A recent report in the Annals of Internal Medicine claims that joint injections of hyaluronic acid (also called viscosupplementation) may do more harm than good. Hyaluronic acid is found in joints as a natural part of the synovial fluid which acts as a lubricant that allows bones to rub against each other smoothly. Swiss researchers, compiling data from 89 trials involving 12,600 participants, claim that injections of hyaluronic acid-derived from rooster combs and bacterial cultures-not only produced little reduction in osteoarthritis (OA) pain, but 14 trials linked its use to adverse effects. One weakness of the study, said medical experts, was the low quality of many of the trials and the inclusion of studies funded by pharmaceutical companies. Alfred Cianflocco, MD, an orthopaedic expert at Cleveland Clinic, added, The study was too rigid-they set the bar at a level significantly higher than that which is considered statistically relevant.