肾形纳米羟基磷灰石/聚酰胺66腰椎间融合器的体外生物力学研究

BIOMECHANICAL STUDY ON KIDNEY-SHAPED NANO-HYDROXYAPATITE/POLYAMIDE 66 CAGE

目的 比较肾形与子弹头形纳米羟基磷灰石/聚酰胺66（nano-hydroxyapatite/polyamide 66,n-HA/PA66）腰椎间融合器（Cage）的生物力学差异。方法 取10具成年雄性白猪L2～L5脊柱标本,相邻两椎体为一运动单位,共20个运动单位,随机分为4组（n=5）：空白对照组（A组）、髓核摘除组（B组）、子弹头形Cage组（C组）、肾形Cage组（D组）。A组不作处理;B组单纯摘除椎间盘髓核;C、D组模拟经椎间孔腰椎间融合术（transforaminallumbar interbody fusion,TLIF）,植入相应Cage并辅以椎弓根螺钉内固定。手术前后摄X线片观察各组椎间隙高度和C、D组Cage的位置。生物力学测试各组前屈、后伸、左侧弯、右侧弯、左旋转、右旋转、压缩7个方向的运动范围（range of motion,ROM）。结果 术前A、B、C、D组椎间隙高度比较差异无统计学意义（F=0.166,P=0.917）;B组手术前后椎间隙高度无明显变化,C、D组椎间隙高度均较术前增加,但差异均无统计学意义（P〉0.05）,B、C、D组术后椎间隙高度两两比较差异无统计学意义（P〉0.05）。C组术后Cage位置偏左,尾端定位针距左边缘为（3.06±0.51）mm;而D组位置更居中,尾端定位针距左边缘为（5.68±0.69）mm;两组比较差异有统计学意义（t=6.787,P=0.000）。C、D组前屈、后伸、左侧弯、右侧弯、左旋转、右旋转、压缩7个方向的ROM均显著低于A、B组,B组均显著高于A组,差异均有统计学意义（P〈0.05）。D组在右侧弯和压缩2个方向的ROM小于C组,差异有统计意义（P〈0.05）;其他方向两组ROM比较差异均无统计学意义（P〉0.05）。结论 两种形状Cage在恢复椎间隙高度方面效果相似,辅以内固定后均能维持脊柱稳定。肾形Cage在轴向压缩和向植入对侧弯曲时ROM更小,在TLIF术中能更理想地放置于椎体中后部。

Objective To compare the biomechanical differences between the kidney-shaped nano- hydroxyapatite/polyamide 66 （n-HA/PA66） Cage and the bullet-shaped n-HA/PA66 Cage. Methods Le-Ls spinal specimens were selected from 10 adult male pigs. L2, L3 and L4, Ls served as a motor unit respectively, 20 motor units altogether. They were divided into 4 groups （n=5）： no treatment was given as control group （group A）; nucleus pulposus resection was performed （group B）; bullet-shaped Cage （group C）, and kidney-shaped Cage （group D） were used in transforaminal lumbar interbody fusion （TLIF） through left intervertebral foramen and supplemented by posterior pedicle screw fixation. The intervertebral height （IH） and the position of Cages were observed on the X-ray films. The range of motion （ROM） was measured. Results There was no significant difference in the preoperative IH among 4 groups （F=0.166, P=0.917）. No significant change was found in IH between at pre- and post-operation in group B （P〉0.05）; it increased after operation in groups C and D, but difference was not statistically significant （P〉0.05）. There was no significant difference in the postoperative IH the left margin was （3.06±0.51） mm in group C （close among groups B, C, and D （P〉0.05）. The distance from Cage to to the left） and （5.68±0.69） mm in group D （close to the middle）, showing significant difference （t=6.787, P=0.000）. The ROM in all directions were significantly lower in groups C and D than in groups A and B （P〈0.05）, and in group A than in group B （P〈0.05）. The right bending and compression ROM of group C were significantly higher than those of group D （P〈0.05）, but no statistically significant difference was found in the other direction ROM （P〉0.05）. Conclusion The bullet-shaped and kidney-shaped Cages have similar results in restoring IH and maintaining the stability of the spine assisted by internal fixation. Kidney-shaped Cage is more stable than bullet-shaped Cage in the axial compression and the bending load opposite implant, it can be placed in the middle and back of the vertebral body more ideally.