Improving Function After Knee Arthroplasty With Weight-Bearing Biofeedback

People who have had knee replacement surgery typically have worse physical function compared to healthy people of similar age. This problem occurs despite completion of standard rehabilitation programs. One reason for less-than-optimal restoration of physical function is that standard rehabilitation does not effectively address habitual movement patterns that persist after surgery. These movement patterns are characterized by patients placing less weight on their surgical leg compared to their non-surgical leg after surgery. This asymmetrical movement pattern has been identified by researchers and shown to not completely resolve after knee replacement surgery, even though the surgery reliably reduces knee pain. The persistence of asymmetrical weight-bearing during every day activity may limit the stimulus needed for full recovery by the muscles and joints of the surgical leg. By promoting increased loading of the surgical leg, a greater stimulus can be provided to promote better functional recovery, compared with standard rehabilitation. As a result, people may subsequently move more symmetrically with improved recovery of physical function. Improved function would in turn promote the person's ability to participate in life events, limiting disability. Considering that over 500,000 knee replacement surgeries occur in the United States each year, maximizing functional recovery and limiting disability following surgery are important goals.

The investigators propose a new method of exercising following knee replacement surgery. This method involves using a commercially available game system to promote "re-loading" of the surgical limb. The game system has games designed to allow the person playing to move objects or characters on a screen by shifting his/her weight from one leg to another while standing on an instrumented "balance board". The investigators have developed an exercise program to promote shifting weight to the surgical limb, by choosing appropriate games and manipulating the goals of those games. It is the investigators' hypothesis that early application of this surgical leg "re-loading" intervention after knee replacement will result in meaningful improvement in physical function by improving movement symmetry.

Inclusion criteria

• unilateral total knee arthroplasty, body mass index <40 kg/m^2

Exclusion criteria

• neurological, vascular or cardiac problems that limited physical function, contralateral knee pain greater than 2/10 on a numerical pain rating scale, severe osteoarthritis or other orthopaedic conditions in the non-operated lower extremity that limited function, sub-acute inpatient rehabilitation following unilateral total knee arthroplasty, uncontrolled diabetes, smoking or drug abuse, living >45 minutes away from the outpatient rehabilitation clinic, surgical complication requiring an altered course of rehabilitation, inability to walk 30 meters without an assistive device or inability to rise from a chair without use of arms