下颌体骨折倾斜角度与坚固内固定稳定性关系有限元分析

目的:用三维有限元的方法分析下颌体骨折倾斜角度与小型钛板坚固内固定后骨折段稳定性的关系。为治疗下颌骨体斜形骨折提供生物力学指导。方法:建立下颌骨体骨折的三维有限元模型,并设定不同的骨折线近中倾斜角度,按照Champy的下颌骨骨折理想固定线进行小型钛板固定,分别模拟切牙咬合及健、患侧磨牙咬合,得出骨折段的相对位移情况。结果:下颌体骨折坚固内固定的稳定性在夹板与骨折线垂直的时候最好,随着骨折线倾斜角度的增大,夹板与骨折线所成角度增大,骨折段的稳定性越来越小,当骨折线倾斜角度大于20°时,骨断端的相对位移超过了150μm。结论:下颌体骨折段的稳定性会随着骨折线倾斜角度的增大而减小。当骨折线倾斜角度大于20°时,应通过改良手术方法或术后增加辅助固位或减小咬合力等措施防止固定失败。

The rigid element analysis of relationship of angles of inclination of body of mandible and stability of rigid internal fixation

Objective To analyze the relationship of angle of inclination of the fracture of the body of mandibule and the stability of the fracture segments after rigid internal fixation using titanium miniplate,and to provide biomechanical guide for curing oblique fractures of the body of mandibule.Method To establish three-dimensional finite element model for the fracture of body of mandible,and setup different angles of medial inclination of fracture lines,then making rigid internal fixation using titanium miniplates according Champys ideal fixation line of mandibular fractures,to simulate incisor occlusion and molar occlusion of uninjured side or injured side.And then the relative displacements of the fracture segments were abtained.Results The stability of rigid internal fixation of the fractures of body of mandible was the best when the fracture lines were vertical with the miniplate.And as the angles of inclination of the fracture lines became larger,the angles of inclination between the miniplates and fracture lines became larger,and the stability of fracture segments became weaker.When the angles of inclination were lager than 20 degrees,the relative displacements of the bone stumps exceeded 150 μm.Conclusion The stabilities of the fracture segments of body of mandible become weaker as the angles of inclination of the fracture lines become larger.When the angles of inclination are lager than 20 degrees,we should change the operation methods or decrease occlusal forces etc to prevent fixation failure.