BOTTOM LINE
Intra-articular hyaluronic acid (Provisc, Synvisc, Suplasyn) is minimally, if at all, more effective than placebo in the treatment of knee osteoarthritis. The evidence of publication bias against negative trials in this meta-analysis suggests that any overall positive effect is overestimated. The highest-molecular-weight hyaluronic acid (Synvisc) may be more effective than lower-molecular-weight hyaluronic acid. (LOE=1a–)