医用超高分子量聚乙烯的改性及其摩擦学特点

背景:超高分子量聚乙烯因其自身优良的理化性能而被广泛应用于医学领域中的人工关节置换。目的:概述医用超高分子量聚乙烯应用于人工关节假体的摩擦磨损性能及其改性研究进展。方法:以"超高分子量聚乙烯、人工关节假体、摩擦磨损机制、摩削";"Ultra-High Molecular Weight Polyethylene,UHMWPE,artificial joint prosthetics,mechanism of friction and wear,wear debris"为关键词,检索1970至2012年ISI数据库、PubMed数据库,1979至2012年CNKI数据库、万方数据库及维普科技期刊数据库中有关医用超高分子量聚乙烯作为人工关节假体的自身摩擦磨损及改性研究。结果与结论:研究证实超高分子量聚乙烯的主要摩擦磨损机制为磨粒磨损、黏附磨损和疲劳磨损。针对其低耐摩擦性能,目前实验室可以通过无机填料改性法,包括羟基磷灰石、氧化锆、炭黑、碳纤维、碳纳米管等,交联法包括有机硅氧烷偶联剂交联和各种离子辐射等方法进行改性,并在各种模拟环境下所进行的摩擦磨损测试,结果证明这些改性后的材料耐磨性能均得到了不同程度提高。对医用超高分子量聚乙烯应用于人工关节假体的摩擦磨损实验研究体系主要包括摩擦磨损模拟试验机、润滑体液、磨损、磨屑的测定和评价等。     

医用超高分子量聚乙烯的改性及其摩擦学特点

背景：超高分子量聚乙烯因其自身优良的理化性能而被广泛应用于医学领域中的人工关节置换。目的：概述医用超高分子量聚乙烯应用于人工关节假体的摩擦磨损性能及其改性研究进展。方法：以＂超高分子量聚乙烯、人工关节假体、摩擦磨损机制、摩削＂;＂Ultra-High Molecular Weight Polyethylene,UHMWPE,artificial joint prosthetics,mechanism of friction and wear,wear debris＂为关键词,检索1970至2012年ISI数据库、PubMed数据库,1979至2012年CNKI数据库、万方数据库及维普科技期刊数据库中有关医用超高分子量聚乙烯作为人工关节假体的自身摩擦磨损及改性研究。结果与结论：研究证实超高分子量聚乙烯的主要摩擦磨损机制为磨粒磨损、黏附磨损和疲劳磨损。针对其低耐摩擦性能,目前实验室可以通过无机填料改性法,包括羟基磷灰石、氧化锆、炭黑、碳纤维、碳纳米管等,交联法包括有机硅氧烷偶联剂交联和各种离子辐射等方法进行改性,并在各种模拟环境下所进行的摩擦磨损测试,结果证明这些改性后的材料耐磨性能均得到了不同程度提高。对医用超高分子量聚乙烯应用于人工关节假体的摩擦磨损实验研究体系主要包括摩擦磨损模拟试验机、润滑体液、磨损、磨屑的测定和评价等。     

人工髋关节摩擦学的研究现状

学术背景:超高分子量聚乙烯是最常用的髋臼材料,植入人体后,由于交变载荷作用和润滑条件差等原因,易产生较多磨屑,导致人工关节松动.目的:了解关节润滑机制,介绍超高分子量聚乙烯人工髋关节的磨损行为及其抗磨性改善的研究现状,探索科学的人工关节摩擦性能评价方法.检索策略:应用计算机检索2000-01/2007-10相关文献,中文数据库有:中国期刊全文数据库(CNKI),维普中文科技期刊全文数据库,万方数字化期刊库,检索词为"髋关节,超高分子量聚乙烯,摩擦学";外文数据库有:IEEE/IEE Electronic Library ,Elsevier电子期刊全文数据库,检索词为"hip simulators, ultra high molecular weight polyethylene ,wear, tribology ".纳入关于关节副的摩擦磨损性能方面的论文,排除重复性研究.文献评价:初检得到729篇文献,阅读标题和摘要进行初筛,排除内容无关或重复者601篇,对剩余128篇进一步分析,最后保留22篇,完全符合纳入标准者进行综述.资料综合:对于超高分子量聚乙烯的研究,主要集中在两个方面,一个是对这种材料的表面改性,另一个是研究其摩擦磨损机制.①研究表明可以通过表面改性来改善超高分子量聚乙烯的磨损性能,如采用离子注入、纳米填充后的超高分子量聚乙烯,抗其磨性和机械性能显著提高.②近年来,对髋关节摩擦学的探索性实验很多,均利用人工关节实验机或传统实验设备评价在不同润滑环境下的摩擦磨损行为,证实在生物关节液中,摩擦副的磨损率较低.结论:对于髋关节材料的研究,国内还停留在利用传统的方法,并不能真实地反映在人体的环境下材料的摩擦磨损性能,所以今后的重点方向是弄清载荷、环境条件与体内人工关节磨损间的相互关系,探索科学的关节副摩擦性能评价方法.     

