Osteoarthritis (OA) of the knee is an increasing problem in an aging population and many patients turn to various types of injection therapies to avoid surgery or strong medications. While interventional pain specialists claim the injections help to relieve pain and disability associated with knee OA, current evidence suggests that these therapies may be largely ineffective, somewhat costly, and possibly even cause harm in some cases.
Writing in the Annals of Internal Medicine, Anne Rutjes, PhD, of the University of Bern in Switzerland, and colleagues report conducting a systematic review and meta-analysis of studies examining viscosupplementation — the intra-articular injection of hyaluronic acid — for symptomatic relief of painful knee OA in adults [Rutjes et al. 2012]. Hyaluronic acid is a lubricant in joint fluid that acts like a shock absorber, but declines with the wear-and-tear of osteoarthritis. An improved form, cross-linked hyaluronic acid, has higher molecular weight that enhances its elastoviscous properties and provides a longer period of residence in the joint space (ie, slower resorption).