Nordic Hamstring Exercise After ACL Reconstruction Reconstruction
Condition: ACL Injury; Muscle Weakness; Neuromuscular Manifestations
MeSH terms: Muscle Weakness; Neuromuscular Manifestations; Anterior Cruciate Ligament Injuries
Study type: Interventional

Summary: 
      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.
    


Intervention name(s): Nordic Hamstring Exercise
Intervention type(s): Other
Intervention description(s): 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.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Eccentric exercise; Hamstrings