BACKGROUND DHS is characterized by chin-on-chest deformity and devastatingly impedes activities of daily living in affected individuals. There is a paucity of literature about the pathophysiology of DHS including knowledge about spinal sagittal alignment. We conducted this study to clarify the relationship between cervical sagittal alignment and global sagittal balance in DHS. METHODS This is a retrospective radiographic study of a case series of DHS. Forty-one patients with diagnosed DHS were enrolled. Measurements were made using lateral standing radiograph. RESULTS C2-C7 sagittal vertical axis (SVA) was estimated as 52.0 ± 2.4 mm. Among sagittal parameters, C7-S1 SVA positively correlated with C2-C7 angle (C2-C7 A) (r = 0.33). For the correlations between C7 and S1 SVA and C2-C7 A, both logistic and linear regression models were used to determine the threshold for C2-C7 A value responsible for global sagittal balance. C2-C7 A of - 15.0 and 6.0 were predicted by logistic and linear regression models and were considered responsible for the occurrence of global positive imbalance. Therefore, we divided into two groups, namely, cervical kyphosis group (C type) and diffuse kyphosis group (D type) by median value of C2-C7 A. Enlarged thoracic kyphosis and global positive imbalance were observed in D type compared to C type. CONCLUSION C2-C7 A exhibited correlations with cervical balance and also with global balance. There should be various type of thoraco-lumbar alignment in DHS. These slides can be retrieved under Electronic Supplementary Material.

中文翻译：

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掉头综合征患者的颈椎与整体矢状位平衡之间的关系。

背景技术DHS的特征是下巴胸部畸形，并严重阻碍了受影响个体的日常生活。关于DHS的病理生理学的文献很少，包括有关脊柱矢状位对准的知识。我们进行了这项研究，以阐明DHS中颈椎矢状位对准与总体矢状位平衡之间的关系。方法这是对DHS病例系列的回顾性射线照相研究。入选了诊断为DHS的41例患者。使用侧向放射线照相进行测量。结果C2-C7矢状垂直轴（SVA）估计为52.0±2.4毫米。在矢状参数中，C7-S1 SVA与C2-C7角（C2-C7 A）正相关（r = 0.33）。对于C7和S1 SVA和C2-C7 A之间的相关性，逻辑模型和线性回归模型均用于确定导致总体矢状平衡的C2-C7 A阈值。Logistic和线性回归模型预测的C2-C7 A分别为-15.0和6.0，被认为是造成整体正失衡的原因。因此，根据C2-C7 A的中位数，我们将其分为颈椎后凸畸形组（C型）和弥漫性后凸畸形组（D型）。与C型相比，D型胸椎后凸畸形和总体正平衡失调。结论C2-C7 A表现出与颈椎平衡以及整体平衡的相关性。在DHS中应该有各种类型的胸腰对准。这些幻灯片可以在电子补充材料下找到。Logistic和线性回归模型预测的C2-C7 A分别为-15.0和6.0，被认为是造成整体正失衡的原因。因此，根据C2-C7 A的中位数，我们将其分为颈椎后凸畸形组（C型）和弥漫性后凸畸形组（D型）。与C型相比，D型胸椎后凸畸形和总体正平衡失调。结论C2-C7 A表现出与颈椎平衡以及整体平衡的相关性。在DHS中应该有各种类型的胸腰对准。这些幻灯片可以在电子补充材料下找到。Logistic和线性回归模型预测的C2-C7 A分别为-15.0和6.0，被认为是造成整体正失衡的原因。因此，根据C2-C7 A的中位数，我们分为颈椎后凸畸形组（C型）和弥漫性后凸畸形组（D型）。与C型相比，D型胸椎后凸畸形和总体阳性失衡。结论C2-C7 A表现出与颈椎平衡以及整体平衡的相关性。在DHS中应该有各种类型的胸腰对准。这些幻灯片可以在电子补充材料下找到。颈椎后凸畸形组（C型）和弥漫性后凸畸形组（D型）的中位数为C2-C7A。与C型相比，D型胸椎后凸畸形和整体正平衡失调。结论C2-C7 A表现出与颈椎平衡以及整体平衡的相关性。在DHS中应该有各种类型的胸腰对准。这些幻灯片可以在电子补充材料下找到。颈椎后凸畸形组（C型）和弥漫性后凸畸形组（D型）的中位数为C2-C7A。与C型相比，D型胸椎后凸畸形和整体正平衡失调。结论C2-C7 A表现出与颈椎平衡以及整体平衡的相关性。在DHS中应有各种胸腰对准方式。这些幻灯片可以在电子补充材料下找到。