改良二步酶消化法行免RPE分离的研究

目的 研究RPE在改良二步酶消化法分离后的离体状态下生物学特性。方法 实验动物为有色家兔，应用显微手术技术完成必要的手术过程，加入酶Ⅰ与酶Ⅱ分离获取细胞，并培养传代计数鉴定。结果 采用改良二步酶消化法获取的原代细胞，呈球形浮于培养液中，细胞内黑色素颗粒多，经传代后细胞生长旺盛染色鉴定见细胞胞浆粉红色，胞核蓝色，可见许多双核细胞。免疫组化法染色鉴定，可见细胞着色率100％，细胞浆被染成深浅不同的黄色。结论 我们采用改良二步酶消化法获取RPE细胞显示出一定优点，细胞损伤小，获取细胞数量多，纯度高，实验时间短，成本相对低廉。     

超高分子量聚乙烯人工关节的摩擦学研究

目的：超高分子量聚乙烯(UHMWPE)工程塑料具有优异的物理和机械性能、生物相容性和化学稳定性、抗冲击性及耐腐蚀性，普遍应用于人工关节软骨-关节臼材料。然而在长期的使用过程中，其表面硬度低、耐磨性差、生物惰性等是其作为医用植入材料不容忽视的问题。文章结合UHMWPE的磨损机制，综述了通过改性，如离子注入，填料改性等，提高UHMWPE的耐磨性研究，并对其发展方向进行了有益探讨。资料来源：应用计算机检索Medline数据库1980—01／2004—06期间的相关文章，检索词为“UHMWPE”和“joint，wear．replacement,modification”，分别组合进行检索，限定文章语言种类为英文。同时计算机检索中国期刊全文数据库、万方数据库2000—01／2004-10期间的相关文章，检索词“超高相对分子质量聚乙烯，人工关节，磨损，离子注入，改性”，限定文章语言种类为中文。资料选择：对资料进行初审，选取试验包括上述干预组和对照组的文献，然后筛除不随机试验的研究，对剩余的文献开始查找全文。资料提炼：共收集到34篇关于UHMWPE关节及磨损的试验，20个试验符合纳入标准，排除14篇。另收集到21篇改性对uHMwPE人工关节磨损性能影响的试验，其中9个试验符合纳入标准，排除12篇．排除的26篇试验中，有22篇因系重复研究，4篇综述：资料综合：29篇文章中，5篇讨论了UHMWPE的磨损机制，7篇研究了离子注入对UHMWPE抗磨性能的影响，5篇讨论了填充改性对UHMWPE关节材料性能的影响。结论：UHMWPE的磨损导致人工关节置换的失效，通过对UHMWPE材料进行改性，如离子注入，填充改性可以提高UHMWPE的硬度，提高抗磨性，减少磨屑，延长人工关节的使用年限。     

