镍钛合金表面改性后生物相容性及其持续动力压应力对骨折愈合的影响

背景:许多研究均特别强调镍离子在镍钛形状记忆合金腐蚀过程中的溶解作用,而这些离子可能对人体造成潜在的危害.应用各种表面处理措施可提高镍钛合金内植入材料的抗腐蚀能力.在现代医学的研究中,非常有必要对表面修饰后镍钛合金的特征进行分析.目的:观察表面改性及未改性的弹性镍钛合金内固定材料对骨折愈合的影响.同时设置髓内钉内固定材料做对照,比较弹性内固定材料在持续应压力下对骨折愈合的影响.设计、时间及地点:随机对照动物实验,于2004-09/2005-03在兰州大学第二医院骨科研究所组织工程实验室完成.材料:类金刚石镀膜镍钛合金环抱器和非镀膜镍钛合金环抱器(4H8-40型)由兰州西脉记忆合金股份有限公司提供,髓内针(ZQY-01型2X150)由天津市金兴达实业有限公司提供.方法:选择清洁级4～6月龄的青紫兰兔30只,按随机数字表法分为3组,类金刚石镀膜镍钛合金环抱器组、非镀膜镍钛合金环抱器组、髓内针内固定组,每组10只.每只兔1%戊巴比妥钠(25 mg/kg)麻醉后行股外侧切口,制成股骨中段横断骨折模型,分别用上述材料固定.主要观察指标:4周后取骨折局部骨痂,检测单位骨痂中无机物含量及碱性磷酸酶、骨钙素及肿瘤坏死因子的表达.并取局部肌肉组织、肝组织及脑组织测定镍离子含量.结果:①类金刚石镀膜镍钛合金环抱器组、非镀膜镍钛合金环抱器组骨痂中无机物含量,碱性磷酸酶、骨钙素及肿瘤坏死因子的表达均高于髓内针内固定组(P＜0.05).②类金刚石镀膜镍钛合金环抱器组和髓内针内固定组肝、脑、骨折周围肌肉组织内镍离子的含量低于非镀膜镍钛合金环抱器组(P＜0.05).结论:弹性内固定明显促进骨折愈合,类金刚石镀膜镍钛合金环抱器的组织相容性优于非镀膜镍钛合金环抱器.

Biocompatibility of surface-modified nickel titanium alloys and the effects of their continuous compressive stress on fracture healing

BACKGROUND:Several researches have highlighted the selective dissolution of Ni ion from the nickel-titanium (NiTi) alloy during the corrosion process,which can lead to potential damage to human body.Different surface treatments will improve the corrosion resistance of NiTi implants.In modern medicines,it is necessary to analyze the characteristics of surface modified NiTi implants.OBJECTIVE:To study the effects of coated and uncoated materials made by elastic nickel-titanium alloy internal fixator on fracture healing and to compare the effects of continuous compressive stress after internal fixator of different types on fracture healing by setting up control group of bone nail internal fixation.DESIGN,TIME AND SETTING:A randomized,controlled,animal experiment was performed at the Laboratory of Tissue Engineering,Institute of Orthopedics,Second Hospital Affiliated to Lanzhou University between September 2004 and March 2005.MATERIALS:Diamond-like carbon coated and nickel-titanium alloy and uncoated nickel-titanium alloy embracing fixator (type 4H8-40) were provided by Lanzhou Ximai Memory Co.,Ltd.,China.Intramedullary nails (type ZQY-01) were purchased from Tianjin Jinxingda Industries Co.,Ltd.,China.METHODS:Thirty Chinchilla rabbits of 4-6 months old were randomly divided into 3 groups (n = 10):diamond-like carbon coated nickel-titanium alloy embracing fixator (group A),uncoated nickel-titanium alloy embracing fixator (group B),and intramedullary fixator (group C).Following anesthesia by injection of 1% sodium pentobarbital (25 mg/kg),transverse fracture models in middle part of the femur were made through a lateral femoral incision and fixed with diamond-like carbon coated nickel-titanium alloy embracing fixator,uncoated nickel-titanium alloy embracing fixator,and intramedullary fixator respectively.MAIN OUTCOME MEASURES:The inorganic substance level,osteocalcin,alkaline phosphatase (ALP) and tumor necrosis factor (TNF) expression in callus surrounding fracture site were detected 4 weeks postoperatively.Ni ion level in muscles surrounding fracture site,live tissue,and brain tissue were also detected.RESULTS:Inorganic substance level and ALP,osteocalcin,and TNF expression were significantly higher in the groups A and B than in group C (P＜0.05).Ni ion level in the liver tissue,brain tissue,and muscles surrounding the fracture were significantly lower in the groups A and C than in group B (P＜0.05).CONCLUSION:Elastic fixation promotes fracture healing.Diamond-like carbon coated nickel-titanium alloy embracing fixator has a better histocompatibility than uncoated group.