Purpose

Separation of C2 growth plates and dens fractures are the most common types of injuries to the axis (C2) in children. Operative treatment of these injuries with the use of direct osteosynthesis requires a profound knowledge of detailed anatomy and dimensions of the axis. The main issue addressed by the study was the age at which the size of the dens is adequate at all levels to accommodate two screws, and the size of the posterior dens angulation angle (PDAA) in a healthy child in individual age periods.

Methods

Dimensions and angles of the dens and C2 in individual age categories in both boys and girls were measured in a series of 203 CT scans of individuals 0–18 years old and on anatomical specimens (42 samples). In addition, 5 histological series of this region from the fetal period were reviewed.

Results

Dimensions of the dens gradually increase with age, with a considerable acceleration during growth spurt periods that are different in boys and girls. PDAA is markedly changing with age; in the fetal period, the dens shows a slight anterior angulation which gradually transforms into posterior angulation, as early as between 4 and 6 years of age. The screw insertion angle changes accordingly.

Conclusion

During growth, there occur changes in PDAA that should be respected in evaluation of transformation of anterior into posterior angulation, as shown by imaging methods. Dens dimensions theoretically allow insertion of two 3.5 mm screws as early as from the age of 1 year.

中文翻译：

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小儿窝的解剖学及其对骨折治疗的意义：解剖学和放射学研究。

目的

C2生长板和牙槽骨骨折的分离是儿童中轴（C2）受伤的最常见类型。使用直接的骨合成术对这些损伤进行手术治疗需要深入了解详细的解剖结构和轴的尺寸。该研究解决的主要问题是，各个年龄段的牙本质大小足以容纳两个螺钉的年龄，以及健康儿童在各个年龄段的后牙后牙成角角度（PDAA）的大小。

方法

通过一系列203例0-18岁个体的CT扫描以及解剖样本（42个样本），测量了男孩和女孩各个年龄类别中的窝点和C2的尺寸和角度。此外，从胎儿期开始对该区域的5个组织学系列进行了回顾。

结果

窝点的尺寸会随着年龄的增长而逐渐增加，在成年高峰期会大大加快，这在男孩和女孩中是不同的。PDAA随着年龄的增长而发生明显变化。在胎儿期，牙窝呈轻微的前角，最早在4至6岁时逐渐转变为后角。螺丝插入角度会相应变化。

结论

在生长过程中，PDAA中会发生变化，如评估成像方法所示，应评估前角向后角的转化。齿孔尺寸理论上允许从1岁起就插入两个3.5毫米螺钉。