Nordic Hamstring Exercise After ACL Reconstruction Reconstruction

Study Overview
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Brief Summary
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Anterior cruciate ligament (ACL) injuries constitute a significant portion of major knee joint injuries sustained by young, active individuals, and significantly increase risk for long-term disability. Yet the recommended solution to restore joint stability following injury--ACL reconstruction (ACLR)--does not prevent post-traumatic knee osteoarthritis (PTOA). Post-traumatic quadriceps (dys)function is a hallmark characteristic following ACLR, reported to accelerate the onset of PTOA after ACL injury, making the recovery of muscle function a primary concern to clinicians. However, hamstrings muscle function is drastically underrepresented relative to the quadriceps in the context of recovery from ACLR, which impedes the ability to develop targeted treatment approaches. Persistent hamstrings weakness is widely reported in patients who undergo ACLR with a hamstring tendon (HT) autograft, which increases ACL strain, and may contribute to higher graft failure rates in this population. To effectively treat muscular impairments, underlying neuromuscular adaptations known to occur in response to ACLR must be targeted. Eccentric exercise is uniquely suited to enhance neuromuscular function. The Nordic hamstring exercise (NHE) is a specific form of eccentric exercise that is clinically relevant and easy to implement, but has not been explored as an intervention for hamstrings neuromuscular dysfunction in patients who undergo ACLR with HT. To establish an evidence-based treatment model, the investigators will use a single-blind, randomized controlled clinical trial to establish the feasibility and efficacy of a 4-week NHE protocol in patients who undergo ACLR with HT. Separate factorial ANOVAs will be used to assess the effects of group (NHE, control) and time (baseline, 4 weeks) on selected outcomes. Effect sizes will be calculated for within- and between-group comparisons. The investigators expect to observe improvements in hamstrings neuromuscular function following the NHE protocol, and that those improvements will be greater than the control group. Additionally, the investigators expect the protocol to be feasible in terms of intervention adherence and patient retention. This study will identify specific barriers to the implementation of NHE in patients who undergo ACLR with HT, and will provide support for the application of an easy to implement clinical intervention able to address a complex neurophysiological problem.

Official Title
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Use of Nordic Hamstring Exercise to Improve Hamstrings Function in Patients After ACL Reconstruction

Conditions
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ACL Injury, Muscle Weakness, Neuromuscular Manifestations

Intervention / Treatment
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* Other: Nordic Hamstring Exercise


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18-35 History of primary, unilateral ACL reconstruction (ACLR) with hamstrings tendon autograft Exclusion Criteria: Lower extremity orthopedic surgery prior to ACLR Post-surgical complication (e.g. infection, delayed healing) Multiple ligament knee injury Treated articular cartilage lesion Known history of knee osteoarthritis Concussion within 6 months History of neurological disorder Currently taking prescription medication that may alter neural excitability (e.g. stimulants, depressants)

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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Nordic Hamstring Exercise<br>A 4-week (10 session), progressive, Nordic Hamstring Exercise (NHE) protocol will be used for this study. | Other: Nordic Hamstring Exercise<br>* A 4-week (10 session), progressive, NHE protocol will be used for this study. Immediately following the completion of study visit 1, patients will be informed about the nature of the NHE protocol. Those available and willing to participate will be randomized to an intervention group (NHE, control). Patients randomized to NHE will receive formal instruction about how to correctly perform the exercise, and will be asked to perform several repetitions to familiarize themselves with the exercise and verify proper technique. At this time, patients will be dismissed from study visit 1, and return visits 2-11 will be scheduled to complete the NHE protocol. Patients will return for a final study visit (12) to record post-intervention measurements within 7 days of completing the NHE protocol. A minimum of 48 hours will be used to separate study visits. To accurately assess patients' ability to perform the NHE, all exercise will be performed on a NordBord Hamstring Testing System.<br>|
| No Intervention: Control<br>Patients randomized to the control group will be instructed to avoid any changes to their normal routine (e.g., physical activity level, strength training, etc.). An investigator not involved in data collection will communicate with patients in the control group on a weekly basis to ensure they have not changed their physical activity level and do not have any questions. Patients randomized to the control group will participate in a minimum of 2 study visits at baseline and 4 weeks. These individuals will have the option to open enroll in the intervention group at the completion of their original 4-week study period. Those who choose to enroll in the intervention group at this time will return for 11 additional visits to complete the NHE protocol (visits 3-12) and final assessment (visit 13) | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in peak eccentric torque | Hamstrings | Baseline, 4 weeks | 
| Change in peak isometric torque | Hamstrings | Baseline, 4 weeks | 
| Change in peak isokinetic torque | Hamstrings | Baseline, 4 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in rate of torque development | Hamstrings | Baseline, 4 weeks | 
| Change in torque coefficient of variation | Hamstrings | Baseline, 4 weeks | 
| Change in central activation ratio | Hamstrings | Baseline, 4 weeks | 
| Change in single leg hop | Hop for distance | Baseline, 4 weeks | 
| Change in active motor threshold | Transcranial magnetic stimulation (TMS) derived outcome in semitendinosus | Baseline, 4 weeks | 
| Change in cortical silent period | Transcranial magnetic stimulation (TMS) derived outcome in semitendinosus | Baseline, 4 weeks | 
| Change in short-interval cortical inhibition | Transcranial magnetic stimulation (TMS) derived outcome in semitendinosus | Baseline, 4 weeks | 
| Change in intracortical facilitation | Transcranial magnetic stimulation (TMS) derived outcome in semitendinosus | Baseline, 4 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Eccentric exercise, Hamstrings