The Effects of Prehabilitative Exercise on Functional Recovery Following Total Knee Arthroplasty

People with knee arthritis have lower levels of physical activity and are more susceptible to suffer from additional medical conditions of heart disease, respiratory conditions, diabetes and stroke. For patients with end stage knee osteoarthritis, total knee arthroplasty (TKA) has been widely accepted as beneficial for increased patient satisfaction and improved function. To provide high quality of care and optimize TKA outcomes, healthcare providers need to make decisions about resource allocation. The theory of Prehabilitation proposes to increase strength, balance and endurance prior to surgery with the benefit of less decline and improved rate of recovery following surgery. Preoperative quadriceps strength and walking ability have been shown to be predictive of function one year post operation. However, systematic reviews of Prehabilitation have been inconclusive and this warrants additional investigation.

Prior studies of Prehabilitation have been inadequately designed or have low levels of therapeutic validity. A prior study completed in Spain provided pre-surgical exercise three times weekly for eight weeks and provides an example of high therapeutic validity with the corresponding significant results post-operation. The objective of this study is to translate knowledge of the pre-surgical exercise program completed in Spain into the local context of a hospital system in Virginia. Due to local area considerations of equipment and time, modifications of the Spanish pre-surgical exercise program are to be tested. These adaptations will allow for implementation within American College of Sports Medicine strength training guidelines using individualized exercise progressions and completion of three clinic based sessions per week.

Subjects that provide informed consent and complete initial screening will be scheduled for two pre-surgical and two post-surgical assessment sessions. On the first assessment session, subjects will be classified into three levels adapted from prior research and input from clinicians and administration to determine the need for pre-surgical preparation. Those subjects in the two most severe levels will be asked to participate in a Prehabilitation exercise program for three times a week for eight weeks and if consent is provided, will be randomized into the control (Joint Education Home Exercise Class only) or the intervention exercise program using a gender stratified randomized sequence generated prior to subject recruitment. The researcher will notify sequential subjects of their group allocation based on the predetermined randomized sequence at the end of the first testing session.

The goal of the prehabilitative exercise is to provide an individualized exercise program to be completed 3x/week for 8 weeks. The exercise sessions will be completed in the rehabilitation office at the Institute of Orthopedics and Neurology (ION) by physical therapy students with oversight from licensed PT at no cost for each subject. Ongoing evaluation of each exercise session will use the Borg Rating of Perceived Exertion (RPE) supplemented with Heart Rate (HR) and Blood Pressure as needed to target the moderate intensity training level (40-60% HR Max) or above as appropriate to each individual. Weekly evaluation of each individual's exercise program will be completed and progressed as able. Outline of Exercise program includes:

• Warm-up (Low intensity < 40% HR Max) 5 minutes of walking or bike
• Flexibility: knee flexion/ext and hamstring stretching
• Strengthening, Balance and Functional activities (Moderate intensity 40-60% HR Max)
• Closed kinetic chain exercises for balance and strengthening: 2-3 sets of 8-20 reps
• Calf raises unilateral/bilateral
• Quarter squats progressed to full squats as tolerated
• Resisted Step Progression (goal of isolated quads)
• Lunge with and without upper extremity support
• Step-ups anteriorly
• Step-downs laterally ▪ Balance program (goal of Single Leg Stance (SLS) and BOSU wobble board unilateral for 30 seconds)
• Weight shifts L/R and A/P
• Standing marching
• Single leg stance
• BOSU B maintain stability
• BOSU B with R/L rocking, A/P rocking
• BOSU B with quarter squats
• BOSU Unilateral
• Progressive Resistance exercises with elastic resistance bands 3 sets of 8-12 RM with 2 min rest period between sets:
• Leg Press bilateral to unilateral (alternate use of total gym or resisted squats)
• Seated Knee Extensions
• Standing Knee Curls
• Elastic band resisted hip ABD L/R (start with side-lying resisted clam shells)
• Manual therapy according to individual patient needs using a pragmatic approach to assist with weight bearing activity (for example squats)
• Cool-down 5 minutes (Low intensity < 40% HR Max) of walking or bike

Statistical comparisons will be conducted using a repeated measures linear mixed model with group, time and group by time as independent variables. Analyses will be adjusted for age, gender, BMI and baseline of the outcome measure. The primary outcome will be the 6MW pre-surgery/pre-exercise compared to one month post-surgery. Secondary outcomes include relevant clinical metrics (e.g. acute length of stay), impairment measures (e.g. strength), physical performance tests (e.g. gait speed and the six-minute walk test), physical activity measured by Actigraph accelerometer, and patient reported outcomes (e.g. PROMIS for global health). All measures will be collected at four time points:

T1) approximately twelve weeks pre-surgery \& before starting the exercise program; T2) approximately two weeks pre-surgery \& after completion of the exercise program; T3) one month after joint replacement surgery; and T4) three months after joint replacement surgery.

Potential benefits at the individual level include improved recovery of function post TKA, and improved overall physical activity. Potential benefits at the company/societal level are improved surgical rehabilitation outcomes including shorter hospital stay, quicker return to function, and decreased pain. In addition, collaboration between the orthopedists, physical therapists and administration to implement new methods such as Prehabilitation contribute to meeting the triple aim of healthcare of improved customer service, higher quality and cost savings as required by Medicare payment bundling.