Dynamic Biomechanical Dorsiflexion Responses and Tolerances of the Ankle Joint Complex

This paper presents comprehensive dorsiflexion responses and tolerances obtained from two types of dynamic tests on whole cadavers conducted at the Renault/PSA Laboratory of Accidentology and Biomechanics (LAB): sled tests and sub-system tests. In all the experiments (on whole cadavers), forces and moments within the ankle joint were accurately measured by means of a custom-designed 6-axis load cell implanted in the tibia, leaving all surrounding musculature intact. The results derived from both the sled tests and the subsystem tests are very similar. Moment-rotation curves are provided for the ankle joint. The force in the Achilles tendon which is not directly measured is calculated using the forces applied to the foot and the forces measured in the tibia. No direct measurement of this force was performed as the aim of those experiments was to get an accurate evaluation of the moment within the ankle joint first The testing indicates that musculature of the leg. even in passive state, strongly influences the response of the ankle when given forces are applied on the foot. This observation suggests that future dummy designs should incorporate these effects. Such force in Achilles tendon may have a protective effect on the ankle joint even when the muscles arc in a passive state, because this force increases the ability of the foot to resist an imposed dorsiflexion rotation. Some injury tolerances from both types of tests are also discussed. Furthermore, the inertial and the geometric properties of the dummy lower limbs are compared with those of the cadavers.