Stability of the braced ankle. A biomechanical investigation.

Thonnard, Jean-Louis;Bragard, Dominique;Willems, Patrick;Plaghki, Léon
(1996) American Journal of Sports Medicine — Vol. 24, n° 3, p. 356-361 (1996)

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  • Thonnard, Jean-LouisUCLouvain
    Author
  • Bragard, DominiqueUCLouvain
    Author
  • Willems, PatrickUCLouvain
    Author
  • Plaghki, LéonUCLouvain
    Author
Abstract
We measured the bare ankle and the braced angle-torque relationships in 12 uninjured volunteers under static and dynamic conditions within the full range of inversion motion. These relationships were measured with a specially designed mechanical device that allowed inversion movements with angular velocities up to 850 deg/sec. In testing the bare ankle under static conditions, the torque showed a 10-fold increase within the full range of motion (average, from 0.9 N-m at 7 degrees to about 8 N-m at 48 degrees of inversion). The slope of the angle-torque relationship increased under dynamic conditions giving higher torque values (up to 18 N-m on average). Both orthoses induced similar additional torques that increased linearly, up to about 6 N-m at 45 degrees, with higher angles of inversion. These additional torques are small compared with the amount of stress applied to the foot during a typical ankle sprain situation, such as recovering from a jump. Therefore, we propose that orthotic devices increase the ankle torque, counteracting the inversion movement, and also prevent the start of the inversion movement by preloading and maintaining the ankle in a proper anatomic position with optimal contact between the articular surfaces.
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Thonnard, J.-L., Bragard, D., Willems, P., & Plaghki, L. (1996). Stability of the braced ankle. A biomechanical investigation. American Journal of Sports Medicine, 24(3), 356-361. https://doi.org/10.1177/036354659602400318 (Original work published 1996)