Numerical simulation of implant-bone interaction following cementless joint replacement

 

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dc.contributor.advisor Martin, John en_ZA
dc.contributor.advisor Spirakis, Thanos en_ZA
dc.contributor.author Starke, Gregory Richard en_ZA
dc.date.accessioned 2014-11-05T17:35:43Z
dc.date.available 2014-11-05T17:35:43Z
dc.date.issued 1996 en_ZA
dc.identifier.citation Starke, G. 1996. Numerical simulation of implant-bone interaction following cementless joint replacement. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/9258
dc.description Bibliography: leaves 143-154. en_ZA
dc.description.abstract The advent of cemented joint replacements has revolutionised the management of patients suffering from chronic arthritis. However, establishing a durable bond between the prosthesis and the surrounding bone remains a considerable problem. As a result, cementless implants have been developed. These components rely on the ingrowth of bone into a porous coating, which covers a portion of the component surface, to achieve the required mechanical interlock. Once mineralised bone tissue has formed within .the porous surface, a stable bond results which will be maintained by the normal bone turnover processes, thereby providing long term attachment. However, one of the problems associated with the use of cementless implants is the unpredictability of the extent of bone ingrowth. The process of osseo-integration is greatly influenced by the magnitude of the micro-motion between the implant and the surrounding bone. Large movements inhibit ingrowth, and may result in the formation of an interfacial fibrous tissue layer. In addition, interface strains will influence the early repair process and guide long term bone remodelling within this region. A numerical model for the prediction of bone formation within the porous surface has been developed. The evolution laws consider the early repair activity, possible fibrous tissue formation, and long term remodelling, as a function of the history of inelastic relative displacements and elastic interface strains. The model is based on the development of an isoparametric interface element, which is suitable for implementation into a non-linear finite element code. In the unbonded condition, the contact is governed by a Coulomb friction formulation. The position and shape of the Coulomb yield surface is altered according to the evolution equations, which govern the development of mineralised tissue within the surface porosity. The strain history and post-operative time are then used to develop a stimulus coefficient, which determines the course of the interface tissue development. If bone tissue is predicted, the subsequent interfacial material will be governed by a remodelling algorithm for the prediction of the long term response. If the bond strength is exceeded, fracture occurs and the joint may open or slide, thus returning to its original, unbonded, state. In the event of large micro-motions, the yield surface and material formulation are altered to include fibrous tissue. The model is used to predict the development of interfacial tissues at the porous surface of a tibial tray component, with a central peg and a PCA (Howmedica, Inc.) femoral stem. Although many factors influence interfacial tissue development, mechanical loads are assumed to be dominant. In the short term, the relationship between micro-motion and interface tissue response has been shown. However, long term remodelling of interfacial tissues has not been widely demonstrated and, therefore, additional experimental data is required to validate the current long term remodelling predictions. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Mechanical Engineering en_ZA
dc.title Numerical simulation of implant-bone interaction following cementless joint replacement en_ZA
dc.type Thesis / Dissertation en_ZA
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Engineering & the Built Environment en_ZA
dc.publisher.department Department of Mechanical Engineering en_ZA
dc.type.qualificationlevel Doctoral en_ZA
dc.type.qualificationname PhD en_ZA
uct.type.filetype Text
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