Correlation of Antioxidant Levels in Synovial Fluid to Intensity of Pain in Osteoarthritis of Knee

Introduction : Osteoarthritis (OA) refers to progressive degeneration of articular cartilage with gradual painful disorganisation of the joint. Lipid peroxidation mediated by free radicals is the major mechanism of cell membrane destruction and cell damage. It is a known that there is an increased oxidative stress in OA and very little is known about the relation between the pain and decreased antioxidant levels. This study aimed at understanding the relation between the level of superoxide dismutase (SOD) and total antioxidant capacity (TAC) of synovial fluid in OA knee with the intensity of pain. Materials and Methods : 30 patients with clinicoradiologically evidence of knee OA were included in the study and pain was scored using Visual Analog Scale. 1ml synovial fluid was aspirated from the knee and superoxide dismutase (SOD) and total antioxidant capacity (TAC) was estimated. Statistical analysis between the pain score and the SOD and the TAC was done independently by Spearman's rank correlation method and correlation coefficient was obtained. Results : It was found that SOD and the TAC values were reduced in our subjects with mean value of 0.06477 ± 0.044814 and 122.51000 ± 50.764829 respectively. The mean value of pain was 6.70 ± 1.317. A significant correlation between SOD level and pain score (p<0.05) was obtained. However, the correlation between TAC level and pain score was not significant (p>0.05). Conclusion : The study concluded that there is a positive correlation between the intensity of pain and SOD levels in the synovial fluid in OA of knee which is due to the increased free radicals produced.