3D-printed arthrodesis endoprosthesis for reconstruction of distal tibia after resection of tumor-A finite element analysis

ZHAO Zhi-qing; WANG Ji-chuan; YAN Tai-qiang; GUO Wei; YANG Rong-li; TANG Xiao-dong

doi:10.3969/j.issn.2095-252X.2023.12.002

Abstract：Objective The clinical outcomes of 3D-printed tumor endoprosthesis for the defect of distal tibia after tumor resection are satisfactory,but the current analysis of its biomechanical properties is limited.To provide theoretical basis for clinical application,a finite element analysis was used to detect the initial strength of the structure.Methods Computerized tomography(CT)data of tibia and fibula from a healthy adult male volunteer were collected.Computer-aided design software was used to established three-dimension models.Two different models were constructed:normal tibia-fibula-talus complex and prosthetic reconstruction.Mechanical analysis was carried out by finite element method with ANSYS software.The contact relation between screw and prosthesis was binding contact,the contact relation between prosthesis and cortical bone was slip contact,and the contact relation between screw and cortical bone was binding contact.Simulated loads of 600 N were applied to the tibial plateau to simulate balanced single-foot standing.With the vertical axis of the tibia as the rotation center,2.7 N·m clockwise and counterclockwise were applied on the tibial plateau to simulate the external rotation load and internal rotation load of the lower limbs.Results When 600 N vertical stress was applied to the tibial plateau,the maximum von Mises compressive stress of the normal tibia-fibular model was 8.27 MPa,and the concentrated area of stress located at the posterior cortex bone in the middle part of the tibia.The maximum deformation site of the model was the lateral tibial plateau and the fibula head,and the deformation distance was 4 mm.When the clockwise and counterclockwise moments of 2.7 N·m were applied,the maximum von Mises compressive stress was 14.25 MPa in the middle tibial cortex,and the maximum displacement point was 2.47 mm in the anterior proximal tibial cortex.In the simulation of one-leg standing,the maximum von Mises compressive stress of the model was 51.98 MPa,located at a cross screw at the distal end of the model.Otherwise,the rest of the model was subjected to uniform stress.The deformation analysis showed that the maximum displacement of the prosthetic body weight model was smaller than that of the normal tibia and fibula model,only 0.74 mm,and it was located on the lateral tibia plateau and the fibula head,which was consistent with the normal tibia and fibula model.When 2.7 N·m clockwise and counterclockwise moments were applied,the maximum von Mises compressive stress was 15.44 MPa and was located at the antirotating screw at the distal end of the implant,and the maximum displacement point was only 0.07 mm at the lateral tibial platform and the release site of the fibula head during rotation.Conclusions The 3D printed prosthesis is a reliable reconstruction method in the bone defect model of the lower tibial segment after resection of the malignant bone tumor,by which the prosthesis and bone will have uniform force and good stability.