'Prehabilitation' exercise program can improve strength, functional ability before knee replacement surgery

Mar 2 2011

A comprehensive "prehabilitation" exercise program for patients with severe knee arthritis can improve strength and functional ability before knee replacement surgery, reports a study in the February issue of The Journal of Strength and Conditioning Research, official research journal of the National Strength and Conditioning Association. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.

The physical gains from exercise before knee replacement may translate into improved recovery after surgery, suggests the new study by Ann M. Swank, Ph.D., CSCS, and colleagues of University of Louisville, Ky.

Increased Leg Strength Leads to Better Functioning and Decreased Pain
The study included 71 patients scheduled for knee replacement surgery because of severe osteoarthritis that could not be managed with pain medications. One group was randomly assigned to a comprehensive prehabilitation program, consisting of light resistance training, flexibility and step exercise, and light walking.

Patients in this "pre-rehab" group exercised three times per week, in the clinic and at home, for four to eight weeks before knee replacement surgery. Patients in the comparison group received standard preoperative care, with instructions to continue their usual activities. The two groups were compared for knee strength and performance on standard functional tests.

When tested one week before surgery, patients who went through the prehabilitation program showed improvements in several key outcomes. In particular, they had a significant ten percent increase in extension strength in the leg scheduled for knee replacement. In contrast, the comparison group had an ten percent decrease in extension strength.

Prehabilitation was also associated with improvement in some functional tests, including the ability to get up from a chair and to climb a set of stairs. Other functional tests, such as walking speed and going downstairs, showed no significant improvement.

In addition, patients in the prehabilitation group also had less pain when performing the functional tests. For patients receiving standard care, performance on some functional tests actually decreased in the weeks before surgery—possibly reflecting increased pain scores.

Osteoarthritis of the knee is a very common condition in older adults, causing pain and gradual declines in the ability to perform everyday tasks. When pain becomes so severe that medications no longer provide relief, knee replacement surgery is the only option. By that time, reduced leg strength may be present for several years—not only decreasing functional ability, but increasing the risk of falls.

Previous studies have evaluated exercise programs to improve leg strength and functional ability before knee replacement surgery, but with limited success. For the new study, Dr. Swank and colleagues developed a comprehensive, progressive short-term exercise program specifically designed to increase leg strength and functional ability.

The results show significant improvements in strength and functioning in the weeks before knee replacement surgery. Strengthening of the leg undergoing knee replacement may be a particularly important factor—exercise may reduce the strength imbalance between legs, thus contributing to the functional improvement. (Although even with exercise, the surgical leg remains significantly weaker than the other leg.)

Dr. Swank and colleagues outline a recommended routine for progressive exercise in patients scheduled for knee replacement surgery. They note that the prehabilitation program was designed to be "easily accessible" and "easily transferred to a home environment." Although their study didn't compare postoperative recovery, the researchers note, "Increases in leg strength and performance of functional tasks before [knee replacement] surgery may result in improved postoperative recovery because preoperative performance of functional tasks has been shown to be a predictor of postoperative performance of functional tasks."

SOURCE The Journal of Strength and Conditioning Research