L_5、S_1前路经椎弓根螺钉固定的生物力学研究

Biomechanics research on L_5,S_1 anterior pedicle screw

目的探讨L5、S1前路经椎弓根螺钉固定生物力学特性。方法 7具完整新鲜尸体腰骶段(L5、S1)脊柱标本,双能X线骨密度测量后排除严重骨质疏松者,分解成两个独立完整椎体(L5、S1)。每个椎体植入前路椎弓根螺钉(ATPS)、后路椎弓根螺钉(PTPS)和椎体螺钉(TVS),对置入的3种螺钉进行旋入扭矩和抗拔出力试验,比较3种螺钉固定方式的最大扭矩和轴向拔出力。结果 L5、S1的平均最大扭矩:ATPS为(1.25±0.01)N·m,PTPS为(1.35±0.01)N·m,TVS为(0.40±0.01)N·m;ATPS和PTPS之间差异无统计学意义(P>0.05),ATPS、PTPS与TVS间差异有统计学意义(P<0.05)。L5、S1的平均最大拔出力:ATPS为(1 630±65)N,PTPS为(1 730±60)N,TVS为(680±50)N;ATPS和PTPS之间差异无统计学意义(P>0.05),ATPS、PTPS与TVS之间差异有统计学意义(P<0.05)。螺钉旋入最大扭矩与螺钉拔出力呈正相关性。结论 L5、S1ATPS和L5、S1PTPS两种固定的平均最大扭矩和平均最大拔出强度差异并不明显,但均大于TVS固定。L5、S1ATPS固定有较好的生物力学优势。

Objectives To study the biolnechanics of L5、S1 anterior pedicle screw （ATPS）. Methods 7 spine specimens of lumbar and sacral segments from 7 complete fresh cadavers （L5, S1 ） were studied, the bone mineral density by dual energT X ray was measured, and the specimen was broken down into two separate complete vertebrae （L5, S1）. Each vertebra is implanted randomly with lumbar 5 sacral 1 standard ATPS, L5, S1 posterior pedicle screw （PTPS） , and L5, S1 vertebral screw （TVS）. The screwing torque and pullout resistance on all three screws was test ed, aiming to compare the greatest axial torque and pullout strength among the three screw positioning. Results The average nlaxinlunl torque of L5, S1 ATPS was （ 1.25± 0.01） N · m, the average nlaxinlunl torque of PTPS was （1.35 ± 0. 01 ） N ·m, and the average lnaxilnuln torque of TVS was （0.40 ±0. 01 ） N · m. The difference between ATPS and PTPS was not statistically significant （P 〉 0. 05 ）, while the difference between ATPS and TVS was statistically significant （P 〈0. 05）. Also for PTPS and TVS, the difference is statistically significant （P 〈0. 05）. The average lnaxilnuln pullout strength of L5, S1 ATPS was （ 1630 ± 65） N, the average lnaxilnuln pullout strength of PTPS was （ 1 730 ± 60） N, and the average lnaxilnuln pullout strength of TVS was （680 ± 50） N. The difference between ATPS and PTPS was not statistically significant （P 〉 0. 05 ）, while the difference between ATPS and TVS was statistically significant （P 〈0. 05）, Also for PTPS and TVS, The differences of maximum torque and pullout strength between L5, S1 ATPS and L5, S1 PTPS. the difference was statistically significant （P 〈 0. 05）. There was a positive correlation between the maximum torque and the pullout strength of the screw. Conclusions it is not obvious, but they are both stronger than L5,S1 TVS. The L5,S1 ATPS has better biolnechanical advantage.