Citation

Parenteau CS, Viano DC. J. Traffic Med. 2000; 28(1-2): 35-44.

Copyright

(Copyright © 2000, International Association for Accident and Traffic Medicine)

DOI

unavailable

PMID

unavailable

Abstract

Objective: In this study, the functional center of rotation of the combined action of human ankle and subtalar joints and the surrounding ligaments surrounding were determined in a two phase kinematic study. Method: In the first phase, the center of rotation was determined as a function of calcaneal position and loading using results of quasi-static tests in dorsiflexion, plantarflexion, inversion and eversion. In the second phase, the tensile mechanical properties of anterior talofibular, calcaneofibular, posterior talofibular, deltoid, talocalcaneal, plantar, and metatarsal ligaments were determined in separate tests on 31 isolated ligament preparations. Results: The center of rotation moved with calcaneal rotation from motion of the ankle and subtalar joints. The center of rotation was in the ankle joint in dorsiflexion/plantarflexion natural range of motion, and shifted posteriorly under forced plantarflexion. The center of rotation was initially in the subtalar joint for inversion/eversion, and shifted superiorly with forced inversion. During forced inversion to failure, the center of rotation actually fell closer to the center of rotation determined during dorsiflexion/plantarflexion. Thus, combination of dorsiflexion/inversion or plantarflexion/inversion may be significant in foot-ankle injury mechanisms. The plantar was the stiffest ligament, at 63 N/mm, followed by the deltoid, at 47 N/mm. The tensile modulus was calculated from the elastic force-strain data. The highest tensile modulus was for the plantar ligament at 26 N/mm2. The calcaneofibular and the deltoid ligaments had the highest ultimate strain at 0.62. Age did not seem to be a significant factor on the tensile properties. Conclusion: This study provides a better understanding of ankle-subtalar joint kinematics. The results were used as input data for the development of a mathematical model of a human foot-ankle biomechanics which can be used to investigate injury mechanisms in car crashes.