空心螺钉与重建钢板固定耻骨联合分离的生物力学稳定性比较

Comparison of the biomechanical stability of cannulated screw and reconstruction plate for the fixation of symphysis pubis diastasis

目的对空心螺钉与重建钢板固定耻骨联合分离的生物力学性能进行测试,为临床应用提供理论依据。方法取温州医学院防腐正常成人骨盆标本15具,随机分成3组。自第5腰椎水平及双大腿中上2/3处将尸体横断。耻骨联合处切开,并将单侧骶棘韧带、骶结节韧带、骶髂前韧带切断,模拟Tile B1型骨盆骨折,依次分别采用5孔重建钢板和6.5 mm空心螺钉内固定治疗耻骨联合分离。将标本固定于生物力学试验机,在腰5椎体上方对其进行垂直轴向压缩生物力学测试,最大负荷达400 N,比较耻骨联合分离的位移程度。结果 3.5 mm 5孔重建钢板和空心螺钉固定,均可显著减少耻骨联合的分离,恢复骨盆环的力学稳定性。其中3.5 mm 5孔重建钢板加4枚皮质骨螺钉于耻骨联合上方固定组,耻骨联合位移为(0.944±0.983)mm,空心螺钉髓内固定组耻骨联合分离为(-0.03±0.378)mm,两者之间存在统计学显著性差异(P<0.05)。结论空心螺钉在生物力学稳定性上优于5孔3.5 mm重建钢板。空心螺钉具有良好的生物力学性能,固定可靠,符合生物学固定的原则。

Objective To test the biomechanical properties of symphysis pubis diastasis fixed by cannulated screw or reconstruction plate and provide the theoretical basis for clinical practice.Method In the experiment,fifteen normal adult specimens’pelvis along with their intact spines from L5 to the proximal 2/3 of both femora were randomly divided into three groups.The symphysis pubis,unilateral anterior sacroiliac joint and ipsilateral sacropi-nous and sacrotuberous ligaments were cut;the intact major pelvic ligaments and hip joints were used to simulate Tile B1 pelvic fracture model.The fixation of five-hole reconstruction plate and 6.5 mm cannulated screw were ap-plied successively to cure symphysis pubis diastasis.The pelves were loaded vertically in the testing machine with astanding posture.The loads were applied through the L5 body to a maximum of approximately 400 N,while the dis-placements of the symphysis pubis were recorded.Results The study showed that two fixations were able to re-duce symphysis pubis gapping and restore the biomechanical stability of pelves.Under the same condition,thedisplacement of symphysis pubis used 3.5 mm five-hole reconstruction plate with 4 cortical screws,and the dis-placement by using cannulated screw were（0.944±0.983）mm and（-0.03±0.378）mm respectively.Therewere significant differences（P0.05）between them.Conclusions The cannulated screw is superior to 3.5mm five-hole screw in biomechanical stability.The cannulated screw has fine biomechanical properties and is a-ble to provide the firm fixation for symphysis pubis diastasis,which fits the principles of biological osteosynthesis.