Fig. 2

Forest plot for functional efficacy meta-analysis. The effect of hyaluronic acid (HA) injections in knee osteoarthritis on function (as measured by Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC], Lequesne, or Knee Injury and Osteoarthritis Outcomes Score [KOOS] scales) at 26 weeks* follow-up is small but statistically significant. Studies are arranged chronologically. *Follow-up time was 26 weeks for all studies except for Petrella et al. 2002 (4 weeks), Dougados et al. 1993 (52 weeks), and Pham et al. 2004 (52 weeks). kDa kilo-Daltons. SMD standardized mean difference