摘要
目的:探讨不同直径与长度螺钉翻修及骨水泥强化后椎弓根固定的强度,评价其生物力学效果.方法:采用10具新鲜成人尸体T10～L5节段共80个椎体标本.首先置入5.5mm/45mm椎弓根螺钉作为对照组.再将脊椎标本随机平分为Ⅰ、Ⅱ两大组.Ⅰ组中40个椎体各随机选择一侧椎弓根应用6.25mm/45mm螺钉翻修(Ⅰ a组),另一侧椎弓根应用7.0mm/45mm螺钉翻修(Ⅰ b组);Ⅱ组中40个椎体各随机选择一侧椎弓根应用6.25mm/55mm螺钉翻修(Ⅱa组),另一侧椎弓根应用7.0mm/55mm螺钉翻修(Ⅱb组).再随机选择56个椎弓根分别行细小螺钉及粗大螺钉骨水泥强化固定翻修(Ⅲa组、Ⅲb组).在858Mini-MTS生物力学实验机上测试最大拔出力及最大扭力矩,并进行统计分析.结果:①6.25mm/45mm螺钉翻修5.5mm/45mm螺钉置入后的椎弓根,其拔出力及扭力矩无明显增加(P＞0.05);应用7.0mm/45mm、6.25mm/55mm及7.0mm/55mm螺钉翻修,把持力及扭力矩均明显增加(P＜0.05).②骨水泥强化固定后,螺钉把持力远大于单纯螺钉翻修组,且与螺钉粗细无关.③在对照组及螺钉翻修组,螺钉把持力与扭力矩间有明显相关性,相关系数r=.86.结论:①椎弓根螺钉翻修时,单纯螺钉直径增加1.5mm或直径增加0.75mm、长度增加l0mm以及骨水泥强化均可达到翻修固定的生物力学要求,以骨水泥强化固定更为明显.②增加螺钉直径与长度的翻修中,把持力与扭力矩是一致的;而应用骨水泥强化固定时,螺钉把持力主要取决于骨水泥本身及添加物-骨界面结合强度.
Objective:To study the biomechanical stability of augmentation and revision of pedical screw fixations with various methods.Method:Ten cadaveric spines from T10 to L5 were harvested in this study,which included a total of eighty thoracic and lumbar vertebrae.Screws of 5.5mm/45mm were implanted to all the pedicles as the controlled group initially.Then,all the specimens were divided into halves as GroupⅠandⅡrandomly.One side pedicles of the forty vertebrae were salvaged with 6.25mm/45mm screws(GroupⅠa),and the other side pedicles of vertebrae were salvaged with 7.0mm/45mm screws(GroupⅠb).In GroupⅡ,6.25mm/55mm and 7.0mm/55mm screws were used to salvage failed pedicles correspondingly(GroupⅡa andⅡb).Finally,56 pedicles were augmented with cement,meanwhile,smaller and larger screws were restored respectively(Group Ⅲa and Ⅲb).The maximum pullout strength and insertional torque of pedicle screws could be tested through 858Mini-MTS.Result:①Compared with the controlled group,there was no obvious increase of the pullout strength and insertional torque in the revision with 6.25mm/45mm screws(P>0.05).The axial pullout strength and insertional torque increased sharply in the revision with 7.0mm/45mm?6.25mm/55mm and 7.0mm/55mm screws(P<0.05).②Augmented by cement,the pullout strength was higher than that in revision groupⅡa andⅡb.But there was no correlation between the pullout strength and the type of screws.③In the controlled and revision groups,there was an apparent correlation between the pullout strength and the insertional torque(r=0.86).Conclusion: ①For the revision screws,both 1.5mm increase in diameter and 0.75mm increase in diameter accompanying with 10mm increase in length will be beneficial to salvage failed pedicles.And the cement augmentation is more rigid.②In the revision of using larger or longer screws,the pullout strength is well correlated with the insertional torque.While augmented by cement,the pullout strength is mainly determined by cement itself and the combination of bone and cement.
出处
《中国脊柱脊髓杂志》
CAS
CSCD
2004年第7期409-413,共5页
Chinese Journal of Spine and Spinal Cord
关键词
胸椎
腰椎
椎弓根
翻修
生物力学
Thoracic vertebrae
Lumbar vertebrae
Pedicle
Revision
Biomechanics
