Department of Neurosurgery, University of Virginia, Charlottesville, VA 22903, USA.
Spinologics Inc., Montreal, Quebec, Canada.
Clin Biomech (Bristol). 2021 Apr;84:105326. doi: 10.1016/j.clinbiomech.2021.105326. Epub 2021 Mar 17.
Bracing and spinal fusion surgery have long been the primary methods for idiopathic scoliosis correction; however, there exist multiple limitations with both techniques. Growth modulation techniques have recently been attempted, but are typically performed across multiple vertebral elements. The aim of this study was to quantify the corrective abilities of a dual-angled, wedge shaped, rigid disc implant designed to correct spinal deformity.
The 3D spinal geometry of four patients was reconstructed using calibrated radiographs, from which personal finite element models were created. Coronal and sagittal Cobb angles and axial stress distribution were calculated pre- and post- simulation of device implantation at the apical vertebral element.
Insertion of a rigid wedged implant resulted in up to 90.1% coronal correction with kyphotic normalization, and reduced axial stress differential within adjacent vertebrae by up to 83.3%. This correction in axial stress differential was seen to propagate to subjacent vertebrae in both rostral and caudal directions. Insertion of two implants yielded greater correction with respect to all three measures.
Local Cobb angle correction, increased kyphotic angle, and a decrease in axial stress differential with adjacent and subjacent vertebral levels demonstrate a potential for deformity correction from within the disc space. The decrease in axial stress differential demonstrates a capacity for growth modulation and reversal of the Heuter-Volkmann principle. Based on qualitative views of spinal shape following device implantation, the wedged implant proved more efficacious in correcting single thoracic curves than double major curves.
支具和脊柱融合术一直是特发性脊柱侧凸矫正的主要方法；然而，这两种技术都存在多种局限性。生长调节技术最近已经尝试过，但通常在多个椎骨元素上进行。本研究的目的是量化一种双角度、楔形、刚性椎间盘植入物矫正脊柱畸形的矫正能力。
使用校准的射线照片重建了四名患者的三维脊柱几何形状，并由此创建了个人有限元模型。在模拟器械植入到顶点椎骨之前和之后，计算了冠状和矢状 Cobb 角以及轴向应力分布。
刚性楔形植入物的插入导致冠状面矫正高达 90.1%，伴有后凸的正常化，并且相邻椎骨的轴向应力差减少了高达 83.3%。这种轴向应力差的矫正被认为在颅侧和尾侧两个方向上传播到下位椎体。插入两个植入物可使所有三个指标的矫正程度更大。
局部 Cobb 角矫正、增加的后凸角以及相邻和下位椎体轴向应力差的降低表明在椎间盘间隙内有矫正畸形的潜力。轴向应力差的降低表明了生长调节的能力和 Heuter-Volkmann 原理的逆转。基于器械植入后脊柱形状的定性观察，楔形植入物在矫正单胸弯方面比双重大弯更有效。
