骨水泥振动器的研制及其对骨水泥-骨界面影响的实验研究

目的 评价骨水泥振动器对提高骨水泥-骨界面微嵌合强度的效果及临床意义.方法 取新鲜成猪股骨100根,随机分成6组;力学测试组:抗拉力实验组(A1)与对照组(A2)和抗压力实验组(B1)与对照组(B2)模型每组各20个;影像学测试组:实验组(C1)与对照组(C2)模型各10个.对模型进行力学及影像学检测,比较实验组与对照组骨水泥-骨界面的微嵌合强度.结果 力学及影像学测定显示实验组骨水泥-骨界面微嵌合强度均高于对照组,二者比较差异具有显著统计学意义(P＜0.01).结论 骨水泥振动器能显著提高骨水泥-骨界面微嵌合强度,对于减少人工假体远期无菌性松动具有一定的意义.     

骨水泥振动器的运用对骨水泥-骨界面微嵌合的影响

目的 评价骨水泥振动器对提高骨水泥-骨界面的整合效果及临床意义. 方法 取新鲜成猪股骨16根,随机分成两组,实验组(A组)与对照组(B组)模型各8根.猪股骨髓腔内应用骨水泥振动器进行骨水泥灌注后(对照组灌注骨水泥不经振动),对每组实验模型进行硬组织切片,每根股骨模型等距选取3个层面,HE染色后在体视显微镜下观察,经电脑Motic Med 6.0数码医学图像分析系统分析测量骨水泥渗透入松质骨腔的厚度,记为渗透厚度,将所得数值进行统计学分析,对比振动组与对照组的骨水泥灌注效果. 结果 体视显微镜下显示实验组骨水泥与骨小梁之间结合紧密,骨水泥在松质骨腔内充填均匀一致,骨水泥与骨小梁之间的结合紧密.对照组骨水泥向松质骨腔内渗透欠佳,在松质骨腔内充填不均匀.结果显示实验组骨水泥渗透厚度高于对照组,差异均具有统计学意义(P＜0.05). 结论 骨水泥振动器能够使骨水泥在骨髓腔内弥散更加均匀,能够促进骨水泥向骨小梁内渗透,从而增加骨水泥与骨小梁之间的微嵌合.     

复合阿伦磷酸钠骨水泥洗提特性的实验研究

目的研究复合阿伦磷酸钠骨水泥的洗提特性及不同阿伦磷酸钠加入量对骨水泥洗提特性的影响。方法制备5组不同阿伦磷酸钠加入量的骨水泥浸提标本,用高效液相色谱仪串联质谱仪测定浸提液中20个不同时间点的药物释放速率和释放总量百分比。结果各组阿伦磷酸钠释放速率先快后慢,随着加入量增加而增大;释放总量百分比在快速释放期（约1周）相似,约11%,而在缓慢释放期差别更大,但在24周时均小于25%。结论骨水泥是一种良好的阿伦磷酸钠的载体和缓释体,阿伦磷酸钠在骨水泥聚合时未被破坏且可从骨水泥中缓慢释放,释放浓度随加入量增加而增加。     

骨水泥型关节假体骨水泥-骨界面相关研究进展

骨水泥型关节假体无菌性松动是影响假体使用寿命的主要问题。假体松动翻修术中取出的金属假体柄研究提示,柄的松动主要发生在骨水泥与骨髓腔内壁界面而非骨水泥与假体柄界面。骨水泥-骨界面的力学强度主要取决于界面区域骨形态和骨水泥与骨之间的交锁程度,影像学、力学测试、有限元分析等研究显示骨水泥-骨界面的扭转力、剪切力、混合力及蠕变-疲劳应力条件下强度变化等微力学变化与假体松动相关。界面反复微动引起的摩损碎屑颗粒和离解产生的微小颗粒物质,引起一系列免疫反应及机体自身对这些颗粒的反应,促使假体周围发生骨溶解,加剧假体松动。该文就骨水泥-骨界面微力学变化特点及假体松动机制作一综述。     

PMMA骨水泥颗粒对大鼠巨噬细胞SOCS1及SOCS3基因表达的影响

目的 观察PMMA骨水泥颗粒对体外培养的巨噬细胞SOCS1及SOCS3基因表达的影响.方法 大鼠腹腔灌洗液筛选法培养巨噬细胞,CD68单抗免疫细胞化学法鉴定细胞纯度和活性,实时荧光定量PCR(Real-time PCR)方法检测巨噬细胞SOCS1及SOCS3基因的表达量,分别观察不同浓度PMMA骨水泥颗粒及一定浓度的骨水泥颗粒作用不同时间对巨噬细胞SOCS1及SOCS3基因表达的影响.结果 PMMA骨水泥颗粒促进了体外培养的巨噬细胞SOCS1及SOCS3基因的表达,并表现出一定的浓度及时间相关性;颗粒浓度在0.25 mg/mL时SOCS1及SOCS3基因表达量明显升高(P<0.05);当颗粒作用时间在24 h左右时SOCS1及SOCS3基因表达升高最显著(P<0.05).结论 PMMA骨水泥颗粒能够促进巨噬细胞SOCS1及SOCS3基因的表达.     

