What is the optimal cutoff value of the axis-line-angle technique for evaluating trunk imbalance in coronal plane?

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• 作者：Rui-Fang Zhang ; MD^a ; Yu-Chuan Fu ; MD^b ; Yi Lu ; MD^b ; Xiao-Xia Zhang ; MD^b ; Yu-Min Hu ; MD^b ; Yong-Jin Zhou ; MD^b ; Nai-Feng Tian ; MD^c ; Jia-Wei He ; MD^b ; ; Zhi-Han Yan ; MD^b ; ^{yanzhihanwz@163.com}
• 关键词：Central sacral vertical line ; Coronal balance ; Interobserver agreement ; Radiography ; Spine ; Kappa statistic
• 刊名：The Spine Journal
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：17
• 期：2
• 页码：230-235
• 全文大小：430 K
• 卷排序：17

文摘

Accurately evaluating the extent of trunk imbalance in the coronal plane is significant for patients before and after treatment. We preliminarily practiced a new method, axis-line-angle technique (ALAT), for evaluating coronal trunk imbalance with excellent intra-observer and interobserver reliability. Radiologists and surgeons were encouraged to use this method in clinical practice. However, the optimal cutoff value of the ALAT for determination of the extent of coronal trunk imbalance has not been calculated up to now.PurposeThe purpose of this study was to identify the cutoff value of the ALAT that best predicts a positive measurement point to assess coronal balance or imbalance.Study Design/SettingA retrospective study at a university affiliated hospital was carried out.Patient SampleA total of 130 patients with C7-central sacral vertical line (CSVL) >0 mm and aged 10–18 years were recruited in this study from September 2013 to December 2014.Outcome MeasuresData were analyzed to determine the optimal cutoff value of the ALAT measurement.MethodsThe C7-CSVL and ALAT measurements were conducted respectively twice on plain film within a 2-week interval by two radiologists. The optimal cutoff value of the ALAT was analyzed via receiver operating characteristic (ROC) curve. Comparison variables were performed with chi-square test between the C7-CSVL and ALAT measurements for evaluating trunk imbalance. Kappa agreement coefficient method was used to test the intra-observer and interobserver agreement of C7-CSVL and ALAT.ResultsThe ROC curve area for the ALAT was 0.82 (95% confidence interval: 0.753–0.894, p<.001). The maximum Youden index was 0.51, and the corresponding cutoff point was 2.59°. No statistical difference was found between the C7-CSVL and ALAT measurements for evaluating trunk imbalance (p>.05). Intra-observer agreement values for the C7-CSVL measurements by observers 1 and 2 were 0.79 and 0.91 (p<.001), respectively, whereas intra-observer agreement values for the ALAT measurements were both 0.89 by observers 1 and 2 (p<.001). The interobserver agreement values for the first and second measurements with the C7-CSVL were 0.78 and 0.85 (p<.001), respectively, whereas the interobserver agreement values for the first and second measurements with the ALAT were 0.91 and 0.88 (p<.001), respectively.ConclusionsThe newly developed ALAT provided an acceptable optimal cutoff value for evaluating trunk imbalance in the coronal plane with a high level of intra-observer and interobserver agreement, which suggests that the ALAT is suitable for clinical use.