RESUMEN
Sodium hyaluronate (SH) is a high molecular-weight polysaccharide composed of repeating polymeric disaccharides of D-glucuronic acid and N-acetyl-D-glucosamine. SH is present in every connective tissue and organ, with synovial fluid having the highest concentration of SH in the body. The effectiveness of oral SH on gonarthrosis is known; although, its influence on the knees of healthy individuals is not. However, as severe diseases may require surgery, it is better to take care of healthy knees before the onset of gonarthrosis. Therefore, the present study investigated the functionality of SH on the knee of healthy individuals. The present study was a randomized double-blind, placebo-controlled trial in which healthy adults (mean age: Placebo group, 61.50±1.59; SH group, 58.50±1.81), rated as grade ≤1 based on the Kellgren-Lawrence classification, were administered 111 mg/day SH for 12 weeks. The evaluation of visual analog scales were performed to assess the discomfort in the knees of the participants and were conducted at baseline, and then 6 and 12 weeks after the start of SH ingestion. Additionally, a locomotive syndrome risk test quantifying the mobility of the participants, a one-leg standing time with eyes open test evaluating the strength of the leg muscle as well as the ability to balance by measuring the time to stand on one leg and a blood test (interleukin-10, aspartate aminotransferase, alanine transaminase, γ-glutamyl transferase, lactate dehydrogenase, creatine kinase and C-reactive protein) were performed at baseline and then 12 weeks after the start of SH ingestion. A significant suppression of knee symptoms were demonstrated in the SH group compared with the placebo group in terms of the total visual analog scale scores for pain, stiffness and discomfort for the 31 healthy adult subjects. Significant suppression of symptoms was also demonstrated in the placebo group in terms of discomfort in the knees when descending stairs and pain in the knees after walking for a longer distance or duration than normal. No significant differences between the two groups were demonstrated in the locomotive syndrome risk test, one-leg standing time with eyes open test and the blood test. The results of the present study suggest the possibility that oral SH may help to maintain a healthy condition of the knees. The study protocol was registered with the University Hospital Medical Information Network Clinical Trial Registry in advance (registration no. UMIN000045980, November 4, 2021).