胆固醇改性普鲁兰纳米粒子的制备及其载药性质

背景:多糖经引入疏水基团后,在水中能自组装成胶束,可作为疏水小分子药物及生物活性大分子(多肽、蛋白和基因)的载体,在医药和生物技术领域有着潜在的应用价值.目的:系统考察胆固醇基取代度和普鲁兰多糖相对分子质量对改性普鲁兰纳米粒子性状的影响.方法:将胆固醇修饰到不同相对分子质量的普鲁兰多糖长链上,合成了一系列取代度不同的胆围醇基-普鲁兰改性多糖,使其在水中自组装成纳米粒子,考察胆固醇取代度及多糖相对分子质量对纳米粒子形态的影响,以阿霉素为模型药物.研究了其在胆固醇基-普鲁兰改性多糖纳米粒子中的包封及体外释放行为.结果与结论:随着相对分子质量和取代度的增加,粒子稳定性增强,临界胶束质量浓度降低.胆固醇基取代度越低、多糖相对分子质量越大,载药量和包封率越高:当取代度和相对分子质量相同时,随着投料比的增加,载药量增加而包封率降低.体外释放结果表明,相对分子质量越大,粒子越稳定,载药量越高,药物释放越慢.     

预损伤与改良传代体外培养许旺细胞的比较(英文)

背景:通过组织工程方法构建神经桥接体修复神经损伤,需要大量纯化体外培养的许旺细胞。目的:对比观察预损伤法和改良传代法获取许旺细胞的纯度与质量。方法:①预损伤法:预损伤SD乳鼠坐骨神经,3d后取出坐骨神经,分离神经外膜,用胰酶、胶原酶消化,差速贴壁除去成纤维细胞,接种培养。②改良传代法:直接获取SD乳鼠坐骨神经,分离神经外膜,运用双酶消化法结合单酶消化法进行许旺细胞原代培养,5～7d后采用单酶快速消化离心法行传代培养,同时纯化许旺细胞。结果与结论:预损伤法和改良传代法体外培养的许旺细胞纯度均达95%以上,两种方法获得的许旺细胞纯度差异无显著性意义(P>0.05)。两种方法获取的许旺细胞形态正常,数量及纯度高,增殖旺盛,说明预损伤法和改良传代法都是体外获取高质量与高纯度许旺细胞的理想方法。     

壳聚糖-空肠弯曲菌外膜黏附蛋白PEB1核酸疫苗纳米粒子的制备

目的研究复凝法制备壳聚糖包裹PEB1纳米粒子的优化条件,并初步探讨其在动物体内的缓释作用。方法雌性清洁级Balb/c小鼠40只,分4组,皮下注射的方式免疫接种。A组:PBS对照组(每只小鼠注射200μl PBS);B组:空白质粒组(每只小鼠注射20μg空白质粒);C组:重组质粒组(每只小鼠注射20μg DNAPEB1);D组:纳米粒子组(每只小鼠注射100μg含20μg DNAPEB1的纳米粒子)。考虑单因素N/P比值、硫酸钠、酸碱度、温度和DNAPEB1浓度对纳米粒子粒径的影响,透射电子显微镜下观察形态;测量纳米粒子粒径和包封率。分组免疫小鼠,检测小鼠血清中抗PEB1抗体含量。结果制备纳米粒子的最适条件为:N/P=5、DNA浓度为100μg/ml、p H=5.5、Na2SO4浓度为0.01 mol/L、水浴温度55℃。扫描电镜图片显示纳米粒子平均粒径在(300±23)nm左右,包封率为(91.23±3.24)%。0~10周重组质粒组抗体水平高于纳米粒子组,12周两组水平相差不大,但14、16周,纳米粒子组水平显著高于重组质粒组。结论 CS-DNAPEB1核酸纳米粒子在小鼠体内对核酸疫苗起到了很好的缓释作用。     

改良法培养人牙髓间充质干细胞及其向神经样细胞的分化

背景:应用改良组织原位培养法后,牙髓间充质干细胞的提取成功率显著提高,但鲜有文献报道其与酶消化法提取干细胞生物学特性的异同.目的:观察改良组织原位培养法与传统酶消化法所获得的牙髓间充质干细胞向神经样细胞分化上的差异.方法:将同一组织来源的标本随机分成两组,分别用改良的组织原位培养法及常规的酶消化法提取人牙髓间充质干细胞,通过免疫组化、流式细胞检测及 RT-PCR 等比较观察其生长情况、抗原表达及向神经样细胞分化能力.结果与结论:改良法原位培养组分离牙髓间充质干细胞与常规分离培养组分离的干细胞在形态学表现,抗原表达及神经向分化能力上无明显区别,但简化了操作流程,且所得细胞数量大.     

