THE EFFECTS OF PREOPERATIVE BLOOD FLOW RESTRICTION TRAINING IN PATIENTS UNDERGOING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Arthrogenic muscle inhibition (AMI) involving the quadricep femoris (QF) muscle group is a common finding in patients undergoing anterior cruciate ligament (ACL) reconstruction, particularly in Canada where wait times for elective surgery are lengthy. In order to combat the challenges of AMI for patients with an ACL injury, blood flow restriction (BFR) training has become an effective new training modality for the rehabilitation of these patients. This has been shown to have beneficial effects in the post-operative period by reducing QF atrophy. However, the use of BFR in the pre-operative setting has yet to be well established. The specific aims of this study were to determine if preconditioning with BFR training in patients awaiting ACL surgery (1) improves QF muscle strength testing and (2) reduces QF muscle group atrophy. We hypothesized that preconditioning with BFR in patients awaiting ACL reconstruction has a beneficial effect on clinical outcomes prior to surgery. All patients over the age of 18 who had a clinical and radiological diagnosis of isolated complete ACL injury and were awaiting surgical intervention were considered eligible for the study. Eligible patients were randomized into the BFR or CONTROL groups. All patients attended 12 physiotherapy sessions involving closed kinetic chain exercises on the affected leg using a leg press machine. The BFR tourniquet was inflated throughout the protocol for the BFR group and left deflated for the CONTROL group. Objective quadriceps and hamstring strength assessments using a Biodex machine were performed at the beginning of the study and at the completion of physiotherapy. Both the affected leg (ACL injury) and unaffected leg (control leg) were evaluated. This study compared pre-intervention vs. post-intervention differences between the two groups. Our primary outcome measure was peak torque (ft-lbs) measured for both knee flexion and extension. Our secondary outcome measures included thigh circumference (mm) and patient reported outcome measures (KOOS and SF-12). To date, 30 of 32 patients have been enrolled in the study and 21 of 32 patients have completed the protocol (BFR = 14, CONTROL = 7). Biodex testing has demonstrated an average increase in affected knee extension strength of 15% and 27% for the BFR and CONTROL groups respectively. Additionally, unaffected knee extension strength increased by 9% in the BFR group and 12% in the CONTROL group. Thigh circumference of the affected knee increased by an average of 9 mm in the BFR group and 15 mm in the CONTROL group. No reported complications or negative effects involving BFR have been reported. Preliminary results have demonstrated an overall strength increase in both BFR and CONTROL groups. The affected knee in both treatment groups have exhibited a greater increase in strength compared to the unaffected knee. No significant statistical differences between the two treatment groups have been noted thus far. This may be attributable to a small sample size and lack of CONTROL patients that have completed the study. Further statistical analysis and comparison between groups is pending upon completion of all 32 patients. If BFR in the pre-operative setting can be shown to provide beneficial effects, it will be a valuable tool in the treatment of AMI among patients with ACL injury.