Asymmetry of Single Leg Vertical Hop Performance and Biomechanics in Adolescent Athletes With Anterior Cruciate Ligament Reconstruction

OBJECTIVE: To assess single leg vertical hop (SLVH) symmetry in adolescent athletes with anterior cruciate ligament reconstruction (ACLR), comparing injured to uninjured limbs. DESIGN: Retrospective Cohort METHODS: 19 patients (15 female; mean age 16.3 years; mean 9.2 months post-ACLR) underwent three-dimensional motion analysis during SLVH. Hop performance and biomechanics were compared between ACLR and contralateral limbs using Wilcoxon signed rank tests. RESULTS: Hop height was significantly lower for the ACLR limb compared with the contralateral side (p = 0.028), with a median LSI of 92.3%. Biomechanical variables demonstrated asymmetry, including peak knee and ankle flexion angles, peak knee flexion moment, total power generation, total power absorption, and percent power absorption contributed by the knee (all p≤0.037) even in subjects who achieved hop height symmetry (LSI height ≥90%). CONCLUSION: Adolescent athletes in late-stage rehabilitation post-ACLR had interlimb asymmetry of biomechanics during the SLVH indicating deficiencies of their ACLR limb and decreased readiness for return to sport.