LOWER LIMB PERFORMANCE AND KINETIC ASYMMETRIES IN PATIENTS FOLLOWING ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Abstract

INTRODUCTION AND AIM Analyses of functional performance and movement strategies at key clinical milestones during rehabilitation are critical to guide rehabilitation and return-to-sport (RTS) decisions post-anterior cruciate ligament reconstruction (ACLR). The aim of this study was to evaluate lower limb performance and kinetics during jumping and hopping in patients post-ACLR. METHODS Seventy-one patients (39 males, 32 females; mean age 27.0 years; height 1.74m; weight 76.5kg) underwent lower limb evaluation at 6.1 and 10-months post-ACLR. Patient-reported outcomes (IKDC-2000, ACL-RSI) were collected at both time points. Ground reaction forces during bilateral and unilateral countermovement jumps (CMJ) on dual force plates were recorded, alongside unilateral horizontal hops for distance (HHD). Paired sample t-tests examined between-limb differences in eccentric and concentric phases of the bilateral CMJ and jump heights and distances of the unilateral CMJ and HHD, respectively, at both time points. Differences in limb asymmetries between the unilateral CMJ and HHD were also examined. Chi square tests were performed to examine differences in meeting known RTS thresholds (>90% limb symmetry index [LSI]). RESULTS Moderate to large asymmetries were observed for concentric (effect size [ES] = -1.06, P<0.001) eccentric phases (ES = 0.54, p<0.001) during the bilateral CMJ at both time points. Greater limb asymmetry was observed in the unilateral CMJ compared to the HHD at 6-months (ES = -0.52; p≤0.001) and 10-months (ES = -0.56; p≤0.001). Significantly more participants “passed” a horizontal hop test versus a vertical hop test at 6 months (χ2=7.07, p=0.008) and at 10 months (χ2=7.52, p=0.006). CONCLUSION Vertical performance metrics can better identify between-limb asymmetries than HHD and should be included in RTS testing batteries following ACLR. Between-limb deficits in key eccentric and concentric phases of the bilateral CMJ are also apparent at 6- and 10-months after ACLR, suggesting a persistent offloading strategy even at the time of RTS.