Knee Arthroplasty Activity Trial
KArAT
1 other identifier
interventional
600
1 country
5
Brief Summary
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.
Trial Health
Trial Health Score
Automated assessment based on enrollment pace, timeline, and geographic reach
participants targeted
Target at P75+ for not_applicable knee-osteoarthritis
Started Apr 2023
Longer than P75 for not_applicable knee-osteoarthritis
5 active sites
Health score is calculated from publicly available data and should be used for screening purposes only.
Trial Relationships
Click on a node to explore related trials.
Study Timeline
Key milestones and dates
First Submitted
Initial submission to the registry
September 24, 2019
CompletedFirst Posted
Study publicly available on registry
September 27, 2019
CompletedStudy Start
First participant enrolled
April 27, 2023
CompletedPrimary Completion
Last participant's last visit for primary outcome
June 15, 2028
ExpectedStudy Completion
Last participant's last visit for all outcomes
June 15, 2028
November 24, 2025
November 1, 2025
5.1 years
September 24, 2019
November 19, 2025
Conditions
Keywords
Outcome Measures
Primary Outcomes (1)
Proportion of Subjects Engaged in at least 150 min/week of moderate-to-vigorous physical activity (MVPA).
The primary outcome of this trial is the proportion of subjects who meet or surpass the PA threshold of 150 minutes per week of at least moderate physical activity, which is defined as 3 metabolic equivalents (METs), at 32-weeks post-TKR.
32-weeks post-TKR
Secondary Outcomes (3)
Change in average daily step count
2-week pre-TKR to 32-weeks post-TKR
Change in weekly minutes of moderate-to-vigorous activity (MVPA)
2 week pre-TKR to 32-weeks post-TKR
Change in average daily sedentary time
2 weeks pre-TKR to 32-weeks post-TKR
Other Outcomes (5)
Durability of changes in activity levels
2 weeks pre-TKR to 24 months post-TKR
Change in pain and functional status
2 weeks pre-TKR to 24 months post-TKR
Change in quality of life
2 weeks pre-TKR to 24 months post-TKR
- +2 more other outcomes
Study Arms (3)
Arm1
OTHERParticipants 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.
Arm2
EXPERIMENTALParticipants 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.
Arm3
EXPERIMENTALParticipants 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.
Interventions
As part of TAC(MI)+FI, participants speak with a health coach at Brigham and Women's Hospital once a week via telephone for weeks 6-13 following surgery, and once every other week for weeks 14-31 after surgery. Participants in this arm can receive financial rewards for achieving weekly physical activity goals, as well as bonus rewards for achieving goals multiple weeks in a row. Over the course of this 6-month long TAC(MI)+FI intervention period, these participants are able to receive up to $680 for meeting physical activity goals, and up to $95 in bonus rewards.
Activity tracking data will be collected on a weekly basis. Participants who receive this intervention are eligible to be entered into a lottery to win one of two $25 rewards for every week they wear their wrist-based activity tracker \>10 hours for \>4/7 days a week, beginning 6-weeks after surgery.
Basic study activities begin two-weeks before TKR and end approximately 24-months after TKR. Basic study activities include: two in-person visits at the local clinic site (2 weeks before TKR and 32-weeks after TKR), having check-in calls with study staff weekly from weeks 1-13 after surgery and every other week for weeks 14-31, completing 6 surveys, and wearing an ActiGraph activity tracker (waist-worn) for five one-week periods throughout the study (2-weeks before-TKR, 32-weeks post-TKR, one-year post-TKR, 18-months post-TKR, two-years post-TKR). All participants will be eligible to receive up to $235 for completing these activities over the course of two years.
Eligibility Criteria
You may qualify if:
- 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)
You may not qualify if:
- 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)
- Subject does not have regular access to a device capable of receiving email or text messages
Contact the study team to confirm eligibility.
Sponsors & Collaborators
- Brigham and Women's Hospitallead
- Northwestern Memorial Hospitalcollaborator
- University of Kansas Medical Centercollaborator
- University at Buffalocollaborator
- University of Nebraskacollaborator
Study Sites (5)
Northwestern Memorial Hospital
Chicago, Illinois, 60611, United States
University of Kansas Medical Center
Kansas City, Kansas, 66160, United States
Brigham and Women's Hospital
Boston, Massachusetts, 02115, United States
University of Nebraska Medical Center
Omaha, Nebraska, 68198, United States
University at Buffalo
Buffalo, New York, 14215, United States
Related Publications (1)
Losina E, Collins JE, Kumara M, Ehrlich-Jones L, Opare-Addo M, Safran-Norton C, Segal NA, Mitchell LM, Kopp PT, Selzer F, Mass H, Paskewicz M, Chang RW, Dunlop D, Chen AF, Lerner S, Chin S, Pellegrini C, Katz JN. KArAT (Knee Arthroplasty Activity Trial): Rationale and design features of a multicenter randomized controlled trial. Osteoarthr Cartil Open. 2024 Aug 23;7(2):100512. doi: 10.1016/j.ocarto.2024.100512. eCollection 2025 Jun.
PMID: 40276263DERIVED
MeSH Terms
Conditions
Interventions
Condition Hierarchy (Ancestors)
Intervention Hierarchy (Ancestors)
Study Officials
- PRINCIPAL INVESTIGATOR
Elena Losina, Ph.D.
Brigham and Women's Hospital
Study Design
- Study Type
- interventional
- Phase
- not applicable
- Allocation
- RANDOMIZED
- Masking
- TRIPLE
- Who Masked
- CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
- Masking Details
- The investigators, care providers, and outcomes assessors will not be appraised of treatment arm.
- Purpose
- TREATMENT
- Intervention Model
- PARALLEL
- Sponsor Type
- OTHER
- Responsible Party
- PRINCIPAL INVESTIGATOR
- PI Title
- Co-Director of OrACORe, Robert W. Lovett Professor of Orthopaedic Surgery at Harvard Medical School
Study Record Dates
First Submitted
September 24, 2019
First Posted
September 27, 2019
Study Start
April 27, 2023
Primary Completion (Estimated)
June 15, 2028
Study Completion (Estimated)
June 15, 2028
Last Updated
November 24, 2025
Record last verified: 2025-11