Cobetto Nikita, Aubin Carl-Eric, Parent Stefan
Department of Mechanical Engineering, Polytechnique Montréal, P.O. Box 6079, Downtown Station, Montreal, Quebec H3C 3A7, Canada; Research Center, Sainte-Justine University Hospital Center, 3175 Côte-Sainte-Catherine Road, Montreal, Quebec H3T 1C5, Canada.
Department of Mechanical Engineering, Polytechnique Montréal, P.O. Box 6079, Downtown Station, Montreal, Quebec H3C 3A7, Canada; Research Center, Sainte-Justine University Hospital Center, 3175 Côte-Sainte-Catherine Road, Montreal, Quebec H3T 1C5, Canada.
Spine Deform. 2018 Sep-Oct;6(5):507-513. doi: 10.1016/j.jspd.2018.01.013.
Computational simulation of lateral decubitus and anterior vertebral body growth modulation (AVBGM).
To biomechanically evaluate lateral decubitus and cable tensioning contributions on intra- and postoperative correction.
AVBGM is a compression-based fusionless procedure to treat progressive pediatric scoliosis. During surgery, the patient is positioned in lateral decubitus, which reduces spinal curves. The deformity is further corrected with the application of compression by cable tensioning. Predicting postoperative correction following AVBGM installation remains difficult.
Twenty pediatric scoliotic patients instrumented with AVBGM were recruited. Three-dimensional (3D) reconstructions obtained from calibrated biplanar radiographs were used to generate a personalized finite element model. Intraoperative lateral decubitus position and installation of AVBGM were simulated to evaluate the intraoperative positioning and cable tensioning (100 / 150 / 200 N) relative contribution on intra- and postoperative correction.
Average Cobb angles prior to surgery were 56° ± 10° (thoracic) and 38° ± 8° (lumbar). Simulated presenting growth plate's stresses were of 0.86 MPa (concave side) and 0.02 MPa (convex side). The simulated lateral decubitus reduced Cobb angles on average by 30% (thoracic) and 18% (lumbar). Cable tensioning supplementary contribution on intraoperative spinal correction was of 15%, 18%, and 24% (thoracic) for 100, 150, and 200 N, respectively. Simulated Cobb angles for the postoperative standing position were 39°, 37°, and 33° (thoracic) and 30°, 29°, and 28° (lumbar), respectively, whereas growth plate's stresses were of 0.54, 0.53, and 0.51 MPa (concave side) and 0.36, 0.53, and 0.68 MPa (convex side) for the three tensions.
The majority of curve correction was achieved by lateral decubitus positioning. The main role of the cable was to apply supplemental periapical correction and secure the intraoperative positioning correction. Increases in cable tensioning furthermore rebalanced initially asymmetric compressive stresses. This study could help improve the design of AVBGM by understanding the contributions of the surgical procedure components to the overall correction achieved.
Level III.
侧卧位及椎体前路生长调节（AVBGM）的计算机模拟。
从生物力学角度评估侧卧位及缆线张紧对术中及术后矫正的作用。
AVBGM是一种基于压缩的非融合手术，用于治疗进展性小儿脊柱侧弯。手术过程中，患者采取侧卧位，这可减小脊柱侧弯角度。通过缆线张紧施加压缩力可进一步矫正畸形。预测AVBGM植入术后的矫正效果仍然困难。
招募20例接受AVBGM治疗的小儿脊柱侧弯患者。利用校准后的双平面X线片获得的三维（3D）重建影像生成个性化有限元模型。模拟术中侧卧位及AVBGM植入过程，以评估术中体位及缆线张紧（100/150/200N）对术中及术后矫正的相对作用。
术前平均Cobb角为56°±10°（胸椎）和38°±8°（腰椎）。模拟的生长板应力在凹侧为0.86MPa，凸侧为0.02MPa。模拟侧卧位平均使Cobb角减小30%（胸椎）和18%（腰椎）。对于100N、150N和200N的缆线张紧力，其对术中脊柱矫正的补充作用分别为15%、18%和24%（胸椎）。术后站立位模拟的Cobb角分别为39°、37°和33°（胸椎）以及30°、29°和28°（腰椎），而三种张紧力下生长板应力在凹侧分别为0.54MPa、0.53MPa和0.51MPa，凸侧分别为0.36MPa、0.53MPa和0.68MPa。
大部分的侧弯矫正通过侧卧位实现。缆线的主要作用是进行补充性的根尖周矫正并确保术中体位矫正。增加缆线张紧力还可重新平衡最初不对称的压缩应力。本研究通过了解手术过程各组成部分对整体矫正效果的作用，有助于改进AVBGM的设计。
III级。
