生物活性玻璃涂层改善椎弓根螺钉稳定性的生物力学研究

目的　分析生物活性玻璃涂层椎弓根螺钉 (BPS)置入椎体后的稳定性 ,探讨生物活性玻璃涂层强化椎弓根螺钉固定的生物力学效果。　方法　采用 7具新鲜成人脊柱标本T1 1 ～L5共 4 9个椎体 ,随机选择 38个椎体 ,每个椎体按标准操作随机选一侧椎弓根置入普通钛合金椎弓根螺钉 (对照组 ) ,另一侧置入生物活性玻璃涂层椎弓根螺钉 (BPS组 )。随机选择 14个椎体 ,螺钉拧入时连接扭矩传感器 ,以测定最大拧紧力矩。然后取经测螺钉最大拧紧力矩的 14个椎体行轴向拔出试验 ,以测定最大轴向拔出力、相对位移以及拔出过程中的能量吸收值 ;随机选择 12个椎体做梯增负荷的周期抗屈试验 ;随机选择 12个椎体行磨阻试验 ,测定摩擦系数。　结果　BPS组最大拧紧力矩高于对照组 (P <0 .0 5 ) ,且最大拔出力较对照侧增加 5 7.71% (P <0 .0 1)、相对位移较对照侧提高 15 .13% (P <0 .0 5 )、能量吸收较对照侧提高 5 8.2 8% (P <0 .0 1)。周期抗屈试验与磨阻试验中 ,BPS组能耐受更强的负荷 ,在同等负荷下产生的位移较小 ,摩擦系数较对照组高 2 1.38%(P <0 .0 5 )。　结论　生物活性玻璃涂层能显著提高椎弓根螺钉置入后的稳定性 ,并因其涂层分布均匀、无粘合剂注入后椎体外渗漏而危及邻近营养血管和神经根之虞 ;内固定系统各螺钉强

Augmentation of pedicle screw fixation with bioactive glass coat: an in vitro biomechanical study

Objective To evaluate the stability and the biomechanical effect of bioglass-coating pedicle screws (BPS) in strengthening the fixation. Methods Forty-nine fresh specimens of T 11 -L 5 thoracolumbar vertebrae from 7 human bodies were employed in the study. Followed by the standard procedure, every vertebra of 38 randomly chosen vertebrae was implanted with a Titanic pedicle screw at a randomized side (control side) and with a BPS at the other side (BPS side). In 14 vertebrae, the maximum axial pulling-out strength, the relative displacement and the energy absorption during pulling out of the screw were determined after their maximum torques were measured by torque sensors. Periodical bending resistance test was made on other 12 randomized vertebrae in a gradient loading. Another 12 vertebral bodies were used in drag friction experiment to determine the friction coefficient of the coat. Results Compared with the control sides, the maximum torque of the BPS sides was higher ( P <0.05). Of the BPS sides, the maximum pulling-out strength averaged 57.71 % greater ( P <0.01), the relative displacement increased by 15.13 % ( P <0.05) and the energy absorption by 58.28% ( P <0.01). In periodical bending resistance test, BPS was found to withstand more cycles or greater loading before loosening. Under the same loading, BPS moved less with a higher friction for 21.38% than that of the control sides ( P <0.05). Conclusions Augmentation with bioglass coat can significantly strengthen the pedicle screw fixation. BPS has a prosperous clinical application for its sound biocompatibility and bioactivity, easy induction of synostosis, firm fixation and evenly distributed coat with impossible leakage into the vertebral canal or onto the surface of pedicle.