Table 1 List of outcome measures collected at each time point

Patient-reported function measured by the Western Ontario and McMaster Universities Osteoarthritis Index Physical Function (WOMAC-PF) subscale is the primary outcome [43, 44]. The WOMAC-PF consists of 17 items related to physical function. Each item is scored on a 5-point Likert-type Scale with descriptors from 0–4 (none, mild, moderate, severe, and extreme difficulty). Scores of each item are summed for a maximum total score on the WOMAC-PF of 68. Higher scores indicate worse functional limitations.

X

X

X

X

Performance-based function is measured by a battery of tests:

X

X

X

X

(1). Self-selected gait speed is assessed in m/sec while patients walk at their regular pace over 4 meters [32, 35].

(2). Chair rise test times participants during 5 repetitions of rising to a full upright position and sitting back down in the chair without assistance. It uses a chair (18”height) without armrests [33, 34].

(3). Single leg stance test records the time of balancing on one leg while keeping the hands on the hips. The test lasts up to 60 sec and is stopped if the swing leg touches the floor, support foot moves on the floor, or arms swing away from the hips [33, 34].

(4). Stair ascend/descend test times participants while climbing up and down a set of 11 stairs (30 cm depth, 17 cm height) using a handrail on the preferred side [31].

(5). Six min walk test assesses the distance covered while walking during 6 min on an unobstructed, rectangular circuit (marked in meters) [33, 34].

(6). Sitting-rising test assesses the ability of participants to sit and rise from the floor [37].

Results of these test are combined using a composite score formed with unit-weighted z scores of constituent tests to provide a more stable measure of the subjects’ underlying functional performance [45].

• Real-time physical activity is measured by the SenseWear Armband (SWA) (Body Media Inc., Pittsburgh PA). The SWA collects information from a tri-axial accelerometer, heat flux, skin temperature, and galvanic signal. The information is integrated and processed by software using proprietary algorithms to provide minute-by-minute estimates of light- and moderate-intensity physical activity. Participants wear the SWM on the back of the right arm during 24 hours/7 days (except during water activities) to obtain 5 complete days of data [46, 47].

X

X

X

X

• Self-reported physical activity is assessed using the Community Healthy Activities Model Program for Seniors questionnaire (CHAMPS). The CHAMPS is a valid instrument that provides information on the types of physical activities such as hobbies, work- and social-related activities, walking, swimming, and dancing [48, 49].

X

X

X

X

Age, gender, race, education, BMI, self-rated health (excellent, good, fair, poor, or bad), discharge placement, number of prior rehabilitation sessions, surgical technique, and surgeon experience.

X

Medication prescribed and over-the-counter used for pain.

X

Comorbidity - assessed by the Cumulative Illness Rating Scale [50].

X

• Fear-avoidance beliefs measured by the Tampa Scale for Kinesiophobia [51].

X

X

X

X

• Anxiety measured using the Beck Anxiety Index [52].

X

X

X

X

• Self-efficacy measured by the Arthritis Self Efficacy Scale [53].

X

X

X

X

• Depressive symptom assessed by the Center for Epidemiologic Studies Short Depression Scale [54].

X

X

X

X

• Pain coping measured by the Coping Strategy Questionnaire [55, 56].

X

X

X

X

• Knee pain measured using an 11-point pain scale.

X

X

X

X

• Knee range of motion measured by a standard goniometer.

X

X

X

X

• Muscle strength of the knee extensors and hip abductor muscle groups using an isokinetic dynamometer (Biodex System 4 Pro, Shirley, NY) [57].

X

X

X

X

Adverse events - such as but not limited to changes in knee symptoms, falls, hospitalizations, and TKR on the other knee.

X

X

X

X

X

X

Attrition- defined as the number of patients dropping out of the study in each group.

X

X

X

Adherence to intervention- estimated by the proportion of sessions attended in each group and the proportion of patients missing each session.

X

X

Co-interventions- defined as additional treatment sought besides the ones prescribed by the study.

X

X

X

X

X

X