Lower Residual Limb for Prosthetic Socket Design
Comfort is among the most important issues when fitting a prosthesis. However, high stress applied to the residual limb, which is not particularly tolerant to loading, can cause discomfort, pain, and tissue breakdown. In an attempt to improve prosthesis fit, it is important to study the stress distribution at the residual limb-socket interface. Computational finite element (FE) modeling allows for efficient parametric analysis and is a useful tool for investigating the load transfer mechanics at the limb-socket interface. Due to the complicated frictional and sliding actions at the interface, however, simulation of the mechanical interaction between the limb and socket is challenging. In addition, a prosthetic socket is usually shape-rectified so as to redistribute the load to load-tolerant regions of the residual limb. After donning the shape-rectified socket, some mechanical stresses known as pre-stresses are produced. Many previous models have incorporated some simplifying assumptions when simulating the friction-slip and pre-stresses. This chapter illustrates a technique that simulates the contact at the limb-socket interface, considering both the friction/slip and pre-stress conditions, by using an automated contact method.