Image-based subject-specific models and simulations are recently being introduced to complement current state-of-the-art mostly static insights of the adult spinal deformity (ASD) pathology and improve the often poor surgical outcomes. Although the accuracy of a recently developed subject-specific modeling and simulation framework has already been quantified, its reliability to perform marker-driven kinematic analyses has not yet been investigated. The aim of this work was to evaluate the reliability of this subject-specific framework to measure spine kinematics in ASD patients, in terms of 1) the overall test-retest repeatability; 2) the inter-operator agreement of spine kinematic estimates; and, 3) the uncertainty of those spine kinematics to operator-dependent parameters of the framework. To evaluate the overall repeatability 1], four ASD subjects and one control subject participated in a test-retest study with a 2-week interval. At both time instances, subject-specific spino-pelvic models were created by one operator to simulate a recorded forward trunk flexion motion. Next, to evaluate inter-operator agreement 2], three trained operators each created a model for three ASD subjects to simulate the same forward trunk flexion motion. Intraclass correlation coefficients (ICC's) of the range of motion (ROM) of conventional spino-pelvic parameters [lumbar lordosis (LL), sagittal vertical axis (SVA), thoracic kyphosis (TK), pelvic tilt (PT), T1-and T9-spino-pelvic inclination (T1/T9-SPI)] were used to evaluate kinematic reliability 1] and inter-operator agreement 2]. Lastly, a Monte-Carlo probabilistic simulation was used to evaluate the uncertainty of the intervertebral joint kinematics to operator variability in the framework, for three ASD subjects 3]. LL, SVA, and T1/T9-SPI had an excellent test-retest reliability for the ROM, while TK and PT did not. Inter-operator agreement was excellent, with ICC values higher than test-retest reliability. These results indicate that operator-induced uncertainty has a limited impact on kinematic simulations of spine flexion, while test-retest reliability has a much higher variability. The definition of the intervertebral joints in the framework was identified as the most sensitive operator-dependent parameter. Nevertheless, intervertebral joint estimations had small mean 90% confidence intervals (1.04°-1.75°). This work will contribute to understanding the limitations of kinematic simulations in ASD patients, thus leading to a better evaluation of future hypotheses.

中文翻译：

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特定主题的脊柱骨盆模型在成人脊柱畸形的坐姿前弯期间可靠地测量脊柱运动学。

最近引入了基于图像的特定主题模型和模拟，以补充目前最先进的成人脊柱畸形 (ASD) 病理学的大多数静态见解，并改善通常较差的手术结果。尽管最近开发的特定主题建模和模拟框架的准确性已经被量化，但其执行标记驱动的运动学分析的可靠性尚未得到研究。这项工作的目的是评估这个特定主题框架的可靠性，以测量 ASD 患者的脊柱运动，就以下方面而言：1）整体测试 - 再测试的可重复性；2) 脊柱运动学估计的操作者间一致性；并且，3）那些脊柱运动学对框架的依赖于操作员的参数的不确定性。评估整体可重复性 1]，四名 ASD 受试者和一名对照受试者以 2 周的间隔参加了重新测试研究。在这两种情况下，一名操作员创建了特定于受试者的脊柱骨盆模型，以模拟记录的躯干前屈运动。接下来，为了评估操作员间的一致性 2]，三名训练有素的操作员分别为三个 ASD 受试者创建了一个模型，以模拟相同的躯干前屈运动。传统脊柱骨盆参数的运动范围 (ROM) 的组内相关系数 (ICC) [腰椎前凸 (LL)、矢状垂直轴 (SVA)、胸椎后凸 (TK)、骨盆倾斜 (PT)、T1 和 T9 -脊柱骨盆倾角 (T1/T9-SPI)] 用于评估运动可靠性 1] 和操作者间协议 2]。最后，蒙特卡罗概率模拟用于评估椎间关节运动学对框架中操作员可变性的不确定性，对于三个 ASD 受试者 3]。LL、SVA 和 T1/T9-SPI 具有出色的 ROM 重测可靠性，而 TK 和 PT 则没有。操作员间的一致性非常好，ICC 值高于重测信度。这些结果表明，操作员引起的不确定性对脊柱屈曲运动学模拟的影响有限，而重测可靠性具有更高的可变性。框架中椎间关节的定义被确定为最敏感的依赖于操作者的参数。尽管如此，椎间关节估计的平均 90% 置信区间很小 (1.04°-1.75°)。