Effects of knee extension constraint training on knee and loading asymmetry during walking and running after unilateral ACL reconstruction: A pilot randomized clinical trial.

BACKGROUND

Asymmetries of knee movements and lower extremity loading in daily activities are highly prevalent and contribute to reinjury and knee osteoarthritis after anterior cruciate ligament reconstruction (ACLR).

PURPOSE: To determine the effects of knee extension constraint training on asymmetries of knee biomechanics and lower extremity loading during walking and running after ACLR.

METHODS

A total of 60 participants with ACLR were randomly assigned to Brace group, Placebo group and Control group. Walking and running gait tests were performed at the ends of Week 12 and Week 48 after ACLR. Two-way ANOVAs with a mixed design were conducted to compare inter-leg difference (ILD) in knee angle, knee moment and vertical ground reaction force (vGRF) between groups and across time points.

RESULTS

Participants in the BRACE group significantly increased peak knee flexion angle of ACLR leg (P = 0.025, ES = 0.207) and decreased ILD of peak knee flexion angle during stance phase of walking at the end of Week 48 (P = 0.014, ES = -1.025). Participants in three groups did not significantly decrease ILD of peak knee extension moment and vGRF during walking and running (P ≥ 0.071).

CONCLUSION

Knee extension constraint training for 36 weeks increased peak knee flexion angle of ACLR leg and decreased asymmetry of peak knee flexion angle during stance phase of walking but not during running. Continued knee extension constraint training has the potential to be used as a training tool in post-ACLR rehabilitation to restore walking asymmetry, pending further high-quality research.