REPRODUCIBILITY AND EQUIVALENCE OF COBBMETER APPLICATION IN THE SAGITTAL EVALUATION OF THE SPINE

ABSTRACT Objective: This study aims to evaluate the reliability and equivalency of using the Cobbmeter application for iPhone compared to the manual measurement method in the analysis of the sagittal spinal alignment. Methods: Cross-sectional, prospective, single-center study that had 20 panoramic radiographs of the spine in lateral view, in a neutral standing position, analyzed blindly and randomly by three independent examiners in three different times. The parameters were pelvic incidence (PI), pelvic tilt (PT) and lumbar lordosis (LL). The statistical analysis was performed to measure the intraclass correlation coefficient (ICC) between the two measurement methods, in addition to measuring the intra and inter-evaluators reliability. Results: For reproducibility analysis, the intra-evaluators ICC using the application resulted in a Kappa (K) of 0.975 for the evaluation of pelvic incidence (PI) evaluation. For pelvic tilt (PT), the K value obtained was 0.981 and the K measured for lumbar lordosis (LL) analysis was 0.987. The inter-evaluators evaluation of reproducibility using the application resulted in a K value of 0.917 for PI, 0.930 for PT and 0.951 for LL. For the assessment of equivalency of methods, comparing the application to the standard method, with a goniometer and dermographic pencil, the K value found for PI was 0.873, for PV was 0.939 and for LL was 0.914. All values were significant (p<0.001) against the null hypothesis. Conclusion: This smartphone application is a valid and reliable instrument for measuring the angle involved in the sagittal balance of the spine. Furthermore, the results show that its applicability is not inferior to the manual method with goniometer and dermographic pencil.

摘要 目的：本研究旨在评估iPhone版Cobbmeter应用程序（Cobbmeter application）用于脊柱矢状面排列分析时，与手工测量方法的可靠性及等效性。
方法：本研究为横断面、前瞻性单中心研究，纳入20张中立站立位脊柱侧位全景放射片，由3名独立检查者在3个不同时间点进行盲法随机分析。测量参数包括骨盆入射角（pelvic incidence, PI）、骨盆倾斜角（pelvic tilt, PT）及腰椎前凸角（lumbar lordosis, LL）。本研究采用统计学分析方法，计算两种测量方法的组内相关系数（intraclass correlation coefficient, ICC），同时评估检查者内部及检查者间的可靠性。
结果：在可重复性分析中，使用该应用程序的检查者内部ICC结果显示，骨盆入射角（PI）评估的Kappa值为0.975；骨盆倾斜角（PT）的Kappa值为0.981；腰椎前凸角（LL）分析的Kappa值为0.987。使用该应用程序的检查者间可重复性评估结果显示，PI的Kappa值为0.917，PT为0.930，LL为0.951。在两种方法等效性评估中，将该应用程序与使用测角计及皮肤标记笔的标准手工测量方法进行比较，PI的Kappa值为0.873，PT为0.939，LL为0.914。所有结果均拒绝原假设，具有统计学意义（p<0.001）。
结论：本智能手机应用程序是一种用于测量脊柱矢状面平衡相关角度的有效且可靠的工具。此外，结果表明其适用性并不劣于使用测角计及皮肤标记笔的手工测量方法。