Niesen Abigail E, Garverick Anna L, Howell Stephen M, Hull Maury L
Department of Biomedical Engineering, University of California, One Shields Avenue, Davis, CA 95616, USA.
Department of Biomedical Engineering, University of California, One Shields Avenue, Davis, CA 95616, USA; Department of Mechanical Engineering, University of California, One Shields Avenue, Davis, CA 95616, USA; Department of Orthopaedic Surgery, University of California Davis Medical Center, 4860 Y Street, Suite 3800, Sacramento CA, 95817, USA.
J Biomech. 2020 Dec 2;113:110078. doi: 10.1016/j.jbiomech.2020.110078. Epub 2020 Nov 5.
Accuracy of model-based radiostereometric analysis (MBRSA) in calculating tibial baseplate migration depends on baseplate shape and orientation relative to the imaging planes. The primary objectives were to introduce a new method for determining the optimal baseplate orientation to minimize bias error during MBRSA and to demonstrate the clinical usefulness of the method using a knee positioning guide to repeatably orient the baseplate. A tibia phantom was rotated to achieve 24 different orientations with three pairs of radiographs acquired at each orientation. Radiographs were processed in MBRSA software and the mean maximum total point motion (MTPM), an indicator of bias error during model registration, was plotted as a function of the rotation angles to determine the optimal orientation and a range of acceptable orientations. The bias error decreased 85% between the reference orientation and the optimal orientation. An acceptable range of orientations was defined by a decrease in bias error more than 50%. Future researchers can use this method to determine the optimal orientation and a range of acceptable orientations for their specific baseplate to minimize bias error. Clinical usefulness was demonstrated by repeatedly imaging a knee model placed in a knee positioning guide (simulated clinical positioning) and demonstrating that the mean orientation ± one standard deviation fell within the acceptable range of orientations. Thus, use of a knee positioning guide was an effective tool for repeatable patient positioning and should be considered for future RSA studies to maintain consistent positioning during a longitudinal study.
基于模型的放射立体测量分析（MBRSA）在计算胫骨基板移位时的准确性取决于基板形状以及相对于成像平面的方向。主要目的是引入一种新方法来确定最佳基板方向，以在MBRSA期间最小化偏差误差，并使用膝关节定位导向器来可重复地定向基板，从而证明该方法的临床实用性。将一个胫骨模型旋转以获得24种不同方向，每个方向采集三对X线片。在MBRSA软件中处理X线片，并将平均最大总点运动（MTPM，模型配准期间偏差误差的一个指标）绘制为旋转角度的函数，以确定最佳方向和可接受方向范围。在参考方向和最佳方向之间，偏差误差降低了85%。通过偏差误差降低超过50%来定义可接受的方向范围。未来的研究人员可以使用此方法为其特定基板确定最佳方向和可接受方向范围，以最小化偏差误差。通过对放置在膝关节定位导向器中的膝关节模型进行重复成像（模拟临床定位），并证明平均方向±一个标准差落在可接受方向范围内，证明了其临床实用性。因此，使用膝关节定位导向器是进行可重复患者定位的有效工具，在未来的RSA研究中应予以考虑，以便在纵向研究期间保持一致的定位。
