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

Abstract

Background We 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. Methods Thirty-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 2x per week for 6 wks), 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. Findings Compared 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. Interpretation The 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.

Continued Improvements in Quadriceps Strength and Biomechanical Symmetry of the Knee After Postoperative Anterior Cruciate Ligament Reconstruction Rehabilitation: Is It Time to Reconsider the 6-Month Return-to-Activity Criteria?

“…Given that healthy participants displayed symmetric knee biomechanics, 16,27 we contend that the asymmetries stemmed from the ACL injury or ACLR, or both. All the knee biomechanical variables that we examined revealed asymmetries greater than 18%, which is more than the allowable 10% asymmetry suggested by Hartigan et al 28 for patients with ACLR to return to sport participation.…”

“…23 From these ensemble averages, the area under the curve (AUC) and the slope of the line ( Figure 1) were calculated as previously described. 16 Our reason for choosing the AUC over peak angle or moment values was explained in an earlier study. 16 The slope of the line accounts for the change in the degrees of knee-joint flexion and knee-extension moments over the first 50% of stance.…”

“…16 Our reason for choosing the AUC over peak angle or moment values was explained in an earlier study. 16 The slope of the line accounts for the change in the degrees of knee-joint flexion and knee-extension moments over the first 50% of stance. The AUC and slope of the line for both the kneejoint flexion and knee-extension moments were then converted into symmetry values using the same method as described for peak isokinetic torque.…”

“…21 6 19.41 kg) participated in our study as part of a larger investigation aimed at understanding muscle dysfunction after ACL injury (Table 1). 16 All patients included in this substudy of our larger investigation had already participated in RTA testing, and we contacted them to participate in additional testing when they were at least 12 months post-ACLR. Patients were eligible for the larger study if they (1) were from 14 to 45 years of age, (2) were planning to complete rehabilitation at our sports medicine clinic, (3) had an acute ACL injury, (4) had no previous history of knee surgery, (5) had no history of previous knee-ligament injury, (6) were not pregnant, and (7) had no history of a heart condition.…”

“…Possible improvements in rehabilitation strategies include early targeting of neurologic inhibition and lingering muscle atrophy, which may lead to superior gains in strength and biomechanical function. 16,40 Furthermore, without changing rehabilitation paradigms, clinicians need to consider whether the time from surgery alone is appropriate for clearing a patient to RTA. Researchers suggested objective RTA criteria for quadriceps strength, 7 biomechanical function, 28 and muscle function.…”