Kinematic association between single-leg squat and hop landing in female athletes following anterior cruciate ligament reconstruction.

Abstract

To examine the association between knee valgus angles during single-leg squats (SLS) and single-leg hop landings (SLHL) in female athletes following anterior cruciate ligament reconstruction (ACLR), given the high risk of second ACL injuries related to dynamic knee valgus during landing. This cross-sectional study included 15 female athletes (mean age: 17.2 ± 1.0 years) after ACLR. Kinematic data during SLS and SLHL were collected using a three-dimensional motion analysis system composed of 10 infrared cameras and four force plates. Peak joint angles were analysed, and correlations between SLS and SLHL kinematics were evaluated. Significant positive correlations were found between SLS and SLHL for hip flexion (r = 0.68), hip adduction (r = 0.80), hip internal rotation (r = 0.90), knee valgus (r = 0.95), knee internal rotation (r = 0.99) and ankle eversion (r = 0.79). In both tasks, knee valgus was negatively correlated with hip flexion (SLS: r = -0.68; SLHL: r = -0.62) and hip internal rotation (SLS: r = -0.66; SLHL: r = -0.55) and positively correlated with hip adduction (SLS: r = 0.61; SLHL: r = 0.57). SLS and SLHL kinematics were evaluated approximately one year after ACLR and were significantly associated in female athletes. These findings suggest that the SLS may serve as a practical tool for identifying and addressing dynamic knee valgus during landing. Level III, cross-sectional observational study.