Luo Ming, Jiang Honghui, Wang Wengang, Li Ning, Shen Mingkui, Li Peng, Xu Genzhong, Xia Lei
Institute of Spinal Deformity, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, 450052, People's Republic of China.
Department of Orthopaedic Surgery, Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science & Technology, Wuhan, People's Republic of China.
BMC Musculoskelet Disord. 2017 Dec 13;18(1):526. doi: 10.1186/s12891-017-1877-6.
Previous studies have reported that rod composition and diameter, as well as the correction technique are key factors associated with thoracic kyphosis (TK) restoration. However, few study has analyzed the correlation between screw density and TK restoration in hypokyphotic adolescent idiopathic scoliosis (AIS).
Fifty-seven thoracic AIS patients with preoperative TK < 10° treated with all pedicle screw fixation with a minimum 2-year follow-up were recruited. Preoperative and postoperative radiographic measurements, and information of posterior instrumentation were reviewed. Pearson and Spearman correlation coefficient analysis were used to assess relationships between change in TK and number of variables. Then, the included patients were classified into two groups (Group 1: postoperative TK ≥ 20°; Group 2: postoperative TK < 20°) to evaluate the influence factors of TK restoration.
The average preoperative TK was 4.75°, which was significantly restored to 17.30° (P < 0.001). Significant correlations were found between change in TK and flexibility of major thoracic curve (r = 0.357, P = 0.006), preoperative TK (r = -0.408, P = 0.002), and screw density of concave side (r = 0.306, P = 0.021), respectively. In the subgroup comparison, 17 patients (29.8%) maintain the postoperative TK ≥ 20°, increased flexibility of major thoracic curve (P < 0.001), screw number of concave side (P = 0. 029), and cobalt chromium rods (P = 0.041) were found in the group of postoperative TK ≥ 20°.
TK restoration remains a challenge for AIS patients with hypokyphosis, especially for the poor flexibility ones. Except for thicker and cobalt chromium rods, screw density of concave side might be another positive predictor of restoring normal kyphosis, which provides a stronger corrective force on the sagittal plane with more pedicle screws.
既往研究报道，棒的组成和直径以及矫正技术是与胸椎后凸（TK）恢复相关的关键因素。然而，很少有研究分析低后凸青少年特发性脊柱侧凸（AIS）中螺钉密度与TK恢复之间的相关性。
招募了57例术前TK＜10°且接受全椎弓根螺钉固定治疗并至少随访2年的胸椎AIS患者。回顾术前和术后的影像学测量结果以及后路内固定信息。采用Pearson和Spearman相关系数分析来评估TK变化与多个变量之间的关系。然后，将纳入的患者分为两组（第1组：术后TK≥20°；第2组：术后TK＜20°），以评估TK恢复的影响因素。
术前平均TK为4.75°，显著恢复至17.30°（P＜0.001）。分别在TK变化与胸主弯柔韧性（r = 0.357，P = 0.006）、术前TK（r = -0.408，P = 0.002）以及凹侧螺钉密度（r = 0.306，P = 0.021）之间发现显著相关性。在亚组比较中，17例患者（29.8%）术后TK≥20°，在术后TK≥20°的组中发现胸主弯柔韧性增加（P＜0.001）、凹侧螺钉数量（P = 0.029）以及钴铬棒（P = 0.041）。
对于低后凸的AIS患者，尤其是柔韧性差的患者，TK恢复仍然是一项挑战。除了更粗的棒和钴铬棒外，凹侧螺钉密度可能是恢复正常后凸的另一个积极预测因素，更多的椎弓根螺钉在矢状面上提供更强的矫正力。
