title: Hyaluronic acid injections relieve knee pain.
abstract: OBJECTIVE
  To evaluate the efficacy of intra-articular viscosupplementation therapy with hyaluronic acid for pain relief of knee osteoarthritis, we conducted a meta-analysis of randomized, double-blinded, placebo-controlled trials.
  
  
  METHODS
  We searched systematically for randomized, double-blinded, placebo-controlled trials of hyaluronic acid (hyaluronan and hylan G-F20) for pain relief of knee osteoarthritis. Studies reporting pain visual analogue scale (VAS) differences were included in the meta-analysis. Changes in pain were measured by VAS for placebo and treatment, and summary estimates of the differences between the 2 arms were calculated at 1 week, 5 to 7 weeks, 8 to 12, and 15 to 22 weeks after the last intra-articular injection. Sources of heterogeneity were assessed using information on quality score, type of viscosupplementation, and VAS change in pain with activity or rest. Heterogeneity across the studies was significant in all analyses (P<.01); therefore a random effect model was used. Pain was measured either on activity or at rest.
  
  
  RESULTS
  Eleven trials (9 hyaluronan and 2 hylan G-F 20) allowed calculation of the summary estimate of difference in change of VAS pain at 1 week, 6 of the 11 allowed the estimation between 5 to 7 weeks and 8 to 12 weeks, and only 3 at 15 to 22 weeks. The summary estimates of VAS differences between therapy and placebo injection: at 1 week, 4.4 (95% confidence interval [CI], 1.1-7.2); at 5 to 7 weeks, 17.7 (7.5-28.0); at 8 to 12 weeks, 18.1 (6.3-29.9) and at 15 to 22 weeks, 4.4 (-15.3 to 24.1).
  
  
  CONCLUSIONS
  Intra-articular viscosupplementation was moderately effective in relieving knee pain in patients with osteoarthritis at 5 to 7 and 8 to 10 weeks after the last injection but not at 15 to 22 weeks.
authors.affiliation: Department of Family Medicine, Section of Geriatric Medicine, University of Cincinnati Medical Center, Cincinnati, Ohio 45267-0582, USA. modawaa@fammed.uc.edu
authors.forename: Arvind
authors.initials: A
authors.lastname: Modawal
authors.forename: Monste
authors.initials: M
authors.lastname: Ferrer
authors.forename: Hyon K
authors.initials: HK
authors.lastname: Choi
authors.forename: Julia A
authors.initials: JA
authors.lastname: Castle
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000191:economics; D003362:Cost-Benefit Analysis; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage* / Q000191:economics; D007270:Injections, Intra-Articular / Q000191:economics; D020370:Osteoarthritis, Knee / Q000188:drug therapy*; D016032:Randomized Controlled Trials as Topic; D012044:Regression Analysis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000276:Adjuvants, Immunologic; D006820:Hyaluronic Acid