'Chicken Shots' May Replace Knee Replacement in Some
Nov. 16, 2001 -- Ben Singletary, 69, can barely remember a time when he didn't suffer from excruciating knee pain due to osteoarthritis. His deteriorating knees forced him to give up his Shreveport, La., ob-gyn practice in 1994, and he underwent surgery a year and a half later to replace his left knee.
"I knew it was only a matter of time before I would have to have surgery on the other knee," Singletary tells WebMD. "It took me about three months to get over the first one, so I put it off as long as I could. When Dr. Waddell told me about the chicken shots, I could have hugged his neck."
Instead of surgery, Singletary underwent a procedure called viscosupplementation, in which hyaluronic acid -- a substance that acts as a shock absorber or cushion -- is injected into the knee joint.
In knees with osteoarthritis, normal joint fluid becomes thin and inflexible, losing its cushioning properties. The procedure was approved for use in the U.S. in 1997 but has been used in Japan and Italy for over a decade. Patients often refer to the series of injections as 'chicken shots' because the injected fluid is extracted from the combs on the back of chicken's heads.
"Or it may be that we are referring to the fact that most of us are scared of surgery," Singletary says. "I'm not sure."
There are two such types of injections available in the U.S. -- Synvisc and Hyalgan. Synvisc is given as a series of three injections into the knee, one week apart. Hyalgan is given as a series of five injections, also one week apart.
Singletary says the series of three injections of Synvisc kept him free of pain for just over a year, and a second series of injections relieved his pain for two more years. At this week's annual meeting of the American College of Rheumatology in San Francisco, orthopaedic specialist David D. Waddell, MD, of LSU Health Science Center, presented two studies evaluating the effectiveness of the knee injection therapy among people with advanced osteoarthritis.
Waddell reported that people like Singletary responded well when given a second course of Synvisc injection treatments after the first course had failed. More than half (57%) of the 129 people who had a second round of injections reported that their knee pain was improved six months later. Waddell tells WebMD that he has given the three-shot series to some people as many as five times, and many are still responding.
In a second study, Waddell and colleagues evaluated the effectiveness of Synvisc injections in delaying knee replacement surgery. People with advanced osteoarthritis who had the injection therapy were compared with those who did not. Those who received the injections were much less likely to need surgery over the following three years than those who did not.