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.
Support Not Justified
Lo says the findings should lead arthritis groups to re-evaluate their position on the treatment. The American College of Rheumatology recommends hyaluronic acid injections for patients who cannot take nonsteroidal anti-inflammatory drugs because of an increased risk of gastrointestinal side effects.
She adds that the high cost of the therapy -- between $300 and $500 per treatment course for the injections alone -- also argues against its use.
"That is pretty expensive for something that is only marginally effective, if it works at all," she says.
Orthopaedic surgeon and researcher David Waddell, MD, has treated many patients with hyaluronic acid injections, and does not believe that the results he has seen are caused by a placebo effect.
Waddell says he had one patient who was able to delay knee surgery for five years by having the injections, and many of his patients have had more modest, but measurable, results.
"I have a personal bias here because I have osteoarthritis and have had two courses of this treatment," the Shreveport, La., physician tells WebMD. " I felt dramatic relief in a very short period of time. It was not complete relief, but this treatment has worked better than taking nonsteroidal medications."
Waddell says his laboratory studies at Louisiana State University may help explain why hyaluronic acid works. He expects to publish the findings from these studies soon.
American College of Rheumatology spokesman Oscar S. Gluck, MD, says there was tremendous excitement about hyaluronic acid when the treatment was first approved, but it became clear pretty quickly that the reality did not live up to the hype for many patients.
He says he only uses the treatment now for patients who have no other nonsurgical therapeutic options and do not want to undergo knee surgery.
"Patients basically have to talk me into it," he says. "I tell them up front that this therapy is considered marginally effective, but if they understand this and still want to put off surgery as long as possible they may try it."