GENERIC, GEOMETRIC FINITE-ELEMENT ANALYSIS OF THE TRANSTIBIAL RESIDUAL LIMB AND PROSTHETIC SOCKET

Finite element (FE) analysis was used to investigate the stress distri bution between the residual limb and prosthetic socket of persons with transtibial amputation (TTA). The pur pose of this study was to devel op a tool to provide a quantitative estimate of prosthetic interface p ressures to improve our understanding of residual limb/prosthetic sock et biomechanics and prosthetic fit. FE models of the residual Limb and prosthetic socket were created. In contrast to previous FE models of the prosthetic socket/residual limb system, these models were not base d on the geometry of a particular individual, but instead were based o n a generic, geometric approximation of the residual limb. These model s could then be scaled for the limbs of specific individuals. The mate rial properties of the bulk soft tissues of the residual limb were bas ed upon local in vivo indentor studies. Significant effort was devoted toward the validation of these generic, geometric FE models; prosthet ic interface pressures estimated via the FE model were compared to exp erimentally determined interface pressures for several persons with TT A in a variety of socket designs and static load/alignment states. The FE normal stresses were of the same order of magnitude as the measure d stresses (0-200 kPa); however, significant differences in the stress distribution were observed. Although the generic, geometric FE models do not appear to accurately predict the stress distribution for speci fic subjects, the models have practical applications in comparative st ress distribution studies.