Three-dimensional finite element model analysis of intramedullary nailing fixation design for large femoral defects in Beagle dogs
Wen Xinghua1, Ding Huanwen1, 2, Cheng Kai1, 2, Yan Xiaonan1, Peng Yuanhao1, 2, Wang Yuning1, Liu Kang1, Zhang Huiwu3
1South China University of Technology, Guangzhou 510641, Guangdong Province, China; 2Guangzhou First People’s Hospital, Guangzhou 510180, Guangdong Province, China; 3Sichuan Orthopedic Hospital, Chengdu 610041, Sichuan Province, China
Abstract: BACKGROUND: Large bone defects occur from time to time, but at present, how to design the prosthesis is still judged by doctors’ subjective experience. The appearance of finite element analysis is expected to change this situation, provide the technical support for clinicians to carry out surgery, and improve the recovery rate of the surgery.
OBJECTIVE: To investigate the effects of implant and intramedullary nail design project on repair of large bone defects in Beagle dogs by finite element analysis.
METHODS: The 3D model of the normal left femur was established based on the CT image data of Beagle dogs. Large bone defect three-dimensional finite element model was set up, from the thickness and quantity of locking nail, the length of the implants and the distance from the center of cross section to locking nail. Four groups of 12 different experimental models (three models per group) were established. Through the finite element analysis, we studied the mechanical and structural characteristics of intramedullary nails after operation, compared biomechanical effects of each model, and obtained the best design scheme.
RESULTS AND CONCLUSION: (1) In the first group, when the locking nail diameter was 2.7 mm, the maximum stress of intramedullary nails was the smallest compared with the other two groups. (2) In the second group, when the number of nails was four, the maximum stress of intramedullary nails was the smallest compared with the other two groups. (3) In the third group, when the length of the implant was 20 mm, the maximum stress of the intramedullary nail was the smallest compared with the other two groups. (4) In the fourth group, when the distance from the nail to the center of the cross section was 30 mm, the maximum stress of the intramedullary nail was the smallest compared with the other two groups. (5) These results verify that after the size of the intramedullary nail is determined, the diameter of the locking nail should be about half of the diameter of the intramedullary nail, and the number of the nail should be four, with two nails on both the upper and lower sides being the best. The length of the implant should be as short as possible, and the distance of the nail from the center of the cross section should be as far as possible.
Key words: large bone defect, implant, intramedullary nail, biomechanics, finite element analysis, Beagle dog