【作者】 贾金鹏；

【导师】 王岩；

【作者基本信息】 中国人民解放军军医进修学院 ， 骨外科学， 2009， 博士

【摘要】 目的:无菌性松动是骨水泥型人工髋关节置换常见的并发症,股骨假体的长期生存率与良好的骨水泥技术密切相关。在股骨远端使用骨水泥塞是现代骨水泥技术的重要组成部分,骨水泥塞能够显著增加髓腔内骨水泥的压力,对股骨柄形成良好的固定。相比普通骨水泥塞在翻修手术或用于股骨峡部以下较宽大部位时的局限性和缺点,可降解并能快速恢复形状的骨水泥塞具有明显的优点。聚乳酸是常用的具有良好生物相容性和可降解性的高分子化合物,已被美国FDA批准并在许多生物医学领域应用。我们设计加工了PLLA与PDLLA的共聚物P(D,L-LA-CO-L,L-LA),对其细胞相容性和力学性能进行研究。利用该材料制作了骨水泥塞,试图设计出一种能够在体内自行降解,并且在髓腔峡部以下能够有效抵抗髓腔内压力和移位的骨水泥塞。方法:通过原位聚合法合成PLLA与PDLLA的聚合物P(D,L-LA-CO-L,L-LA)并加工成骨水泥塞。采用采用细胞形态学观察法和细胞增殖法观察该材料与兔骨髓干细胞的相容性。用倒置相差显微镜观察细胞形态和生长情况,细胞增值率通过CCK-8检测。采用溶血试验检查材料对血液红细胞的溶解作用,测定红细胞溶解和血红蛋白游离的程度。采用福尔马林浸泡防腐的人体股骨进行实验。股骨远端在髁上截骨,近端保留15mm左右的股骨距。插入软钻逐级扩髓,直到软钻与股骨峡部的皮质相接触为止。软钻的直径即为股骨峡部的直径。选取2对峡部直径为12mm的股骨作为实验样品。采用髓腔锉由小到大依次打入对髓腔塑形。选择并置入合适大小的骨水泥塞。分别测试3种骨水泥塞在股骨峡部以上和股骨峡部以下的力学特点。记录骨水泥塞的抵抗压力的能力和向髓腔远端移位的关系。结果:体外实验显示不同浓度的P(D,L-LA-CO-L,L-LA)浸提液下培养的兔骨髓干细胞生长和形态与对照组无明显差异。细胞毒性实验无明显毒性。溶血实验未见明显溶血反应发生,溶血指数为0.28%,低于国家标准(5%)。体外测试表明,三种骨水泥塞的表现各异并与使用位置有关。当用于髓腔峡部以上时,所有类型骨水泥塞的抵抗压力的能力均超过345KPa,即Noble发表文章中认为的骨水泥塞应具备的抵抗压力的能力。用于股骨峡部以下时,除了一个较大型号并且发生侧翼严重磨损的超高分子量聚乙烯骨水泥塞外,其余的超高分子量聚乙烯骨水泥塞均在较小的压力下失败。P(D,L-LA-CO-L,L-LA)骨水泥塞在用于股骨峡部以下时具有最强的抵抗压力的能力。新型骨水泥塞在体外实验中至少能够抵抗超过740 kPa的压力。结论:P(D-L-LA-CO-L,L-LA)具有良好的生物相容性。用于股骨近端时,新型的可降解骨水泥塞同其他两种常用骨水泥塞一样,能够有效抵抗髓腔内的压力并防止向远端移位。常用的聚乙烯骨水泥塞在用于股骨峡部以下时在压力较低的情况下即告失败,可降解形状记忆骨水泥塞由于其形状记忆的特点,在用于髓腔峡部以下部位时能够有效抵抗髓腔内的压力,具有一定的优势。如何进一步降低玻璃化温度和找到更简单的使用方法需要进一步研究。其在体内的降解过程还需要实验来证实。更多还原

