经S_(1)椎弓根拉力螺钉固定骶髂关节分离的钉道分析

Lag screw path for fixation of sacroiliac joint dislocation through S_(1) pedicle

背景:经皮骶髂螺钉内固定已经成为治疗骶髂关节分离的首选方法,但目前很多采用平行水平面的方式置入螺钉,此置钉方法风险相对较高,易受人体骨盆变异的影响,且很难实现双螺钉固定,需寻找一种新的内固定方式。目的:通过骨盆3D模型,模拟7.3 mm拉力螺钉固定骶髂关节,然后进行测量和统计分析,确定最佳髂骨进针点和空间角度。方法:用Mimics 21.0软件对60例骨盆CT数据进行3D重建,建立60例骨盆3D模型。从臀部外上方尽量靠近髂嵴上缘的位置,经S_(1)椎弓根到S_(1)椎体上1/3中点模拟置入7.3 mm拉力螺钉(尾向置钉法),在冠状面上平行下移5-8 mm置入第二个拉力螺钉。所有病例必须满足双螺钉安全置入要求,然后在软件中测量第一个拉力钉轴线与水平面、矢状面和冠状面的偏离角度,观察和分析髂骨进针点的位置。结果与结论:①进针点在小骨盆内边缘垂直切线上稍偏外的位置;②男性最佳置钉通道与水平面偏离角α、矢状面偏离角β、冠状面偏离角γ分别为(12.56±6.14)°,(66.42±5.45)°,(18.68±5.09)°;女性分别为(9.78±5.31)°,(69.46±5.34)°,(16.86±5.94)°。男女间α、β有显著差异,γ无明显差异;③尾向置入骶髂螺钉技术,空间角度相对稳定;④骼骨进针点在前后位投影面上的小骨盆内边缘垂直切线略偏外侧,变异较小;⑤对于大多数的患者,可以实现2个平行螺钉固定;⑥因此,骶髂螺钉尾向置入技术可以作为临床使用的进针方法。

BACKGROUND:Percutaneous sacroiliac screw fixation has become the preferred method for the treatment of sacroiliac joint dislocation.However,at present,the screw is mostly inserted parallel to the horizontal plane.This method of screw placement has relatively high risk,which is easily affected by human pelvis variation,and is difficult to achieve double-screw fixation.Therefore,a new internal fixation method should be developed.OBJECTIVE:To simulate the internal fixation of the sacroiliac joint using a lag screw of 7.3 mm in diameter in a three-dimensional model of the pelvises,followed by measurement and statistical analysis,thus to determine the best iliac screw entry point and spatial angle.METHODS:Mimics 21.0 software was used for three-dimensional remodeling based on computed tomography data of the pelvis in 60 cases.From the top of the buttocks as close as possible to the upper edge of the iliac crest,a 7.3 mm lag screw was inserted through the S_(1) pedicle to the midpoint of the upper 1/3 of the S_(1) vertebral body(the screw was inserted entirely from the caudal direction),and the second lag screw was inserted 5-8 mm below the first screw on the coronal plane.All cases must meet the requirements for safe placement of double screws,then the deviation angles between the axis of the first lag screw and the horizontal plane,sagittal plane,and coronal plane were measured in the software,and the position of the iliac screw entry point was observed and analyzed.RESULTS AND CONCLUSION:Screw entry point was slightly outside the vertical tangent to the inner edge of the small pelvis.The optimal angles of the screw placement path to the horizontal,sagittal and coronal planes wereα(12.56±6.14)°,β(66.42±5.45)°andγ(18.68±5.09)°in males,respectively,and wereα(9.78±5.31)°,β(69.46±5.34)°,andγ(16.86±5.94)°in females,respectively.There were significant differences inαandβbetween male and female,but not inγ.The sacroiliac screw could be inserted entirely from the caudal direction,at a relatively stable spatial angle.The entry point of the ilia was positioned slightly outside the vertical tangent of the inner edge of the small pelvis on the anteroposterior projection plane,and the variation was small.To conclude,insertion of two parallel screws can be achieved in most patients.Therefore,the caudal insertion of sacroiliac screw can be used as a clinical screw entry method.