Improved hamstring strength and knee position sense are associated with enhanced landing mechanics after anterior cruciate ligament reconstruction.

Abstract

Return-to-sport decisions after anterior cruciate ligament reconstruction (ACLR) rely on diverse criteria, including neuromuscular performances and functional testing. This study investigates the relationships between neuromuscular parameters, specifically angle-specific strength and proprioception, and knee kinematics during the landing phase of a single-leg hop task in patients 6-12 months post-ACLR. This cohort study included 25 participants (44% women; mean age 28 ​± ​10 years) who underwent primary ACLR. Demographic and surgical data were collected at 6 weeks postoperatively. Follow-up testing at a mean 8 months post-ACLR included isokinetic assessments of knee extensor and flexor strength to measure peak torques and angle-specific torques, as well as evaluations of position sense. Functional performance was assessed via the single hop for distance (SHD) test, with kinematic analysis of knee flexion during landing. Landing quality was evaluated using the SHD Landing Error Scoring System (SHD-LESS) scale. Multivariate models explored the associations between limb dominance, strength, proprioception, and knee kinematics during landing. Correlations between landing quality and patient-reported outcome measures (PROMs), including psychological readiness and self-reported function, were analyzed. The operated limb exhibited significantly lower strength in knee flexors (p ​< ​0.050) and extensors (p ​< ​0.001), with the largest deficits observed in angle-specific extensor torque (effect size d ​> ​0.9). No significant limb differences were found in position sense. The operated limb demonstrated shorter SHD distances (p ​= ​0.001), increased knee flexion at initial contact (p ​= ​0.009) and reduced total flexion during landing (p ​= ​0.002) compared to the uninjured limb. Limb dominance influenced knee flexion at initial contact (p ​= ​0.018). Greater hamstring strength (p ​= ​0.013) and improved position sense (p ​= ​0.002) were associated with increased knee flexion during landing. Poor landing mechanics, reflected by SHD-LESS scores, were correlated with impaired position sense (p ​= ​0.004) and worse PROMs (p ​< ​0.050). Enhancing hamstring strength and position sense may reduce bilateral kinematic discrepancies and improve landing control after ACLR. Limb dominance influences symmetrical kinematics at initial contact. Asymmetrical landing is associated with poorer PROMs, highlighting the importance of assessing both neuromuscular control and functional performances in rehabilitation. NCT06524869. III.