knee osteoarthritis
Fluid injections don’t seem to work

THE QUESTION Knees afflicted with osteoarthritis have too little synovial fluid to lubricate and cushion the joint, leading to pain and loss of movement. Should fluid injections, called viscosupplementation, be considered a viable treatment option?

THIS STUDY analyzed data from 89 studies, involving 12,667 adults with knee osteoarthritis. They had been randomly assigned to have one or more injections of hyaluronic acid, a component of synovial fluid, or a derivative or to have placebo injections or no treatment. During a follow-up period of about four months, people who had viscosupplementation reported slightly less pain than the others, though the decrease was described as “clinically irrelevant.” No improvement was found in use of the knee. After treatment, those given viscosupplementation had more instances of so-called flare-ups (a hot, painful, swollen knee for a few days) and effusions (too much fluid in the knee) and were more likely to have cardiovascular or musculoskeletal problems or problems that led to hospitalization or disability. The authors wrote that because of the potential for harm, “administration of these preparations should be discouraged.”

WHO MAY BE AFFECTED? Adults with knee osteoarthritis, which stems from the breakdown of cartilage that protects the knee joint, allowing bones to rub together. This can result from injury or excess weight, but the most common origin is simply a wearing away over time. People of any age can develop osteoarthritis, but most often it starts after age 40. About 27 million people in the United States have osteoarthritis.

CAVEATS The authors indicated that not all studies included adequate data on adverse events. The analysis included the results from six studies that had not been published previously; all were funded by pharmaceutical companies.

FIND THIS STUDY June 12 online issue of Annals of Internal Medicine ( ).

LEARN MORE ABOUT osteoarthritis at

Linda Searing

The research described in Quick Study comes from credible, peer-reviewed journals. Nonetheless, conclusive evidence about a treatment's effectiveness is rarely found in a single study. Anyone considering changing or beginning treatment of any kind should consult with a physician.