Higher Fibrosis Scores Associated With Lower Radiographic Severity in Knee OA

In patients with knee osteoarthritis (OA), higher fibrosis scores are associated with lower radiographic disease severity over time, with fibrosis inversely linked to inflammatory-related histologic aspects of the disease, according to the combined results of 3 prospective observational cohort studies published in Osteoarthritis and Cartilage.

The investigators sought to explore the associations between different histologically assessed, inflammatory synovial characteristics and subsequent clinical and structural aspects of disease in individuals with knee OA. Patients with knee OA, from early to advanced disease, were recruited from 3 different ongoing studies. Biopsies of synovial tissue were obtained and assessed to evaluate the longitudinal association between histologically assessed parameters and clinical features, including pain, functioning and stiffness, and fatigue, as well as structural aspects, including  Kellgren and Lawrence (KL)-grade, joint space narrowing (0 to 3) and osteophytes (0  to 3), and total knee replacement (TKR) surgery. These features were repeatedly evaluated during follow-up and were evaluated using linear mixed model analysis and Cox proportional hazards analysis.

Biopsies taken from 83 patients were examined. Follow-up was a median of 1.4 years for clinical aspects of disease and 1.8 years for structural aspects of disease. Both fibrosis and fibrin deposition were inversely correlated with inflammatory features of disease. In addition, higher fibrosis scores were linked to lower scores on KL-grade, joint space narrowing, and osteophytes, whereas higher scores of perivascular edema, thickness of synovial linking, and vascularization were associated with higher scores on structural aspects during follow-up. There were no associations reported between each of the histologic features and any of the clinical aspects evaluated or the likelihood of a patient undergoing TKR during follow-up.

The investigators concluded that inflammatory-related histologic features of disease in patients with knee OA are associated with subsequent increased radiologic severity of OA, whereas fibrosis appears to protect against this event, thus providing a potential therapeutic target for OA treatment. Additional well-designed longitudinal studies are warranted to replicate and confirm these findings.

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Reference

Minten MJM, Blom A, Snijders GF, et al. Exploring longitudinal associations of histologically assessed inflammation with symptoms and radiographic damage in knee osteoarthritis: combined results of three prospective cohort studies [published online November 15, 2018]. Osteoarthritis Cartilage. doi:10.1016/j.joca.2018.10.014