Finite Elemental Analysis of the displaced disc in TMJ.

颞下颌关节内错位(TMJ)是指关节盘相对于髁突和关节隆起的错位。随着关节造影术的发展，以及随后的TMJ关节断层摄影术，已经证实关节盘前移位与关节点击和锁定有关。自那以后，人们利用关节学技术进行了大量的研究，以建立关节盘位置和形态的真实图像。关节盘在闭合位置的变形被描述为反向双凹、双平面或双凸。然而，在最大钳口打开位置的盘状结构尚未被报道。现在，磁共振成像(MRI)可以很容易地显示出TMJ内错位患者的关节盘位置。但MRI不能显示椎间盘形态。本研究的目的是制作永久移位的TMJ关节盘的三维图像，用于研究开口位的关节盘形态。Matria…方法：对100例陈旧性TMJ关节盘移位患者同时拍摄116张最大张口位多层面关节片。一支铅笔作为参照点被放在涉及五部电影的胶片盒式磁带上。在数字化前，在透明纸上描绘每个胶片的以下结构的参考点和轮廓：外耳道、关节窝、关节隆起、上室染料的下缘、下室染料的上缘和髁突。随后，使用图形输入板光标对关节结构的参考点和轮廓进行数字化。用COSMOZONE-2S(Nikon Co.)软件进行三维重建。上腔内染料的下缘(蓝色)和下腔内染料的上缘(橙色)分别表示盘的上缘和下缘。所有评估都是由同一观察员进行的。结果：所有关节在最大张口位时，关节盘形态均发生变形。可分为四种类型：1)折叠盘结构，2)扭曲盘结构，3)压缩盘结构，4)组合盘结构讨论：这一结果可能给我们提供一个线索，为什么一些减少的盘移位转变为永久性的盘移位。关节盘三维图像的应用可在不增加患者额外风险的情况下提高常规关节造影的诊断价值，并可对关节内紊乱患者的复杂关节盘畸形提供新的见解。较少

Internal derangement of the temporomandibular joint(TMJ) means a malposition of the articular disc relative to the condyle and articular eminence. With the development of arthrography and,subsequently ,arthrotomography of the TMJ, it has been established that anterior disc displacement is related to joint clicking and locking. Since then, a lot of researches have been done using arthrographic technique to establish an actual image of disc position and configuration.Disc deformation at the jaw closing position has been described as reversed biconcave, biplanar, or biconvex. Nevertheless, Disc configuration at the maximal jaw opening position has not yet been reported. Now, magnetic resonance imaging(MRI) has easily revealed disc position in the patients with internal derangement of TMJ. But MRI can not reveal disc configuration. The aim of this study was to produce 3-dimensional images of permanent displaced disc of TMJ for study of disc configuration at the jaw opening position. Matria … More ls and methods: 116 simultaneous multisectional arthrotomograms at the maximal jaw opening position were taken from 100 patients with permanent disc displacement of TMJ. A leaden marker for a reference point was put on the film cassette which involved five films. Prior to digitizing, the reference point and the contours of the following structures of each film were traced on transparent paper: external auditorycanal, glenoid fossa, articular eminence, the inferior border of the dye in the upper compartment, the superior border of the dye in the lower compartment, and condyle. Subsequently, the reference point and contours of the joint structures were digitized with the tablet cursor. Three-dimensional reconstruction was performed by the software package COSMOZONE -2S(Nikon Co.). The inferior border of the dye in the upper compartment(blue) and the superiorborder of the dye in the lower compartment(orange) means the upper and lowerborder of disc, respectively. All assessments were performed by the sameobserver. Result:On all of the joints, disc configuration was deformed at the maximal jaw opening position. Four types of disc deformity were discerned:1) folding disc configuration,2) twisted disc configuration , 3) compressed disc configuration, 4) combination disc configuration Discussion: This results may give us a hint about why some reducing disc displacement change in to permanent disc displacement. The use of three-dimensional disc images may improve the diagnostic value of conventional arthrotomogram at no additional risk to the patients and may provide new insights into the complex deformities of disc in the patients with internal derangement of TMJ. Less