Little J P, Izatt M T, Labrom R D, Askin G N, Adam C J
Paediatric Spine Research Group, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia.
Clin Biomech (Bristol). 2012 Jun;27(5):415-21. doi: 10.1016/j.clinbiomech.2011.12.004. Epub 2012 Jan 4.
Adolescent idiopathic scoliosis is a complex three-dimensional deformity, involving a lateral deformity in the coronal plane and axial rotation of the vertebrae in the transverse plane. Gravitational loading plays an important biomechanical role in governing the coronal deformity, however, less is known about how they influence the axial deformity. This study investigates the change in three-dimensional deformity of a series of scoliosis patients due to compressive axial loading.
Magnetic resonance imaging scans were obtained and coronal deformity (measured using the coronal Cobb angle) and axial rotations measured for a group of 18 scoliosis patients (Mean major Cobb angle was 43.4°). Each patient was scanned in an unloaded and loaded condition while compressive loads equivalent to 50% body mass were applied using a custom developed compressive device.
The mean increase in major Cobb angle due to compressive loading was 7.4° (SD 3.5°). The most axially rotated vertebra was observed at the apex of the structural curve and the largest average intravertebral rotations were observed toward the limits of the coronal deformity. A level-wise comparison showed no significant difference between the average loaded and unloaded vertebral axial rotations (intra-observer error=2.56°) or intravertebral rotations at each spinal level.
This study suggests that the biomechanical effects of axial loading primarily influence the coronal deformity, with no significant change in vertebral axial rotation or intravertebral rotation observed between the unloaded and loaded condition. However, the magnitude of changes in vertebral rotation with compressive loading may have been too small to detect given the resolution of the current technique.
青少年特发性脊柱侧凸是一种复杂的三维畸形，包括冠状面的侧向畸形和横平面中椎体的轴向旋转。重力负荷在控制冠状面畸形方面起着重要的生物力学作用，然而，关于其如何影响轴向畸形却知之甚少。本研究调查了一系列脊柱侧凸患者在轴向压缩负荷作用下三维畸形的变化。
对一组18例脊柱侧凸患者（平均主 Cobb角为43.4°）进行磁共振成像扫描，测量冠状面畸形（采用冠状面 Cobb角测量）和轴向旋转。使用定制开发的压缩装置，在无负荷和有负荷状态下对每位患者进行扫描，施加相当于50%体重的压缩负荷。
压缩负荷导致主 Cobb角平均增加7.4°（标准差3.5°）。在结构曲线的顶点观察到轴向旋转最大的椎体，在冠状面畸形的极限处观察到最大的平均椎体内旋转。逐水平比较显示，平均负荷和无负荷状态下的椎体轴向旋转（观察者内误差=2.56°）或每个脊柱水平的椎体内旋转之间无显著差异。
本研究表明，轴向负荷的生物力学效应主要影响冠状面畸形，在无负荷和有负荷状态下未观察到椎体轴向旋转或椎体内旋转有显著变化。然而，鉴于当前技术的分辨率，压缩负荷下椎体旋转的变化幅度可能太小而无法检测到。
