Dual-Compartment Anti-Inflammatory and Chondroprotective Effects of Intra-Articular Hydrolyzed Collagen in Experimental Osteoarthritis

<i>Background and Objectives</i>: Osteoarthritis (OA) is a degenerative joint disease involving inflammation, oxidative stress, and extracellular matrix (ECM) degradation, leading to cartilage damage and joint dysfunction. This study aimed to evaluate the chondroprotective effects of intra-articular hydrolyzed collagen in a rat model of knee OA using a dual-compartment biochemical and histological approach. <i>Materials and Methods</i>: Twenty male Sprague-Dawley rats underwent ACL transection to induce osteoarthritis and were randomly assigned to receive intra-articular hydrolyzed collagen or saline once weekly for three weeks. At six weeks, knee joints were evaluated histologically using the Mankin score. Synovial fluid and cartilage homogenates were analyzed via enzyme-linked immunosorbent assay (ELISA) for cytokines, cartilage degradation markers, and oxidative stress indicators. <i>Results</i>: The collagen-treated group demonstrated significantly lower Mankin scores. Levels of pro-inflammatory cytokines, interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), as well as cartilage degradation markers, matrix metalloproteinase-13 (MMP-13), C-terminal crosslinked telopeptide of type II collagen (CTX-II), and cartilage oligomeric matrix protein (COMP), were significantly reduced (<i>p</i> < 0.05). Additionally, oxidative stress indicators including inducible nitric oxide synthase (iNOS), total oxidant status (TOS), and oxidative stress index (OSI) were decreased, while total antioxidant status (TAS) was increased in both synovial fluid and cartilage homogenates (<i>p</i> < 0.05). <i>Conclusions</i>: Intra-articular hydrolyzed collagen reduced inflammation, oxidative stress, and extracellular matrix (ECM) degradation, indicating potential chondroprotective effects across both synovial and cartilage compartments.