Ankle Biomichanic Essay

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Biomechanical Analysis of Ankle Kinematics and Ligament Strain in Snowboarding By Sébastien Delorme A Thesis submitted to The University of Ottawa in Partial Fulfillment of the Requirement for the Doctor of Philosophy in Mechanical Engineering January 2004 Department of Mechanical Engineering, University of Ottawa Ottawa-Carleton Institute for Mechanical and Aerospace Engineering © Sébastien Delorme Abstract Because snowboarders are known to injure their ankles more often than alpine skiers, it has been postulated that stiffer snowboard boots would provide better protection to the ankle ligaments than current soft boots do. To test this hypothesis, we have measured the kinematics of the feet and lower legs of five snowboarders riding down a course of 10 gates on a ski hill using an electromagnetic motion tracking system. Results were obtained with each snowboarder wearing soft boots and stiffer step-in boots. The measurements were expressed in anatomically relevant rotations of the ankle joint complex. Two models were developed to predict ligament strains from rotations of the ankle joint complex: 1) a statistical model using published ligament strain measured on cadaver specimens at various combinations of ankle rotations as an interpolation and extrapolation table to predict strains in two ankle ligaments at the rotations measured during the snowboarding trials; 2) a personalized 2-degrees-of-freedom kinematic model of the ankle joint complex, based on the Denavit-Hartenberg formulation of serial-link manipulators, to predict strains in five ankle ligaments from the relative position of the shank and foot. The experimental results showed that the left and right ankles are asymmetrically rotated, mostly in dorsiflexion, eversion and external rotation. Compared to step-in boots and bindings, soft boots and strap bindings allowed more rotation

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