钉-棒系统与外固定支架固定骨盆不稳定损伤模型的生物力学比较

Biomechanical comparison of pedicle screw-rod system and pelvic external fixator in models of rotatory unstable pelvic injury

目的通过对钉-棒系统和骨盆髂骨翼外固定支架固定骨盆水平旋转不稳定损伤模型的生物力学进行测试，对比两者固定骨盆的力学稳定性，为临床治疗提供理论依据。方法取经福尔马林处理的正常成人骨盆标本7具，保留从L5至股骨近端中上20cm的骨盆标本，保留完整的耻骨联合、双侧髋关节、双侧骶髂关节、双侧骶结节韧带、双侧骶棘韧带、双侧骶髂前韧带、双侧骶髂后韧带。将骨盆置于AGX生物力学试验机上，模拟人体正常双足站立中立位，由L5垂直向下加压至500N，依次测量下述4种情况下的耻骨联合位移：①完整骨盆；②骨盆水平旋转不稳定Tile B1型损伤模型；③钉-棒系统固定骨盆Tile B1型损伤模型；④骨盆髂骨翼外固定支架固定骨笳Tile B1型损伤模型。结果在500N的压力下，4组耻骨联合位移由小到大依次为完整骨盆[（0．121±0．025）mm]、钉-棒系统固定模型[（0．656±0．103）mm]、髂骨翼外固定支架固定模型[（1．512±0．101）mm]、Tile B1型损伤模型[（4．512±0．391）mm]，4组间两两比较差异均有统计学意义（P〈0．05）。结论钉-棒系统固定骨盆水平旋转不稳定损伤模型的生物力学稳定性明显优于骨盆髂骨翼外固定支架，能有效恢复骨盆环的力学稳定性。

Objective To compare the biomechanieal performances of pedicle screw-rod system versus pelvic ala ilium external fixator in cadaverie models of rotatory unstable pelvic injury. Methods Seven cadaverie specimens of normal adult pelvis were used for the test, retaining intact spines from the fifth lumbar vertebra to the proximal 20 centimeters of both femurs, intact pubic symphysis, bilateral hip joints, bilateral sacroiliac joints, bilateral sacrotuberous ligaments, bilateral sacrospinous ligaments, bilateral anterior sacroiliac ligaments and bilateral posterior sacroiliac ligaments. The pelvic specimens were put in an AGX biomechanical testing machine at a standing neutral posture and subjected to a vertical load of up to 500 N downward from the L5 body. The displacements of the symphysis pubis were recorded sequentially in the following 4 conditions： 1. intact pelvis; 2. pelvic Tile B1 injury in simulation of rotatory unstable injury of the pelvis in which the symphysis pubis was cut off and accompanied with ruptures of ipsilateral sacrospinous and sacrotuberous ligaments; 3. pelvic Tile BI injury fixated with the pedicle screw-rod system; 4. pelvic Tile B1 injury fixated with the pelvic ala ilium external fixator. Results Under the vertical load of 500 N, displacements of the symphysis pubis increased significantly from condition 1 （0. 121 ± 0. 025 mm）, to condition 3 （0. 656 ±0. 103 mm）, to condition 4 （1. 512 ±0. 101 ram） and last to condition 2 （4. 512 ±0. 391 mm）. The difference between any two conditions was significant （ P 〈 0.05） . Conclusion Fixation by the pediele screw-rod system is significantly better than that by the pelvic ala ilium external fixator for rotatory unstable pelvic injury, because the former can more effectively restore the biomechanical stability of the pelvic ring.