Association between ankle angle at initial contact and biomechanical ACL injury risk factors in male during self-selected single-leg landing

Abstract

Background: Increasing the ankle plantar-flexion angle at initial contact (IC) during landing reduces the impact features associated with landing, such as the vertical ground reaction force and loading rate, potentially affecting the risk of anterior cruciate ligament (ACL) injury. However, the relationships between the ankle plantar-flexion angle at IC and the previously identified biomechanical factors related to noncontact ACL injury have not been studied.

Research question: Thus, the purpose of this study was to determine whether significant relationships exist between the ankle plantar-flexion angle at IC and the biomechanical factors related to noncontact ACL injury.

Methods: The peak anterior tibial shear force, peak external knee valgus moment, peak knee valgus angle, and combined peak external knee valgus plus tibial internal rotation moments were measured in 26 individuals while performing self-selected, single-leg landing. Pearson correlation analyses were performed to assess the relationships between the ankle plantar-flexion angle at IC and the biomechanical factors mentioned above.

Results: The greater ankle plantar-flexion angle at IC was related to smaller the peak knee valgus moment (r = -0.5, p = 0.009) and the combined peak knee valgus plus internal rotation moments (r = -0.58, p = 0.001).

Significance: These results suggest that large ankle plantar-flexion angle at IC might be associated with lesser loading of the knee frontal plane and altering the self-selective ankle angle may result in biomechanical changes associated with ACL injury risk.

Keywords: ACL injury risk factor; Initial contact ankle angle; Knee frontal plane loading; Landing method; Single-leg landing.