A Simulation-Based Analysis of The Effects of Variable Prosthesis Stiffness On Interface Dynamics Between The Prosthetic Socket and Residual Limb

Abstract

Introduction: Loading of a residual limb within a prosthetic socket can cause tissue damage such as ulceration. Computational models and simulations may be useful tools for estimating tissue loading within the socket and thus provide insights into how interventions (e.g. prosthesis designs or rehabilitation techniques) affect residual limb-socket interface dynamics. The purpose of this study was to model and simulate residual limb-socket interface dynamics and evaluate the effects of varied prosthesis stiffness on interface dynamics during gait. Methods: A spatial contact model of a residual limb-socket interface was developed and integrated into a gait model with a below-knee amputation. Gait trials were simulated for four subjects walking with low, medium, and high prosthesis stiffness settings. The effects of prosthesis stiffness on interface kinematics, normal pressure, and shear stresses were evaluated. Mean group responses and a subject-specific case study were analyzed. Results: Model-predicted outcome values were similar to those reported previously in sensor-based experiments; however, there were no discernable effects of prosthesis stiffness on interface dynamics among the group data (p>0.05). Subject-specific data showed decreased external rotation in the low stiffness trials, though high variability was present in the data. Conclusions: These methods may be useful to aid experimental studies by providing insights into the effects of varied prosthesis design parameters or gait conditions on residual limb-socket interface dynamics. Data suggest that these effects may be subject-specific.