The effect of foot landing position on biomechanical risk factors associated with anterior cruciate ligament injury.
BACKGROUND
Identification of biomechanical risk factors associated with anterior cruciate ligament (ACL) injury can facilitate injury prevention. The purpose of this study is to investigate the effects of three foot landing positions, "toe-in", "toe-out" and "neutral", on biomechanical risk factors for ACL injury in males and females. The authors hypothesize that 1) relative to neutral, the toe-in position increases the biomechanical risk factors for ACL injury, 2) the toe-out position decreases these biomechanical risk factors, and 3) compared to males, females demonstrate greater changes in lower extremity biomechanics with changes in foot landing position.


METHODS
Motion capture data on ten male and ten female volunteers aged 20-30 years (26.4 ± 2.50) were collected during double-leg jump landing activities. Subjects were asked to land on force plates and target one of three pre-templated foot landing positions: 0° ("neutral"), 30° internal rotation ("toe-in"), and 30° external rotation ("toe-out") along the axis of the anatomical sagittal plane. A mixed-effects ANOVA and pairwise Tukey post-hoc comparison were used to detect differences in kinematic and kinetic variables associated with biomechanical risk factors of ACL injury between the three foot landing positions.


RESULTS
Relative to neutral, landing in the toe-in position increased peak hip adduction, knee internal rotation angles and moments (p < 0.01), and peak knee abduction angle (p < 0.001). Landing in the toe-in position also decreased peak hip flexion angle (p < 0.001) and knee flexion angle (p = 0.023). Landing in the toe-out position decreased peak hip adduction, knee abduction, and knee internal rotation angles (all p < 0.001). Male sex was associated with a smaller increase in hip adduction moment (p = 0.043) and knee internal rotation moment (p = 0.032) with toe-in landing position compared with female sex.


CONCLUSIONS
Toe-in landing position exacerbates biomechanical risk factors associated with ACL injury, while toe-out landing position decreases these factors.
Stanford University School of Medicine, Stanford University, Stanford, CA, USA.|Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA.|Human Performance Lab, Stanford Sports Medicine Center, 341 Galvez Street, Stanford, CA, 94305, USA.
Andrew A
AA
Tran
Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA.|Human Performance Lab, Stanford Sports Medicine Center, 341 Galvez Street, Stanford, CA, 94305, USA.
Corey
C
Gatewood
Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA.
Alex H S
AH
Harris
Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA.|Department of Bioengineering, Stanford University, Stanford, CA, USA.|Human Performance Lab, Stanford Sports Medicine Center, 341 Galvez Street, Stanford, CA, 94305, USA.
Julie A
JA
Thompson
Stanford University School of Medicine, Stanford University, Stanford, CA, USA. jdragoo@stanford.edu.|Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA. jdragoo@stanford.edu.|Human Performance Lab, Stanford Sports Medicine Center, 341 Galvez Street, Stanford, CA, 94305, USA. jdragoo@stanford.edu.
Jason L
JL
Dragoo
ACL; Anterior cruciate ligament; Biomechanics; Dynamic valgus; Landing pattern