NCT04107649: KArAT

Knee Arthroplasty Activity Trial

Active, enrolled NA Last updated 24 November 2025

What this trial tests

NA trial testing Telephonic Active Coaching (Motivational Interviewing) + Financial Incentives in Knee Osteoarthritis in 600 participants. Participants enrolled and being followed up; not accepting new ones.

Timeline

27 April 2023

Primary endpoint
15 June 2028

15 June 2028

Quick facts

Lead sponsor	Brigham and Women's Hospital
Phase	NA
Status	Active, enrolled
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	triple
Primary purpose	treatment
Enrollment	600
Start date	27 April 2023
Primary completion	15 June 2028
Estimated completion	15 June 2028
Sites	5 locations across United States

Drugs / interventions tested

• Telephonic Active Coaching (Motivational Interviewing) + Financial Incentives
• Wrist based activity tracker wear
• Basic Study Activities

Conditions studied

• Knee Osteoarthritis — all drugs for Knee Osteoarthritis →
• Total Knee Replacement — all drugs for Total Knee Replacement →

Sponsor

Brigham and Women's Hospital

Who can join

Adults 40 to 85, any sex, with Knee Osteoarthritis or Total Knee Replacement. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

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.

Publications & conference data

No peer-reviewed publications indexed yet for this trial.