Date Published: January 25, 2019
Publisher: Public Library of Science
Author(s): Kazuma Uebayashi, Kiyokazu Akasaka, Akihiro Tamura, Takahiro Otsudo, Yutaka Sawada, Yu Okubo, Toby Hall, Nathan Schilaty.
The anterior cruciate ligament (ACL) is often injured during sport. The Star Excursion Balance Test (SEBT) has been used to evaluate ankle and knee stability of the supporting leg while reaching in eight different directions with the non-stance leg. We hypothesized that the SEBT might be useful in categorising ACL injury risk. The purpose of this study was to clarify the relationship between knee valgus alignment during single leg drop landing (SDL) and alignment of the trunk and lower limb during the SEBT.
A three-dimensional motion analysis system was used to measure the trunk, hip and knee angles during SDL and the SEBT. Groupings were allocated based on 5 degrees of knee valgus angle during SDL. Independent t-test’s were used to identify differences in the trunk, hip and knee angles between the two groups.
The knee valgus angles in the knee valgus group were greater than those in the control group in five directions of the SEBT (p < 0.05). In addition, the hip internal rotation angle in the knee valgus group was lower than that in the control group during two directions of the SEBT (p < 0.05). Furthermore, the knee flexion and trunk right rotation angles in the knee valgus group were lower than those in the control group in two directions of the SEBT (p < 0.05). Decreases in hip internal rotation, knee flexion and trunk rotation to the supporting leg during the SEBT might be considered as risk factors for non-contact ACL injury.
Anterior cruciate ligament (ACL) injury is a serious and potentially devastating injury for athletes, and is common in many sports including soccer, basketball, handball and lacrosse. Injuries can be classified as either contact or non-contact with up to 70% classified as non-contact [1–5]. While non-contact ACL injury prevention programs have been widely studied, Distefano et al. suggested that ACL injury prevention programmes should be matched to the ACL injury risk of participants and designed along these characteristics . Therefore, it is important to establish an evaluation method where the risk of non-contact ACL injury can be classified.
In this study, the subjects who had knee valgus greater than 5° during SDL showed a specific alignment of the trunk and supporting leg in the reach directions of A, AM, M, PM and AL during the SEBT. In addition to an increase in knee valgus in the reach directions of A, AM, M, PM and AL, our results showed that a decrease in trunk rotation to the supporting leg occurred during direction PM, with a decrease in hip internal rotation during directions AM and AL and a decrease in knee flexion during direction M. These findings may have value in identifying risk factors for non-contact ACL injury. Even though previous studies have reported that increased knee valgus angle combined with increased hip internal rotation angle are the main risk factor for non-contact ACL injury [24, 25], our results indicate that injury risk could be potentially picked up by evaluating the SEBT in reach directions AM and AL as these directions increased knee valgus angle combined with decreased hip internal rotation angle. The slow nature of the SEBT might provide easier evaluation of trunk and leg control than the relatively fast task of jump landing. Our results suggest that characteristic poor alignment of the trunk and the supporting leg during the SEBT in directions A, AM, M, PM and AL should be evaluated for each reach direction, and that these examinations might be useful in detecting ACL injury risk.