Camino Willhuber Gaston, Zderic Ivan, Gras Florian, Wahl Dieter, Sancineto Carlos, Barla Jorge, Windolf Markus, Richards Robert Geoff, Gueorguiev Boyko
AO Research Institute Davos, Clavadelerstrasse 8, 7270, Davos, Switzerland.
Hospital Italiano de Buenos Aires, Buenos Aires, Argentina.
Int Orthop. 2016 Jul;40(7):1537-43. doi: 10.1007/s00264-015-3007-0. Epub 2015 Oct 5.
Treatment of posterior pelvic ring injuries is frequently associated with pain or/and high mortality rates. Percutaneous sacro-iliac (SI) screw fixation has proved to be one of the methods of choice, providing minimal operative time, blood loss and wound-related morbidity. However, fixation failures due to secondary fracture dislocation or screw backing out have been reported. There is a little knowledge regarding the impact of varying screw orientation and quality of reduction on the fixation strength.
The purpose of the present study was biomechanical investigation of joint stability after SI screw fixation and its dependence on quality of reduction and screw orientation.
Thirty-two artificial hemi-pelvices were assigned to four study groups and simulated SI dislocations were fixed with two SI screws in oblique or transverse screw orientation and anatomical or non-anatomical reduction in group A (oblique/anatomical), B (transverse/anatomical), C (oblique/non-anatomical) and D (transverse/non-anatomical). Mechanical testing was performed under progressively increasing cyclic axial loading until fixation failure. SI joint movements were captured via optical motion tracking. Fixation performance was statistically evaluated at a level of significance p = 0.05.
The highest cycles to failure were observed in group A (14038 ± 1057), followed by B (13909 ± 1217), D (6936 ± 1654) and C (6706 ± 1295). Groups A and B revealed significantly longer endurance than C and D (p ≤ 0.01).
Different screw orientations in the presented model do not influence substantially SI joint stability. However, anatomical reduction is not only mandatory to restore a malalignment, but also to increase the SI screw fixation strength and prevent fixation failures.
骨盆后环损伤的治疗常常伴随着疼痛或/和高死亡率。经皮骶髂螺钉固定已被证明是一种首选方法，具有最短的手术时间、最少的失血量和与伤口相关的发病率。然而，已有报道称存在因继发性骨折脱位或螺钉退出导致的固定失败情况。关于不同螺钉方向和复位质量对固定强度的影响，目前了解甚少。
本研究的目的是对骶髂螺钉固定后关节稳定性及其对复位质量和螺钉方向的依赖性进行生物力学研究。
将32个人工半骨盆分为四个研究组，模拟骶髂关节脱位，在A组（斜向/解剖复位）、B组（横向/解剖复位）、C组（斜向/非解剖复位）和D组（横向/非解剖复位）中用两枚骶髂螺钉以斜向或横向螺钉方向及解剖或非解剖复位进行固定。在逐渐增加的循环轴向载荷下进行力学测试，直至固定失败。通过光学运动跟踪记录骶髂关节运动。在显著性水平p = 0.05下对固定性能进行统计学评估。
A组观察到的失效循环次数最高（14038±1057），其次是B组（13909±1217）、D组（6936±1654）和C组（6706±1295）。A组和B组的耐久性明显长于C组和D组（p≤0.01）。
在本模型中，不同的螺钉方向对骶髂关节稳定性影响不大。然而，解剖复位不仅是恢复错位所必需的，而且还能增加骶髂螺钉固定强度并防止固定失败。
