Orthopaedic Department, Peking University Third Hospital, Beijing, China.
Neurosurgery. 2012 Nov;71(5):976-84; discussion 984. doi: 10.1227/NEU.0b013e31826cdd3b.
Atlas occipitalization and congenital C2-3 fusion often result in atlantoaxial dislocation (AAD) and superior odontoid migration that requires occipitocervical fixation. The widely used technique is posterior occiput-C2 fixation with pedicle screws. However, congenital C2-3 fusion cases tend to have thinner C2 pedicles that are inadequate for normal-sized pedicle screw fixation. With the presence of AAD, the strength of the fixation is further compromised as the C2 pedicle screws (C2PS) sustain considerable cephalic shearing force during the reduction procedure. Therefore, a novel technique has been developed to augment the C2 pedicle screw fixation with a strengthening cable.
To introduce and assess this new technique.
Seventy-six patients who underwent this procedure were reviewed. The position of the instrument and resultant fusion were examined retrospectively. In the biomechanical test, 6 fresh specimens were subjected to 2 types of fixation in the order of Oc-C2 screw-plate fixation followed by additional use of strengthening cable. Under 3 loading modes (extension-flexion, lateral bending, and axial rotation), the relative movement between the occiput and C2 was measured and compared in the form of range of motion.
The average follow-up time was 26 months. Solid fusion was achieved in 75 patients (98.7%) as assessed radiologically. The only patient who experienced hardware failure eventually obtained solid fusion between the occiput and C2 after revision. Biomechanically, there was significant difference between the occiput and C2 fixation and cable-strengthened fixation in range of motion for all modes.
This technique is a promising option for the treatment of AAD with congenital C2-3 fusion and occipitalization. Biomechanically, this technique can reduce the occipital-axial motion significantly compared with occiput-C2 fixation.
寰枕融合和先天性 C2-3 融合常导致寰枢椎脱位（AAD）和齿状突上移，需要寰枢椎固定。常用的技术是后路枕骨-C2 固定加椎弓根螺钉。然而，先天性 C2-3 融合病例的 C2 椎弓根往往较薄，不足以进行正常大小的椎弓根螺钉固定。由于存在 AAD，在复位过程中，C2 椎弓根螺钉（C2PS）承受相当大的颅向剪切力，固定的强度进一步受到影响。因此，开发了一种新的技术，通过加强电缆来增强 C2 椎弓根螺钉固定。
介绍和评估这项新技术。
回顾性分析 76 例接受该手术的患者。检查器械的位置和最终融合情况。在生物力学试验中，6 个新鲜标本依次进行 Oc-C2 螺钉-钢板固定和额外使用加强电缆两种固定方式，在伸展-屈曲、侧屈和轴向旋转 3 种加载模式下，测量枕骨和 C2 之间的相对运动，并以活动范围的形式进行比较。
平均随访时间为 26 个月。影像学评估 75 例（98.7%）患者融合牢固。1 例患者发生内固定失败，经翻修后枕骨和 C2 之间获得牢固融合。生物力学上，在所有模式下，枕骨和 C2 固定与电缆加强固定的活动范围均有显著差异。
对于伴有先天性 C2-3 融合和枕骨化的 AAD，该技术是一种有前途的治疗选择。生物力学上，与枕骨-C2 固定相比，该技术可显著减少枕骨-枢轴运动。
