Standing interface stresses as a predictor of walking interface stresses in the trans-tibial prosthesis

Interface pressures and shear stresses within the socket, in standing and w alking, were measured for two unilateral, male, trans-tibial amputee subjec ts, during two sessions each. The ratios of equal weight-bearing standing s tresses to peak walking stresses showed regional variation, ranging from 0. 24:1 for pressure over the anterior region to 1.01:1 for resultant interfac e shear stress over the lateral region. Interface stresses in standing were only moderate predictors of peak walking stresses. The best correlation co efficient between standing in full weight-bearing and peak walking stress w as 0.88 for pressure over the lateral region. As the amputees progressed fr om minimal to full weight-bearing in standing, and then to walking, the int erface stresses increased in a nonlinear fashion, consistent with the assum ption that the anterior tibia provides much resistance to the bending momen t in the sagittal plane during walking.