Sprained ankles are typically treated with "RICE" -- rest, ice, compression and elevation -- which can reduce pain and swelling but has no effect on recovery time, Dr. Robert J. Petrella of the University of Western Ontario in East London, the study's lead author, told Reuters Health. "None of these things really act on the site of injury."

While non-steroidal anti-inflammatory drugs, such as ibuprofen and naproxen, ease swelling and may reduce disability, he added, they have a number of potential side effects, such as gastrointestinal bleeding and kidney and heart damage.

Doctors currently use hyaluronic acid to treat joint pain and stiffness in rheumatoid arthritis patients, Petrella noted. The material is unique, he added, because it changes its structure in response to the physical demands of the body. For example, it shifts to an elastic form in the knee joint, while acting more like a lubricant in lower-impact joints.

He and his colleagues randomly assigned 158 athletes who suffered an ankle sprain to receive injections of hyaluronic acid or a placebo. Patients received the first injection at study enrollment and the second four days later. All of the subjects underwent standard RICE therapy with bracing or taping of the ankle as needed. Petrella and his team followed the patients for 90 days.

The athletes who received hyaluronic acid reported significantly less pain with walking and weight bearing after day 8, 30 and 90, compared with the placebo group. Ninety percent of the athletes who received hyaluronic acid returned to their sport after eight days, compared with 71 percent of those who received placebo.

Those given hyaluronic acid also reported being more satisfied with the treatment than the patients given placebo. No serious side effects were seen in any of the study participants.

The injections are believed to work by forming a kind of scaffold along the injured ankle ligaments, Petrella said. Hyaluronic acid also is known to scavenge free radicals, the tissue-damaging byproducts of oxygen metabolism that can contribute to inflammation.

Efforts are now underway in the U.S., Canada and elsewhere to seek regulatory approval from the government for hyaluronic acid in treating ankle sprains, he added.

SOURCE: Clinical Journal of Sports Medicine, July 2007.

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