Introduction: Osteoarthritis (OA) is a progressive, degenerative disease that leads to joint pain, tenderness, stiffness, locking, effusion, reduced motion, swelling, crepitus, and disability. The pain in OA is the most significant clinical feature and impacts function, mobility, quality of life, and the reason for medical advice. Methods: Fifty individuals with primary knee OA in the age range of 45–90 years were chosen at random for the research (N=50). The American College of Rheumatology's diagnostic criteria were employed to diagnose osteoarthritis, and a visual analogue scale was utilized to score the severity of pain. Knee OA was graded using the Kellgren-Lawrence (K-L) radiographic assessment method. The antioxidant levels of superoxide dismutase in the synovial fluid were measured by using a spectrophotometric assay. Results: Grades 1, 2, 3, and 4 have SOD activity values of 1.43±0.55, 1.44±0.72, 0.92±0.52, and 0.87 ±0.52 U/ml, respectively, in synovial fluid. Synovial fluid SOD activity was higher in grades 1 & 2 of KOA as compared to grades 3 &4 and the difference was statistically significant (p<0.05). Conclusions: There was a link between K-L grade and synovial antioxidant activity level. In the late stages of knee osteoarthritis, the antioxidant enzyme (SOD) activity was reduced.According to the results of this study, regular antioxidant supplementation to early osteoarthritis patients may delay disease progression by improving the antioxidant status of the knee, which neutralises free radicals and thus prevents cartilage damage.