Objectives: This study aims to analyze the biomechanics of three kinds of rigid internal fixation methods for condylar head fractures.
Methods: A three dimensional finite element model of the normal mandible was constructed. It was then used to prepare condylar head fracture finite element model and three kinds of rigid internal fixation finite element model (unilateral tension screw, bilateral tension screw, tension screw+titanium plate). The mechanical characteristics and changes of the mandible condyle under the same mechanical conditions were compared among the three different rigid internal fixation methods.
Results: The maximum equivalent stress and displacement of the non-free end of condyle under the rigid internal fixation method of unilateral tension screw were 71.03 MPa and 4.72 mm, respectively. The maximum equivalent stress and displacement of the free end of condyle were 78.45 MPa and 4.50 mm, respectively. The maximum stress of fracture suture was 3.27 MPa. The maximum equivalent stress and displacement of the non-free end of condyle under the rigid internal fixation method of bilateral tension screw were 70.52 MPa and 4.00 mm, respectively. The maximum equivalent stress and displacement of the free end of condyle were 72.49 MPa and 3.85 mm, respectively. The maximum stress of fracture suture was 2.33 MPa. The maximum equivalent stress and maximum displacement of the non-free end of condyle under the rigid internal fixation method of tension screw+titanium plate were 67.26 MPa and 2.66 mm, respectively. The maximum equivalent stress and maximum displacement of the free end of condyle were 69.66 MPa and 2.50 mm, respectively. The maximum stress of fracture suture was 2.18 MPa.
Conclusions: The tension screw+titanium plate rigid internal fixation method is the most conducive to biomechanical distribution for condylar head fractures.
目的: 对3种方式的坚固内固定髁突头部骨折进行生物力学分析。方法: 首先构建正常下颌骨三维有限元模型，然后在此基础上构建出髁突头部骨折三维有限元模型以及单侧向拉力螺钉、双侧向拉力螺钉、侧向拉力螺钉+钛板3种坚固内固定的三维有限元模型。比较在相同力学条件时，3种坚固内固定方式下颌骨髁突力学特点及变化情况。结果: 单侧向拉力螺钉坚固内固定方式下，髁突骨折非游离端的最大等效应力、最大位移分别为71.03 MPa、4.72 mm，游离端的最大等效应力、最大位移分别为78.45 MPa、4.50 mm，骨折缝的最大等效应力为3.27 MPa。双侧向拉力螺钉坚固内固定方式下，髁突骨折非游离端的最大等效应力、最大位移分别为70.52 MPa、4.00 mm，游离端的最大等效应力、最大位移分别72.49 MPa、3.85 mm，骨折缝的最大等效应力为2.33 MPa。侧向拉力螺钉+钛板坚固内固定方式下，髁突骨折非游离端的最大等效应力、最大位移分别为67.26 MPa、2.66 mm，游离端的最大等效应力、最大位移分别为69.66 MPa、2.50 mm，骨折缝的最大等效应力为2.18 MPa。结论: 侧向拉力螺钉+钛板坚固内固定髁突头部骨折的方式最为符合生物力学分布。.
Keywords: condylar head fracture; rigid internal fixation; three dimensional finite element analysis.