无菌性松动假体－骨界面溶骨因子和成骨因子表达的对比研究

目的 对比研究无菌性松动假体周围界膜中溶骨因子和成骨因子的表达,进一步探讨磨损颗粒致界面骨溶解的生物学原因。方法 采用逆转录－聚合酶链反应（ｒｅｖｅｒｓｅ ｔｒａｎｓｃｒｉｐｔｉｏｎ ｐｏｌｙｍｅｒａｓｅ ｃｈａｉｎ ｒｅａｃｔｉｏｎ,ＲＴ－ＰＣＲ）和计算机图像分析的方法,分别检测溶骨区界膜（含磨损颗粒）和非溶骨区界膜中ＰＤＧＦ－Ｂ和ＢＭＰ－７ ｍＲＮＡ的表达量,并以正常滑膜、骨性关节炎（ｏｓｔｅ     

复杂全髋关节置换术和翻修术——髋臼打压植骨-骨水泥技术

无论是骨水泥型或非骨水泥型人工全髋关节,无菌性松动都是其植入后远期失败的主要原因,而且这一渐进性过程经常导致假体周围大量骨丢失.而如何处理假体周围骨丢失,就成为翻修手术中的关键问题.多年来,治疗骨缺损的最佳方案一直存在争议,而我们采用的同种异体打压植骨和骨水泥技术的结合是一种非常有效的方法.我们使用这种方法已经有20多年的经验,并且取得了很好的长期随访结果.     

PMMA骨水泥颗粒对大鼠巨噬细胞SOCSl及SOCS3基因表达的影响

目的 观察PMMA骨水泥颗粒对体外培养的巨噬细胞SOCSl及SOCS3基因表达的影响。方法 大鼠腹腔灌洗液筛选法培养巨噬细胞,CD68单抗免疫细胞化学法鉴定细胞纯度和活性,实时荧光定量PCR(Real-time PCR)方法检测巨噬细胞SOCSl及SOCS3基因的表达量,分别观察不同浓度PMMA骨水泥颗粒及一定浓度的骨水泥颗粒作用不同时间对巨噬细胞SOCSI及SOCS3基因表达的影响。结果 PMMA骨水泥颗粒促进了体外培养的巨噬细胞SOCSI及SOCS3基因的表达,并表现出一定的浓度及时间相关性;颗粒浓度在0.25 mg/mL时SOCSI及SOCS3基因表达量明显升高(P<0.05);当颗粒作用时间在24 h左右时SOCSI及SOCS3基因表达升高最显著(P<0.05)。结论 PMMA骨水泥颗粒能够促进巨噬细胞SOCSl及SOCS3基因的表达。     

初次全髋置换术无骨水泥股骨部件的早期无菌性松动

挪威关节成形术登记处记录了１９８７－１９９３年共行首次全髋置换术２４４０８例。其中２９０７例用的是无骨水泥股骨部件。作者比较了８种类型假体的治疗结果，每一种的使用都在１００例以上。假体部件存活期以Ｋａｐｌａｎ－Ｍｅｉｅｒ法估计，将股骨部件因无菌性松动再行翻修术作为存活期终结。术后４．５年，估计全部置入物因无菌性松动行翻修术的机率为４．５％。Ｂｉｏ－Ｆｉｔ柄为１８．６％，Ｆｅｍｏｒｄ槽１３．６％，Ｐ     

Stress transfer at the femoral bone/bone cement interface as a function of the cement thickness

Summary When a cement canal prosthesis is used as the femoral component in total hip replacement (THR), the penetration depth of the bone cement can be varied according to the cement implantation pressure. Using experimental data which give a relation between the pressure applied to the cement at implantation and the resulting shape of the cement layer, a three-dimensional finite element study was performed to calculate the stress distribution at the bone/bone cement interface. The calculations show that the interface stresses increase with increasing depth of penetration by the cement layer. The explanation of this effect is that as the bone cement penetrates further into the cancellous bone, the cancellous bone is stiffened and can no longer act as a soft interposition between cortical bone and bone cement. From these results and from the clinical requirement that as little bone as possible be destroyed in any kind of alloarthroplasty, we conclude that the penetration depth of bone cement into cancellous bone in THR should be minimized to the depth necessary in order to achieve sufficient initial stability of the implant. The results show that a cement-canal prosthesis meets these requirements if a cement implantation pressure of 1.0 bar is used.     

