An interventional study of Adaptive Daily Step Promotion in Anterior Cruciate Ligament Injuries, sponsored by University of Georgia. Recruiting at 1 site in United States. Open to participants aged 16 Years to 40 Years. Per ClinicalTrials.gov, last updated 2026-04-29.
Sponsored by University of Georgia · Not applicable, Interventional, and Treatment
Optimal knee joint loading, which refers to the forces acting on the knee caused by daily activities such as daily steps, plays an essential role in maintaining knee articular cartilage health and reducing the risk of osteoarthritis (OA). After anterior cruciate ligament reconstruction (ACLR), individuals take fewer daily steps as compared to uninjured controls resulting in insufficient knee joint loading to joint tissues, but it is unclear how changes in daily steps impact knee joint cartilage health in OA development. Therefore, the overall single arm, longitudinal pre-test post-test study objective is to determine the mechanistic links between knee joint loading as measured by daily steps and comprehensive magnetic resonance imaging (MRI) measures of knee joint cartilage health post-ACLR. The central hypothesis is that individuals post-ACLR who take low daily steps will demonstrate deconditioned, less resilient cartilage characterized by poor tibiofemoral cartilage composition and greater cartilage strain.
Osteoarthritis (OA) is a leading cause of disability. Identifying modifiable mechanisms of poor knee joint health development for disease prevention strategies are critical to improving long-term health. Aberrant mechanical loading has been theorized as a primary risk factor for knee OA. Most studies primarily focus on mechanical mechanisms of excessive joint loading in OA development. However, recent evidence suggests that joint underloading may also play a role. The effects of low loading frequency assessed via daily steps in real world settings on knee joint health is an understudied parameter of aberrant mechanical loading in individuals at risk for OA. Individuals with anterior cruciate ligament (ACL) injury who undergo ACL reconstruction (ACLR) surgery are a representative population to assess the effects of low loading frequency on knee joint health because they are at elevated risk for posttraumatic OA development and demonstrate low daily steps compared to uninjured individuals. Therefore, the overall study objective is to determine the mechanistic links between joint loading frequency and comprehensive magnetic resonance imaging (MRI) measures of knee joint cartilage health in individuals post-ACLR. The central hypothesis is that individuals post-ACLR who take low daily steps will demonstrate deconditioned, less resilient cartilage characterized by poor tibiofemoral cartilage composition and greater cartilage strain which represent equally important, but independent measures of cartilage health. Furthermore, increasing daily steps using a 16-week daily step promotion paradigm in individuals post-ACLR who underload (\<8000 daily steps which is predictive of physical inactivity) will recondition cartilage by improving tibiofemoral cartilage composition and strain. The proposed study aims to determine: 1) associations between daily steps with tibiofemoral cartilage composition and strain in ACLR individuals (n=56) using an observational cross-sectional study design, and 2) the effects of increasing daily steps over 16-weeks on tibiofemoral cartilage composition and strain in ACLR individuals with low daily steps (n=28) using a single arm, longitudinal pre-test post-test study design. The proposed study is innovative because it builds on observational studies linking underloading with poor knee joint health and will be the first study to mechanistically determine how altering loading frequency (i.e., increasing daily steps) affects comprehensive in vivo measures of cartilage health in individuals at risk for OA. Successful completion of the proposed study will provide foundational evidence for the development of a future randomized controlled trial to determine the efficacy of an adaptive daily step promotion.
625 studies on the registry are indexed under Anterior Cruciate Ligament Injuries; 192 are open to participants now.
This study's planned enrollment of 56 is close to the median of 56 across 458 interventional studies indexed under Anterior Cruciate Ligament Injuries.
Browse Anterior Cruciate Ligament Injuries studies →University of Georgia is the lead sponsor of 74 studies on the registry; 16 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants who meet study criteria and are enrolled in adaptive daily step promotion intervention
Behavioral: Adaptive Daily Step Promotion
Participants will wear a Fitbit monitor on their non-dominant wrist during a 10 to 14 day "run-in" screening to capture daily steps reported by the Fitbit but no daily step goals will be sent to the participant. The Fitbit monitor will be worn during all waking hours except water activities, and compliance will be considered as a day with ≥1,000 steps. Next, participants will undergo a 16-week intervention wearing the Fitbit monitor on their wrist and receive a text message each morning with a personalized, adaptive daily step count goal and a link used to confirm receipt of the goal. The preceding 10 days of step data will be rank ordered and the 60th percentile step count will be set as the goal for the next day. Goals will not exceed 10,000 daily steps.
