下肢对线的普通 X 线片测量的角度准确性：远距 X 线片与正交 X 线片。
Angular accuracy of plain radiographic measurements in leg alignment: Teleoroentgenogram versus orthoroentgenogram.
机构信息
Division of Radiology, Department of Medical Technology, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Department of Orthopaedic Surgery, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
出版信息
J Orthop Sci. 2022 May;27(3):642-647. doi: 10.1016/j.jos.2021.02.011. Epub 2021 Apr 14.
BACKGROUND
The purpose of the present study was to evaluate the accuracy of the measurements associated with leg alignment on a teleoroentgenogram and an orthoroentgenogram.
METHODS
The models being irradiated were manufactured and represented 10° varus and 15° varus leg alignment, in which the true values of hip-knee-ankle angle (HKAA), mechanical axis (MA) length, and percentage of MA (%MA) were already known. HKAA, MA length, and %MA were measured in various radiographic conditions of the teleoroentgenogram and orthoroentgenogram. Then, the differences between the radiographic measurement values and the corresponding true values were analyzed.
RESULTS
Regarding HKAA, the teleoroentgenogram provided accurate angular measurements with minimal differences between the measurement and true value in both the 10° and 15° varus models, irrespective of the radiographic condition. In the orthoroentgenogram, the modified method measured accurate HKAA; however, the standard method showed significant angular measurement errors with a 0.6° and 1.0° difference from the true value in the 10° and 15° varus models, respectively. This angular measurement error of HKAA in the standard orthoroentgenogram became significantly larger with object-to-image distance. Regarding MA length, the orthoroentgenogram exhibited accurate length measurements. In contrast, the teleoroentgenogram showed a significant length measurement error for the MA length. Regarding %MA, significant differences from the true values of 2.0% and 2.4% were observed in the modified orthoroentgenograms of the 10° and 15° varus models, respectively. The teleoroentgenogram and standard orthoroentgenogram reproduced the accurate measurement value of %MA in the 10° and 15° varus models.
CONCLUSION
A teleoroentgenogram is a reliable modality for accurate angular measurements such as HKAA and %MA. An orthoroentgenogram has the potential to measure both HKAA and length accurately if the radiographic condition was modified; however, measurement error in %MA may occur.
背景
本研究的目的是评估在 teleoroentgenogram 和 orthoroentgenogram 上测量下肢对线时的准确性。
方法
被照射的模型是制造的，代表了 10°和 15°的内翻畸形，其中已经知道髋膝踝角（HKAA）、机械轴（MA）长度和 MA 百分比（%MA）的真实值。在 teleoroentgenogram 和 orthoroentgenogram 的各种放射条件下测量了 HKAA、MA 长度和%MA。然后，分析了放射测量值与相应真实值之间的差异。
结果
在 HKAA 方面，在 10°和 15°内翻模型中，无论放射条件如何，teleoroentgenogram 都提供了准确的角度测量值，测量值与真实值之间的差异最小。在 orthoroentgenogram 中，改良方法测量了准确的 HKAA；然而，标准方法显示出明显的角度测量误差，在 10°和 15°内翻模型中与真实值的差异分别为 0.6°和 1.0°。在标准 orthoroentgenogram 中，HKAA 的这种角度测量误差随着物像距离的增大而显著增大。在 MA 长度方面，orthoroentgenogram 显示出准确的长度测量值。相比之下，teleoroentgenogram 显示出 MA 长度的显著长度测量误差。在%MA 方面，在 10°和 15°内翻模型的改良 orthoroentgenogram 中，分别观察到与真实值的 2.0%和 2.4%的显著差异。在 10°和 15°内翻模型中，teleoroentgenogram 和标准 orthoroentgenogram 再现了%MA 的准确测量值。
结论
在 teleoroentgenogram 是一种可靠的方式，可以准确测量 HKAA 和%MA 等角度。如果修改放射条件，orthoroentgenogram 有可能准确测量 HKAA 和长度；然而，%MA 可能会出现测量误差。
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