前椎体束缚(VBT)是针对选定的青少年特发性脊柱侧凸患者的新型无融合治疗选择,正在引起广泛的兴趣。这项研究的主要目的是研究VBT内系绳预张力对脊柱生物力学的影响,包括矢状和横向参数以及主要运动,耦合运动,和应力作用在L2上端板。为此,我们使用了经过校准和验证的L1-L2脊柱有限元模型.将VBT仪器插入L1-L2段的左侧,并在不同方向上承受6Nm的外部纯力矩。从VBT后的初始位置测量仪器脊柱的运动范围(ROM)。本机脊柱和VBT仪器的ROM的大小,预张力为100N,200N,300N,分别,3.29°,2.35°,延伸1.90°和1.61°,3.30°,3.46°,2.79°,屈曲2.17°,2.11°,1.67°,右轴向旋转1.33°和1.06°,和2.10°,1.88°,左轴向旋转1.48°和1.16°。在屈伸期间,在天然脊柱中观察到微不足道的耦合横向弯曲运动。然而,预张力为100N的VBT仪表,200N,和300N产生0.85°的耦合右侧弯曲,0.81°,和0.71°时的延伸和耦合左横向弯曲0.32°,0.24°,屈曲时0.19°,分别。在横向弯曲期间,在原生脊柱中观察到0.33-0.40°的耦合延伸运动,但是预张力为100N的VBT仪器,200N,和300N产生0.67°的耦合屈曲,0.58°,在左侧(植入物的侧面)横向弯曲和1.28°的耦合延伸期间,为0.42°,1.07°,右侧弯曲时0.87°,分别。因此,椎体束缚产生耦合运动。椎体内的系带预张紧减少了脊柱的运动。
Anterior Vertebral Body Tethering (VBT) is a novel fusionless treatment option for selected adolescent idiopathic scoliosis patients which is gaining widespread interest. The primary objective of this study is to investigate the effects of tether pre-tension within VBT on the biomechanics of the spine including sagittal and transverse parameters as well as primary motion, coupled motion, and stresses acting on the L2 superior endplate. For that purpose, we used a calibrated and validated Finite Element model of the L1-L2 spine. The VBT instrumentation was inserted on the left side of the L1-L2 segment with different cord pre-tensions and submitted to an external pure moment of 6 Nm in different directions. The range of motion (ROM) for the instrumented spine was measured from the initial post-VBT position. The magnitudes of the ROM of the native spine and VBT-instrumented with pre-tensions of 100 N, 200 N, and 300 N were, respectively, 3.29°, 2.35°, 1.90° and 1.61° in extension, 3.30°, 3.46°, 2.79°, and 2.17° in flexion, 2.11°, 1.67°, 1.33° and 1.06° in right axial rotation, and 2.10°, 1.88°, 1.48° and 1.16° in left axial rotation. During flexion-extension, an insignificant coupled lateral bending motion was observed in the native spine. However, VBT instrumentation with pre-tensions of 100 N, 200 N, and 300 N generated coupled right lateral bending of 0.85°, 0.81°, and 0.71° during extension and coupled left lateral bending of 0.32°, 0.24°, and 0.19° during flexion, respectively. During lateral bending, a coupled extension motion of 0.33-0.40° is observed in the native spine, but VBT instrumentation with pre-tensions of 100 N, 200 N, and 300 N generates coupled flexion of 0.67°, 0.58°, and 0.42° during left (side of the implant) lateral bending and coupled extension of 1.28°, 1.07°, and 0.87° during right lateral bending, respectively. Therefore, vertebral body tethering generates coupled motion. Tether pre-tension within vertebral body tethering reduces the motion of the spine.