Blood Flow Restriction Therapy for the Post-Operative Rehabilitation of Anterior Cruciate Ligament Reconstruction With Quadriceps Tendon Autograft: A Randomized, Controlled Trial

The overall objective of the proposed research is to conduct a prospective, randomized controlled trial to investigate whether the addition of BFR therapy to standard post-operative rehabilitation regimen significantly improves clinical outcomes following ACLR standardized with respect to both surgical technique and graft selection. The investigator's central hypothesis is that the addition of BFR therapy has the potential to accelerate surgical recovery, expedite return-to-duty, and maximize medical readiness following ACLR. In the proposed trial validated isokinetic and isometric quadriceps strength testing will be used to quantify the effect of therapy on quadriceps strength, patient reported outcome measures will be used to assess for functional clinical improvement, while quadriceps musculature volume as measured on MRI will be used as an effort independent measure of quadriceps recovery. The rationale for using this modality is based upon the fact that the measurement of quadriceps CSA and muscle volume as surrogates for overall quadriceps function is well described, and a number of studies have convincingly demonstrated positive correlations between these parameters and quadriceps strength4, 17. However, in spite of these reports, the acceptance acknowledging MRI as a surrogate for quadriceps strength remains limited. Therefore, isokinetic and isometric quadriceps strength of both the operative and non-operative knee extensors (quadriceps) will be measured pre-operatively within 7-10 days approximately prior to ACLR and post-operatively at approximately 16 weeks, 28 weeks, 40 weeks, and 56 weeks. MRI of bilateral thighs will be performed immediately prior to ACLR to establish a baseline CSA in the operative and non-operative lower extremity. Then a repeat MRI will be performed following the conclusion of a standardized 12-week (approximately) post-operative rehabilitation regimen among patients randomized to either a standard rehabilitation regimen (REHAB) or a rehabilitation regimen with BFR (REHAB + BFR.) Finally, MRI will be repeated at 56 weeks post-operative to examine for latent changes in CSA once patients have been returned to unrestricted physical activities.

AIM 1: To determine if the addition of BFR therapy to a standard post-operative rehabilitation protocol increases functional strength and quadriceps muscle volume as measured with magnetic resonance imaging (MRI) after ACLR.

Hypothesis: The addition of BFR therapy to a standard post-operative rehabilitation regimen following ACLR will increase quadriceps strength and muscle volume when compared to a standard post-operative rehabilitation regimen measured at approximately 16-weeks post-operative.

AIM 2: To determine if any observed increases in quadriceps strength and muscle volume are sustained beyond the cessation of BFR therapy at approximately 56 weeks post-operative.

Hypothesis: Observed increases in quadriceps strength and muscle volume will be sustained beyond the cessation of BFR therapy at 56 weeks post-operative.