Bambakidis Nicholas C, Feiz-Erfan Iman, Horn Eric M, Gonzalez L Fernando, Baek Seungwon, Yüksel K Zafer, Brantley Anna G U, Sonntag Volker K H, Crawford Neil R
Division of Neurological Surgery, Phoenix, Arizona, USA.
J Neurosurg Spine. 2008 Feb;8(2):143-52. doi: 10.3171/SPI/2008/8/2/143.
The stability provided by 3 occipitoatlantal fixation techniques (occiput [Oc]-C1 transarticular screws, occipital keel screws rigidly interconnected with C-1 lateral mass screws, and suboccipital/sublaminar wired contoured rod) were compared.
Seven human cadaveric specimens received transarticular screws and 7 received occipital keel-C1 lateral mass screws. All specimens later underwent contoured rod fixation. All conditions were studied with and without placement of a structural graft wired between the skull base and C-1 lamina. Specimens were loaded quasistatically using pure moments to induce flexion, extension, lateral bending, and axial rotation while recording segmental motion optoelectronically. Flexibility was measured immediately postoperatively and after 10,000 cycles of fatigue.
Application of Oc-C1 transarticular screws, with a wired graft, reduced the mean range of motion (ROM) to 3% of normal. Occipital keel-C1 lateral mass screws (also with graft) offered less stability than transarticular screws during extension and lateral bending (p < 0.02), reducing ROM to 17% of normal. The wired contoured rod reduced motion to 31% of normal, providing significantly less stability than either screw fixation technique. Fatigue increased motion in constructs fitted with transarticular screws, keel screws/lateral mass screw constructs, and contoured wired rods, by means of 19, 5, and 26%, respectively. In all constructs, adding a structural graft significantly improved stability, but the extent depended on the loading direction.
Assuming the presence of mild C1-2 instability, Oc-C1 transarticular screws and occipital keel-C1 lateral mass screws are approximately equivalent in performance for occipitoatlantal stabilization in promoting fusion. A posteriorly wired contoured rod is less likely to provide a good fusion environment because of less stabilizing potential and a greater likelihood of loosening with fatigue.
比较三种枕颈固定技术（枕骨[Oc]-C1经关节螺钉、与C-1侧块螺钉刚性互连的枕骨嵴螺钉以及枕下/椎板下钢丝塑形棒）所提供的稳定性。
七具人体尸体标本接受经关节螺钉固定，七具接受枕骨嵴-C1侧块螺钉固定。所有标本随后均接受塑形棒固定。所有情况均在颅骨基部和C-1椎板之间有无放置结构性移植钢丝的情况下进行研究。通过施加纯力矩以诱发标本屈伸、侧弯和轴向旋转，同时以光电方式记录节段运动，对标本进行准静态加载。在术后即刻以及10000次疲劳循环后测量柔韧性。
使用带钢丝移植的Oc-C1经关节螺钉时，平均活动范围（ROM）降至正常的3%。枕骨嵴-C1侧块螺钉（同样带移植）在伸展和侧弯时提供的稳定性低于经关节螺钉（p < 0.02），ROM降至正常的17%。钢丝塑形棒使运动降至正常的31%，提供的稳定性明显低于任何一种螺钉固定技术。疲劳使采用经关节螺钉、嵴螺钉/侧块螺钉结构以及塑形钢丝棒的结构中的运动分别增加了19%、5%和26%。在所有结构中，添加结构性移植均显著提高了稳定性，但程度取决于加载方向。
假设存在轻度C1-2不稳定，Oc-C1经关节螺钉和枕骨嵴-C1侧块螺钉在促进融合的枕颈稳定方面性能大致相当。后部钢丝塑形棒因稳定潜力较小且因疲劳而松动的可能性较大，不太可能提供良好的融合环境。
