Author(s): TAMANG, A., WOJTYLKA, C., NETO, T., SEIL, R., FAYAD, J., Institution: LIROMS, Country: LUXEMBOURG, Abstract-ID: 2601

INTRODUCTION:
Return-to-sport (RTS) assessments following anterior cruciate ligament reconstruction (ACLR) often show limited inter-limb differences during running 9–12 months post-surgery, with asymmetries limited to reduced knee range of motion when evaluated using kinematic analysis¹. In comparison, limb asymmetries persist in jumping tasks even after patients meet RTS criteria². Joint coordination analysis may provide additional insight into these differences by examining joint interactions that could uncover neuromuscular adaptations not evident in traditional kinematic analysis³. This study investigated interlimb coordination during running at RTS following ACLR using a vector coding approach to determine whether coordination analysis can detect alterations that may explain the asymmetries observed during jump tasks.
METHODS:
As part of RTS testing, ACLR patients performed treadmill running at a self-selected comfortable speed (BORG Scale 5). Kinematics of running were collected using a 16 camera markerless motion capture system (100Hz, Miqus Video, Qualisys AB, Gothenburg, Sweden). Hip, knee, and ankle joint angles were calculated in the sagittal and frontal planes. To assess kinematic asymmetries, joint angles at mid-stance were extracted and compared between the operated and contralateral limbs. To assess joint coordination, proximal–distal joint couplings were then constructed for hip–knee and knee–ankle interactions in sagittal–sagittal, frontal–frontal, sagittal–frontal, and frontal–sagittal configurations. A modified vector coding technique was applied to generate angle–angle plots and compute coupling angles across the stance phase of running. Inter-limb differences were assessed using paired t-tests or Wilcoxon tests.
RESULTS:
Forty-five ACLR patients (30 males, 15 females; age 17.7 ± 2.3 years; 9.3 ± 1 months post-surgery) were included. Kinematic analysis revealed minimal asymmetries, limited to a reduced sagittal plane knee and ankle range of motion on the operated side. In comparison, coordination analysis identified significant inter-limb differences in the hip sagittal–knee frontal and knee sagittal–ankle frontal coupling angles. Angle–angle plots further demonstrated altered hip frontal–knee sagittal coordination, showing an increased hip adduction on the operated side as a compensatory strategy for reduced knee excursion.
CONCLUSION:
Although kinematic metrics were limited to a reduced sagittal plane motion, coordination analysis revealed persistent changes in joint coupling patterns at RTS. These findings suggest that modifications persist in the operated side at RTS, indicating that adaptations in movement organisation are happening beyond the isolated knee range of motion.

References:
1. Pairot-de-Fontenay et al., Sports Med 49, 1411–1424 (2019).
2. Ebert JR et al., Int J Sports Phys Ther. 2021 Apr 1;16(2):393-403.
3. Freedman Silvernail J et al., J Appl Biomech. 2018 Jun 1;34(3):226-231