T2 relaxation times in the medial femoral condyle
MRI marker of T2 relaxation times of medial femoral articular cartilage (i.e collagen organization) at pre-intervention (baseline)
Time frame: pre-intervention (baseline)
T2 relaxation times in the lateral femoral condyle
MRI marker of T2 relaxation times of lateral femoral articular cartilage (i.e collagen organization) at pre-intervention (baseline)
Time frame: pre-intervention (baseline)
T2 relaxation times in the medial tibial condyle
MRI marker of T2 relaxation times of medial tibial articular cartilage (i.e collagen organization) at pre-intervention (baseline)
Time frame: pre-intervention (baseline)
T2 relaxation times in the lateral tibial condyle
MRI marker of T2 relaxation times of lateral tibial articular cartilage (i.e collagen organization) at pre-intervention (baseline)
Time frame: pre-intervention (baseline)
Change in T2 relaxation times in the medial femoral condyle
Change in MRI marker of T2 relaxation times of medial femoral articular cartilage (i.e collagen organization) from pre-intervention to post-intervention
Time frame: pre-intervention (baseline), post-intervention (~18 weeks)
Change in T2 relaxation times in the lateral femoral condyle
Change in MRI marker of T2 relaxation times of lateral femoral articular cartilage (i.e collagen organization) from pre-intervention to post-intervention
Time frame: post-intervention (~18 weeks)
Change in T2 relaxation times in the medial tibial condyle
Change in MRI marker of T2 relaxation times of medial tibial articular cartilage (i.e collagen organization) from pre-intervention to post-intervention
Time frame: pre-intervention (baseline), post-intervention (~18 weeks)
Change T2 relaxation times in the lateral tibial condyle
Change in MRI marker of T2 relaxation times of lateral tibial articular cartilage (i.e collagen organization) from pre-intervention to post-intervention
Time frame: pre-intervention (baseline), post-intervention (~18 weeks)
Average cartilage strain in the medial femoral condyle
MRI marker of cartilage strain (i.e., acute change in cartilage thickness/resting cartilage thickness) of medial femoral articular cartilage at pre-intervention (baseline)
Time frame: pre-intervention (baseline)
Average cartilage strain in the lateral femoral condyle
MRI marker of cartilage strain (i.e., acute change in cartilage thickness/resting cartilage thickness) of lateral femoral articular cartilage at pre-intervention (baseline)
Time frame: pre-intervention (baseline)
Average cartilage strain in the medial tibial condyle
MRI marker of cartilage strain (i.e., acute change in cartilage thickness/resting cartilage thickness) of medial tibial articular cartilage at pre-intervention (baseline)
Time frame: pre-intervention (baseline)
Average cartilage strain in the lateral tibial condyle
MRI marker of cartilage strain (i.e., acute change in cartilage thickness/resting cartilage thickness) of lateral tibial articular cartilage at pre-intervention (baseline)
Time frame: pre-intervention (baseline)
Change in average cartilage strain in the medial femoral condyle
Change in MRI marker of cartilage strain (i.e., acute change in cartilage thickness/resting cartilage thickness) of medial femoral articular cartilage from pre-intervention to post-intervention
Time frame: pre-intervention (baseline), post-intervention (~18 weeks)
Change in average cartilage strain in the lateral femoral condyle
Change in MRI marker of cartilage strain (i.e., acute change in cartilage thickness/resting cartilage thickness) of lateral femoral articular cartilage from pre-intervention to post-intervention
Time frame: pre-intervention (baseline), post-intervention (~18 weeks)
Change in average cartilage strain in the medial tibial condyle
Change in MRI marker of cartilage strain (i.e., acute change in cartilage thickness/resting cartilage thickness) of medial tibial articular cartilage from pre-intervention to post-intervention
Time frame: pre-intervention (baseline), post-intervention (~18 weeks)
Change in average cartilage strain in the lateral tibial condyle
Change in MRI marker of cartilage strain (i.e., acute change in cartilage thickness/resting cartilage thickness) of lateral tibial articular cartilage from pre-intervention to post-intervention
Time frame: pre-intervention (baseline), post-intervention (~18 weeks)
Daily steps
Average steps per day over 7 day physical activity monitor wear at pre-intervention (baseline)
Time frame: Pre-intervention (baseline)
Change in daily steps
Change in average steps per day over 7 day physical activity monitor wear from pre-intervention to post-intervention
Time frame: Pre-intervention (baseline), post-intervention (~18 weeks)
Change in Knee Injury and Osteoarthritis Outcome Score Quality of Life subscale
Change in Knee injury Osteoarthritis Outcome Score (KOOS) Quality of Life subscale to measure knee-related quality of life from pre-intervention to post-intervention. A higher score indicates better knee-related quality of life. Min = 0 and Max = 100
Time frame: Pre-intervention (baseline), post-intervention (~18 weeks)
Plan to share: Yes — Upon completion of the of the proposed projects, the overall data set will include outcome measures including: Participant demographics Knee injury history ACLR surgical procedure data Patient reported outcomes of self-reported knee function, physical activity, and psychological recovery Daily steps throughout the intervention using a Fitbit Daily steps before and after the intervention using a research grade tri-axial accelerometer Habitual gait speed Gait biomechanics at habitual gait speed Magnetic resonance imaging (i.e., T1ρ, T2, and Dess)) of the tibiofemoral and patellofemoral joint All of the information will be linked together, but deidentified. The data will be available to those who submit a formal written request to the PI and commit to only using the data for researcher purposes unplanned by the investigators. The data cannot be used to recruit or contact participants and must be destroyed or returned following the data analysis.
Supporting information: Study protocol, Informed consent form
Time frame: Data will be available for 10 years once all formal data collection, processing, and primary analysis is complete.
Access criteria: The data will be available to those who submit a formal written request to the PI and commit to only using the data for researcher purposes unplanned by the investigators.
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Anterior Cruciate Ligament Injuries →
University of Georgia