Abstract

Internal fixation with rigid metal plates is a widely accepted technique for the treatment of bone fractures. The objective of this study is to evaluate the response of bone, fracture plate, screws and callus at different stages of healing to various applied loads. A three-dimensional, half-symmetric finite element model was developed. The stress and strain states in the assembly were investigated for pure compression, pure tension, twisting moment and combination of compressive and shear forces, which generate a bending moment, simulating getting up from a chair, carrying a suitcase and turning a screw driver. Two types of commonly used fracture plates were compared: 316 stainless steel and Ti-6Al-4V titanium alloy. The results of this research showed that there is less stress shielding of the bone with the titanium alloy plate and screws than with the stainless steel ones. The maximum equivalent von-Mises stress was found to be less in compression and tension than in bending and twisting. The majority of load transfer within the assembly occurred in the screws. For large bending and twisting moments stresses can be higher than the strength of the stainless steel plate. Excessive loading should thus be avoided to prevent possible failure. The research further found that the relative motion between bone and fracture plate was largest during tensile loading