Le Navéaux Franck, Aubin Carl-Eric, Parent Stefan, O Newton Peter, Labelle Hubert
Polytechnique Montreal, Department of Mechanical Engineering, P.O. Box 6079, Downtown Station, Montreal, Quebec, H3C 3A7, Canada.
Research Center, Sainte-Justine University Hospital Center, 3175, Cote Sainte-Catherine Road, Montreal, Quebec, H3T 1C5, Canada.
Eur Spine J. 2017 Jun;26(6):1676-1683. doi: 10.1007/s00586-017-4958-1. Epub 2017 Feb 8.
Flattening of rods is known to reduce the correction capability of the instrumentation, but has not been studied in 3D. The aim is to evaluate the rods shape 3D changes during and immediately after instrumentation, and its effect on 3D correction.
The 5.5 mm CoCr rods of 35 right thoracic adolescent idiopathic scoliosis patients were measured from rod tracings prior to insertion, and reconstructed in 3D from bi-planar radiographs taken intra-operatively after the correction maneuvers and 1 week post-operatively. The rod bending curvature, maximal deflection and orientation of the rod's plane of maximum curvature (RPMC) were computed at each stage. The relation between rod contour, kyphosis and apical vertebral rotation (AVR) was assessed.
Main thoracic Cobb angle was corrected from 58° ± 10° to 15° ± 8°. Prior to insertion, rods were more bent on the concave side (curvature/deflection: 39° ± 8°/25 ± 6 mm) than the convex side (26° ± 5°/17 ± 3 mm). Only the concave rod shape changed after the correction maneuvers execution (flattening of 21° ± 9°/13 ± 7 mm; p < 0.001) and stayed unchanged post-operatively. After instrumentation, the RPMC was deviated from the sagittal plane (concave side: 27° ± 19°/convex side: 15° ± 12°). There was a significant association between kyphosis change and the relative concave rod to spine contour (rod curvature-pre-operative kyphosis) (R = 0.58) and between AVR correction and initial differential concave/convex rods deflection (R = 0.28).
Correction maneuvers induce a significant change of the concave rod profile. Both rods end in a plane deviated from the sagittal plane which is representative of the spinal curvature 3D orientation. Differential rod contouring technique has a significant impact on the resulting thoracic kyphosis and transverse plane correction.
已知棒材变平会降低器械的矫正能力，但尚未在三维空间中进行研究。目的是评估器械植入期间及植入后立即发生的棒材形状三维变化，及其对三维矫正的影响。
对35例右胸青少年特发性脊柱侧凸患者的5.5毫米钴铬合金棒材，在植入前通过棒材描记进行测量，并在矫正操作后术中及术后1周拍摄的双平面X线片上进行三维重建。在每个阶段计算棒材弯曲曲率、最大挠度以及棒材最大曲率平面（RPMC）的方向。评估棒材轮廓、后凸畸形和顶椎旋转（AVR）之间的关系。
主胸弯Cobb角从58°±10°矫正至15°±8°。植入前，棒材在凹侧比凸侧更弯曲（曲率/挠度：39°±8°/25±6毫米）（凸侧为26°±5°/17±3毫米）。在执行矫正操作后，仅凹侧棒材形状发生变化（变平21°±9°/13±7毫米；p<0.001），术后保持不变。器械植入后，RPMC偏离矢状面（凹侧：27°±19°/凸侧：15°±12°）。后凸畸形变化与相对凹侧棒材与脊柱轮廓（棒材曲率-术前后凸畸形）之间存在显著相关性（R=0.58），AVR矫正与初始凹/凸侧棒材挠度差异之间存在显著相关性（R=0.28）。
矫正操作会导致凹侧棒材轮廓发生显著变化。两根棒材最终都位于偏离矢状面的平面内，这代表了脊柱曲率的三维方向。差异棒材塑形技术对最终的胸段后凸畸形和矢状面矫正有显著影响。
