Intra-articular Hyaluronic Acid for Treatment of Osteoarthritis of the Knee

To the Editor: Dr Lo and colleagues¹ concluded that intra-articular hyaluronan injections have little benefit for osteoarthritis (OA) of the knee and that the effect is similar in magnitude to the superiority of nonsteroidal anti-inflammatory drugs (NSAIDs) over acetaminophen. It is important to recognize that the reported effect size is small because it is measured over a control that cannot be considered a simple placebo. Arthrocentesis has been reported to provide symptomatic relief in patients with a significant effusion.² Effectiveness trials are more clinically relevant than efficacy trials, for the former are more directly related to outcomes of actual practice. In contrast, however, most trials of intra-articular hyaluronan have been efficacy trials, which were required for regulatory approval. Thus, it is important to point out that 2 recent effectiveness trials have found intra-articular hyaluronan injection to be both clinically beneficial and cost effective.^3-5