Neuro-Spine Program, Division of Pediatric Neurosurgery, Texas Children's Hospital, and Department of Neurosurgery, Baylor College of Medicine, Houston, Texas, USA.
J Neurosurg Spine. 2012 Nov;17(5):390-6. doi: 10.3171/2012.8.SPINE12767. Epub 2012 Sep 14.
Lateral mass screws are routinely placed throughout the subaxial cervical spine in adults, but there are few clinical or radiographic studies regarding lateral mass fixation in children. The morphology of pediatric cervical lateral masses may be associated with greater difficulty in obtaining adequate purchase. The authors examined the lateral masses of the subaxial cervical spine in pediatric patients to define morphometric differences compared with adults, establish guidelines for lateral mass instrumentation in children, and define potential limitations of this technique in the pediatric age group.
Morphometric analysis was performed on CT of the lateral masses of C3-7 in 56 boys and 14 girls. Measurements were obtained in the axial, coronal, and sagittal planes.
For most levels and measurements, results in boys and girls did not differ significantly; the few values that were significantly different are not likely to be clinically significant. On the other hand, younger (< 8 years of age) and older children (≥ 8 years of age) differed significantly at every level and measurement except for facet angularity. Sagittal diagonal, a measurement that closely estimates screw length, was found to increase at each successive caudal level from C-3 to C-7, similar to the adult population. A screw acceptance analysis found that all patients ≥ 4 years of age could accept at least a 3.5 × 10 mm lateral mass screw.
Lateral mass screw fixation is feasible in the pediatric cervical spine, particularly in children age 4 years old or older. Lateral mass screw fixation is feasible even at the C-7 level, where pedicle screw placement has been advised in lieu of lateral mass screws because of the small size and steep trajectory of the C-7 lateral mass. Nonetheless, all pediatric patients should undergo high-resolution, thin-slice CT preoperatively to assess suitability for lateral mass screw fixation.
成人颈椎后路常使用侧块螺钉固定，但关于儿童侧块固定的临床和影像学研究较少。儿童颈椎侧块的形态可能与获得足够的把持力更为困难有关。作者研究了儿童下颈椎侧块的形态，以确定与成人相比的形态学差异，为儿童侧块器械固定制定指南，并定义该技术在儿童年龄段的潜在局限性。
对 56 名男孩和 14 名女孩的 C3-7 颈椎侧块 CT 进行了形态计量学分析。测量在轴位、冠状位和矢状位进行。
在大多数水平和测量值中，男孩和女孩的结果没有显著差异；少数显著不同的数值不太可能具有临床意义。另一方面，年龄较小（<8 岁）和年龄较大（≥8 岁）的儿童在每个水平和测量值上都有显著差异，除了关节角度。与成人相似，与螺钉长度密切相关的矢状对角线在从 C-3 到 C-7 的每个连续尾侧水平均增加。螺钉接受分析发现，所有年龄≥4 岁的患者都可以接受至少 3.5×10mm 的侧块螺钉。
儿童颈椎后路侧块螺钉固定是可行的，特别是在年龄 4 岁或以上的儿童。即使在 C-7 水平，侧块螺钉固定也是可行的，因为 C-7 侧块体积小且轨迹陡峭，因此建议使用椎弓根螺钉替代侧块螺钉。然而，所有的儿科患者都应该在术前进行高分辨率、薄层 CT 检查，以评估是否适合侧块螺钉固定。
