Intraarticular injections of sodium hyaluronate (Na-HA) appear effective in reducing subjective symptoms of osteoarthritis (OA) and may also have protective effects on the cartilage matrix. The present study analyzed the suppressive effects of Na-HA on the release and degradation of aggrecan and on levels of nitric oxide (NO) in the joint fluid of patients with knee OA.
Sixteen OA patients with knee joint effusion were treated by 5 weekly intraarticular injections of Na-HA. Prior to each Na-HA injection, joint fluid was collected to determine the levels of chondroitin 4-sulfate (C4S) and chondroitin 6-sulfate (C6S), intact aggrecan and NO.
One week after the final injection, the joint fluid levels of C4S, C6S, and NO were significantly decreased. In contrast, the joint fluid level of intact aggrecan was stable during the series of Na-HA injections. A trend was seen for a positive correlation (P < 0.1) between the clinical score and C4S or C6S joint fluid levels, and for a negative correlation between the joint fluid levels of intact aggrecan and C4S or C6S. No significant correlations were observed between joint fluid levels of NO, the clinical score, and levels of C4S, C6S, and intact aggrecan.
The results of this study suggest that intraarticularly injected Na-HA is able to improve the clinical symptoms of OA partially based on its ability to reduce the release and degradation of aggrecan and/or to enhance the synthesis of aggrecan in the joint tissues of the patients with knee OA. While Na-HA also reduces the NO level in the joint fluid of patients with knee OA, this effect may be independent from the other effects of Na-HA.