OSTEOARTHRITIS Is viscosupplementation really so unsafe for knee OA?

The latest in a series of meta-analyses of trials assessing viscosupplementation for knee osteoarthritis is the first to raise concerns about its safety. Questions remain, however, regarding the methodological rigour with which the serious adverse events were analyzed, and the biological plausibility of the events reported. McAlindon, T. E. & Bannuru, R. R. Nat. Rev. Rheumatol. 8, 635-636 (2012); published online 11 September 2012; doi:10.1038/nrrheum.2012.152