纳米Ag-SiO2导尿管的细胞毒性评价

背景:具有抗菌活性的纳米Ag-SiO2导尿管可有效降低普通医用导尿管相关性尿路感染的发生率,其物理、化学性质发生很大变化,所以对其安全性需重新评价。目的:比较纳米Ag-SiO2导尿管和普通医用导尿管浸提液对兔尿道上皮细胞的体外细胞活性影响,初步评价纳米Ag-SiO2导尿管的生物安全性。方法:应用机械分离与酶消化法分离培养兔尿道上皮细胞,在体外行扩增后制成细胞悬液,将培养液更换为浸泡纳米Ag-SiO2导尿管及普通导尿管的培养液,采取四甲基偶氮唑盐比色法量化两组浸提液对兔尿道上皮细胞的体外细胞毒性。用酶联免疫检测仪分别测定两组体外细胞的吸光度值,并计算其相对增殖率(RGR),进行毒性评价及比较。结果与结论:纳米Ag-SiO2导尿管和普通医用导尿管均毒性轻微。纳米Ag-SiO2导尿管与普通医用导尿管相对增殖率均数间背景:具有抗菌活性的纳米Ag-SiO2导尿管可有效降低普通医用导尿管相关性尿路感染的发生率,其物理、化学性质发生很大变化,所以对其安全性需重新评价。目的:比较纳米Ag-SiO2导尿管和普通医用导尿管浸提液对兔尿道上皮细胞的体外细胞活性影响,初步评价纳米Ag-SiO2导尿管的生物安全性。方法:应用机械分离与酶消化法分离培养兔尿道上皮细胞,在体外行扩增后制成细胞悬液,将培养液更换为浸泡纳米Ag-SiO2导尿管及普通导尿管的培养液,采取四甲基偶氮唑盐比色法量化两组浸提液对兔尿道上皮细胞的体外细胞毒性。用酶联免疫检测仪分别测定两组体外细胞的吸光度值,并计算其相对增殖率(RGR),进行毒性评价及比较。结果与结论:纳米Ag-SiO2导尿管和普通医用导尿管均毒性轻微。纳米Ag-SiO2导尿管与普通医用导尿管相对增殖率均数间差别无显著性意义(P>0.05)。结果表明,纳米Ag-SiO2导尿管对细胞的生长繁殖同普通医用导尿管一样影响轻微,无(或)低细胞毒性,符合医疗器械生物学评价标准要求。     

The potential role of phagocytic capacity in the osteolytic process induced by polyethylene wear particles

Osteolysis induced by ultra-high molecular weight polyethylene wear particles is the major cause of long-term failure of artificial joints. We examined the effects of wear particles on bioactivity by analysing the biophysical aspects of particle phagocytosis. We estimated the maximum number of internalized particles (the phagocytic capacity) for particles of various sizes and shapes. We demonstrated that elongated particles had a smaller phagocytic capacity than spherical particles of the same volume. A review of the literature showed that the ratio of particle concentration (number of particles/number of cells) to phagocytic capacity is critical for particle-induced biological responses. When this ratio was < 1, the biological response was approximately proportional to the ratio itself. When this ratio was > 1, limited changes in the biological response were observed. The saturation level of the phagocytic capacity for a particle population appears to reflect the degree of polyethylene particle-induced biological response.     

颅内外血管狭窄支架置入后血浆同型半胱氨酸的变化

选择2003-02/2006-02北京天坛医院应用血管内支架成形术治疗的25例颅内外动脉狭窄的患者.患者对治疗及实验均知情同意.于颈内动脉颅内、外段以及椎、基底动脉25根狭窄的血管上放置25枚支架,术后6～12个月复查数字减影血管造影,评估血管再狭窄情况.采用高效液相色谱分析术前、术后3 d和造影复查时血浆同型半胱氨酸水平.术后随访6～12个月时12例(48%)出现了再狭窄,其中6例再狭窄超过50%,余6例再狭窄10%～30%.另外13例血管未发现明显再狭窄.术前两组血浆同型半胱氨酸水平比较差别无显著性意义(P > 0.05);支架置入后3 d 两组血浆同型半胱氨酸水平均高于术前(P < 0.01);6～12个月复查时再狭窄组的患者血浆同型半胱氨酸水平高于未狭窄组,差别有显著性意义(P < 0.05).结果提示支架置入后血浆同型半胱氨酸水平增高可能与术后再狭窄有关.     

