正常儿童齿状突影像学测量

目的测量不同年龄儿童正常齿状突的参数,确立不同年龄儿童正常齿状突的各种参数变化,为儿童齿状突中空拉力螺钉内固定提供参数依据。方法利用CT二维重建技术,测量120例不同年龄组儿童正常齿状突基底横断面松质骨、皮质骨的横径、纵径,模拟入钉点（C2椎体前下缘中点）至齿状突尖部前角、后角的角度及距离,最佳角度及最佳长度。结果正常儿童齿状突基底部基本呈圆形,纵径稍大于横径,各参数随年龄增大而增大。入钉的安全角度范围：16°～36°,最佳入钉角度范围：19°～22°。3～5岁、6～9岁和10～14岁3组的钉道长度安全范围分别为8～14mm、10～16mm、12～21mm;最佳长度分别为13～14mm、15～16mm、19～20mm。枢椎高度随年龄增加而逐渐增大。结论对于Ⅱ型齿状突骨折儿童进行齿状突螺钉固定时,可根据不同年龄齿状突的不同参数变化,选择相应的螺钉直径、长度和进钉方向。

Image measurement of os odontoideum in normal children

Objective To identify the morphometric changes of normal os odontoideum in children of different age and to provide parameters for screw fixation. Methods CT scanning data of 120 children＇s normal os odontoideum in different age groups were measured. The parameters was as followed： transverse and vertical diameters of cancellous bone and cortical bone in os odontoideum basilar part, angle and distance from simulation screw insertion point （anterior midpoint of C2 vertebral body） to odontoid process anterior angle as well as posterior angle, the optimal insertion angle, and the optimal screw length. Results The basilar part of normal os odontoideum was roughly round, and vertical diameter was slightly larger than transverse diameter. All parameters measured in this study increased with advancing age. The safety screw insertion angle range was 16° to 36°, the optimal insertion angle ranged from 19° to 22°. In 3-5 years group, the safety screw path length range in 3-5 years, 6-9 years and 10-14 years group was 8 to 14 mm, 10-16 mm and 12-21 mm respectively, the optimal screw length range in the above groups was 13-14 mm, 15-16 mm and 19-20 mm. The height of axis showed a growing dimension followed by the advancing age in all groups. Conclusion For children with odontoid screw fixation for the treatment of II type odontoid fracture, it would be safe to select the appropriate screw diameter, length and direction according to parameter changes of os odontoideum in different age.