Knee Arthroplasty Activity Trial

Total knee replacement (TKR) is a common and costly procedure widely used to relieve pain and improve function in patients with symptomatic advanced knee osteoarthritis (OA). As of 2013, the annual incidence of TKR was over 680,000 surgeries and annual costs exceeded $11 billion. Growing evidence suggests that while pain and functional status improve following TKR, physical activity (PA) typically does not surpass pre-TKR levels. Engagement in PA can meaningfully improve quality of life (QoL), pain, and function. Given the large investment in TKR, the effectiveness and cost-effectiveness of TKR could be substantially increased if TKR recipients became more physically active.

The Knee Arthroplasty Activity Trial (KArAT) is a randomized controlled trial and participants will be randomly assigned to one of three arms. Participants across all arms will receive usual post-operative care for TKR surgery. Participants in the first arm will complete basic study activities, such as responding to surveys and attending two in-person clinic visits. Participants in the second arm will do the same and also receive a wrist-based physical activity tracker intervention. Participants in the third arm will receive a telephonic active coaching (motivational interviewing) and financial incentives (for reaching physical activity goals) (TAC(MI)+FI) based intervention, as well as a wrist-based physical activity tracker intervention. The second and third arms will be eligible to receive lottery-based financial rewards for wearing a wrist-worn activity tracker for twenty-four months during the study.

The investigators have designed the KArAT trial with two specific aims. First, to conduct a parallel three-arm RCT to establish the efficacy and sustainability of the effect of personalized intervention built on the principles of behavioral science and behavioral economics in improving PA among sedentary people who have undergone TKR. Our second aim is to establish the cost-effectiveness and budget impact of TAC(MI)+FI to improve PA in persons who have undergone TKR.

The three arms will include:

Arm 1: Usual post-TKR care

Arm 2: Usual post-TKR care + Wrist-based physical activity tracker wear

Arm 3: Usual post-TKR care + Wrist-based physical activity tracker wear + Telephonic Active Coaching (Motivational Interviewing) + Financial Incentives (TAC(MI)+FI).

Eligibility Criteria:
Inclusion Criteria:

* Age 40-85 years
* English-speaking
* Scheduled to undergo primary, unilateral total knee replacement (TKR) at one of the 4 recruitment centers
* OA is principal underlying indication for TKR
* During an accelerometer run-in period lasting one week at baseline (prior to surgery), subjects must show that they can comply with waist-worn physical activity tracker protocols by wearing the activity tracker for ≥4/7 days of the week for ≥10 hours/day
* Regular access to a personal computer, laptop, tablet, or smartphone for wrist-worn activity tracker syncing
* Satisfying average baseline steps/day criteria (calculated from waist-worn activity tracker data from the run-in period)

Exclusion Criteria:

* Non-English speaking
* Residence in nursing home
* Diagnosis of dementia, epilepsy, Parkinson's Disease, or diabetes with peripheral neuropathy
* Inflammatory arthritis (rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, reactive arthritis, systemic lupus erythematosus, polymyalgia)
* Psychological issues that preclude participation
* Inpatient or other musculoskeletal surgery scheduled within six months following index primary TKR
* Uses a wheelchair to ambulate (subjects who use a cane will be eligible)
* Surgeon-documented other reason for study exclusion
* Subject does not have regular access to a device capable of receiving email or text messages