Size and shape of biomaterial wear debris

A literature review of wear debris is presented. Included are debris retrieved at revision of total joint replacement and at autopsy, as well as debris produced in vitro in wear testers and joint simulators or otherwise fabricated for biological experiments. Observations of wear debris in vivo and in vitro are classified in tabular form according to material type, origin, size, shape and color. Polymer particles, most commonly ultra-high molecular weight polyethylene (UHMWPE), exhibit the largest size range and appear as granules, splinters or flakes, while ceramic particles possess the smallest size range and have a granular structure. Metal particles seen in vivo and in vitro, whether from cobalt-chromium alloys or, less frequently, other alloys, form granular or needle-like shapes and generally are smaller than polymer particles but larger than ceramic particles. Particles generated in joint simulators resemble the size and shape of in vivo wear particles from total joint replacement (TJR) retrieved at revision or autopsy. However, particles prepared in vitro, whether in simulators or by other means, do not consistently resemble wear debris particles from TJR.     

超高分子量聚乙烯/Al2O3人工关节副磨合期磨损颗粒的形态特征

背景:人工关节磨粒作为一种载体不但包含了关节磨损的大量信息,而且也有研究表明磨粒的存在是引起Charnley型全髋关节置换术失败的主要原因.目的:考察蒸馏水润滑条件下超高分子量聚乙烯/Al2O3关节副在关节模拟试验机上运行时产生的磨粒形态特征及超高分子量聚乙烯髋臼的磨损机制.设计:在关节模拟试验机上进行模拟试验.单位:徐州工程学院机电工程学院.材料:髋臼材料为超高分子量聚乙烯(UHMWPE),相对分子质量 3 000 000,密度0.935 g/cm3,硬度30 HB,断裂强度35 MPa,吸水率 < 0.01%.关节球材料为Al2O3陶瓷,密度4 g/cm3,硬度90 HRA,抗拉强度 > 450 MPa,韧性7 MPaM1/2.方法:实验于2003–12/2005–07在中国矿业大学摩擦学试验室完成.采用髋关节模拟试验机评价Al2O3-UHMWPE关节副的摩擦学性能.试验条件:室温,相对转速100 r/min,接触载荷784 N,蒸馏水润滑,试验周期为1.5×106转.超高分子量聚乙烯髋臼的磨损量每隔3×105转测量一次.测量时髋臼取出后置于超声波清洗器中用蒸馏水清洗 3 min,在80 ℃烘箱中烘干40 min后在干燥器中冷却至室温.采用感量为0.01 mg的BT211D型电子天平,并按"参考试样法"测量髋臼试件的磨损质量损失,计算磨损率.称重停机时同时提取一次润滑液样品(20 mL).用扫描电镜观察样品中的磨粒形貌以及超高分子量聚乙烯髋臼的磨损表面.用X射线能量色散谱确定磨粒成分.用LS100R型激光粒度分析仪(含LS SVM Plus分析平台)测量磨粒粒度分布情况.主要观察指标:磨粒的形态特征及粒度分布;超高分子量聚乙烯髋臼的磨损率及磨损情况.结果:超高分子量聚乙烯/Al2O3关节副产生的磨粒尺寸在0.3～180 μm间变化,绝大部分磨粒尺寸为5～20 μm.磨粒群体中99%以上是超高分子量聚乙烯磨粒,根据形态特征可分为5类:球形磨粒、撕裂磨粒、片状磨粒、疲劳剥块及杆状磨粒.Al2O3磨粒主要表现为边界平直的片状或立方体状.在关节副磨合阶段,随着超高分子量聚乙烯髋臼磨损率的降低,磨粒分布曲线呈现出由凸、陡向平缓发展的趋势,且磨粒群体中积聚数量最多的磨粒的尺寸在逐渐减小.电镜观察结果显示,超高分子量聚乙烯髋臼的磨损面上存在由磨粒磨损形成的多方向性犁沟、粘着磨损及微观接触疲劳磨损和大范围塑性变形的痕迹.结论:①超高分子量聚乙烯髋臼的主要磨损机制是磨料磨损、粘着磨损、微观疲劳磨损和由塑性变形引起的剥块.②磨粒群体中积聚数量最多的磨粒的尺寸较小.     

