Experimental And Numerical Simulation Of In Vivo Preloading Force To Promote Bone Integration At The Femoral-implant Interface

The purpose of this study is to analyze the mechanical properties of interface cancellous bone of titanium alloy prosthesis and the effect of preload on the reconstruction of interface bone.Twelve 2.5-month-old male New Zealand white rabbits were selected.Eight of them were used as the operation group.A hole with a diameter of 1.98 mm was made on the lateral side of the right femoral condyle.A 3D printed titanium alloy porous implant with a porosity of 70%,a diameter of 2mm and a height of 5mm was implanted by the way of interference,which made the implant bone interface produce preload.The other four were fed as the control group freely.After 12 weeks of natural feeding,the defect interface was fully healed.The strength of the integrated bone was calculated and analyzed by finite element method according to the micro CT image.The results show that the preload between implant and bone interface can promote the process of bone reconstruction.However,due to the uneven distribution of preload and the stress shielding and stress concentration of the implant,the amount of bone at the interface is not evenly distributed,and there are stress shielding and concentration areas in the upper part of the titanium alloy prosthesis,and bone absorption occurs.On the basis of three-dimensional modeling and finite element analysis,the histomorphology of the femur samples was detected and analyzed,and the results of micro CT scanning were compared and analyzed by using vgstudy software.The three-dimensional bone trabeculae shape parameters of the femoral condyle area in the free feeding group and the operation group were compared.It was found that there were new bone trabeculae in the titanium alloy prosthesis,but there were bone resorption in many areas Harvest phenomenon.In order to further observe the condition of the bone trabecula around the titanium alloy prosthesis,the specimen was sliced and the scanning electron microscope was used to detect the surface image of the specimen.The results showed that there were new bone trabeculae in the titanium alloy implant,but there were defects in the area around the titanium alloy implant.The reason for the defects was that the excessive load restrained the bone trabeculae Growth.Further use of infrared spectroscopy analysis,through the analysis of the content of hydroxyapatite and the change of protein structure,we found that titanium alloy prosthesis can promote the overall bone reconstruction.