Fracture and fatigue properties of acrylic bone cement

The purpose of this study was to characterize the relative and combined effects of sterilization, molecular weight, and mixing method on the fracture and fatigue performance of acrylic bone cement. Palacos® R brand bone cement powder was sterilized using ethylene oxide gas (EtO) or gamma irradiation. Nonsterile material was used as a control. Molecular weights of the bone-cement powders and cured cements were measured using gel permeation chromatography. Hand and vacuum mixing were employed to mold single edge-notched bend specimens for fracture toughness testing. Molded dog-bone specimens were used for fatigue tests. Electron microscopy was used to study fracture mechanisms. Analysis of variance and Student t-tests were used to compare fracture and fatigue performance between sterilization and mixing groups. Our results indicate that vacuum mixing improved significantly the fracture and fatigue resistance (P < .05, P < .07) over hand mixing in radiation-sterilized and EtO-sterilized groups. In vacuum-mixed cement, the degradation in molecular weight resulting from gamma irradiation decreased fracture resistance significantly when compared with EtO sterilization and control (P < .05). A corresponding decrease in fatigue resistance was observed in the cement that was degraded severely by a radiation dose of 10 MRad (P < .05). In contrast, EtO sterilization did not result in a significantly different fracture resistance when compared with unsterilized controls for vacuum-mixed cement (P > .1). For hand-mixed cement, fracture and fatigue resistance appeared to be independent of sterilization method. This independence is believed to be the result of higher porosity that compromised the mechanical properties and obscures any effect of sterilization. Our results indicate that a combination of nonionizing sterilization and vacuum mixing resulted in the best mechanical performance and is most likely to contribute to enhanced longevity in vivo.     

The interface between ionomer cement and bone in the porcine cervical spine

Summary The interface between bone and ionomer cement has been studied in twelve young adult pigs 1–6 months after anterior cervical discectomy, removal of adjacent end plates and grafting of the bone defect with ionomer cement. Methods used to study the interface were fluorescence microscopy, scanning electron microscopy, electron microprobe analysis and radiological investigation. The interface in all animals consisted of collagenous tissue. The amount of collagenous fibres was related to the amount of residual movement within the motion segment: animals undergoing anterior plating after reconstruction of the bone defect presented with more or less compactly organized collagenous tissue. Sequential fluorochromic marking of osteoid formation revealed a vital bone bed around the interface but no signs of direct bone apposition to the ionomer cement plug. No signs of toxicity or graft rejection were noted.Ionomer bone cement contrary to experimental and clinical experience induces the formation of a connective tissue layer of different density in the porcine cervical spine.     

Comparison of the fatigue characteristics of centrifuged and uncentrifuged Simplex P bone cement

Fatigue test specimens of Simplex P bone cement (Howmedica Inc., Rutherford, NJ) prepared according to the manufacturer's instructions and specimens of Simplex P prepared by centrifuging the cement immediately after mixing were subjected to fully reversed tension-compression fatigue tests at initial strain levels ranging from 0.01 to 0.001. S:N curves for both cement preparations were generated and compared on the basis of regression analysis, Weibull analysis, and Student's t tests. Centrifuged Simplex P was able to withstand significantly more fatigue cycles than uncentrifuged Simplex P at all strain levels tested. Importantly, at the more physiologic strain levels of 2,000 and 1,000 microstrain, the centrifuged cement demonstrated superior fatigue life. Specifically, at the 1,000-microstrain level eight of the 11 uncentrifuged specimens fractured before undergoing 10 million cycles. Of those that failed, the average number of cycles to failure was 1.8 million with a range of 560,000 to 4 million cycles. In contrast, all 11 centrifuged specimens tested at 1,000 microstrain remained intact at 10 million cycles.     

The effect of centrifugation on the fatigue life of bone cement in the presence of surface irregularities

Reduction of the porosity of bone cement by centrifugation significantly improves the fatigue life of the cement when smooth, waisted specimens are tested. However, bone cement in vivo has surface irregularities at the interdigitation of the cement with the trabecular bone. The effect of centrifugation on the fatigue life of Simplex P in specimens containing surface irregularities was investigated by examining both composite specimens of trabecular bone and bone cement and specimens containing a sharp, circumferential notch. For the specimens with the sharp notch, the bone cement that had been centrifuged lasted significantly longer in fatigue (47,039 +/- 40,277 cycles) than the uncentrifuged specimens (3103 +/- 1950 cycles). Eleven of 15 uncentrifuged specimens broke at the location of a void, rather than the notch. In contrast, when the porosity was reduced by centrifugation, 13 of the 15 specimens broke at the notch. For the specimens that were a composite of bone cement and trabecular bone, the centrifuged specimens had a significant increase in fatigue life compared to the uncentrifuged specimens when tested at both 7 MPA (641,056 +/- 444,131 cycles vs. 237,969 +/- 124,153 cycles) and 15 MPA (8800 +/- 4673 cycles vs. 1534 +/- 719 cycles). Reduction of porosity in bone cement by centrifugation significantly extends its fatigue life even in the presence of trabecular bone or sharp surface notches as used in total joint replacements. These data support the concept that reduction of porosity of bone cement by centrifugation may extend the duration of fixation of the components in cemented total joint arthroplasties.