婴幼儿胸腰椎椎弓根形态的CT测量及其意义

Anatomic measurement of the pedicle of vertebral arch of the infant and its significance

目的研究3岁以下婴幼儿胸腰椎椎弓根的解剖学特点，探讨椎弓根螺钉固定的可行性、安全性。方法收集中南大学湘雅二医院CT资料室内52例3岁以下婴幼儿的相关影像学数据，通过薄层密扫和三维重建技术分别在横断面、矢状面和冠状面对T1～L5椎弓根内径、椎弓根外径、椎弓根长度、椎弓根内倾角和椎弓根高度进行测量，总结婴幼儿胸腰椎椎弓根的解剖学特点。结果婴幼儿椎弓根直径最小的节段为T5或T6椎体，平均直径在3．0mm以下。椎弓根直径的整体变化趋势从T1至T5逐渐减小，帕至巧逐渐增大。年龄〈18个月儿童L4以上的平均椎弓根内径〈3．0mm，T3至19节段的平均椎弓根外径〈3．5mm。年龄18—36个月儿童巧至髓节段的平均椎弓根内径〈3．0mm，T4至T7节段的平均椎弓根外径〈3．5mm。椎弓根的直径、长度和高度与年龄呈明显正相关。结论18个月以下婴幼儿T3至，T9节段，18个月以上婴幼儿T4至T7节段的平椎弓根过于细小，置人椎弓根螺钉可行性低，风险较高。对3岁以下胸椎和腰椎疾患婴幼儿在T9节段以下进行椎弓根螺钉固定是可行、安全的。

Objective To quantify the morphometric characteristics of the pedicles of the infantile thoracolumbar spine and to determine the feasibihty and safety of pedicle screw fixation in very young children. Methods A total of 52 patients younger than three years of age underwent standard spiral computed tomography （CT） were enrolled in this study. The patients were grouped according to age, group 1 （0 - 18 months of age） and group 2 （ 18 - 36 months of age）. Images were reformatted, and multiplanar reconstructions were used to attain images of thoracic and lumbar pedicles on sagittal, coronal and transverse planes. The measurements included the inner and outer pedicle diameters on the transverse plane, pedicle sagittal diameter, pedicle length and the pedicle angle on the transverse. Characteristics of the pedicles of the immature thoracic and lumbar spine were studied. Results Pedicle diameters on the transverse plane decreased gradually from T1 to T5 and increased gradually from T6 to L5. The shortest transverse diameter of the thoracic pedicle was T5 or T6. The inner diameter of the segment of IA in infant （ younger than eighteen months） was less than 3.0 mm and the external diameter less than 3.5 mm from T3 to T9. The inner diameter of the segment from T5 to T8 in infant （more than eighteen months） was less than 3.0 mm and the external diameter from T4 to T7 was less than 3.5 mm. The sagittal diameter was significantly more than the transverse diameter. Pedicle diameters on the transverse plane, the sagittal diameter, and the length of the pedicle changed significantly with age, but the pedicle angle did not changed significantly with age. Conclusions The pedicles in the segment from T3 to T9 of less than eighteen months and from T4 to T7 of more than eighteen months were too small, there was no feasibility and safety of pedicle screw fixation. So pedicle screw fixation was feasible and safe for below T9 segment in the infants who are younger than three years old.