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 study. METHODS: Nineteen 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 = .028), with a median limb symmetry index (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 ≤ .037) even in participants who achieved hop height symmetry (LSIheight ≥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. JOSPT Open 2026;4(3):321-327. Epub 18 May 2026. doi:10.2519/josptopen.2026.0199.