MONDAY, Feb. 28 (HealthDay News) -- Ankle sprains seem to boost the risk of developing painful osteoarthritis in the joint, new research suggests.

The finding indicates that intensive rehabilitation is needed after chronic ankle instability or strains to help ward off the degenerative joint disease, according to the study authors.

For years, experts have known that arthritis in the ankle often occurs after a fracture of the joint. But arthritis that affects the hip and knee is usually related to wear and tear, experts say.

However, it has long been debated whether recurrent ankle sprains or ankle instability alone -- without a fracture -- can also lead to arthritis. The new research says that that is the case, although not everyone agrees the debate is over.

Swiss researchers led by Dr. Victor Valderrabano and Dr. Beat Hintermann of the Orthopaedic Department of the University of Basel evaluated 268 patients with ankle arthritis. Of these, 221, or 82.5 percent, had had a fracture and 47, or 17.5 percent, had had chronic ankle instability with recurrent sprains but no fractures. It took a little longer for arthritis to develop in those patients with sprains, compared to those with fractures: about 22.5 years for the sprain group and 21 years for the fracture group, the researchers said.

They presented their findings Saturday at the American Orthopaedic Foot and Ankle Society annual winter meeting in Washington, D.C.

The study isn't the first to suggest the sprain-and-arthritis link, Valderrabano said. "Already in the '70s, one paper showed that lateral ankle instability [involving the outer ligaments] could cause ankle arthritis," he said. "In our paper we addressed the analysis not only of the lateral but also of the medial ankle sprains."

Valderrabano said arthritis may develop after an ankle sprain due to lingering instability and increased forces at the surface of the joint.

The finding could affect a large number of people. An estimated 50 million U.S. adults have some disability resulting from arthritis, according to the society.

Ankle sprains and fractures are very common during sports and recreational activities. Up to 40 percent of patients with ankle injuries experience chronic instability in the joint, the authors said, and up to 80 percent of those people develop arthritis in the ankle.

Osteoarthritis is characterized by the breakdown of the joint's cartilage. Cartilage breakdown causes bones to rub against each other, causing pain and loss of movement, according to the Arthritis Foundation.

Yet not everyone agrees that the link between ankle sprains and arthritis is so clear-cut.

"People have looked at this many times in the past and it has not held up to scientific scrutiny," said Dr. Stuart Miller, an orthopedic surgeon at Union Memorial Hospital in Baltimore. "Clinically we suspect there is a connection," he said, but no definitive proof exists.

Miller and the Swiss researchers agree on one point: anyone with recurrent ankle sprains needs an intensive rehabilitation program of physical therapy. The person should strengthen muscles to become more immune to injury. Follow-up with a doctor to determine if the ankle is still unstable is crucial, too, said the Swiss team.

More information

For more information on arthritis of the ankle, visit the American Academy of Orthopaedic Surgeons.