Computer modelling of the heat flow in surgical cement during endoprosthesoplasty

Journal of Achievements in Materials and Manufacturing Engineering 01/2007;
Source: DOAJ

ABSTRACT Purpose: The problem of the modelling of the surgical cement behaviour during implantation has beenpresented in the paper. The purpose was to find the proper model describing the temperature fields in the boneduring the surgery treatment.Design/methodology/approach: Computer modelling has been used to predict the temperature influence on thebone tissue during polymerization process.Findings: During orthopaedic surgical procedures with the use of methyl polymethacrylate surgical cements, thetemperature sometimes reaches 80°, which causes atrophy of the bone tissue. The process occurs locally, sinceit depends on both the amount of polymerization heat generated during the reaction and on the heat exchangeconditions at cement-bone tissue and bone cement – implant boundaries. Striving to better understand theabove-mentioned phenomena through a model approach, models were developed under the study to calculatetemperature distributions in the bone and in implant components during the procedure of endoprosthesis stemimplantation. Calculations were made for different cement layer thickness variants and for different amountof cement concentrated around the top of the stem. The characteristics of temperature changes with time indifferent points of the bone and cement have been determined and temperature distributions in bone and cementfor selected instants of time have been worked out.Practical implications: The analysis carried out makes it possible to determine the location of areas mostthreatened with an adverse effect of an elevated temperature. In each case, they are located in the vicinity ofthe top of the endoprosthesis stem. These conclusion together with obtained data should be important for thesurgeons during surgical operation..Originality/value: The work presents the own method of heat flow modelling during the polymerization of surgicalcements. The results of the own method of the heat source characteristic description has been shown as well.

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    • "Determining conditions of mechanical loading in tissue surrounding implants or prosthesis functioning in organisms belongs to one of the basic tasks of engineering of biomaterials [1] [2] [3] [4] [5]. A typical example of that is an evaluation of mechanical interactions on dental prosthetic solution [6] [7] [8] [9] [10]. "
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    ABSTRACT: of loading state of tissue denture foundation.Design/methodology/approach: During FEM numerical modeling there was made evaluation of loading state of denture foundation tissues pressed by a hard denture and relined by a silicone layer.Findings: Maximum shear is observed under mucous surface at bone on the side of process prominence. Soft tissues injuries and pain discomfort might result from exceeding both tolerances of pressure and shear, which maximum values are located in the opposite areas. Maximum pressure values are present in central areas at tips of edentulous ridges. The layers of relining material results in a decrease and balancing of maximum pressure values. It decreases tendencies of slip and frictional injuries occurrence by means of reducing tangential stresses on the mucous interface. Nevertheless, the transfer of part of loadings on ridges slopes results in increased shear inside of the tissue at the side of the convexity. In bone tissue at the tips of edentulous ridges there is observed decrease of principal stresses and the lack of significant changes of equivalent von Mises stresses.Research limitations/implications: One of the model simplifying assumptions was the assumption of isotropic linear elasticity of materials mechanical characteristics and denture adherence to its foundation.Practical implications: Recommended to relining are injuries occurring in the central area of bone convexities. If, in spite of a proper denture fit, there is still a typical ulceration at the side of the ridges convexity, use of relining increases shear of those area of the tissue, conducing development of a typical deep ulcer located usually from the bone towards the surface of soft tissues.Originality/value: Tangential stresses and loads on mucous surface are not the only one criterion of evaluation and diagnosis of mucous membrane loading state.
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    • "An example of the model application for the determination of thermal field in the femoral bone with an endoprosthesis' stem is shown in Fig. 1c. The described model approach was used to prepare a quantitative description of material requirements for adaptation of implants f i xed with the use o f s u rgical cement [5]. I n t h e calculations, different cement amounts around the endoprosthesis' stem were assumed. "
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    ABSTRACT: Purpose: Problems of the modelling of the surgical cement behaviour during implantation have been presented in the paper. The purpose was to validate the FEM model describing the temperature fields in the bone during the surgery treatment.Design/methodology/approach: The physical laboratory modelling has been used to perform validation of the model that makes it possible to predict the temperature influence on the bone tissue during polymerization process.Findings: Due to its non-invasive nature, the computer models’ validation method applied in the study seems to be the right solution for the research on surgical procedures of endoprosthesis implantation. However, a particular emphasis should be placed on a correct selection of thermophysical properties of the designed laboratory models. Relying on the calculations and research results, similar local values of maximum temperatures were obtained. Practical implications: The computer modelling methods presented in the paper together with the analytical approach are of great importance to both forecasting the implants’ behaviour during a surgical procedure and in their operational conditions, as well as in the selection and modification process of surgical cements’ material properties. The analysis carried out makes it possible to determine the location of zones most threatened with an adverse effect of an elevated temperature. They are located in the vicinity of the top of the endoprosthesis stem.Originality/value: The work presents the own method of validation of the FEM model used for heat flow modelling.
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    • "His results from the model indicated that an auto accelerating heat production and a residual monomer concentration were able to cause bone tissue damage and affected the mechanical properties of the cement. J. Okrajni et al.(2007, [11]) proposed a mathematical model of the heat flow in surgical cement during implantation. "
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    ABSTRACT: This paper proposes a mathematical model of heat transfer in the cemented hip replacement using the metal-metal im-plant with no cup. Computational domain consists of three subregions including a femur region, an implant region and a femoral canal region. The femoral region is divided into two parts which are the top and the bottom parts occupied by the cement and the ambient air. The governing equation is a unsteady heat equation. Heat transfer by conduction is considered in this study. Finite element formula for the solution of heat transfer problem is derived. Effect of the initial temperature of the cement and the implant material on heat transfer process are investigated. Numerical results show that the initial temperature has significant effect whereas the implant materials has less effect. Keywords— unsteady heat equation, finite element method, ce-mented hip replacement, mathematical model, femur bone, implant material.
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