Are gel knee injections worth a shot?

Injections of gel-like substances may be making inroads into the established arsenal of treatments for painful, arthritic knees.

Physical therapy, nutritional supplements, anti-inflammatory painkillers, corticosteroid injections and more help some but not all of the estimated 27 million Americans with osteoarthritis, many trying to stave off joint-replacement surgery. The condition -- caused by the breakdown of cartilage in the knee, usually from the wear-and-tear of normal activity over time -- leaves too little cushioning between bones in the knee. Pain results, and movement becomes restricted.

So are gel injections, called viscosupplementation, worth a shot?

"My personal experience is with the right patient it does work, and it's a reasonable choice that's not terribly invasive," said Dr. Michael J. Sileo, an orthopedic surgeon specializing in sports medicine in East Setauket. Sileo said he now does at least 300 to 500 gel injections in knees a year, adding that doctors who specialize only in knee treatments probably do many more.

BENEFITS SEEN

Dr. James Penna, an assistant professor in the orthopedics department at the Stony Brook University School of Medicine, said he's also seen benefits from the injections.

"I have seen a lot of people -- especially people with early arthritis or low-grade inflammation in the knee -- get six to 12 months relief" from gel injections, Penna said. "About 75 percent of my patients are glad they go through the treatment."

Evidence from clinical studies has been mixed. The Agency for Healthcare Research and Quality, part of the U.S. Department of Health and Human Services, notes that studies that have compared people who did and did not get the injections have found little improvement from the shots. Several studies in the past six months, though, have reported improvements in pain and mobility among people given the knee injections, although some of the studies were financed by companies that make the injectable substances and long-term effects were not evaluated.

RELIEF IS TEMPORARY

Even for people who do feel better after getting an injection, though, the treatment may not be the end of the line.

"It doesn't prevent the inevitable," Penna said. "If you need a knee replacement down the road, you still will."

The slippery gel-like material is injected directly into the knee. It's designed to replace the joint's natural lubricating substance, hyaluronic acid, which has been shown to be lacking in people with osteoarthritis, according to the American Academy of Orthopaedic Surgeons.

Penna said that the injections are an in-office procedure that's fast, simple and not very painful. The different types now on the market require one, three or five shots, he said. Risks are minimal, he added, noting that he's seen just one person who's had localized inflammation after an injection.

Most insurance companies cover gel injections once or twice a year, Sileo said.

The best results, he noted, are when patient and doctor are on the same page and have realistic expectations of relief.

"I recommend that most patients give it a full three months before making a decision as to how much it helped," Sileo said. "Most studies show it takes between six weeks and three months before you get the maximum benefits of the injection."

Once in the knee, the gel substance doesn't work rapidly, Sileo explained, but slowly and progressively over time.

Sometimes, the benefits can last much longer -- even a couple of years, he said.