Biomechanical analysis of mandibular reconstruction with a fibular flap by fixation based on mortise and tenon joint structure
10.3760/cma.j.cn114453-20201219-00637
- VernacularTitle:一种基于榫卯结构的腓骨重建下颌骨固定方法的生物力学分析研究
- Author:
Wenqing WEI
1
;
Jing HAN
;
Junlei HU
;
Jiannan LIU
Author Information
1. 上海理工大学医疗器械与食品学院 200093
- Keywords:
Mandibular reconstruction;
Finite element analysis;
Imaging, three-dimensional;
Mortise and tenon joint structure
- From:
Chinese Journal of Plastic Surgery
2021;37(5):520-527
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To analyze the stress and displacement distribution of mandibular reconstruction with fibular flap by fixation based on mortise and tenon joint structure with three-dimensional finite element analysis.Methods:A 66-year-old male patient with no fracture or deformity of the mandible was admitted to the Department of Oral and Maxillofacial Head and Neck Oncology of the Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine in August 2020. The imaging data of the mandible and fibula of the patients were obtained with CT scan. Three-dimensional reconstruction and reverse reconstruction were performed with software Mimics 17.0 and GeomagicWrap 2017 to obtain the three-dimensional models of the mandible and fibula. The model of mandibular reconstruction with fibular flap was obtained by software Solidworks 2017 and Geomagic Design X 64. The cortical bone and cancellous bone were segmented by Boolean operation. The vertical occlusal state was simulated (the loading condition was 125 N downward along the axis of the central incisor and 250 N downward along the axis of the second and third molars). Three dimensional finite element analysis was used to compare and analyze the stress and displacement distribution characteristics of the mandible and internal fixation before and after bone healing with the mortise and tenon joint structure combined with lag screws and traditional titanium plates. After optimized the boundary conditions of the mandible based on the mortise and tenon joint structure, the stress and displacement distribution of the internal fixation and mandible were measured.Results:In terms of stress distribution, under the condition of bone non-union, the stress peak of the internal fixator fixed by mortise and tenon structure was distributed at the junction of bone section and internal fixator, which was 304.07 MPa. The peak stress of the titanium plate fixation was 345.39 MPa at the broken end of the posterior bone. After bone healing, the stress peak distributions of the internal fixator fixed by mortise and tenon structure remained unchanged, which was 58.47 MPa. The stress of the internal fixator was concentrated to the contact point between the titanium nail and the titanium plate, which was 92.06 MPa.In addition, after the boundary conditions were optimized, the stress distribution of the bones was uniform, and the peak stress of internal fixation was 88.56 MPa, which was significantly lower than the maximum yield strength of titanium (860 MPa). In terms of displacement, under the condition of bone non-union, the displacement peaks of the two fixation methods were both located in the right mental foramen in the middle of the lower margin of the mandible and involved the anterior osteotomy surface. The peak value of mandible displacement in tenon and mortise fixation was 1.307 mm, which was slightly lower than that in titanium plate fixation, 1.447 mm.After bone healing, the main displacements of the two fixation methods were located close to the middle of the lower margin of the mandible and did not involve the osteotomy surface. The displacement peak value of titanium plate fixed mode was 0.518 mm, which was less than that of tenon and mortise fixed mode. Under the condition of bone non-union, the peak displacement of the mandible was 0.212 mm after the boundary of the tenon and mortise fixation model was optimized.Conclusions:The tenon and mortise design combined with lag screw fixation is a safe and effective method for the mandible reconstruction with a fibular flap.
