三维有限元模型分析OSAHS患者下颌不同前伸位置的舌骨位置变化的研究
【摘要】
目的：建立阻塞性睡眠呼吸暂停低通气综合征（OSAHS）患者上气道及毗邻结构的三维有限元模型，通过逐步前伸下颌，观察OSAHS患者舌骨位置的改变及其与下颌前伸量之间的关系，为下颌前伸类口腔矫治器治疗OSAHS的机理研究提供理论依据。
方法：对OSAHS患者上气道行薄层CT扫描，以DICOM格式输出数据，采用Mimics三维建模软件和Ansys有限元分析软件建立上气道及毗邻结构的三维有限元模型，然后通过加载下颌骨逐步前伸，观察舌骨位置的变化及其规律。
结果：建立了OSAHS患者上气道及毗邻结构的三维有限元模型，规定采用10节点的Solid 92四面体单元划分网格，按要求划分网格后，皮质骨、松质骨、肌肉及气道得到的单元数和节点数分别为：562920、50141、336789个单元，544929、84869、303134个节点。通过逐步前伸下颌骨，舌骨位置向上向前移动，随着下颌逐步前伸，气道所观察截面横径逐渐减小，而截面矢状径逐渐增大，截面的形状更趋于长轴位于矢状方向的椭圆形。经统计学回归分析，下颌骨前伸与舌骨位置变化相关，并得出回归系数方程：y=-0.03+0.232x。
结论：应用螺旋CT技术联合使用Mimics三维建模软件、Ansys有限元分析软件建立OSAHS患者上气道及其毗邻结构三维有限元模型，该模型的几何相似性较好，使用灵活；通过下颌逐步前伸，对舌骨位置变化进行分析，显示下颌骨前伸与舌骨位置变化呈正相关，证实了研究方法的可行性，为下颌前伸矫治器治疗OSAHS提供理论依据，同时为后续研究患者上气道生物力学分析打下良好的基础。
【关键词】：阻塞性睡眠呼吸暂停低通气综合征；下颌前伸；上气道腭咽；三维有限元法
The three-dimensional Finite Element analysis of an Obstructive Sleep Apnea Hypopnea Syndrome Patient’s hyoid bone position changement with titrated mandibular advancement
ABSTRACT(https://www.daowen.com)
Obstructive sleep apnea hypopnea syndrome（OSAHS）is characterized by repetitive sleep apnea，oxygen saturation decreased due to upper airway collapse.
There are many studies about position changes of hyoid in OSAHS patient，but whether if there is relevence between position change of hyoid and mandibular advancement，and even there is regulation in position change of hyoid are still in argue.Most of the past studies are two-dimensional，three-dimensional methods such as computerized tomography（CT）are still and interval.These methods can analyze one movement position of hyoid while Three-dimensional Finite Element analyse can analysis the whole process of position changeofhyoidwithmandibularadvancementescapingfromextraradiationanddisturbance.
Three-dimensional finite element method is the most advanced and effective method of biomechanical analysis in medicine.This study obtained the accurate DICOM format of the image information of OSAHS patient’s upper airway by using spiral CT scan and establish an accurate，flexible simulation OSAHS patient’s upper airway model by using Mimics and Ansys software.Through loading of mandibular advancement，position change of hyoid can be simulated，which lay the foundation for the OSAHS patient’s upper airway biomechanical analysis，as well as provide a theoretical basis for Oral appliance optimal design for OSAHS therapy，while exploring a new way of thinking for future research of OSAHS.
Objective：Construct a three-dimensional finite element model of the Upper airway and adjacent structure of an Obstructive sleep apnea hypopnea syndrome patient and regulate protrusion of mandibular，the position changes of hyoid and its relationship with the mandibular protrusion can be observed and analysized which providing theoretical basis for mechanism studies of treatment to OSAHS with mandibular protraction.
Methods：DICOM format image information of an OSAHS patient’s upper airway obtained by thin-section CT scanning and digital image processing were utilized to construct a three-dimensional finite element model by Mimics and Ansys software.And then titrated mandibular advancement，the changes and the law of palatopharyngeal part observed by biomechanics and morphologic.
Results：A case of OSAHS and the adjacent upper airway structure of three-dimensional finite element model is constructed which is formed by solid 92 tetrahedral unit of a 10-node mesh.The model has cortical bone：562920 elements，544929 nodes；spongy bone：50141 elements，84869 nodes；muscle and upper airway：336789 elements，303134 nodes.After mandibular advancement，hyoid part of three-dimensional finite element of OSAHS change significantly.The main manifestations are：the hyoid move ahead and upward；the section ofpalatopharyngeal part which shape of oval reduce in transverse diameter while increase in sagittal diameter.Regression analysis has been taken between mandibular advancement and displacement of hyoid bone，which showed that they relevant greatly.A regression equation have been reached：y=-0.03+0.232x.
Conclusion：Establish accurate，flexible three-dimensional finite element model of the upper airway and vicinity structure of an OSAHS patient with the use of spiral CT technology and Mimics software，Ansys software.The model has good geometric similarity and good flexibility.Through mandibular advancement，palatopharyngeal part on OSAHS loading analysis of finite element model，the effective show great relevance between mandibular advancement and the hyoid displacement，which confirming that the study is feasibility，providing a theoretical basis for treatment of OSAHS with Mandibular advancement appliance and laying a good foundation for the following study of upper airway in OSAHS patients with biomechanical analysis.
Key words：obstructive sleep apnea hypopnea syndrome；hyoid；palatopharyngeal part of upper airway；three-dimensional finite element method