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TECHNICAL PAPERS

In Vitro Measurement of the Restraining Role of the Anterior Cruciate Ligament During Walking and Stair Ascent

[+] Author and Article Information
A. M. Ahmed, C. McLean

Department of Mechanical Engineering, McGill University, Montreal, Quebec, Canada

J Biomech Eng 124(6), 768-779 (Dec 27, 2002) (12 pages) doi:10.1115/1.1504100 History: Received July 01, 1999; Revised May 01, 2002; Online December 27, 2002
Copyright © 2002 by ASME
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References

Figures

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Simulator actuation system schematic. (a) Muscle actuation. (b) Foot-floor reaction actuation. For clarity, the moment actuation lever arm axis B has been shown displaced. In the simulator, it is coincident with the approximate knee joint flexion/extension axis A.
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Tibiofemoral relative displacement axes. (a) Coordinate axes for rotations. (b) Coordinate axes for translations.
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Typical knee radiographs used for the determination of the point Ot, the translations of which are measured. (a) Frontal radiograph. (b) Lateral radiograph. Note that the patellar hardware is unrelated to this study.
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Input functions used in the simulation. (a) Walking, knee angle. (b) Walking, tibial axial force component of the foot-floor reaction. (c) Walking, flexion/extension moment component of the foot-floor reaction; 1: extensor muscle force intensive; 2: biphasic. (d) Stair ascent, knee angle. (e) Stair ascent, tibial axial force component of the foot-floor reaction. (f ) Stair ascent, flexion/extension moment component of the foot-floor reaction.
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Tibial displacements (average ±1 STD) corresponding to the walking cycle when using the extensor muscle force intensive flexion/extension moment pattern. (a) to (e): as a function of percentage gait cycle. (f ) to (j): as a function of knee angle. The relation of the knee angle with the location in the gait cycle is highlighted as follows, 1: heel-strike; 2: maximum knee angle in stance; 3: minimum knee angle in terminal stance; 4: toe-off; 5: maximum knee angle (in swing).
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The effect of ACL excision on tibial displacements for the walking cycle. (a) to (c): the increase in displacements (average ±1 STD) after ACL excision as a function of percentage gait cycle. Only the significantly affected displacements, measured using the extensor muscle force intensive flexion/extension moment pattern are shown. (d): comparison of the average increases in anterior/posterior translation as a function of percentage gait cycle, using the extensor muscle force intensive moment patter (1) and the biphasic moment pattern (2). (e) to (g): the same as (a) to (c), but as a function of flexion angle. (h): the same as (d), but as a function of flexion angle.
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Tibial displacements (average ±1 STD) corresponding to the stair ascent cycle. (a) to (e): as a function of percentage gait cycle. (i) to (j): as a function of knee angle. The relation of the knee angle with the location in the gait cycle is highlighted as follows, 1: heel strike; 2: maximum knee angle in stance; 3: toe-off; 4: maximum knee angle (in swing).
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The effect of ACL excision on tibial displacements (average ±1 STD) for the stair ascent cycle. The regions of significance are indicated as “S.” (a) and (c): increase in anterior translation. (b) and (d): increase in internal rotation.
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Comparison with in vivo results of the out-of-plane rotations measured in this study for the walking cycle using the extensor muscle force intensive flexion/extension moment pattern (1), and biphasic flexion/extension moment pattern (2). (a) Adduction rotation. (b) Internal rotation.

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