By Anne Harding

NEW YORK (Reuters Health) - Most people who tear the main ligament responsible for stabilizing the knee do not need surgery to rebuild it, according to a study in which researchers compared surgery to physical therapy.

"Our research showed that reconstruction of the anterior cruciate ligament (ACL), which is quite common, is not a prerequisite for restoring muscle function," Dr. Eva Ageberg of Lund University, Sweden, told Reuters Health. She and her colleagues note that about half of Swedish patients who rupture the ligament undergo reconstructive surgery, while 90 percent of US patients do.

People who injure the ACL lose stability in the knee, boosting their risk of developing osteoarthritis. But despite widespread use of ACL reconstructive surgery, there is no evidence that patients who have the operations are any less likely to develop osteoarthritis.

To investigate the role of surgery in recovery of muscle function and strength, Ageberg and her team compared 36 people who had undergone ACL reconstruction and at least four months of "moderately aggressive" physical therapy to 18 patients who had physical therapy only.

There were no significant differences between the two groups on any of the muscle function tests or in muscle strength, the researchers found. Overall, roughly two-thirds of the patients performed normally on the single tests of muscle function, while just half showed normal performance on batteries of tests.

In Sweden, Ageberg noted, patients who rupture their ACL will first undergo several months of training, and will then be evaluated as to their need for surgery. In the US, surgery typically happens before training.

"If you do the surgery it doesn't assure that your muscles are good after that," Ageberg said. "You need rehabilitation after surgery even for a longer time than if you don't undergo surgery." For many people, she added, leg muscle training may be all they need to restore the stability of their knee.

She and her colleagues are now investigating their hypothesis that poor muscle function predicts osteoarthritis risk. "If this hypothesis is confirmed, it means that training is even more important than we believe today."

SOURCE: Arthritis & Rheumatism, December 15, 2008.

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