by Cooper B. Wilhelm
If you're considering viscosupplementation as a treatment for your knee osteoarthritis (OA), you should definitely read this. A meta-study recently published in the Annals of Internal Medicine found 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 that acts as a cushion, absorbing impacts, and as a lubricant, allowing bones to rub against each other smoothly. However, people with OA have less hyaluronic acid in their joints, which contributes to the condition's characteristic painful wearing away of cartilage and bone.
In viscosupplementation, forms of hyaluronic acid derived from rooster combs or bacteria are injected into the joint to supplement what natural hyaluronic acid remains. Though used in humans since 1987 (and in racehorses well before that), the US Food and Drug Administration only approved viscosupplementation in 1997, and then only to treat OA in the knee.
In this recent meta-analysis, Swiss researchers compiled data from 89 clinical trials with over 12, 600 participants. Only studies that tested viscosupplementation for knee OA in adults and included some sort of "sham" or other non-intervention control (the surgical equivalent of a placebo) were included.
The majority of the studies (71 trials with 9,617 participants) found that viscosupplementation produced only a small reduction in pain. In fact, according to the researchers, 18 large-scale trials with 5,094 participants between them found viscosupplementation made such a small difference as to make practically no difference at all, and thus be "clinically irrelevant."
In addition to finding limited efficacy, 14 of the trials linked the use of viscosupplementation to adverse events. Although a weakness of the meta-analysis was an insufficient amount of data about adverse events and safety, the research suggests that viscosupplementation could lead to an increased risk of cardiovascular and gastrointestinal problems.
Other weaknesses of the meta-study include the low quality of many of the trials and the inclusion of some unpublished studies funded by pharmaceutical companies. However, the researchers who conducted the meta-study still recommend that doctors and people with OA steer clear of this treatment option.
Last Reviewed June 28, 2012
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