Upper extremity inverse dynamics model for crutch-assisted gait assessment.

Current inverse dynamics models of the upper extremity (UE) are limited for the measurement of Lofstrand crutch-assisted gait. The objective of this study is to develop, validate, and demonstrate a three-dimensional (3-D) UE motion assessment system to quantify crutch-assisted gait in children. We propose a novel 3-D dynamic model of the UEs and crutches for quantification of joint motions, forces, and moments during Lofstrand crutch-assisted gait. The model is composed of the upper body (i.e., thorax, upper arms, forearms, and hands) and Lofstrand crutches to determine joint dynamics of the thorax, shoulders, elbows, wrists, and crutches. The model was evaluated and applied to a pediatric subject with myelomeningocele (MM) to demonstrate its effectiveness in the characterization of crutch gait during multiple walking patterns. The model quantified UE dynamics during reciprocal and swing-through crutch-assisted gait patterns. Joint motions and forces were greater during swing-through gait than reciprocal gait. The model is suitable for further application to pediatric crutch-user populations. This study has potential for improving the understanding of the biomechanics of crutch-assisted gait and may impact clinical intervention strategies and therapeutic planning of ambulation.