Article

Despite having a fully functional knee and hip in both legs, asymmetries in joint
moments of the knee and hip are often seen in gait of persons with a unilateral
transtibial amputation (TTA), possibly resulting in excessive joint loading. We
hypothesize that persons with a TTA can walk with more symmetric joint moments at
the cost of increased effort or abnormal kinematics. The hypothesis was tested
using predictive simulations of gait. Open loop controls of one gait cycle were
found by solving an optimization problem that minimizes a combination of walking
effort and tracking error in joint angles, ground reaction force and gait cycle
duration. A second objective was added to penalize joint moment asymmetry,
creating a multi-objective optimization problem.
A Pareto front was constructed
by changing the weights of the objectives and three solutions were analyzed to
study the effect of increasing joint moment symmetry.
When the optimization
placed more weight on moment symmetry, walking effort increased and kinematics
became less normal, confirming the hypothesis. TTA gait improved with a moderate
increase in joint moment symmetry. At a small cost of effort and abnormal
kinematics, the peak hip extension moment in the intact leg was decreased
significantly, and so was the joint contact force in the knee and hip. Additional
symmetry required a significant increase in walking effort and the joint contact
forces in both hips became significantly higher than in able-bodied gait.
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Langue : ANGLAIS