Hyaluronic acid is a naturally occurring substance
found in the synovial fluid. Injection of a highly purified, cross-linked form allows for longer retention within the synovial fluid to supplement joint viscosity, lubrication, and absorption of compressive forces. A Cochrane review of viscosupplementation found that hyaluronic acid had an effect for up to 6 months, with peak benefit at 5 to 13 weeks after injection. Improvement in pain, function, and global assessment was comparable with oral NSAIDs, with more local reactions but fewer systemic side effects.
However, on the contrary, a more recent meta-analysis demonstrated moderate short-term pain relief but concluded that the risk for adverse events was not negligible. The overall benefit was small and clinically irrelevant.68 Thus, viscosupplementation may be considered as a presurgical option for patients with elevated surgical risk who need treatment in addition to exercise and other available analgesic therapies.