翼外肌在髁突矢状骨折愈合过程中对髁突形态改建影响的动物实验研究

目的 观察翼外肌在髁突矢状骨折愈合过程中对髁突形态的改建是否有影响以及是否会进一步导致关节强直的发生。方法 将12只健康成年绵羊随机分为2组，均以右侧颞下颌关节作为手术实验侧，人为手术造成髁突矢状骨折。一组保留翼外肌在髁突内极的附丽，行使其功能，另一组切断翼外肌在髁突内极的附丽，阻断其功能，术后即刻行MRI检查，确定翼外肌是否离断。术后1周对动物模型行CT三维检查，测量髁突骨折块的移位距离及髁突内外径的改变，术后4周、12周及24周时处死动物，再次行CT检查，多平面重建后对髁突形态相关参数测量，以观察髁突的形态变化。结果 通过CT三维测量，两组髁突内外径的改变有明显的差异（P＜0.05），证实翼外肌对髁突游离骨折端有牵拉作用，保留翼外肌功能组，对髁突矢状骨折后髁突形态的影响更明显。结论 此动物模型的建立，证实翼外肌对髁突矢状骨折后髁突形态改建的确有影响，为进一步研究“翼外肌牵张成骨在创伤性颞下颌关节强直发生中的作用研究”提供研究平台。

Animal experimental study on the role of the lateral pterygoid muscles in healing process of the sagittal fracture of mandibular condyles

Objective To examine whether they may further cause joint ankylosis lateral pterygoid muscles influence the condyle morphology in the healing process of sagittal fracture of mandibular condyles(SFMC).Methods Twelve healthy adult sheep were included in our study,and all the animals were treated with surgery to make the condyles fracture on the right side of the temporomandibular joint.The animals were randomly divided into two groups:the pterygoids of sheep in one group were cut and not able to function.The others in the other group were not cut.They were still on the internal poles of the fractured condyles and their functions remained.We immediately examined whether the pterygoid muscles were cut(or not) by MRI after the operation.3D computed tomograms(CT) were taken 1,4,12 and 24 weeks after the operation.Measure the displacement of the internal poles of the fractured condyles,and changes in internal and external diameters of mandibular condyles.The sheep were put to death 4,12,and 24 weeks after operation.3D CT were taken then.After multiplanar reconstruction,measure related parameters about condyles so as to observe the change of condyles.Results The CT scanning showed that changes in the internal and external diameters of mandibular condyles were obviously different in the two groups(P<0.05),that the internal poles of the fractured condyles were distracted by the pterygoid muscles and that the influence on the condyle morphology after sagittal fracture was more obvious in the group where functions of the lateral pterygoid were kept.Conclusions The building of this animal model proves that the lateral pterygoid muscle does influence the condyle morphology after sagittal fracture.This study provide research platform for the study of "the role of distraction osteogenesis of the lateral pterygoid muscle in traumatic ankylosis of temporomandibular joint".