2023, Vol. 27 ›› Issue (18): 2809-2813

Finite element analysis of stress changes after elastic fixation between metatarsal bones for correction of hallux valgus deformity

Yang Jun, Kong Weifeng, Yuan Xiaoqing, Jin Rongzhong, Li Guijun   

Abstract: BACKGROUND: Although the elastic fixation between the first and second metatarsal bones can achieve satisfactory clinical effects in the treatment of hallux valgus, the reported risk of complications of stress fracture of the second metatarsal bone is higher. In the previous study of the research group, good clinical results were obtained using this elastic fixation in the treatment of hallux valgus.  
OBJECTIVE: To further verify the safety and reliability of the technique by establishing a finite element model of hallux valgus surgery for the fixation of the first and second metatarsal bones, and perform mechanical loading analysis.
METHODS: Based on the CT image of a female hallux valgus patient as modeling data, relevant operations were carried out to establish a three-dimensional model of hallux valgus using the software Mimics 19.0, Geomagic Studio, Hypermesh 12.0, and ANSYS 19.0. The hallux valgus model was divided into three kinds of surgical models according to surgical sites: from the base of the distal segment of the first metatarsal to the base of the distal segment of the second metatarsal (group A), the middle segment (group B), and the proximal base (group C) of the second metatarsal. The three groups of surgical models were subjected to horizontal mechanical loading to gradually reduce the intermetatarsal angle for mechanical test analysis. To simulate the stress mode of the human body when standing, the vertical loading mechanics were gradually performed on the upper segment of the tibia and fibula, and the mechanics and deformation of the whole foot and the first and second metatarsal bones were observed.  
RESULTS AND CONCLUSION: (1) In terms of stress, when the horizontal force applied to the angle between the first and second metatarsal bones was 50, 100, 200, and 300 N, the maximum stress at the overall action point of the metatarsal bones occurred in group B. The maximum stress of the first metatarsal occurred in the model of group A. The maximum stress of the second metatarsal occurred in the model of group C. The minimum stress of the second metatarsal occurred in the B model. (2) In terms of deformation, the lateral displacement of the first metatarsal was the largest in model A, followed by group B, the smallest in group C. The difference between the models in each group was small for vertical application. (3) The results showed that models of group A and group B had better orthopedic ability and were less likely to cause stress fracture of the second metatarsal. This study provides mechanical data for the clinical implementation of the first and second metatarsal elastic fixation to correct hallux valgus surgery without osteotomy.
Key words: hallux valgus, biomechanics, osteotomy, finite element analysis, metatarsal bone fixation, elastic fixation