钉棒系统与髋臼上外固定架在骨盆Tile B1损伤模型中的生物力学比较

Biomechanical comparison of internal fixation by nail-stick and supraacetabular external fixation for the simulation of Tile B1 of the pelvis

目的通过比较钉棒系统与髋臼上外固定架固定骨盆Tile B1损伤模型的生物力学稳定性,为临床治疗选择更佳固定方式提供理论依据。方法取近期防腐的正常成人骨盆标本7具,保留从第5腰椎到股骨近端中上2/3的骨盆标本,保留双侧骶髂关节、双侧髋关节、双侧骶髂后韧带、双侧骶髂前韧带、双侧骶棘韧带、双侧骶结节韧带及完整的耻骨联合。将骨盆标本置于AGX生物力学实验机上,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耻骨联合切开,伴单侧骶棘韧带、骶结节韧带、骶髂前韧带切断,模拟骨盆水平旋转不稳定TileB1损伤;③钉棒系统固定骨盆Tile B1损伤模型;④髋臼上外固定架固定骨盆Tile B1损伤模型。结果完整骨盆组的耻骨联合位移最小,为(0.125±0.024)mm。骨盆Tile B1损伤模型无固定组的耻骨联合位移最大,为(4.589±0.366)mm。钉棒系统和髋臼上外固定架固定Tile B1损伤模型,均可显著减少耻骨联合的分离,恢复部分骨盆环的力学稳定性。其中椎弓根钉棒系统固定的耻骨联合位移为(0.626±0.097)mm,髋臼上外固定架固定为(1.022±0.095)mm,两者之间存在统计学差异(P<0.05)。结论钉棒系统在骨盆Tile B1损伤模型中的生物力学稳定性优于髋臼上外固定架,能有效恢复骨盆环的力学稳定性。

Objective To test the biomechanics of Tile B1 of the pelvis fixed by nail-stick internal fixation and supraacetabular external fixation,to compare pelvic biomechanical stability to provide a theoretical basis for clinical treatment. Methol~ Seven normal adult pelvic specimens, along with their spines from the fifth lumbar vertebra to the proximal 2/3 of both femora, retaining intact hip joints and major pelvic ligaments. The pelvic were loaded vertically in the AGX biomechanics testing machine with a standing posture. The displacements of the symphysis pubis were recorded until a maximum of approxi- mately 500N applying to load through the Ls body. Testing was first performed on intact pelvic and then the symphysis pubis, u- nilateral anterior sacroiliac joint,and ipsilateral sacropinous and sacrotuberous ligaments were cut to make the models of the simulation of rotatory unstable injury of the pelvis （Tile B1 ）. A Tile B1 injury was simulated on each pelvis. The following fixa- tion were then applied：nail-stick internal fixation and the supraacetabular external fixation fixed to supraacetabular region of the anterior. Results This study showed that two fixations could significantly decrease displacement of symphysis pubis and partly restore the biomechanical stability of pelvic. Under the same condition, the symphysis pubis motion [（0.125±0.024）mm]with in- tact pevic was the smallest, and the symphysis pubis motion [（4.589±0.366）mm] with Tile B1 was the largest. The displacement of symphysis pubis with nail-stick internal fixation was （0.626±0.097）mm,and the symphysis pubis motion used supraacetabular external[ fixation was （1.022±0.095）mm. There were differences between two fixations（P〈0.05）. Conclusion The internal fix- ation by nail-stick is more effective in maintain and restoration in biomechanical stability of pelvis than supraacetabular external fixation in Tile B1 of the pelvis.