国人前路齿突螺钉置入安全角度与齿突容纳能力的影像学分析

Imaging analysis of safe angle of anterior screw fixation in odontoid process and capacity of odontoid process in Chinese people

目的以CT三维重建资料为基础，对3种不同标志方法引导的前路齿突螺钉置人的安全角度及可靠性进行分析，并评估国人齿突的容纳能力。方法应用影像归档和通信系统（PACS)对选取的141例国人颈椎CT三维重建资料中的齿突图像进行测量分析，其中男96例，女45例。分别以寰椎前结节、枢椎椎体下终板、C3椎体前缘切线为标志，测量不同标志线下前路齿突螺钉置钉的安全角度范围、最佳置钉角度与最佳置钉长度，并对男性与女性的最佳置钉长度进行比较分析。进一步测量齿突基底部最窄矢状内径与外径、基底部最窄冠状内径与外径，分析国人齿突是否能够容纳2枚直径为3.5 mm的皮质骨螺钉，并分别对男性与女性齿突基底部径线长度及齿突的螺钉容纳能力进行比较。结果以寰椎前结节、枢椎椎体下终板、（：3椎体前缘切线作标志线置钉的安全角度范围分别为22.82°~30.37°、55.55。~63.08。、13.83。~ 21.42。；最佳置钉角度分别为27.09。±2.98。、58.85。±4.43。、18.09。±5.09。；最佳置钉长度为(38.35 ± 2.93 ) m m ,其中男性为（39.04 ± 2.89 ) m m ,女性为（36.89 ± 2.46 ) mm,两者比较差异有统计学意义（尸<0_05 )。齿突基底部最窄冠状内径、外径分别为（6_21 ± 1.01) mm、（ 8_87 ± 1_04 ) mm,最窄矢状内径、外径分别为( 7_16 ± 1.13 ) 皿n、(10.34±0.98) m m ,男性与女性齿突基底部矢状、冠状径线相比较，差异均有统计学意义(P<0.05)。141例资料中，有65例（46% )齿突冠状面能够容纳2枚直径为3.5 mm的皮质骨螺钉，其中男50例，女15例，两者比较差异有统计学意义(P < 0 .0 5 );在齿突基底部的矢状径线上，有128例（91% )能够容纳2枚直径为3.5 mm的皮质骨螺钉，其中男92例，女36例，两者比较差异有统计学意义( 户<0.05)。结论以寰椎前结节、枢椎椎体下终板及C3椎体前缘切线做标志线，前路齿突置钉的安全角度范围分别为22.38°~30.43°、55.52°~63.54°、13.38°~21.53°。齿突的矢状径有容纳2枚螺钉的更大空间，为国人前路齿突交叉置钉提供了可能。

Objective Based on the 3D reconstruction CT data, to analyze the safety and reliability of the anterior screw fixationguided by 3 different mark lines, and assess the capacity of odontoid process in Chinese people. Methods CT scans of odontoidprocess in 141 adult patients were measured on picture archiving and communication systems ( PACS ), including 96 males and45 females. Anterior tubercle of atlas ( ATA ), inferior endplate of axis ( AE ) and anterior margine tangent of C3 vertebral body( C 3 ) were selected as 3 different mark lines to evaluate safe screw angle, optimum screw angle and optimum screw length foranterior odontoid process screw fixation, and the difference in optimum screw length between male and female was also analyzed.The minimum coronal, saggital external and internal diameters of the odontoid process were further evaluated for whether theChinese peopled odontoid process can accommodate 2 screws with the diameter of 3.5 mm. And the length of basal region andthe capacity of odontoid process were compared between the male and female. Results Guided by anterior tubercle of the atlas,inferior endplate of the axis and anterior margine tangent of C 3 vertebral body , the safe screw angles for anterior odontoid processscrew fixation were 22.38.-30.43.,55.52.-63.54.and 13.42.-21.53.respectively; and optimum screw angles were 27.09° ±2.980,58.85° ± 4.434.and 18.09.± 5.086° respectively. Optimum screw length was ( 38.35 ± 2.93 ) mm, ( 39.04 ± 2.89 ) mmin male and ( 36.89 ± 2.46 )mm in fem ale, and the difference between male and female was statistically significant( 尸<0.05 )?Minimum coronal external and internal diameters were ( 8.87 ± 1.04 ) mm and ( 6.21 ± 1.01 ) mm, and minimum saggitalexternal and internal diameter were ( 10.34 ± 0.98 ) mm and ( 7.16 ± 1.13 ) mm respectively, and the difference betweenmale and female was statistically significant( P < 0.05 ). Of the 141 data, odontoid process of 65 patients( 46% ) had ability toaccommodate 2 screws with the diameter of 3.5 mm on the coronal plane, including 50 males and 15 females, and the differencebetween male and female was statistically significant ( P < 0.05 ). Odontoid processes of 128 cases ( 91% ) had enough space for2 screws with the diameter of 3.5 mm on the saggital plane, consisting of 96 males and 32 females, and the difference betweenmale and female was statistically significant ( P < 0.05 ). Conclusion Anterior tubercle of the atlas, inferior endplate of theaxis and anterior margine tangent of C3 vertebral body can be used as landmarks for anterior odontoid process screw fixation, andsafe screw angles for screw fixation are 22.38°-30.43°, 55.52°-63.54° and 13.42°-21.53° respectively. The odontoid process hasenough space for fixation with 2 screws with the diameter of 3.5 mm on the saggital plane, which provides evidence for anteriorcross screw fixation to treat odontoid fracture in Chinese people.