Three-dimensional finite element modeling and mechanical analysis of knee joint in patients with mild knee osteoarthritis / 中国医学物理学杂志

ABSTRACT

Objective To establish a three-dimensional finite element model of knee joint in patients with mild knee osteoarthritis in the absence of CT and MRI with thin layer thickness,and to analyze the stress distributions of the tibial plateau.Methods A female patient with mild knee osteoarthritis was selected as the study object,and received serial CT scan from pelvis to distal tibia of fibula.The obtained files in DICOM format were imported into Mimics software for extracting the bony structures of knee joint through threshold segmentation,and then optimizing the extracted structures with Edit Masks,Cavity Fill and Region Grow.The generated model of bony structures was imported into 3-matic for smoothing and wrapping,and Geomagic Wrap was used for bony structure processing with mesh doctor inspection,surface defect repair and surface fitting.The cartilages,meniscus and ligaments were established by contour extension,and assembled with bony structures in SolidWorks in the way of origin coincidence.After defining material properties and contact relationships,meshing,and setting constraints and loads in ANSYS software,the stress distributions of the tibial plateau when standing with both legs were analyzed.Results A complete knee joint model including bony structure,cartilage and ligament was successfully established.When standing with two legs,the peak value of contact stress was about 1.21 MPa,and the maximum stress was 0.72 MPa at the medial middle of tibial plateau and lateral tibial plateau.The 62.7%and 37.3%of the total load were borne by the inner and outer compartments.Conclusion The model of the total knee joint is established with CT extraction and software rendering,and the finite element analysis results meet clinical expectations,indicating that the model established by the proposed method is reliable and can be used for follow-up research.