Knee Problem Analysis

Abstract— The main aim is to develop the three dimensional solid finite element model of knee joint to predict stress in its individual components (Femur, Tibia, Menisci and Patella) and to determine the load carried by a pre – selected ligamentous tissue. This work assists to analyze a knee response to a dynamically applied load. This simulated analysis will serve to be an alternative approach to destructive tests and intrusive procedures and helps to achieve closer simulation to reality. The main expectation is to simulate the whole articulation using three dimensional solid models. This paper will aid to control the geometry of movements of knee joint. This Modeling will be helpful to study underlying mechanisms for knee injuries.

Index

Construction of bone models is performed usually on the basis of CT (computed tomography) scans.

II. METHOD

A. 3D CAD Model Computerized tomography (CT) scans of human knee were used to capture bone geometry. CT scans were obtained from a 22 year old healthy male volunteer. Scanning was carried out on the left knee. Mimics calculate surface 3D models from stacked image data such as CT images through image segmentation. The process was conducted in all three orthogonal planes by rotation and translation of CT images until the corresponding structures were matched. Subsequently, 3D geometry of the knee joint was reconstructed from high resolution CT images at intervals of 0.5mm in all three anatomical planes using Mimics software. The 3D scanned data were transformed into highly accurate surface, polygon and native CAD models using Geomagic studio software. In case of error in the Mimics model, it can be rectified in Geomagic studio software. The generated surface model was converted in to iges

Both meniscus and ligaments were designed in CATIA as different components. The data’s for length and cross sectional area of ligaments, ligament insertion sites, menisci peripheral length range, area of Contact points of meniscus were obtained from previous FE and experimental studies. At last stage of the design; bones, meniscus and ligaments were assembled in CATIA.

B. Finite Element Mesh The assembled solid Model from CATIA was converted to surface model in Hypermesh by deleting the solid body. The intersection surface in the assembly model was trimmed. The intersection surfaces which were improper, was recovered with proper surface from the other proper end of the component. The surfaces were made proper using toggle edge. 2D elements were created by selecting the surface of the single component at once and triangular mesh of element size 0.5 was given to get the accurate results. The edges were repaired by replacing the nodes