Early- and Late-Stage Benefits of Blood Flow Restriction Training on Knee Strength in Adolescents After Anterior Cruciate Ligament Reconstruction

Background:Blood flow restriction training (BFRT) after anterior cruciate ligament reconstruction (ACLR) is rising in popularity because of its benefits in reducing muscle atrophy and mitigating knee strength deficits.Purpose:To investigate the impact BFRT has on adolescent knee strength after ACLR at 2 postoperative time points: at 3 months and the time of return to sport (RTS).Study Design:Cohort study; Level of evidence, 3.Methods:A prospective intervention (BFRT) group was compared to an age-, sex-, and body mass index-matched retrospective control group. Patients aged 12 to 18 years who underwent primary ACLR with a quadriceps tendon autograft were included. Along with a traditional rehabilitation protocol, the BFRT group completed a standardized BFRT protocol (3 BFRT exercises performed twice weekly for the initial 12 weeks postoperatively). Peak torque values for isometric knee extension and flexion strength (at 3 months and RTS) and isokinetic strength at 180 deg/s (at RTS) as well as Pediatric International Knee Documentation Committee (Pedi-IKDC) scores were collected. Differences between the BFRT and control groups were compared with 2-way mixed analysis of variance and 1-way analysis of variance.Results:The BFRT group consisted of 16 patients (10 female; mean age, 14.84 +/- 1.6 years) who were matched to 16 patients in the control group (10 female; mean age, 15.35 +/- 1.3 years). Regardless of the time point, the BFRT group demonstrated significantly higher isometric knee extension torque compared to the control group (2.15 +/- 0.12 N center dot m/kg [95% CI, 1.90-2.39] vs 1.74 +/- 0.12 N center dot m/kg [95% CI, 1.49-1.98], respectively; mean difference, 0.403 N center dot m/kg; P = .024). The BFRT group also reported significantly better Pedi-IKDC scores compared to the control group at both 3 months (68.91 +/- 9.68 vs 66.39 +/- 12.18, respectively) and RTS (89.42 +/- 7.94 vs 72.79 +/- 22.81, respectively) (P = .047).Conclusion:In adolescents, the addition of a standardized BFRT protocol to a traditional rehabilitation protocol after ACLR significantly improved knee strength and patient-reported function compared to a traditional rehabilitation program alone.