Effect of Altered Mechanical Loading in ACLR

Study Overview
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Brief Summary
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Altered loading is a causative factor for the development of knee osteoarthritis following anterior cruciate ligament reconstruction (ACLR), and real-time biofeedback may be an effective intervention to manipulate altered mechanical loading about the knee. The purpose of this study is to 1) determine if ACLR participants are able to acquire and retain various loading patterns using real-time biofeedback, 2) determine the effect of altered loading on lower extremity biomechanics during walking gait, and 3) determine the effect of altered loading on biochemical markers of collagen turnover and inflammation during walking gait.

Detailed Description
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Participants will attend 4 testing sessions. Lower extremity biomechanical outcomes and blood samples will be taken before and following the participant walking at a self-selected speed for 20 minutes. During the 20 minutes of treadmill walking real-time biofeedback will be displayed in an attempt to alter mechanical loading. Participants will complete a control, overloading, under-loading, average loading testing session. Order of loading condition will be randomized.

Official Title
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Effect of Altered Mechanical Loading on Lower Extremity Biomechanics and Biochemical Markers in Individuals With an Anterior Cruciate Ligament Reconstruction

Conditions
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Anterior Cruciate Ligament Reconstruction

Intervention / Treatment
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* Other: Real-Time Biofeedback


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Have a history of a primary, unilateral ACLR using either a hamstring or patellar tendon autograft, cleared by a physical for full return to physical activity with no limitations, and participate in at least 30 minutes of physical activity 3 times per week Exclusion Criteria: History of injury to either leg, other than ACLR (e.g. ankle sprain, muscle strain), within 6 months prior to participation in the study, history of lower extremity surgery other than ACLR, history of osteoarthritis or current symptoms related to knee osteoarthritis (e.g. pain, swelling, stiffness), currently pregnant, or planning to become pregnant while enrolled in the study, cardiovascular restrictions that limit the participant's ability to participate in physical activity.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Overloading<br>Participants will walk on a force-instrumented treadmill for 20 minutes and will be provided visual biofeedback consisting of bilateral vertical ground reaction force. A target will be placed at 10% greater than the participant's baseline vertical ground reaction force. Participants will be asked to alter their walking gait in an attempt to reach the target line with each step. | Other: Real-Time Biofeedback<br>* A custom written MatLab script will sample bilateral peak vertical ground reaction forces and display the magnitude in real time on a screen placed in front of the participant. A target line will be placed in the middle of the screen which corresponds to one of the three loading conditions. Participants will be instructed to alter their movement in an attempt to match each limb's vertical ground reaction force to the target line.<br>|
| Experimental: Underloading<br>Participants will walk on a force-instrumented treadmill for 20 minutes and will be provided visual biofeedback consisting of bilateral vertical ground reaction force. A target will be placed at 10% lower than the participant's baseline vertical ground reaction force. Participants will be asked to alter their walking gait in an attempt to reach the target line with each step. | Other: Real-Time Biofeedback<br>* A custom written MatLab script will sample bilateral peak vertical ground reaction forces and display the magnitude in real time on a screen placed in front of the participant. A target line will be placed in the middle of the screen which corresponds to one of the three loading conditions. Participants will be instructed to alter their movement in an attempt to match each limb's vertical ground reaction force to the target line.<br>|
| Experimental: Average<br>Participants will walk on a force-instrumented treadmill for 20 minutes and will be provided visual biofeedback consisting of bilateral vertical ground reaction force. A target will be placed at the average of each participant's baseline vertical ground reaction force between limbs. Participants will be asked to alter their walking gait in an attempt to reach the target line with each step. | Other: Real-Time Biofeedback<br>* A custom written MatLab script will sample bilateral peak vertical ground reaction forces and display the magnitude in real time on a screen placed in front of the participant. A target line will be placed in the middle of the screen which corresponds to one of the three loading conditions. Participants will be instructed to alter their movement in an attempt to match each limb's vertical ground reaction force to the target line.<br>|
| No Intervention: Control<br>Participants will walk for 20 minutes on a force-instrumented treadmill and will not be provided biofeedback. | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in acquisition as measured in root mean square error (RMSE) between loading conditions |  | Change in acquisition over 20 minute intervention | 
| Difference in joint loading as measured in peak vertical ground reaction force normalized to body weight (xBW) between loading conditions |  | Change in joint loading over 20 minute intervention | 
| Difference in cartilage turnover as measured in serum concentration of cartilage oligomeric matrix protein (pg/mL) between loading conditions |  | Chance in cartilage turnover over 20 minute intervention |