Knee Arthroplasty Activity Trial
Key facts
- Who runs it
- Brigham and Women's Hospital
- Where
- Boston, Buffalo, Chicago, Kansas City, and Omaha, United StatesSee the 5 sites
- Trial code
- Status
- Active, not recruiting
- People taking part
- 600 people, planned
- Started
- 27 Apr 2023
- Expected to end
- 15 Jun 2028
- Type of study
- Interventional, 3 groups
- Treatments tested
- Telephonic Active Coaching (Motivational Interviewing) + Financial Incentives
- Wrist based activity tracker wear
- Basic Study Activities
- Record updated
- 24 November 2025
Who can take part
- Age
- 40 years to 85 years
- Sex
- Women and men
- Healthy volunteers
- Cannot take part
The registry criteria, word for word
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Who can take part
- 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)
Who cannot take part
- Inpatient or other musculoskeletal surgery scheduled within six months following index primary TKR
- Subject does not have regular access to a device capable of receiving email or text messages
- Diagnosis of dementia, epilepsy, Parkinson's Disease, or diabetes with peripheral neuropathy
- Non-English speaking
- Residence in nursing home
- Inflammatory arthritis (rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, reactive arthritis, systemic lupus erythematosus, polymyalgia)
- Psychological issues that preclude participation
- Uses a wheelchair to ambulate (subjects who use a cane will be eligible)
- Surgeon-documented other reason for study exclusion
Where in United States
- Brigham and Women's HospitalBoston, United StatesNo longer taking part
- University at BuffaloBuffalo, United StatesNo longer taking part
- Northwestern Memorial HospitalChicago, United StatesNo longer taking part
- University of Kansas Medical CenterKansas City, United StatesNo longer taking part
- University of Nebraska Medical CenterOmaha, United StatesNo longer taking part
About the trial
What the trial wants to find out
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.
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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 3 groups in the trial
- Arm1Other group
Participants in this arm receive usual post-operative care and complete all basic study activities, which include: attending 2 in-clinic visits at designated time-points, having regular check-in calls with study staff over the intervention period, wearing and returning waist-worn activity trackers at 5 time points over two years, and completing 6 study surveys.
Treatment: Basic Study Activities
- Arm2Treatment being tested
Participants in this arm receive usual post-operative care, complete all basic study activities (as described in arm 1) and receive the wrist-based activity tracker intervention.
Treatment: Wrist based activity tracker wear and Basic Study Activities
- Arm3Treatment being tested
Participants in this arm receive usual post-operative care, complete all basic study activities (as described in arm 1), receive wrist-based activity tracker intervention, and receive the TAC(MI)+FI.
Treatment: Telephonic Active Coaching (Motivational Interviewing) + Financial Incentives, Wrist based activity tracker wear, and Basic Study Activities
Data and sources
- Registry record
- Listed on ClinicalTrials.gov.
- Record updated
- 24 November 2025