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Title: Development of a finite element model of the knee using patient specific magnetic resonance imaging data and biomechanical testing of soft tissues
Author: Li, Joanna Yuen
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2013
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This thesis presents the findings of investigations carried out relating to the creation of full joint contact patient specific finite element models for correlation with biological studies in the study of Osteoarthritis (OA) development. To understand the relationship between altered loading and biological changes in articular cartilage (AC), a method for predicting stresses and strains experienced inside the tissues is required. An in-vitro study was conducted to explore the possibility of correlating finite element (FE) and gene expression study results. FE models were used to predict the stresses and strains inside the AC for explants subjected to different loading conditions. The study demonstrated that the accurate representation of AC surface geometry is crucial and current flat surface axisymmetric cylinder representations used in AC explant modelling introduces significant error in the prediction of tissue mechanical behaviour. Cutting of the AC explant to achieve a flat surface can affect the biological, mechanical and tribology behaviour of the tissue. Thus, a method for creating explant specific finite element models with the use of digital image correlation (DIC) was developed and is presented, allowing for surface layer preservation in AC explants for correlated gene expression and inverse FE. Reconstruction of tissue geometries from magnetic resonance (MR) imaging scan data of the knee was explored. It was possible to segment both hard and soft tissues from the same set of MR imaging scan data. Meshing of the geometries using a fundamentally voxel based algorithm proved to cause significant error in the segmented volume. An alternative contour based algorithm needs to be explored. Uncertainties concerning the presence and modelling of meniscotibial ligaments (MTLs) in full joint contact FE models found in literature were addressed. An anatomy study revealed that the MTLs are found in both the medial and lateral side of the joint around the periphery of the anterior, middle and posterior portion of the menisci. With the use of cross polarised light microscopy, it was established Page | VII that MTLs consist of Type I collagen orientated in the circumferential direction around the menisci. As a result, the MTLs were modelled as an anisotropic membrane. Using the full joint contact finite element model, the influence of MTLs on knee joint kinematics was investigated. It was found that the MTLs reinforce the function of the meniscal horns and circumferential fibres in the meniscus and help constrain the meniscus. Therefore, it was concluded that the MTLs are mechanically significant in the stabilisation of knee joints and should be included in knee models for accurate prediction of knee joint behaviour.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QM Human anatomy ; TJ Mechanical engineering and machinery