Improving Rehabilitation Outcomes After Total Hip Arthroplasty

The 4MW test measures the time to walk 4 meters and has been used to generate gait speed values, which have been associated with morbidity and mortality in older adults. Higher numbers indicate better speed values. Participants will perform the 4MW with instructions to walk in their "normal, everyday pace." 4MW will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

The 30 second sit-to-stand test assesses functional lower extremity strength and endurance, and has been validated and found reliable in older adults at various physical activity levels and physical independence levels. Higher numbers indicate better lower extremity strength and endurance. 30 STS will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

Participants will also perform the FGA, which is a 10-item objective outcome measure designed to measure dynamic balance while walking in the presence of external demands, and will provide information on patients' stability before and after THA. The FGA has been shown to be a reliable and valid measure, effective in classifying fall risk in older adults and predicting unexplained falls. Scores range from 0-30, with higher scores indicating better functions. FGA will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

Isometric strength of the quadriceps and hip abductor muscles will be assessed on a handheld dynamometer. All strength testing will be performed in positions that minimize the risk of hip dislocation post-operatively, while still allowing for optimal trunk and pelvic stabilization. Isometric quadriceps strength testing will be performed in sitting at 0 hip flexion and 60 knee flexion. Isometric hip abduction strength testing will be performed in side lying at 0 flexion/extension and 0 hip abduction. Testing will include warm-up repetitions, followed by three separate maximal voluntary isometric contractions while receiving visual and verbal feedback. Strength will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

Patients will complete hip abductor endurance testing using a static single-limb balance test,. This modified Trendelenburg test assesses neuromuscular control during single limb stance and indicates the ability of the lateral hip muscles to maintain pelvic control during closed-chain, functional tasks and therefore serves as a measure of hip abductor muscle endurance. This test will be performed using a high-speed motion-capture system to assess lateral pelvic tilt. Differences in length of time pelvic control is maintained will be analyzed from preoperative to postoperative assessments during the single-limb task on the surgical leg. Trendelenburg will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

Surgical limb peak internal hip abduction moment will be calculated with 3-D instrumented motion analysis. Continuous internal hip abduction moments will be calculated during functional task performance using a standard inverse dynamics approach integrating kinematic and kinetic data using Visual 3D software (C-Motion, Germantown, MD). Peak internal hip moment during activity is a measurement of muscle activity during the task and provides insight to how muscles are activated during the task. Since the intervention exercise program targeted improving recruitment of the hip abductor moments during gait and other functional tasks, we calculated internal hip abduction moments. From the continuous hip moments, peak surgical limb internal hip abduction moments during the Loading Response phase of the stance period of the walking trials will be collected. Moments will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

ActiGraph activity monitors assess physical activity (PA) using accelerometry, which allows objective evaluation of the relative volume (steps/day) and intensity (activity counts) of physical activity with high validity and reliability. Each participant will wear the ActiGraph for at least 4 days at all time points to assess average daily PA (steps/day). Higher number of steps indicates higher level of physical activity. PA will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

The Veterans RAND (VR-12) is a reliable, self-report survey for assessing health-related quality of life. The questions in this survey correspond to seven different health domains: general health perceptions, physical functioning, role limitations due to physical and emotional problems, bodily pain, energy/fatigue levels, social functioning and mental health. Answers are summarized into two scores, a Physical Component Score (PCS) and a Mental Component Score (MCS) which then provides an important contrast between the respondents' physical and psychological health status. Each component score is summarized from 0 to 100, with a higher score indicating a better outcome. VR-12 scores will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

The WOMAC is a self-report questionnaire that assesses the impact of osteoarthritis on pain, stiffness, and disability. The WOMAC has been shown to be a valid, reliable, and responsive instrument often used in clinical trials. Scores range from 0-96, with higher scores indicating more pain, stiffness, and disability. WOMAC scores will also be assessed at mid-intervention (POST1, 4 weeks) and 26-week evaluation (POST3).

The PAM survey assesses patient knowledge, skill, and confidence for self-management, as self-efficacy exhibits a positive relationship with preventive actions and health outcomes. The Continuous Score is a composite score of the available 10 items, ranging from 0-100, wherein a higher score indicates a higher activation (better outcomes). The PAM Level is the mean of the 4 Categorical Levels, wherein a higher score indicates a higher activation (better outcomes). Categorical Level 1: disengaged and overwhelmed; Categorical Level 2: becoming aware but still struggling; Categorical Level 3: taking action \& gaining control; Categorical Level 4: maintaining behaviors \& pushing further. Specific cut offs for each Categorical Level are unavailable, as scoring is proprietary.

The PAM survey assesses patient knowledge, skill, and confidence for self-management, as self-efficacy exhibits a positive relationship with preventive actions and health outcomes. The Categorical Levels are frequency distribution of the scores between 1-100, wherein a higher Categorical Level indicates a higher activation (better outcomes). Categorical Level 2: becoming aware but still struggling; Categorical Level 3: taking action \& gaining control; Categorical Level 4: maintaining behaviors \& pushing further. Specific cut offs for each Categorical Level are unavailable, as the scoring is proprietary.

The motivation scales asks the participant "How motivated do you feel to participate in physical therapy?", and rating on a 0 (not at all motivated) to 10 (very motivated) scale. Higher scores indicate higher level of motivation.