Naderi S, Crawford N R, Song G S, Sonntag V K, Dickman C A
Dokuz Eylül University Hospital, Department of Neurosurgery, Balcova Izmir, Turkey.
Spine (Phila Pa 1976). 1998 Sep 15;23(18):1946-55; discussion 1955-6. doi: 10.1097/00007632-199809150-00005.
Four combinations of cable-graft-screw fixation at C1-C2 were compared biomechanically in vitro using nondestructive flexibility testing. Each specimen was instrumented successively using each fixation combination.
To determine the relative amounts of movement at C1-C2 after instrumentation with various combinations of one or two transarticular screws and a posterior cable-secured graft. Also to determine the role of each component of the construct in resisting different types of loading.
Spinal stiffness increases after instrumentation with two transarticular screws plus a posterior wire-graft compared with a wire-graft alone. Other C1-C2 cable-graft-screw combinations have not been tested.
Eight human cadaveric occiput-C3 specimens were loaded nondestructively with pure moments, and nonconstrained motion at C1-C2 was measured. The instrumented states tested were a C1-C2 interposition graft attached with multistranded cable; a cable-graft plus one transarticular screw; two transarticular screws alone; and a cable-graft plus two transarticular screws.
The transarticular screws prevented lateral bending and axial rotation better than the posterior cable-graft. The cable-graft prevented flexion and extension better than the screws. Increasing the number of fixation points often significantly decreased the rotation and translation (paired t test; P < 0.05). Axes of rotation shifted from their normal location toward the hardware.
It is mechanically advantageous to include as many fixation points as possible when atlantoaxial instability is treated surgically.
使用无损柔韧性测试对C1-C2节段的四种缆线-移植骨-螺钉固定组合进行体外生物力学比较。每个标本依次使用每种固定组合进行器械植入。
确定使用一枚或两枚经关节螺钉与后路缆线固定移植骨的不同组合进行器械植入后C1-C2节段的相对运动量。同时确定该结构各组成部分在抵抗不同类型载荷中的作用。
与单纯使用钢丝移植骨相比，使用两枚经关节螺钉加后路钢丝移植骨进行器械植入后脊柱刚度增加。其他C1-C2缆线-移植骨-螺钉组合尚未进行测试。
对八个新鲜人尸体枕骨-C3标本施加纯力矩进行无损加载，并测量C1-C2节段的非约束运动。测试的器械植入状态包括：用多股缆线连接的C1-C2椎间移植骨；缆线-移植骨加一枚经关节螺钉；仅两枚经关节螺钉；以及缆线-移植骨加两枚经关节螺钉。
经关节螺钉在防止侧方弯曲和轴向旋转方面比后路缆线-移植骨更好。缆线-移植骨在防止屈伸方面比螺钉更好。增加固定点数量通常会显著减少旋转和平移（配对t检验；P < 0.05）。旋转轴从其正常位置向硬件方向偏移。
手术治疗寰枢椎不稳时，尽可能增加固定点数量在力学上具有优势。
