DETERMINATION OF FOOT-PLATE SPACING FOR SWIVEL WALKERS BY AN OPTIMIZATION METHOD

Abstract

Swivel walkers have been useful devices in ambulation for many young paraplegic patients for being advantageous in providing reliable stability, easy handling, and hands-free walking. The placement of the foot-plates on swivel walkers affects the gait efficiency. However, the determination of the foot-plate spacing has been purely empirical and no theoretical work has been attempted before. This study aimed to develop a dynamic model of the swivel walker in the coronal plane to formulate an optimal design problem such that the energy loss due to impact could be computed and minimized within a feasible range of the coronal-plane movement. Children of heights from 0.75 to 1.45 m and weights from 15 to 45 kg fitted with the conventional swivel walkers were simulated. The results indicated that the range of the foot-plate spacing was roughly between 1/4 and 1/6 of the body heights. A regression formula was also derived to estimate foot-plate spacing with respect to the heights and weights of the simulated subjects for clinical applications. We conclude that the theoretical framework not only builds a foundation to determine the foot-plate spacing, but also reveals the dynamic behavior of the swivel walkers in the coronal plane. The results could be applied to the design of other biped locomotion systems.