Arthritis "Chicken Shots" May Not Work
Analysis Finds Osteoarthritis Knee Treatment Only Slightly More Effective Than Placebo
Dec. 16, 2003 -- New research shows a popular, but controversial, treatment for osteoarthritis of the knee to be ineffective. Patients who received hyaluronic acid injections fared only slightly better than those given placebo injections in a review of almost two dozen studies.
Hyaluronic acid injections were approved in the U.S. for patients with osteoarthritis (OA) of the knee in 1997, and are considered to be an alternative treatment for those who want to delay knee replacement surgery for as long as possible. The treatment is also recommended for use in people with OA who are at risk for stomach bleeds and ulcers that cannot take other medications such as anti-inflammatories. But there has been much controversy among physicians who treat arthritis patients about the therapy's effectiveness.
"There are physicians out there who use this treatment a lot and there are others who don't use it at all," researcher Grace H. Lo, MD, of Boston University School of Medicine tells WebMD. "We felt that it was important to do this analysis, because the studies are so conflicting."
In the osteoarthritic knees, normal joint cartilage becomes thin and loses its ability to act as a cushion or shock absorber. Hyaluronic acid is believed to help the shock absorbing properties of normal joints, improving the joints' performance. Two types of injections are approved for use in the U.S. -- Synvisc (Wyeth Pharmaceuticals) is given as a series of three injections and Hyalgan (Sanofi-Synthelabo Inc.) is given as a series of five injections.
Patients often refer to the injections as "chicken shots" because the hyaluronic acid is extracted from chicken combs.
In the new analysis, published in the Dec. 17 issue of the Journal of the American MedicalAssociation, researchers pooled data from 22 studies comparing hyaluronic acid injections with injections of salt water-based placebo treatments.
They found little difference in treatment outcome among the two groups. Patients who received placebo treatments had responses that were approximately 80% as strong as those who received hyaluronic acid. This led the researchers to conclude that much of the treatment's effectiveness is caused by the placebo effect -- the idea that a patient's belief in a particular treatment causes it to work.