下颌角骨折坚强内固定生物力学的三维有限元法分析

目的 采用三维有限元法分析下颌角骨折张力带固定与双列小型板内固定的稳定性.方法 选取健康成年志愿者1例,通过三维有限元法建立正常下颌骨模型,建立骨折线,制作内固定系统,并最终建立三维有限元模型,分析前牙咬合、双侧后牙咬合、左侧后牙咬合和右侧后牙咬合四种咬合方法两种内固定最大应力情况及骨折断端相对移位情况.结果 张力带内固定最大应力和双列小型板固定时的最大应力分别集中在钛板中断和钛板上侧的中段.在前牙咬合及骨折对侧后牙咬合时张力带最大应力低于双列小型板固定系统最大应力,张力带内固定前牙咬合及骨折对侧后牙咬合时骨折断端相对移位较大,超过0.15 mm安全移位阈值.结论 三维有限元模型建立下颌角骨折可信度较高,双列小型板固定生物力学分析稳定性高于张力带内固定方法,而张力带内固定治疗下颌角骨折需对患者咬合力的调整进行指导,稳定性也可达到安全范围.

Biomechanical analysis of rigid internal fixation for mandibular angle fracture through three-dimensional finite element method

Objective To analyze the stability of two-miniplate internal fixation and tension band internal fixa-tion for mandibular angle fracture by three-dimensional finite element method (3D-FEM). Methods A healthy adult volunteer was chosen. The normal mandible model was established by 3D-FEM, with the fracture line and internal fixa-tion system established, and finally, a three-dimensional finite element model was established. The maximum stress and the relative displacement of fracture of the two internal fixation methods for anterior teeth occlusion, bilateral posterior teeth occlusion, left posterior teeth occlusion and right posterior teeth occlusion were analyzed. Results The maximum stress concentrated in the middle of the titanium plate for tension band internal fixation, and in the middle of the upper plate for two-miniplate internal fixation. The maximum stress of tension band internal fixation was lower than that of two-miniplate internal fixation for anterior teeth occlusion and contralateral posterior teeth occlusion, and the relative dis-placement of fracture of tension band internal fixation was larger for anterior teeth occlusion and contralateral posterior teeth occlusion (0.15 mm more than safe shift threshold). Conclusion Mandibular angle fracture model is established under the three dimensional finite element model with good credibility. The stability of two-miniplate internal fixation is higher than that of tension band internal fixation. Guidance for the adjustment of occlusal force should be performed to make the stability in safe range when treating mandibular angle fracture with tension band internal fixation.