Combination of eccentric exercise and neuromuscular electrical stimulation to improve biomechanical limb symmetry after anterior cruciate ligament reconstruction

• NMES together with eccentric exercise restored biomechanical symmetry most similar to healthy individuals at 7 months following ACL reconstruction.
• A longer eccentric intervention may be beneficial to biomechanical limb symmetry.
• This study provides preliminary evidence of therapies that positively influence movement post-ACL reconstruction.

BackgroundWe have previously reported that an eccentrically-based rehabilitation protocol post-ACLr induced greater quadriceps activation and strength than a neuromuscular electrical stimulation (NMES) intervention and was just as effective as a combined NMES and eccentric intervention. However, the effect an eccentrically-based intervention has on restoring normal knee mechanics during a single-legged landing task remains unknown.MethodsThirty-six individuals post-injury were placed into four treatment groups: NMES and eccentrics, eccentrics-only, NMES-only, standard of care, and healthy controls participated. NMES and eccentrics received a combined NMES and eccentric protocol post-reconstruction (each treatment 2 × per week for 6 weeks), whereas groups NMES-only and eccentric-only received only the NMES or eccentric therapy, respectively. To evaluate knee mechanics limb symmetry, the area under the curve for knee flexion angle and extension moment was derived and then normalized to the contralateral limb. Quadriceps strength was evaluated using the quadriceps index.FindingsCompared to healthy, reduced sagittal plane knee limb symmetry was found for groups NMES-only, ECC-only and standard of care for knee extension moment (P < 0.05). No difference was detected between healthy and NMES and eccentrics (P > 0.06). No difference between groups was detected for knee flexion angle limb symmetry (P > 0.05). Greater knee flexion angles and moments over stance were related to quadriceps strength.InterpretationThe NMES and eccentrics group was found to restore biomechanical limb symmetry that was most closely related to healthy individuals following ACL reconstruction. Greater knee flexion angles and moments over stance were related to quadriceps strength.