Improving Function After Knee Arthroplasty With Weight-Bearing Biofeedback (RELOAD)

Foundation for Physical Therapy, Inc., National Institutes of Health (NIH), National Institute on Aging (NIA), Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

The purpose of this study is to determine if rehabilitation using weight-bearing biofeedback training following total knee arthroplasty (TKA) is more effective than standard rehabilitation methods in promoting weight-bearing symmetry through the lower limbs during functional activities such as sit-to-stand transfers and walking. Secondary outcomes of interest include functional measures and internal moment at the hip, knee, and ankle joints during sit-to-stand and walking.

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.

RELOAD participants participated in two 30-minute training sessions/week with a physical therapist for a total of 6 weeks, focusing on promoting WB symmetry using a progressive series of activities adapted to video games. These biofeedback training sessions were provided in addition to the standard of care rehabilitation that the CONTROL group received. Total dose of exercise across groups was matched.

CONTROL participants were provided two weeks of home rehabilitation (6 visits) by a physical therapist. Patients then progressed to outpatient rehabilitation, consisting of 4 weeks of treatment for a total of 6 weeks of standard of care rehabilitation. Total dose of exercise across groups was matched.

Patients in the experimental group completed the same standard of care rehabilitation program as the control group. Thus, the experimental intervention was in addition to the standard intervention. Upon discharge to home, patients in the RELOAD group began the weight bearing (WB) biofeedback phase of the study. Patients participated in two 30-minute training sessions/week with a physical therapist for a total of 6 weeks, focusing on promoting WB symmetry using a progressive series of activities adapted to video games.

Standard inpatient rehabilitation began on post-operative day 1 and lasted for an average of 3.2 days. After hospital discharge, two weeks of home rehabilitation (6 visits) were provided by physical therapists. Patients progressed to outpatient rehabilitation, consisting of 4 weeks of treatment. As such, 6 weeks of rehabilitation following hospital discharge was implemented for both groups.

Weight-bearing ratio is measured during transitions between sitting and standing and is indicated by symmetry in vertical ground reaction force (vGRF) between lower limbs. Ratios reported are (vGRF of the Surgical Limb):(vGRF Non-Surgical Limb).

Weight-bearing ratio is measured during walking as the ratio between lower limbs in peak vertical ground reaction force (vGRF) during the loading response phase of the stance period of gait. Ratios reported are (vGRF of the Surgical Limb):(vGRF Non-Surgical Limb).

The Five Times Sit-to-Stand Test is quantified as the total time required for an individual to rise from and return to a chair five times in a row.

Internal joint moments at the hip, knee, and ankle were calculated using an inverse dynamics approach from data collected using embedded force plates and a 6-camera motion analysis system to assess reflective marker positions placed at landmarks of the upper limbs, trunk, and lower limbs.

Self-selected walking speed was recorded for three passes across the middle 6 meter section of a walkway. The average of the 3 passes is reported.

Internal joint moments at the hip, knee, and ankle were calculated using an inverse dynamics approach from data collected using embedded force plates and a 6-camera motion analysis system to assess reflective marker positions placed at landmarks of the upper limbs, trunk, and lower limbs.

Weight-bearing ratio is measured during transitions between sitting and standing and is indicated by symmetry in vertical ground reaction force (vGRF) between lower limbs. Ratios reported are (vGRF of the Surgical Limb):(vGRF Non-Surgical Limb).

Weight-bearing ratio is measured during walking as the ratio between lower limbs in peak vertical ground reaction force (vGRF) during the loading response phase of the stance period of gait. Ratios reported are (vGRF of the Surgical Limb):(vGRF Non-Surgical Limb).

The Five Times Sit-to-Stand Test is quantified as the total time required for an individual to rise from and return to a chair five times in a row.

Internal joint moments at the hip, knee, and ankle were calculated using an inverse dynamics approach from data collected using embedded force plates and a 6-camera motion analysis system to assess reflective marker positions placed at landmarks of the upper limbs, trunk, and lower limbs.

Self-selected walking speed was recorded for three passes across the middle 6 meter section of a walkway. The average of the 3 passes is reported.

Internal joint moments at the hip, knee, and ankle were calculated using an inverse dynamics approach from data collected using embedded force plates and a 6-camera motion analysis system to assess reflective marker positions placed at landmarks of the upper limbs, trunk, and lower limbs.

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

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