Härtl Roger, Chamberlain Robert H, Fifield Mary S, Chou Dean, Sonntag Volker K H, Crawford Neil R
Spinal Biomechanics Laboratory, Division of Neurological Surgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013, USA.
J Neurosurg Spine. 2006 Oct;5(4):336-42. doi: 10.3171/spi.2006.5.4.336.
Two new techniques for atlantoaxial fixation have been recently described. In one technique, C-2 intralaminar screws are connected with C-1 lateral mass screws; in the second, C-1 and C-3 lateral mass screws are interconnected and C-2 is wired sublaminarly. Both techniques include a C1-2 interspinous graft. The authors compared these techniques with the gold-standard, interspinous graft-augmented C1-2 transarticular screw fixation and with a control C1-2 interspinous graft fixation procedure alone.
In six human cadaveric occiput-C4 specimens, nonconstraining 1.5-Nm pure moments were applied to induce flexion, extension, lateral bending, and axial rotation during which three-dimensional angular motion was measured optoelectronically. Each specimen was tested in the normal state, with graft alone (after odontoidectomy), and then in varying order after applying each construct with a rewired graft. All three constructs allowed significantly less angular motion at the C1-2 junction than the wired interspinous graft alone during lateral bending and axial rotation (p < 0.01, paired Student t-test) but not during flexion or extension. Transarticular screw fixation with an interspinous graft allowed less motion at the atlantoaxial junction than the two new constructs in several conditions. Differences were greater between the transarticular screw construct and the intralaminar screw construct than between the transarticular screw construct and the C1-3 lateral mass screw construct. During lateral bending and axial rotation, the C1-3 construct allowed less motion at the atlantoaxial junction than the intralaminar screw construct.
Biomechanically, the gold-standard C1-2 transarticular screw fixation outperformed the two new techniques during lateral bending and axial rotation. Wiring C-2 to C1-3 rods provided greater stability than C1-2 laminar screws, but it sacrificed C2-3 mobility. It is unknown whether the small differences observed biomechanically would lead to clinically relevant differences in fusion rates.
最近描述了两种新的寰枢椎固定技术。一种技术是将C2椎板内螺钉与C1侧块螺钉连接；另一种技术是将C1和C3侧块螺钉相互连接，并在C2椎板下进行钢丝固定。两种技术均包括C1-2棘突间植骨。作者将这些技术与金标准的棘突间植骨增强的C1-2经关节螺钉固定以及单独的对照C1-2棘突间植骨固定术进行了比较。
在6个尸体枕骨-C4标本上，施加非约束性1.5牛米的纯力矩以诱导屈伸、侧弯和轴向旋转，在此期间通过光电方式测量三维角运动。每个标本先在正常状态下进行测试，然后在齿突切除后仅植入植骨进行测试，接着在应用每种带有重新固定植骨的固定结构后按不同顺序进行测试。在侧弯和轴向旋转过程中，所有三种固定结构在C1-2关节处允许的角运动均明显少于单独的钢丝棘突间植骨（p < 0.01，配对学生t检验），但在屈伸过程中并非如此。在几种情况下，经关节螺钉固定并植入棘突间植骨在寰枢关节处允许的运动比两种新的固定结构更少。经关节螺钉固定结构与椎板内螺钉固定结构之间的差异大于经关节螺钉固定结构与C1-3侧块螺钉固定结构之间的差异。在侧弯和轴向旋转过程中，C1-3固定结构在寰枢关节处允许的运动比椎板内螺钉固定结构更少。
在生物力学方面，金标准的C1-2经关节螺钉固定在侧弯和轴向旋转过程中优于两种新技术。将C2与C1-3棒进行钢丝固定比C1-2椎板螺钉提供了更大的稳定性，但牺牲了C2-3的活动度。生物力学上观察到的微小差异是否会导致融合率在临床上的相关差异尚不清楚。
