Haraden CA, et al. - A total of 48 knees of 25 participants were characterized for an extensive array of synovial fluid (SF) biomarkers by the contributors to identify a SF biomarker profile characteristic of individuals with an inflammatory osteoarthritis (OA) endotype. VCAM-1 and MMP-3 with synovial inflammation; sVCAM-1, sICAM-1, TIMP-1, and VEGF with radiographic OA severity; and VEGF, MMP-3, TIMP-1,sICAM-1,,sVCAM-1,, and MCP-1 with OA symptoms were significant associations of SF biomarkers. All the subsets of six SF biomarkers were linked to synovial inflammation in OA, as well as radiographic and symptom severity. Furthermore, they were observed to be specifically correlated to indicators of activated macrophages and neutrophils. Hence, the results attested to an inflammatory OA endotype that could help for therapeutic targeting of a subset of individuals at high risk for knee OA progression.