上颌骨LeFortⅠ型骨折坚强内固定的生物力学研究

Biomechanical study of rigid internal fixation for maxillary LeFort I fracture

目的 运用三维有限元的方法对应用不同数目的＂L＂形、直形四孔小型接骨板在上颌骨LeFort Ⅰ型骨折不同部位固定的稳定性进行生物力学分析,为临床治疗提供指导.方法 建立LeFort Ⅰ型骨折小型钛板四种固定方式的三维有限元模型;计算不同固定方法在三种咬合情况下上颌骨的应力、内固定系统的应力以及骨折段的位移,对比其固定效果以及不同咬合情况对固定稳定性的影响.结果 在相同咬合情况下,内固定系统的应力与骨折段位移从小到大的排列顺序均为：颧上颌和鼻上颌支柱以＂L＂形钛板固定,颧上颌和鼻上颌支柱以直形钛板固定,颧上颌支柱以＂L＂形钛板固定,鼻上颌支柱以＂L＂形钛板固定;相同固定方式下,骨折处位移从大到小排列顺序为：磨牙咬合、前磨牙咬合、前牙咬合.结论 上颌骨LeFortⅠ型骨折应用＂L＂形钛板固定稳定性好于直形钛板;颧上颌支柱固定效果好于鼻上颌支柱固定;仅应用2块小型钛板固定存在隐患;磨牙咀嚼不利于骨折的愈合.

Objective To biomechanically study the fixation stability of different numbers and shapes of the titanium miniplates （L-shaped and straight four-hole miniplates） in the treatment of maxillary LeFortⅠ fracture by using three-dimensional finite element method so as to provide reference for clinical treatment of the fractures. Methods Three-dimensional finite element model of maxillary LeFortⅠ fracture was established with four kinds of rigid internal fixation （RIF） methods to calculate the stress of the maxilla and the RIF as well as the displacement of the fracture segment under three kinds of occlusion.Then, the fixation stability of different methods was compared. Results Under the same occlusion condition, the decreasing order of the displacement of the fracture segment was the L-shaped plate fixation at both buttress of the maxillary and nasal maxillary zygomatic, the straight four-hole miniplates fixation at both buttress of the maxillary and nasal maxillary zygomatic, the L-shaped plate fixation at the zygomatic maxillary buttress and the L-shaped plate fixation at naso-maxillary buttress. Under the same fixation method, the decreasing order of the displacement of the fracture segment was molar occlusion, premolar oeclusion and incisor occlusion. Conclusions The fixation stability of the L-shaped plate fixation is better than the straight four-hole miniplate fixation for the treatment of LeFortⅠ fracture. Fixation at the zygomaticmaxillary buttress is better than at the naso-maxillary buttress. Use of only two miniplates to fix the LeFort Ⅰ fracture may not be stable. Molar occlusion is not good for fracture healing.