摘要
背景:有研究表明磷酸钙骨水泥通过改善骨与螺钉界面的质量,从而强化螺钉的即刻和早期固定强度。目的:实验拟验证磷酸钙骨水泥对颈椎前路单皮质骨螺钉的强化作用。设计:对比观察。单位:中南大学湘雅医学院附属湘雅一医院骨科。材料:实验于2003-09/2004-01在中南大学材料科学与工程学院电子拉伸力学性能室完成。由张家港市欣达医疗器械有限公司生产的颈椎前路单皮质骨自攻螺钉,材质为纯钛。注射型磷酸钙骨水泥由上海瑞邦生物材料有限公司生产。轴向拔出套筒由中南大学机械制造基地制造。方法:①选取4具新鲜青年男性尸体C3～C6椎体标本共16个椎体,单个椎体骨密度测量,证实无骨质疏松。4具新鲜老年男性尸体C3～C6椎体标本共16个椎体,单个椎体骨密度测量,证实骨质疏松。标本由中南大学湘雅医学院解剖教研室提供,死者生前自愿捐献遗体,家属均知情同意。每组随机选择12个椎体进行3个试验,轴向拔出试验选取6个椎体,周期抗屈试验和抗屈后抗剪切试验选取6个椎体。在椎体前方中线两侧8mm处向中线倾斜5°攻丝锥导孔,钻出钉道备用,不穿透椎体后方骨皮质。②轴向拔出实验:随机选取椎体一侧置入螺钉作为对照组,在材料实验机上行轴向拔出实验,拔出速率为5 mm/min。螺钉拔出后用磷酸钙骨水泥0.10～0.15mL修复钉道再次置入螺钉作为修复组,另一侧直接以磷酸钙骨水泥填充后置入螺钉作为强化组,37℃下放置24h后再行轴向拔出试验。③周期抗屈试验和抗屈后抗剪切试验:随机选取椎体一侧置入螺钉作为对照组,另一侧直接以磷酸钙骨水泥填充后置入螺钉作为强化组行周期抗屈试验和抗屈后抗剪切试验。主要观察指标:①螺钉的最大轴向拔出力。②周期抗屈实验后螺钉的位移。③周期抗屈后螺钉的最大抗剪切力。结果:①轴向拔出试验:骨质正常椎体,对照组拔出力为(313±64)N,修复组为(376±88)N,强化组为(446±121)N;骨质疏松椎体,对照组拔出力为(106±47)N,修复组为(154±67)N,强化组为(191±80)N。修复组、强化组的轴向拔出力均明显高于对照组(P<0.05)。②周期抗屈实验:强化组在相同载荷下产生的位移明显小于对照组(P<0.05)。③最大抗剪切力:骨质正常椎体:对照组为(301±79)N,强化组为(395±105)N。骨质疏松椎体:对照组为(87±39)N,强化组为(149±63)N,强化组的最大抗剪切力明显强于对照组(P<0.05)。结论:磷酸钙骨水泥能提高螺钉的轴向拔出力及抗剪切能力,在骨质疏松时强化效果更加明显。
BACKGROUND： Calcium phosphate cement （CPC） can strengthen the immediate and early fixation of screws by improving the quality of bone and the surface of screws. OBJECTIVE： To evaluate the biomechanical efficacy of CPC in augmentation of anterior cervical unicortical screw fixation. DESIGN： A study of controlled observation. SETTING： Department of Orthopaedics of First Xiangya Hospital of Xiangya Medical College of Central South University. MATERIALS： Experiments were performed at the Room of Electromechanical Tensile Property of College of Material Science and Engineering of Central South University from September 2003 to January 2004. Anterior cervical unicortical screw （pure titanium） was produced by Zhangjiagang Xinda Medical Equipment Co., Ltd. Injectable calcium phosphate cement was produced by Shanghai Ruibang Biomaterial Co., Ltd. Axial pull-out sleeve was produced by Machine Manufacture Center of Central South University. METHODS： 1.Sixteen cervical vertebrae （C3-6） of four fresh young man cadavers with fine results in bone mineral density （BMD） test and sixteen cervical vertebrae （C3-6） of 4 fresh old man cadavers with poor results in BMD test were selected. Specimens were provided by Department of Anatomy of Xiangya Medical College of Central South University. Mortal remains of the deceased were donated according to the will of the dead. Informed consents were obtained from their family members. Twelve vertebrae were selected in each group for three tests. Six vertebrae were selected in pull-out test, and six vertebrae in cyclic bending test and sheafing test. Screw holes, which were 8 mm apart from the midline and 5° inclined centrally, were made on both sides in the front part of the vertebra. Cortical bone was not penetrated. 2.A screw was randomly inserted into one side hole, which was considered to be a control group. Pull-out test was performed on material testing machine at 5 mm/min. The screw hole was filled with CPC （0.10-0.15 mL） to repair the screw hole, and then the screw was implanted, which was considered to be a restoration group. The screw hole was injected with CPC, and then the screw was implanted, which was considered to be a augmentation group. 24 hours later, pull-out test was conducted again at 37℃. 3.The screw was randomly implanted into one side hole （as a control group）. The screw hole was injected with CPC, and then screw was implanted （as an augmentation group）. Both groups received cyclic bending test and sheafing test. MAIN OUTCOME MEASURES： 1.The maximal axial pull-out strength of screws, 2.displacement of screws after cycle bending test,3.the maximal shear strength after cycle bending test. RESULTS： 1.The axial pull-out test： In normal vertebrae, axial pull-out strength was （ 313±64 ） N, （ 376±88 ） N and （446±121 ） N in the control group, the restoration group and the augmentation group respectively. In osteoporotic vertebrae, axial pull-out strength was （ 106 ± 47 ） N, （ 154 ± 67 ） N and （ 191 ± 80） N in the control group, the restoration group and the augmentation group respectively. The axial pull-out strength in the restoration group and augmentation group was significantly bigger than in the control group （P 〈 0.05）. 2.The cyclic bending test： The displacement of the unicortical screw in the augmentation group was much smaller than in the control group （P 〈 0.05）. 3. In normal vertebrae, the maximal shear strength was （ 301 ± 79 ） N and （ 395 ± 105 ） N in the control group and the augmentation group respectively. In the osteoporotic vertebrae, the maximal shear strength was （ 87 ± 39 ） N and （ 149±63 ） N in the control group and the augmentation group respectively. The maximal shear strength was significantly bigger in the augmentation group than in the control group （P 〈 0.05）. CONCLUSION： CPC can enhance the axial pull-out strength and sheafing ability of the screw. The augmentation is more evident in osteoporosis patients.
出处
《中国组织工程研究与临床康复》
CAS
CSCD
北大核心
2008年第6期1196-1200,共5页
Journal of Clinical Rehabilitative Tissue Engineering Research
