Broberg Jordan S, Yuan Xunhua, Teeter Matthew G
Department of Medical Biophysics, Schulich School of Medicine & Dentistry, Western University, Canada.
Imaging Research Laboratories, Robarts Research Institute, Schulich School of Medicine & Dentistry, Western University, Canada.
J Biomech. 2018 May 17;73:238-242. doi: 10.1016/j.jbiomech.2018.03.033. Epub 2018 Mar 29.
Radiostereometric analysis (RSA) is a highly accurate technique used to provide three-dimensional (3D) measurements of orthopaedic implant migration for clinical research applications, yet its implementation in routine clinical examinations has been limited. Previous studies have introduced a modified RSA procedure that separates the calibration examinations from the patient examinations, allowing routine clinical radiographs to be analyzed using RSA. However, in order to calibrate the wide range of clinical views, a new calibration object is required. In this study, a universal, isotropic calibration object was designed to calibrate any pair of radiographic views used in the clinic for RSA. A numerical simulation technique was used to design the calibration object, followed by a phantom validation test of a prototype to verify the performance of the novel object, and to compare the measurement reliability to the conventional calibration cage. The 3D bias for the modified calibration method using the new calibration object was 0.032 ± 0.006 mm, the 3D repeatability standard deviation was 0.015 mm, and the 3D repeatability limit was 0.042 mm. Although statistical differences were present between the universal calibration object and the conventional cage, the differences were considered to be not clinically meaningful. The 3D bias and repeatability values obtained using the universal calibration object were well under the threshold acceptable for RSA, therefore it was successfully validated. The universal calibration object will help further the adoption of RSA into a more routine practice, providing the opportunity to generate quantitative databases on joint replacement performance.
放射性立体测量分析（RSA）是一种高度精确的技术，用于为临床研究应用提供骨科植入物移位的三维（3D）测量，但它在常规临床检查中的应用一直有限。先前的研究引入了一种改良的RSA程序，将校准检查与患者检查分开，从而可以使用RSA分析常规临床X光片。然而，为了校准广泛的临床视图，需要一个新的校准物体。在本研究中，设计了一种通用的各向同性校准物体，用于校准临床中用于RSA的任何一对X光视图。使用数值模拟技术设计校准物体，随后对原型进行体模验证测试，以验证该新型物体的性能，并将测量可靠性与传统校准笼进行比较。使用新校准物体的改良校准方法的3D偏差为0.032±0.006毫米，3D重复性标准差为0.015毫米，3D重复性极限为0.042毫米。虽然通用校准物体与传统校准笼之间存在统计学差异，但这些差异被认为在临床上无意义。使用通用校准物体获得的3D偏差和重复性值远低于RSA可接受的阈值，因此它得到了成功验证。通用校准物体将有助于推动RSA在更常规实践中的应用，为生成关于关节置换性能的定量数据库提供机会。
