Fujitani Ryotaro, Omokawa Shohei, Iida Akio, Santo Shigeru, Tanaka Yasuhito
Department of Orthopaedics, Ishinkai Yao General Hospital, Affiliated Hospital of Nara Medical University, Osaka, Japan.
J Hand Surg Am. 2012 Mar;37(3):454-9. doi: 10.1016/j.jhsa.2011.10.056. Epub 2012 Jan 30.
The teardrop angle (TDA) is a newly characterized radiographic parameter that some authors propose as an indicator of articular incongruity of the lunate facet. The purposes of this study were to investigate intra-observer and interobserver reliability of the measurements of the TDA and to determine whether the TDA is a reliable indicator of articular step and gap formation after distal radius fracture.
We studied radiographs of 24 uninjured wrists and 24 wrists with intra-articular distal radius fractures. On standard and 10° tilt views of lateral wrist radiographs, the teardrop represents the volar rim of the lunate facet, and the TDA is defined as the angle between the central axis of the teardrop and the radial shaft. We examined interobserver and intra-observer reliability for 3 observers using the intraclass correlation coefficient (ICC) for measurements of the uninjured and fractured wrists. For subjects with fractures, we determined correlation of the TDA-volar tilt with the articular step and gap measured by computed tomography using simple linear regression.
There was almost perfect intra-observer (ICC = 0.95) and interobserver (ICC = 0.93) reliability in the fractured wrists. We observed substantial intra-observer (ICC = 0.64) and fair interobserver (ICC = 0.28) reliability in the uninjured wrists on the standard lateral radiographs. On the 10° tilt views, intra-observer and interobserver reliability in the uninjured wrists increased to substantial levels (ICC = 0.76 and 0.61, respectively). The TDA-volar tilt was significantly associated with articular step and gap on computed tomography.
The TDA, measured on the lateral radiograph of the wrist, exhibits higher intra-observer and interobserver reliability in fractured wrists compared with uninjured wrists. On the 10° tilt views, the reliability increased in the uninjured wrists. Measurement of the TDA in plain radiographs may allow direct estimation of articular incongruity as seen on sagittal computed tomography reconstruction images.
泪滴角（TDA）是一个新确定的影像学参数，一些作者提出它可作为月骨小关节面关节不协调的指标。本研究的目的是调查TDA测量的观察者内和观察者间可靠性，并确定TDA是否是桡骨远端骨折后关节台阶和间隙形成的可靠指标。
我们研究了24例未受伤手腕和24例桡骨远端关节内骨折手腕的X线片。在标准的和10°倾斜的腕关节侧位X线片上，泪滴代表月骨小关节面的掌侧边缘，TDA定义为泪滴中轴线与桡骨干之间的角度。我们使用组内相关系数（ICC）对3名观察者测量未受伤和骨折手腕的情况进行观察者间和观察者内可靠性检查。对于骨折患者，我们通过简单线性回归确定TDA-掌侧倾斜度与通过计算机断层扫描测量的关节台阶和间隙之间的相关性。
骨折手腕的观察者内（ICC = 0.95）和观察者间（ICC = 0.93）可靠性几乎完美。在标准侧位X线片上，我们观察到未受伤手腕的观察者内可靠性较高（ICC = 0.64），观察者间可靠性一般（ICC = 0.28）。在10°倾斜位片上，未受伤手腕的观察者内和观察者间可靠性提高到较高水平（分别为ICC = 0.76和0.61）。TDA-掌侧倾斜度与计算机断层扫描上的关节台阶和间隙显著相关。
与未受伤手腕相比，在腕关节侧位X线片上测量的TDA在骨折手腕中表现出更高的观察者内和观察者间可靠性。在10°倾斜位片上，未受伤手腕的可靠性有所提高。在平片上测量TDA可能有助于直接估计矢状面计算机断层扫描重建图像上所见的关节不协调情况。
