Evaluation of Alignment of the A/K Socket with 6-Axis Forces and Moments.

Abstract

This paper deals with an application study of 6-axis forces and moments such as two shearing forces (Fx, Fy), compression (Fz), two bending moments (Mx, My) and a torsional moment (Mz) that are acting on the stump of the thigh during walking. The goal of this study is invention of an evaluative method for alignment of the A/K socket with the above-mentioned 6-axis forces and moments. There are two types of alignments of A/K sockets. One is rotation. The toe of A/K prosthesis is set inside (toe-in) or outside (toe-out). The another is inclination. The socket is inclined backward. In this study, the 6-axis forces and moments are measured with these two settings. One A/K amputee walked while wearing his A/K prosthesis, which is equipped with the 6-axis force and moment sensor. As a result of the walking experiments, the differences between the adjusted alignment and the above-mentioned two settings were determined, and the following observations were made. In the case of the toe-in setting, it is difficult for the amputee to walk smoothly because the stability of the side direction decreases. On the other hand, in the case of the inclined-backward setting, the stability of the knee joint at heel contact decreases, so the amputee cannot walk smootly.