Citation

Button KD, Braman JE, Davison MA, Wei F, Schaeffer MC, Haut R. J. Biomech. Eng. 2015; 137(6): e061004.

Copyright

(Copyright © 2015, American Society of Mechanical Engineers)

DOI

10.1115/1.4029979

PMID

25751589

Abstract

While previous studies have investigated the effect of shoe-surface interaction on injury risk, few studies have examined the effect of shoe rotational stiffness. The hypothesis of the current study was that ankles externally rotated to failure in shoes with low rotational stiffness would allow more talus eversion than those in shoes with a higher rotational stiffness, resulting in less severe injury. Twelve (six pairs) of cadaver lower extremities were externally rotated to gross failure while positioned in 20 degrees of pre-eversion and 20 degrees of pre-dorsiflexion. One ankle in each pair was constrained by a football shoe with a stiff upper while the other was constrained by a football shoe with a flexible upper. Experimental bone motions were input into specimen-specific computational models to measure ligament strains at failure. Ankles in flexible shoes failed at 97.4 ± 47.0 Nm which was greater than the failure torque for ankles in stiff shoes (89.2 ± 44.9 Nm) in addition to allowing 6.7 ± 2.4 degrees of talus eversion during rotation, significantly greater than the 1.7 ± 1.0 degrees for ankles in stiff shoes. All ankles failed by either medial ankle injury or syndesmotic injury, or a combination of both. Complex (more than one ligament or bone) injuries were noted in 4 of 6 ankles in stiff shoes and 1 of 6 ankles in flexible shoes. Models of ankles in flexible shoes showed significantly less strain in the deltoid at failure, but significantly more strain in three of four subtalar ligaments. The current study suggests flexibility (or rotational stiffness) of the shoe may play an important role in both the risk and severity of ankle injuries in athletes.

Keywords: American football;

Language: en