髋臼前柱拉力螺钉内固定理想位置的数字化研究

Digital study of the ideal position of lag screw internal fixation in the anterior column of the acetabulum

目的应用数字化技术寻找髋臼前柱拉力螺钉内固定的理想位置,并测量其相关参数,提高拉力螺钉植入的准确度。方法收集2019年1月—2020年1月CT扫描的133例266个半骨盆原始数据(男78例,女55例;年龄18~65岁,平均42岁),生成三维模型。根据骨性通道外周骨皮质与拉力螺钉的关系提出髋臼前柱拉力螺钉内固定理想位置的新标准,按照该标准进行模拟植钉。螺钉位于理想位置后测量以下指标:虚拟螺钉最大允许直径(达上述新标准的圆柱体直径,R)、长度(两侧入钉点中心的距离,L),逆行入钉点位置(入钉点与耻骨联合中点、耻骨结节的距离,分别为D1、D2)和顺行入钉点位置(入钉点与髂前上棘、坐骨大切迹的距离及与髋臼后上缘顶点的垂直距离,分别为D3、D4、D5);计算虚拟螺钉在理想位置的方向(螺钉与水平面、矢状面、冠状面的夹角,分别为∠β、∠γ、∠δ)。结果虚拟螺钉最大允许直径范围男性为5.70~14.10 mm,平均9.25 mm;女性为4.40~10.40 mm,平均7.29 mm。髋臼前柱拉力螺钉顺行植钉入钉点位于髋臼顶点外上方2.0~2.5 cm,与髂前上棘和坐骨大切迹距离几乎相等,约为5 cm;逆行植钉入钉点位于耻骨结节外下方2.5~3.0 cm。髋臼前柱螺钉位于理想位置时,男女性间除∠β、∠γ比较差异无统计学意义(P>0.05)外,其余各指标比较差异均有统计学意义(P<0.05);左右侧间除D4、∠β比较差异无统计学意义(P>0.05)外,其余各指标比较差异均有统计学意义(P<0.05)。结论髋臼前柱骨性通道中,全部男性可容纳直径<5.70 mm的螺钉、女性可容纳直径<4.40 mm的螺钉,男、女性的顺行或逆行植钉入钉点位置不同。使用数字化技术个性化测量适宜的螺钉参数,可提高髋臼前柱骨折拉力螺钉内固定的准确度和稳定性。

Objective To find the ideal position of lag screw internal fixation in the anterior column of acetabulum by digital technology, and measure its related parameters, so as to improve the accuracy of lag screw implantation. Methods The CT scan data of 266 semi-pelvic raw in 133 cases(78 males and 55 females, aged 18-65 years old with an average age of 42 years) were collected between January 2019 and January 2020 to compose three-dimensional models. According to the relationship between the peripheral bone cortex of the anatomical channel and the lag screw, a new standard for the ideal position of lag screw fixation in the anterior column of acetabulum was proposed to simulate the implantation of the screw. After the screw was in the ideal position, the following indicators were measured: the maximum allowable diameter of the virtual screw(the diameter of the cylinder up to the new standard, R), the length(the distance between the center of the nail point on both sides, L);the position of the retrograde nail point(the interval between the nail insertion points and the midpoint of the pubic symphysis and the pubic tubercle, respectively, D1 and D2) and the position of the antegrade nail insertion point(the distance between the nail insertion point and the anterior superior iliac spine, the major ischial notch, and the vertical distance between the nail insertion point and the apex of the posterior upper edge of the acetabulum, respectively, D3, D4, D5);and the direction of the virtual screw at the ideal position(the angle between the screw and the horizontal plane, sagittal plane, and coronal plane, respectively, ∠β, ∠γ,∠δ) were calculated. Results The maximum allowable diameter of virtual screws was 5.70-14.10 mm for males, with an average of 9.25 mm;for females, it was 4.40-10.40 mm with an average of 7.29 mm. The antegrade insertion point of the anteroposterior acetabular lag screw was located at 2.0-2.5 cm above the apex of the acetabulum, which was almost the same distance from the anterior superior iliac spine and the ischial notch, about 5 cm;the insertion point of the retrograde implant was located at the pubic bone 2.5-3.0 cm below the nodule. When the acetabular anterior column screw was in the ideal position, there was no significant difference in the comparison of ∠β and ∠γ between the male and the female(P>0.05), and the differences in the other indicators were significant(P<0.05). Except for D4 and ∠β showing no significant difference between the left and right sides(P>0.05), the differences in the other indicators were significant(P<0.05). Conclusion In the bony channel of the anterior column of the acetabulum, all males can accommodate screws with a diameter of <5.70 mm, and females can accommodate screws with a diameter of <4.40 mm. The anterograde or retrograde screw insertion points are different for male and female. The use of digital technology to individually measure the appropriate screw parameters can improve the accuracy and stability of the lag screw internal fixation for acetabular anterior column fractures.