We terminated the study due to covid 19 difficulties.

The participant population for this study will be a convenience sample of 40 active duty soldiers and cadets at West Point, New York (NY) who are recovering from anterior cruciate ligament reconstruction (ACLR) and are cleared to return to run by their medical provider. Two groups will be utilized in this pre-test, post-test, single-blind randomized controlled trial study design. The purpose of this study is to determine if patients recovering from ACLR benefit from running gait retraining to adopt a forefoot strike pattern and 5-10% increase in step rate when compared to a traditional walk to run program.

The participant population for this study will be a convenience sample of 40 active duty soldiers and cadets at West Point, NY who are recovering from Anterior Cruciate Ligament Reconstruction (ACLR) and are cleared to return to run by their medical provider. Two groups will be utilized in this repeated measures, single-blind, randomized controlled trial study design. The purpose of this study is to determine if patients recovering from ACLR benefit from running gait retraining when compared to a traditional walk-to-run program. Patient reported outcome measures, running kinetic data and running kinematic data, along with biomarkers of cartilage turnover and clinical outcomes will be assessed in two groups of post-operative ACLR patients. All participants, regardless of group, will be instructed in a 4-week home exercise program to ensure runners have adequate strength prior to returning to full running activities. They will be provided an instructional handout and compliance log at the date of their initial running biomechanical assessment. The home exercise program will consist of exercises focused on stretching and strengthening of the hip, knee, calf and foot musculature. One group will receive technology assisted clinician guided gait retraining to reduce lower extremity loading parameters (intervention) while the control group will return to running with a traditional return to run program (control). Regardless of group, all runners will have their running form and foot strike pattern analyzed using an instrumented treadmill and high-speed motion capture initially, at the pre-intervention, post-intervention, and follow-up time point. During the intervention period, regardless of group, all runners will complete in-clinic follow-ups with their study assigned medical provider. During these visits the control group will only receive standard run program feedback. During these visits the intervention group will receive technology-guided clinician-assisted gait retraining cues to reduce ground reaction forces during running. Kinetic data, kinematic data, and perceived running pain and running function will be collected at the pre-intervention, post-intervention and follow-up timepoints to include average vertical loading rate (AVLR), AVLR symmetry, impulse, foot strike pattern (FSP), contact time, step length, step rate, Visual Analog Scale for Running Pain during running, Visual Analog Scale for Running Pain worst pain, Visual Analog Scale for Running Pain during after running, Single Assessment Numeric Evaluation, Knee Injury and Osteoarthritis Outcome Score (KOOS), and University of Wisconsin Running and Recovery Index (UWRI). Biological samples will be collected from all runners regardless of group at the pre-intervention time point and the post-intervention timepoint. Biological samples will be tested using ELISA for several biomarkers of interest and the concentration of these biomarkers will be compared within and between groups over time. A pan-omics (e.g. metabolomics, proteomics, and transcriptomics) approach will be used to test for novel biomarkers that will also compare within and between groups over time. Our military service members are at greater risk of ACL injury, greater risk of early onset knee Osteoarthritis (OA), and are required to maintain high levels of fitness to remain in the military. It is therefore clinically important to identify interventions to improve patient reported outcomes, return to duty rates, and reduce lower extremity loading parameters in military service members returning to run after ACLR.

Inclusion Criteria:

1. Able and willing to give informed consent
2. Between 18-50 years of age
3. Active duty Soldier or cadet
4. History of Anterior Cruciate Ligament Reconstruction in the last 18 months
5. Cleared to return to run by their Department of Defense medical provider (primary care physician, orthopedic surgeon, physical therapist, or athletic trainer)
6. Ability to perform 20 unassisted single leg heel raises bilaterally
7. Ability to perform 10 pain-free, symmetrical, single-leg squats to between 45-60 degrees bilaterally
8. Ability to perform 20 pain-free single leg hops in place bilaterally

Exclusion Criteria:

1. Currently on an Army running limiting profile
2. Concomitant Posterior Cruciate Ligament or Lateral Cruciate Ligament injury
3. Concomitant meniscectomy >50%
4. History of inflammatory arthritis or gout
5. History of ACL injury to either knee
6. History of major lower-extremity joint injury and/or surgery
7. Known pregnancy currently or in the previous 6 months

The outcomes assessors will be blind to treatment group.