Histologic identification of polyethylene wear debris using Oil Red O stain.

Ultra high molecular weight polyethylene (UHMWPE) wear particles are frequently implicated in causing failure of total joint arthroplasties by eliciting a foreign body reaction. The majority of these particles are subcellular and many are submicron in size. Identification of these small particles of UHMWPE by conventional histologic techniques is difficult. We have therefore investigated the utility of Oil Red O (ORO) stain to identify UHMWPE on histologic sections. A wide variety of specimens was studied including an experimental rabbit model with subcutaneous implantation of polyethylene particles as well as specimens from clinical cases with joint arthroplasties. The sensitivity and specificity of ORO stain was compared to conventional polarized light microscopy for the identification of particulate UHMWPE debris. The ORO stain was found to be as sensitive in identifying particulate UHMWPE debris as polarized light microscopy. However, ORO stain was less specific: two specimens did not contain any UHMWPE also stained with ORO. Careful examination of standard hematoxylin and eosin stained sections with polarized light was therefore more specific for the identification of particulate UHMWPE. As a single test, the ORO stain does not appear to offer any clear advantage specifically for the identification of UHMWPE.     

Microfabrication of PDLLA scaffolds

This study aimed to comprehend the potentialities of the microfabrication to produce tissue-engineering scaffolds. Structures presenting homogeneously distributed pores of size 100 and 200 μm were fabricated through layer-by-layer deposition of filaments of poly(D,L-lactic acid) (PDLLA) prepared from dichloromethane/dimethylformamide solutions. Rheological tests on the solution and molecular weight distributions of PDLLA, solvent cast films and microfabricated scaffolds were performed to determine which material conditions are optimal for the microfabricated system and to identify any possible material modification induced by the process. In vitro qualitative preliminary cell culture studies were conducted using MG63 osteoblast cell lines after assuring the non-cytotoxicity of the scaffold material by the lactate dehydrogenase in vitro toxicology assay; biological evaluations were initially performed using scaffolds with the smaller (100 μm) pore size. Scanning electron microscopy imaging was used to determine cell morphology distribution. A second cell culture test was performed, using the scaffold with the higher (200 μm) porosity. Confocal laser microscopy (CLM) was utilized to examine cell morphology and growth behaviour. Cellular metabolic activity and viability were also examined using Alamar Blue assay and further verifications were performed using CLM. Cell culture studies indicated homogeneous distribution, high viability and metabolic activity. Pore dimension affects cell distribution: pores < 100 μm acted as barrier structures for the MG63 osteoblast cell line; penetration inside the matrix was hindered and cells grew on the outer part. Increasing pore size resulted in a more homogeneous cell distribution and penetration of cells inside the structure was achieved.     

不同材料人工髋关节关节面磨损对无菌性松动的影响

目的:分析各种人工髋关节假体材料在实际应用中的优势和存在的问题,对不同材料人工髋关节关节面的磨损对无菌性松动的影响进行评价.方法:以"生物材料,人工髋关节,假体,髋关节表面置换"为中文关键词,"biological materials,hip,prosthesis,hip resurfacing"为英文关键词,采用计算机检索1990-01/2009-12相关文章.纳入与不同材料人工髋关节关节面的磨损对无菌性松动的影响相关的文章;排除重复研究或Meta分析类文章.结果:人工髋关节的寿命和关节面的磨损密切相关,人工髋关节置换在临床应用研究过程中,出现无菌性松动等问题,这些问题的产生不但与假体的设计有关,而且与假体所用材料有着密切的关系,比较了不同人工髋关节假体材料的性能,为临床选择一种具耐磨损、生物相容性好的理想人工髋关节假体材料提供依据.结论:髋关节假体材料的表面改性和人体髋关节生物摩擦行为是未来研究的热点,髋关节假体材料性能评价体系的完善是亟待解决的问题.     

