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NEW YORK (Reuters Health) - For osteoarthritis of the knee, hylan or hyaluronic acid injections are equally effective, but hylan can potentially cause more adverse events, a new study shows. Based on this plus the higher cost of hylan, the researchers "see no rationale for the continued use of hylan in patients with knee osteoarthritis."
Treatment with hylan or hyaluronic acids is given to restore the elasticity and viscosity of synovial fluid, the lubricating fluid surrounding the joints, which is depleted in patients with osteoarthritis, note Dr. Peter Juni from University Berne, Switzerland and colleagues.
Hyaluronic acids are naturally occurring substances in the body's connective tissues that cushion and lubricate the joints. (Hyaluronic acids are also used cosmetically to increase the volume and fullness of aging skin.)
Hylan is a modification of hyaluronic acid that was created to increase the viscosity and decrease the clearance around the joints.
In the current study, reported the journal Arthritis and Rheumatism, Juni's team compared the efficacy and safety of hylan and two different hyaluronic acids in 660 patients with symptomatic knee osteoarthritis.
The patients were randomly assigned to receive one cycle consisting of three injections per knee of one of these three preparations. Pain scores were measured after 6 months, after which patients were offered a second cycle of treatment.
The researcher found no evidence of any differences in the effectiveness of any of the three preparations in any of the analyses performed. "Pain relief was similar in all three groups," the investigators report.
However, the most expensive, high molecular weight hylan was associated with more local adverse events, especially during the second treatment cycle, they note.
To their knowledge, Juni and colleagues note, this study is the largest trial to date comparing these treatments for knee osteoarthritis and the only industry-independent trial.
"Given the consistent and robust lack of an advantage in efficacy of hylan over hyaluronic acids and the potential for an increased risk of local adverse events," the researchers conclude, "we see no indication for further clinical trials with this preparation."
SOURCE: Arthritis and Rheumatism, November 2007.
