In their complex review of pharmacologic interventions for treatment of knee osteoarthritis, Bannuru and colleagues (1) reported that intra-articular (IA) hyaluronic acid had the highest effect size for relief of pain compared with oral placebo. That comparison is misleading, because the appropriate control for IA hyaluronic acid is IA placebo injection.

Although the authors and the accompanying editorial (2) note that the apparent efficacy of hyaluronic acid may result from the stronger placebo effect of an injection, the comparison with oral placebo gives unwarranted credibility to the efficacy of hyaluronic acid and is subject to misinterpretation. For ...