髋臼后柱骨折逆行拉力螺钉固定导向装置研制及初步验证

Development and preliminary validation of guide apparatus for retrograde lag screw fixation of posterior column acetabular fracture

目的设计经皮逆行拉力螺钉固定髋臼后柱骨折的导向装置并验证其可行性和准确性。方法利用Mimics10．01软件对33例正常成人骨盆（66个半骨盆）的螺旋CT扫描数据重建三维模型，以坐骨结节中心（O）、髂前上棘（A）与髂后上棘骨性突出点（B）连线中点（I）连线OI为中轴线置入虚拟圆柱体，直径6．5mm圆柱体在髂窝处低位的穿出点（i）到点O的距离即逆行拉力螺钉长度。记录圆柱体不进入关节的最大直径即最大螺钉直径（d），测量相关解剖学参数，根据测量结果设计出导向装置，并在Mimics软件、骨盆标本及尸体标本上进行验证。结果66个三维半骨盆全部成功置入圆柱体，测得男性AB为（156．26±7．28）mm，女性AB为（151．38±8．11）mm；男性0i为（139．53±7．56）mm，女性Oi为（125．15±11．17）mm；男性d为（12．19±1．97）mill，女性d为（10．19±2．14）mm。男女AB、Oi、d距离的差异均有统计学意义（t=2．574，5．992，3．923，P均〈0．05）。在导向装置安全性验证中：18例半侧骨盆标本模拟置钉实验、33例三维半骨盆使用Mimics软件模拟置钉验证导向装置一髂骨固定点置钉的安全性、18例骨盆标本模拟置钉验证导向装置一坐骨结节进针点、2例人体标本模拟置钉实验均得到了很好的验证结果。结论以OI为中轴置入后柱螺钉是安全可行的。根据髋臼后柱拉力螺钉进钉结果设计的导向装置可以准确地辅助经皮逆行拉力螺钉的置入。

Objective To devise the guide apparatus for percutaneous retrograde lag screw fixa- tion of fracture in posterior column of the acetabulum and validate its feasibility and accuracy. Methods Based on spiral CT data of bilateral hemi-pelvis in 33 normal adults, three-dimensional pelvic models were reconstructed using Mimics 10.01 software. Virtual cylindrical implants were placed along the axis connecting the center of ischial tuberosity and the midpoint of most prominent bony points on anterior su- perior iliac spine and on posterior superior iliac spine and related anatomical parameters were measured. The guide apparatus was developed according to the measuring results and validated in Mimics software, pelvic specimens and cadaveric specimens. Results There was no implant failure. Mean distance be- tween the most prominent bony points on anterior superior iliac spine and on posterior superior iliac spine was （ 156.26 ±7.28 ） mm in males, while （ 151.38± 8.11 ） mm in females （ t = 2. 574, P 〈 0. 05 ） ; mean length of the virtual cylinder was （139.53 ±7.56） mm in males, but （125.15± 11.17） mm in females（ t = 5. 992, P 〈 0.05 ） ; mean maximum diameter of the virtual cylinder was （ 12.19 ± 1.97 ） mm in males, while （ 10.19 ± 2.14） mm in females （t= 3. 923, P 〈 0.05 ）. In testifying safety of the guide ap- paratus, all obtained good results. Conclusions Posterior column screws can be placed along the axis. The guide apparatus based on the entry results of posterior column lag screws can assist percutaneous lag screw placement accurately.