膝關節軟骨之多尺度有限元素模擬及其於腳踏車踩踏之應用

Abstract

Cycling has been commonly used by people for commuting, exercise, and leisure activity. Additionally, it is frequently used for rehabilitation exercise after knee injury or surgery. It not only strengthens the leg muscles but also reduces the pain, stiffness, and disability caused by osteoarthritis (OA). OA is usually characterized by elevated fluid content, reduced collagen content and lose its collagen network organization. A multi-scale model was developed for analyzing the mechanical behavior of collagen fibril network inside articular cartilage from healthy subjects and patients with OA during cycling The geometry of the knee was obtained from 3D reconstruction of computer tomography scan and the articular cartilage surface was acquired from magnetic resonance imaging scan. The finite element (FE) method was used to analyze microstructures under mechanical loading. The boundary conditions (BC) were gathered from the dynamic fluoroscopy system. Collagen fibrils were modeled as a viscoelastic material that can perform a stress relaxation and the material properties were taken from the literature. Current results showed that the initiation of early OA was probably caused by the stiffening of collagen fibril which may subsequently lead to embrittlement and drive the disease progression. Furthermore, the repetitive movement might cause the fibril to undergo permanent deformation, thus change in material properties and became stiffer. Therefore, it is possible that doing a functional activity for a long time without resting may cause early OA. This study might provide more accurate results for diagnostic basis and reference in the treatment, rehabilitation, or assistive device development for cartilage.