By Larry Hand
Chronic ankle instability (CAI) has been linked to development of early ankle osteoarthritis (OA), but questions remain as to how and why the degeneration occurs and how bracing and other interventions might slow the process.
Multiple studies have found associations between CAI and ankle OA, dating back to an April 1979 report published in the Journal of Bone & Joint Surgery that documented ankle OA in 78% of cases of chronic lateral ankle instability after at least 10 years. More recently, an April 2006 American Journal of Sports Medicine study of 30 patients with end-stage ligamentous ankle OA found that 52% were unstable and 76% had a history of recurrent sprain.
A recent paper in the October issue of Foot & Ankle Specialist contributed another piece to the puzzle. Researchers from the Kaiser San Francisco Bay Area Foot and Ankle Residency in Oakland, CA, reviewed records of 28 patients with prolonged lateral ankle instability who underwent ankle arthroscopy between 2004 and 2008. They determined that all patients experienced inflammation of the synovial membrane, seven had talar cartilage fibrillation, and four experienced talar dome cartilage defect, among other effects.
“Ankle osteoarthritis is really an up-and-coming trend that’s beginning to be investigated more—which is a good thing,” said Patrick McKeon, PhD, ATC, assistant professor in the Division of Athletic Training at the University of Kentucky College of Health Sciences in Lexington. “Ankle replacements are just gaining popularity.”
Reducing the risk of ankle OA could be as simple as reducing the incidence of ankle sprain, said Cathleen Brown Crowell, PhD, ATC, co-director of the Biomechanics Laboratory in the Department of Kinesiology at the University of Georgia in Athens.
“We do not know for sure, but more sprains increase the risk of OA, so decreasing the number of sprains experienced would be a goal. Sprains can be reduced in people with CAI through ankle bracing and ankle rehabilitation,” Brown said.
However, individuals with ankle OA have both mechanical and functional deficits that may limit opportunities for intervention, said McKeon.
“On the functional side we know that we can change improper biomechanics as well as improper or impaired postural control and sensory motor control through rehabilitation,” McKeon said. “We might not be able to alter the mechanical side by any means other than surgical intervention.”
It’s important to treat patients early, said Curt Bertram, CO, general manager of the Hanger Orthopedic Group in Milwaukee, WI.
“When you have ankle instability, you’re putting abnormal stress on the obvious structures of your ankle that aren’t designed to handle that,” Bertram said. “The patient is experiencing premature wear on the joint and
thus is developing osteoarthritis prematurely. As an orthotist, the best thing to do is correct that with an orthotic device.”
Practitioners also agreed that ankle bracing can help treat ankle OA and possibly prevent its development.
“Wearing an ankle brace can decrease the number of sprains,” Crowell said. “There is no evidence that braces are harmful to the joint. Individuals with ankle instability should ask a rehabilitation professional for the brace that best fits their needs.”
Bracing can help, especially in acute cases, Bertram said.
Why some people with CAI develop ankle OA and others don’t probably depends on other health factors such as obesity, diabetes, tobacco use, and level of physical activity, practitioners said.
“The greater your mass, the greater force you’re putting on the ankles. Severe instability combined with obesity and poor health certainly contributes to a higher risk for developing ankle OA,” Bertram said.
Phillip Gribble, PhD, ATC, associate professor of kinesiology and director of athletic training at the University of Toledo in Ohio, said the need now is to conduct prospective studies of two cohorts of people, those who develop ankle OA after ankle injury and those who don’t.
“We need prospective studies to determine the effectiveness of interventions,” Gribble said. “Something as benign to the public as an ankle sprain really has the potential to become a major public health problem.”
Sponsored by an educational grant from Med Spec