Centre for Spinal Studies and Surgery, Queen's Medical Centre, Nottingham, UK.
University of Nottingham, AR UK Centre for Sports Exercise and Osteoarthritis, Nottingham, UK.
Bone Joint J. 2020 Apr;102-B(4):513-518. doi: 10.1302/0301-620X.102B4.BJJ-2019-1069.R1.
Significant correction of an adolescent idiopathic scoliosis in the coronal plane through a posterior approach is associated with hypokyphosis. Factors such as the magnitude of the preoperative coronal curve, the use of hooks, number of levels fused, preoperative kyphosis, screw density, and rod type have all been implicated. Maintaining the normal thoracic kyphosis is important as hypokyphosis is associated with proximal junctional failure (PJF) and early onset degeneration of the spine. The aim of this study was to determine if coronal correction per se was the most relevant factor in generating hypokyphosis.
A total of 95 patients (87% female) with a median age of 14 years were included in our study. Pre- and postoperative radiographs were measured and the operative data including upper instrumented vertebra (UIV), lower instrumented vertebra (LIV), metal density, and thoracic flexibility noted. Further analysis of the post-surgical coronal outcome (group 1 < 60% correction and group 2 ≥ 60%) were studied for their association with the postoperative kyphosis in the sagittal plane using univariate and multivariate logistic regression.
Of the 95 patients, 71.6% (68) had a thoracic correction of > 60%. Most (97.8%) had metal density < 80%, while thoracic flexibility > 50% was found in 30.5% (29). Preoperative hypokyphosis (< 20°) was present in 25.3%. A postoperative thoracic hypokyphosis was four times more likely to occur in patients with thoracic correction ≥ 60% (odds ratio (OR) 4.08; p = 0.005), after adjusting for confounding variables. This association was not affected by metal density, thoracic flexibility, LIV, UIV, age, or sex.
Our study supports the 'essential lordosis' hypothesis of Roaf and Dickson, i.e. with a greater ability to translate the apical vertebra towards the midline, there is a commensurate lengthening of the anterior column due to the vertebral wedging. Cite this article: 2020;102-B(4):513-518.
通过后路矫形显著矫正冠状面青少年特发性脊柱侧凸会导致后凸减少。术前冠状面曲线的大小、钩的使用、融合节段的数量、术前后凸、螺钉密度和棒的类型等因素都与后凸减少有关。保持正常的胸椎后凸很重要，因为后凸减少与近端交界性失败（PJF）和脊柱早期退变有关。本研究的目的是确定冠状面矫正本身是否是导致后凸减少的最相关因素。
共纳入 95 例患者（87%为女性），中位年龄为 14 岁。测量术前和术后 X 线片，并记录手术数据，包括上固定椎（UIV）、下固定椎（LIV）、金属密度和胸椎灵活性。进一步分析术后冠状面结果（组 1<60%矫正，组 2≥60%矫正）与术后矢状面后凸的关系，采用单变量和多变量逻辑回归分析。
95 例患者中，68 例（71.6%）胸椎矫正度>60%。大多数患者（97.8%）金属密度<80%，而胸椎灵活性>50%的患者占 30.5%（29 例）。术前存在轻度后凸（<20°）的患者占 25.3%。在调整混杂变量后，胸椎矫正度≥60%的患者发生术后胸椎后凸的可能性是对照组的 4 倍（优势比（OR）4.08；p=0.005）。这种相关性不受金属密度、胸椎灵活性、LIV、UIV、年龄或性别影响。
本研究支持 Roaf 和 Dickson 的“基本前凸”假说，即通过增加顶椎向中线的平移能力，椎体楔形导致前柱相应延长。
