椎间盘和关节突关节在退变性脊柱侧凸发生发展中的作用

Effects of intervertebral disc and articular facet joint on occurrence and development of degenerative scoliosis: a biomechanical analysis on cadaveric spine

目的 :对退变腰段脊柱尸体标本进行生物力学测试,探讨椎间盘和关节突关节在退变性脊柱侧凸发生和发展中的作用。方法:对39例腰骶椎(T12～S1)新鲜尸体标本进行CT扫描,并行三维重建,测量脊柱侧凸Cobb角、椎间隙楔形角(Cobb角)、关节突关节冠状位角,应用Ostrix Dicom Viewer影像系统对椎间盘、关节突退变程度分别根据Mimura及Lane评分标准评估。利用脊柱力学测试仪以±7.5Nm、0.005Hz对标本进行力学加载,获取每个椎间隙屈伸(flexion-extension,FE)、侧屈(lateral bending,LB)及旋转(axial torsion,AT)的活动度(range of motion,ROM)和中性区(neutral zone,NZ),每个测试模式的第三个周期测试结果用于数据分析。将ROM、NZ测试数据利用单因素方差分析进行组间比较,将椎间盘退变程度评分、椎间盘形态(椎间隙Cobb角)及关节突关节退变程度评分、关节突关节形态(不对称角)与ROM、NZ进行Pearson相关性分析。结果:39例腰骶椎标本均为退变型,按Cobb角分为3组:Cobb角>10°为退变性脊柱侧凸组(degenerative scoliosis group,DS组),共5例;3°≤Cobb角≤10°为侧凸前组(pre-degenerative scoliosis group,PS组),共9例;Cobb角<3°为无侧凸组(none scoliosis group,NS组),共25例。总共187个脊柱功能单位,其中38例存在关节突关节不对称。PS组及DS组AT的ROM和NZ均显著性大于NS组(P<0.05),而FE和LB的ROM与NZ均无显著性差异(P>0.05);椎间盘退变程度与AT的ROM和NZ有显著相关性(P<0.05),椎间隙Cobb角即椎间盘的不对称与AT的ROM和NZ有显著相关性(P<0.05);关节突关节退变程度与AT的ROM和NZ有显著相关性(P<0.05);关节突关节的不对称与脊柱ROM和NZ无显著相关性(P>0.05)。结论:椎间盘和关节突关节的退变均可使脊柱旋转增加,椎间盘退变的不对称可促使脊柱旋转而导致侧凸的形成及进展,关节突关节的不对称形态与侧凸的发生相关性不大。

Objectives： To investigate the role of intervertebral disc and articular facet joint in occurrence and development of degenerative scoliosis by biomechanical analysis on cadaveric lumbar specimens. Methods： A total of 39 fresh cadaveric lumbosacral spines（T12-S1） was evaluated by three-dimensional CT, scoliosis Cobb′s angles, wedging angle of discs and orientation of facet joints were measured. The Osirix Dicom imaging system was used to assess the degeneration of intervertebral disc and facet joints with Mimura and Lane′s standard. Spine mechanical tests were performed in sinusoidal displacement control with a maximum torque equal to 7.5Nm and a frequency of 0.005Hz, and intervertebral disc range of motion（ROM）, neutral zone（NZ） of flexion-extension（FE）, lateral bending（LB） and axial torsion（AT） were obtained. Each specimen underwent 3 times of test, and the results of the 3rd test were collected for data analysis. The ROM and NZ test data were compared among groups by one-way ANOVA. Pearson correlation analysis was performed on the degenerative degree of intervertebral disc, the shape of disc（intervertebral Cobb angel）, the degenerative degree of facet joints, the shape of facet joints（asymmetric angle）, with ROM and NZ. Results： All the 39 lumbar spine specimens were degenerated, among them 5 specimens were in degenerative scoliosis（DS） group with Cobb angles 〉10°, 9 specimens were in pre-degenerative scoliosis（PS） group with Cobb angles between 3° and 10°, and 25 specimens were in none scoliosis（NS） group with Cobb angles 〈3°. Among the total 187 functional spinal uints（FSU）, 38 pairs of facet joints were asymmetrical. In comparison among the three groups, biomechanical analysis showed that AT in PS group and DS group was significantly greater than that in NS group（P〈0.05）, FE and LB had no significant difference among 3 groups（P〉0.05）. Correlation analysis showed that the degenerative degree of intervertebral discs and facet joints and the wedging angles of discs were positively correlated to AT（P〈0.05）. There was no significant difference between asymmetrical facet joints and spine biomechanical parameters（P〉0.05）. Conclusions： Degeneration of intervertebral disc and facet joint can cause greater AT, and asymmetric degeneration of intervertebral discs can cause spinal rotation and DS formation. There is no correlation between asymmetric degeneration of facet joints and DS formation.