【Abstract】 Objective:A septic loosening is a common long-term complication of cemented femoral components in hip armroplasty.Improved cementing technique could increases cemented femoral component survival.The use of a cement restrictor in cemented femoral fixation during hip arthroplasty is an important part of modern cementing technique.Cement restrictor can increase intramedullar cement pressure significantly and create an optimum cementing of the femoral stem.Compared of the limitation and disadvantage of the UHMWPE cement restrictor in potential revision surgery or used below the femoral isthmus,the biodegradable and sharp memory cement restrictor has immense advantages.Poly lactic acid is a well-known synthetic polymer with excellent biocompatibility and degradability,which has been approved by American FDA and used in various biomedical fields.In this thesis,the preparation, cytocompatibility and biomechanical properties of copolymer of PLLA and PDLLA were studied.We designed a novel restrictor with the copolymer,which can degrade in medullary cavity and can reliable resist distal migration and pressure created by cement pressurized.Methods:We fabricatied the copolymer P(D,L-LA-CO-L,L-LA) by PLLA and PDLLA via in site intercalative polymerlization and made a novel biodegradable sharp memory cement restrictor.Biocompatibility of the copolymer with rabbit bone marrow stem cell was investigated by means of cell morphology and cell proliferation.The morphology of the cells was observed by inverted phase contrast microscope and cell proliferation determined by CCK-8 assay. Hemolysis was evaluated in vitro through measuring erythrocyte lyses and ferrohemoglobin freeing degree with indirect contact method.We used human femora preserved by formalin in all experiments.The femora were sectioned distally at the epicondylar and preserved 15 mm of the calear femorale.Insert soft reamer by gradually increased size until the reamer contacted with the cortex of the femoral isthmus.The size of the reamer was regarded as the diameter of the isthmus.We selected two pairs of femur whose diameter was 12mm as the specimen.The femoral canal is prepared with a series of broaches that create an envelope for the implant.Remove the broach and measure the size of the canal,and then insert a suitable cement restrictor.The mechanical proprieties of the restrictors were test above and below the femoral isthmus.The relationship of pressure resists ability and distal migration was recorded.Results:The number of rabbit bone marrow stem cells increased significantly and the morphology was normal.The growth and morphology of the cells in different concentration of P(D,L-LA-CO-L,I.-LA) extraction medium had no difference to control group.Cytotoxicity test showed that P(D,L-LA-CO-L,L-LA) did not have obvious toxicity to rabbit bone marrow stem cells.Hemolysis test suggested that the P(D,L-LA-CO-L,L-LA) did not have obvious hemolysis reaction.The hemolysis index was 0.28%,which was less than the national standard(5%).There was variation in the performance of the three cement restrictors and changed with the position.When used above the isthmus of the femur,all kinds of restrictors were successful to resist pressures greater than 345KPa,which has been described by Noble in an earlier publication.But,most of UHMWPE cement restrictors failed at low pressures when deployed below the isthmus,except a larger diameter restrictor which had serious wear on the wings. P(D,L-LA-CO-L,L-LA) cement restrictor could resist the greatest pressures when the restrictor used below the femoral isthmus.The novel cement restrictor could resist cement pressures of more than 740KPa in vitro.Conclusions:The P(D,L-LA-CO-L,L-LA) copolymer has an excellent biocompatibility.The novel restrictor can reliably resist intramedullar cement pressure and distal migration at the proximal femur as well as the two types of UHMWPE restrictors.The UHMWPE restrictors with a smaller diameter failed at low pressures when deployed below the isthmus and the restrictor with a larger diameter could resist pressures of 345KPa but may create wear particles.The biodegradable shape memory cement restrictor can reliably resist intramedullar cement pressure.When used below the isthmus,this kind of restrictor had some advantages because of its sharp memory and degradable property.How to decrease its Tg temperature and find an easy to use method for the novel restrictor still need to be further study.More study should be performed to prove its degradable character in vivo.更多还原