Thermal Behaviour of Bone Cement in Hip Replacement

Abstract

This work involved the study of heat transfer in a cemented hip replacement. The recent rise in cemented hip replacement in Orthopaedic and trauma surgery is of alarming concern to the material usage and conditions it been subjected to. Bone cementing which is the main technology providing the bonding mechanism between the femur cavity and the prosthesis stem is the polymerization reaction between the powder and liquid monomer which is an exothermic reaction. This heat transfer mechanisms between the bone cement, the prosthesis stem and the femur bone is of concern to biomechanics engineers. The ANSYS 15.0 software was used in conjunction with the Autodesk software to model the scenario and simulate it using steady state thermal-structural analysis. It was found that the temperature that resulted from the exothermic reaction of the PMMA polymer (used as bone cement) raised the temperature in the assembly creating a heat flux amounting to 5.11x10-7W/m2 in which only 2.83x10-7 W/m2 got to the femur bone while the rest was absorbed by the prosthesis stem and the femur bone. The specific heat capacities of PMMA and femur bone were calculated as1.297kJ/kg.K and 0.59kJ/kg.K respectively. The Young Modulus for PMMA was found as 28.78GPa and 18.79GPa for femur bone. These show that it is possible to determine these properties from the simulation studies.