Analysis of Force Transmission by a Knee Loading Device from Skin and Soft Tissue to Knee Joint Elements

Abstract

Dynamic loading to a knee joint is considered to be an effective modality for enhancing the healing of long bones and cartilage that are subject to ailments like fractures, osteoarthritis, etc. We developed a knee loading device and tested it for force application. The device applies forces on the skin, whereas force transmitted to the knee joint elements is directly responsible for promoting the healing of bone and cartilage. However, it is not well understood how loads on the skin are transmitted to the cartilage, ligaments, and bone. Based on a CAD model of a human knee joint, we conducted a finite element analysis (FEA) for force transmission from the skin and soft tissue to a knee joint. In this study, 3D models of human knee joint elements were assembled in an FEA software package (SIMSOLID). A wide range of forces was applied to the skin with different thickness in order to obtain approximate force values transmitted from the skin to the joint elements. The maximum Von Mises stress and displacement distributions were estimated for different components of the knee joint. The results demonstrate that the high load bearing areas were located on the posterior portion of the cartilage. This prediction can be used to improve the design of the knee loading device.