) 5. To assess changes of clinical symptoms, radiological grades and biological markers after different intra-articular treatments (CTC, HA, PRP) 6. To study the distribution of cellular populations in the joint fluid (synoviocytes, macrophages, lymphocytes, mesenchymal stem cells) according to the clinical and radiographic phenotype 7. To assess the correlations between the level of different biomarkers in serum, synovial fluid and their levels on tissue samples from OA joint obtained during joint replacement. 8. To study in vitro the effect of purified glycosamninoglycan (GAG) from synovial fluid and PRP on the metabolism of synoviocytes, macrophages and mesenchymal stem cells from autologous synovial fluid 9. To study in vitro the effect of purified GAGs from synovial fluid and PRP on the metabolism of synoviocytes, chondrocytes, mesenchymal stem cells obtained from human joint tissue samples (synovial membrane, cartilage) obtained during joint replacement. * Cross-sectional study 1. To assess the correlations between clinical symptoms (pain, function, quality of life, effusion, congestive flare) and radiographic phenotype and serum and synovial biomarkers at inclusion. 2. To compare serum and synovial biomarkers between subjects with knee OA and those with chronic inflammatory rheumatism (rheumatoid arthritis, spondyloarthritis) at inclusion. Method: 300 patients with knee pain related to knee OA (n=200) or chronic inflammatory rheumatism (spondylarthritis and rheumatoid arthritis) (n=100) requiring arthrocentesis and/or intra-articular injection will be enrolled in the Rheumatology department from Henri Mondor Hospital. A longitudinal follow-up will be proposed to patients with knee OA in addition to the participation in the cross-sectional study. The follow-up will include at least one visit each year or more in case of painful flare-up or new intra-articular injection. The follow-up will last a maximum of 10 years or less in case of joint replacement.

IDENTIFICATION OF BIOMARKERS ASSOCIATED WITH THE SEVERITY AND RADIO-CLINICAL PROGRESSION OF KNEE OSTEOARTHRITIS