Prediction and experimental verification of residual limb/prosthetic socket interface pressures for below-knee amputees

he interface stress distribution between the residual limb and the prosthetic socket ultimately determines the comfort of the prosthesis. The purpose of this research was to investigate below-knee residual limb/prosthetic socket biomechanics through the use of finite element models, and to use these models to predict the interface stress distribution, thereby providing an objective means of evaluating prosthetic socket designs.;Finite element models of the below-knee residual limb and prosthetic socket system were created. These models were not based on a particular amputee's geometry, but instead were based on a generic, geometric approximation of the residual limb. These models could then be scaled appropriately for each amputee; individual CT scans were obviated, and the painstaking tasks of digitization and mesh development were avoided.;Parametric analyses were conducted using this initial finite element model to investigate the sensitivity of the residual limb/socket interface pressures to variations in: (i) material properties, (ii) socket rectification, and (iii) residual limb geometry.;To complete the finite element models for individual analyses, in vivo indentor studies of the below-knee amputee's residual limb were conducted using an LVDT/load cell device to estimate bulk soft tissue properties. The resulting force-displacement relationships were highly nonlinear, and ten-fold variations in local stiffness were observed.;To investigate the ability of a generic, geometric finite element model of the residual limb and socket to predict interface pressures, local normal stresses for several below-knee amputees were measured using miniature Kulite diaphragm pressure transducers in a variety of socket designs and static load/alignment states. These experimental results were compared to normal stress values predicted by an appropriately scaled generic, geometric finite element model using the experimentally determined soft tissue properties, and using...