Characteristics of wear particles and wear behavior of retrieved PEEK-on-HXLPE total knee implants: a preliminary study

Polyether-ether-ketone (PEEK) has been used clinically for intervertebral fusion and internal fixators in spine and trauma surgery because of its mechanical properties and bioinertness. The present study aimed to assess the suitability of PEEK as an alternative material to cobalt–chromium–molybdenum alloy in total knee arthroplasty (TKA) and evaluate the in vivo wear property on the contact surface of the PEEK-on-highly cross-linked polyethylene (HXLPE). PEEK prosthesis was designed and manufactured using injection molding based on the computed tomography data of a standard goat right hind limb. Fifteen goats underwent TKA using PEEK-on-HXLPE prosthesis on the right hind limb. The goats were sacrificed at 12, 24, and 48 weeks postoperatively. The mean surface roughness (R_a) of the retrieved components, proinflammatory cytokines in the synovial fluid, and characteristics of wear particles in the synovial membrane were investigated using laser confocal microscopy, ELISA and polarized light microscopy. The R_a of the femoral component was about 0.08, 0.1, 0.2, and 0.26 μm at pre-study, 12-, 24-, and 48 weeks in the retrievals, respectively. The R_a of the HXLPE bearing samples was approximately 0.38, 0.4, 0.1, and 0.42 μm at pre-study, 12-, 24-, and 48 weeks in the retrievals, respectively. The median size of the particles was 2.63 μm, 1.98 μm, and 3.00 μm at 12, 24, and 48 weeks, respectively. The particles ranged in size from 0.4 μm to 15 μm, and particles <1 μm accounted for 7–13%, those of size 2–5 μm accounted for 67–76%, and those >5 μm accounted for 11–22%. Levels of interleukin (IL)-6, IL-10, and tumor necrosis factor-α (TNF-α) were significantly increased in synovial fluids at 24- and 48 weeks after surgery. Wear occurred on the surfaces of the PEEK and HXLPE material and the size of most wear particles was 1–5 μm. This induced an inflammatory response in the synovial membrane and release of proinflammatory cytokines. A high polishing process may be necessary to lengthen the life of the PEEK prosthesis by reducing the wear and the generation of debris. The PEEK prosthesis as a new generation of artificial joints is promising to be used clinically in the future.

Polyether-ether-ketone (PEEK) has been used clinically for intervertebral fusion and internal fixators in spine and trauma surgery because of its mechanical properties and bioinertness.     

Size Measurement of Tissue Debris Particles Generated from Pulsed Ultrasound Cavitational Therapy – Histotripsy

Extensive mechanical tissue fractionation can be achieved using successive high intensity ultrasound pulses (“histotripsy”). Histotripsy has many potential medical applications where noninvasive tissue removal is desired (e.g., tumor ablation). There is a concern that debris generated by histotripsy-induced tissue fractionation might be an embolization hazard. The aim of this study is to measure the size distribution of these tissue debris particles. Histotripsy pulses were produced by a 513-element 1 MHz array transducer, an 18-element 750 kHz array transducer and a 788 kHz single element transducer. Peak negative pressures of 11 to 25 MPa, pulse durations of 3 to 50 cycles, pulse repetition frequencies of 100 Hz to 2 kHz were used. Tissue debris particles created by histotripsy were collected and measured with a particle sizing system. In the resulting samples, debris <6 μm in diameter constituted >99% of the total number of tissue particles. The largest particle generated by one of the parameter sets tested was 54 μm in diameter, which is smaller than the clinic filter size (100 μm) used to prevent embolization. The largest particles generated using other parameter sets were larger than 60 μm but the value could not be specified using our current setup. Exposures with shorter pulses produced lower percentages of large tissue debris (>30 μm) in comparison to longer pulses. These results suggest that the tissue debris particle size distribution is adjustable by altering acoustic parameters if necessary. (E-mail: zhenx@umich.edu)