Pre-operative Electrical Stimulation for Anterior Cruciate Ligament (ACL) Injury

Quadriceps muscle weakness is a common consequence of ACL injury. This muscle weakness is
considered to result from neural inhibition preventing full muscle contraction and is
referred to as arthrogenic muscle inhibition (AMI). AMI hinders rehabilitation by preventing
gains in strength, increasing the risk of re-injury, and potentially placing patients at
risk for chronic degenerative joint conditions. Quadriceps weakness that occurs following
ACL injury is also thought to be caused by muscle atrophy which is thought to manifest due
to alterations in muscle architecture, selective fiber atrophy or even neural deficits such
as AMI. Importantly, interventions that are designed to counter this muscle weakness are
required in order to promote long-term knee joint health. Hence, the purpose of the current
study is to determine the efficacy of interventions that target quadriceps weakness to
improve quadriceps muscle function and biomechanics in patients prior to and following ACL
reconstruction. Specifically, the efficacy of neuromuscular electrical stimulation aimed at
improving quadriceps neural activity and eccentric exercise intended to minimize quadriceps
muscle atrophy will be investigated. The investigators expect that patients who receive the
electrical stimulation therapy will demonstrate improvements in quadriceps strength and
activation. Furthermore, it is expected that patients who receive both the electrical
stimulation and eccentric intervention will demonstrate markedly greater gains in quadriceps
strength and activation than patients who receive only the electrical stimulation therapy or
standard of care post-surgery. The investigators also hypothesize that the patients who
receive the electrical stimulation therapy and/or eccentrics will display knee motion
similar to uninjured control subjects.