骨移植与骨水泥增强对治疗骨质疏松椎体的生物力学相容性有限 元评估

目的 研究松质骨粒移植增强和骨水泥增强对治疗节段和相邻非治疗节段的生物力学相容性 影响,探讨椎体重建前后的荷载传导机制。方法 选取正常男性青壮年脊柱L1-L2节段标本进行薄层 CT扫描,构建正常的和骨折复位后疏松的功能脊柱单元三维有限元模型,模拟经皮穿刺椎体后凸 成形术(PKP)在L2椎体核心注入骨水泥,模拟经皮骨移植(Optimesh)在L2椎体核心置入松质骨粒,按 照脊柱三柱理论施加轴向压缩、前屈和后伸荷载进行有限元分析。结果 质骨粒移植增强或骨水泥增强后相邻节段椎体应力应变的变化甚微;但是,治疗节段增强区域的应力应变明显改变。另外,骨质疏松、松质骨粒移植增强、骨水泥增强对脊柱三柱轴向压缩位移和椎间盘平均内压没有影响。结论 松质骨粒移植增强和骨水泥增强均能恢复疏松椎体的总体刚度和强 度,有利于椎体功能重建;但从椎体与增强材料间的力学相容性和生物相容性的观点看,松质骨粒 移植增强优于骨水泥增强。     

How to determine the permeability for cement infiltration of osteoporotic cancellous bone

Cement augmentation is an emerging surgical procedure in which bone cement is used to infiltrate and reinforce osteoporotic vertebrae. Although this infiltration procedure has been widely applied, it is performed empirically and little is known about the flow characteristics of cement during the injection process. We present a theoretical and experimental approach to investigate the intertrabecular bone permeability during the infiltration procedure. The cement permeability was considered to be dependent on time, bone porosity, and cement viscosity in our analysis. In order to determine the time-dependent permeability, ten cancellous bone cores were harvested from osteoporotic vertebrae, infiltrated with acrylic cement at a constant flow rate, and the pressure drop across the cores during the infiltration was measured. The viscosity dependence of the permeability was determined based on published experimental data. The theoretical model for the permeability as a function of bone porosity and time was then fit to the testing data. Our findings suggest that the intertrabecular bone permeability depends strongly on time. For instance, the initial permeability (60.89 mm(4)/N(*)s) reduced to approximately 63% of its original value within 18 seconds. This study is the first to analyze cement flow through osteoporotic bone. The theoretical and experimental models provided in this paper are generic. Thus, they can be used to systematically study and optimize the infiltration process for clinical practice.     

椎体注射骨水泥强化治疗骨质疏松性胸腰椎体压缩骨折

背景：椎体成形注射骨水泥可在复位骨折的同时,达到矫正后凸畸形、增强椎体强度、消除椎体病变的效果。 目的：分析椎体注射骨水泥强化疗法在骨质疏松性胸腰椎体压缩骨折中的应用效果。 方法：选择84例骨质疏松性胸腰椎体压缩性骨折患者,病变椎体T6-L4,其中男37例,女47例,年龄58-80岁,采用随机数表法均分为2组,研究组进行椎体注射骨水泥强化治疗,对照组进行卧床休息、定期进行腰背肌功能锻炼的保守治疗。对比两组治疗前后的目测类比评分、功能障碍评分和椎体高度。 结果与结论：两组治疗前的椎体高度、目测类比评分和功能障碍评分比较差异均无显著性意义;研究组治疗后3个月的椎体高度为(1.653±0.168) cm,显著高于对照组的(1.521±0.200) cm(P < 0.05);研究组随访3个月及末次随访的目测类比评分和功能障碍评分均低于对照组(P < 0.05)。对照组治疗后,2例发生压疮,3例发生深静脉血栓,1例发生肺炎,2例发生泌尿系统感染;研究组4例发生骨水泥渗漏,但未引发明显的临床症状。对照组中有3例发生再骨折,研究组有4例发生再骨折,两组再骨折发生率比较差异无显著性意义(P > 0.05)。表明椎体注射骨水泥强化治疗骨质疏松性胸腰椎体压缩性骨折能迅速镇痛,短期内改善患者生活质量,且能较好恢复脊椎高度。     

骨髓间充质干细胞复合异体骨修复松质骨缺损

背景：有研究表明骨髓间充质干细胞及异体骨可促进骨缺损的修复,但骨髓间充质干细胞复合异体骨对于松质骨缺损的修复效果至今少有报道。 目的：观察骨髓间充质干细胞复合异体骨修复兔松质骨缺损效果。 方法：在新西兰大白兔双侧股骨外侧髁造成0.6 cm×1.2 cm 的松质骨缺损,一侧设为模型组,骨缺损处植入复合骨髓间充质干细胞的异体骨,另一侧设为对照组,单纯植入异体骨。 结果与结论：植入后4,8,12周,大体观察、X射线检查和苏木精-伊红染色观察结果显示,模型组在新骨成长方面,缺损区修复方面均优于对照组。植入后12周,模型组骨缺损区可见大量骨小梁形成及成熟的板层骨组织,骨缺损基本修复。对照组骨缺损区仅可见大量编织骨形成,骨缺损尚未得到有效修复。模型组Lane-Sandhu法X射线结合组织学观察评分高于对照组(P < 0.05)。生物力学检测结果显示,植入后12周,模型组股骨髁最大压力载荷、载荷/应变比值均高于对照组(P < 0.05),最大应变位移较对照组低(P < 0.05)。结果证实,骨髓间充质干细胞复合异体骨可有效修复兔股骨髁松质骨缺损,且修复效果明显优于单纯异体骨移植。     

A new bioresorbable polymer for screw augmentation in the osteosynthesis of osteoporotic cancellous bone: a biomechanical evaluation

The aim of the study was to assess the mechanical efficacy of a new resorbable polymer developed on the basis of alkylene bis(dilactoyl)-methacrylate to improve the anchorage of osteosynthesis material in cancellous bone. Cancellous bone screws were inserted in bovine as well as in human vertebrae and human femoral condyles and were augmented with the new polymer or polymethylmethacrylate (PMMA), respectively. Nonaugmented screws were used as controls. A removal torque test, a dynamic fatigue test, and a pullout test were performed. Augmentation with the new polymer increased the removal torque by 84% in human femoral bone. In the dynamic fatigue test of bovine vertebrae, the removal torque after cyclic loading was 115% higher for the new polymer compared to the nonaugmented controls. In the human vertebrae, the reinforcement with the new polymer increased the removal torque after dynamic loading by 114%. The augmentation with the new polymer increased the pullout force by 88% in bovine vertebrae and by 118% in human vertebrae in comparison to nonaugmented screws. It was concluded that augmentation by the new resorbable polymer significantly enhanced the anchorage of bone screws in cancellous bone. The mechanical efficiency of the new polymer was comparable to that of PMMA cement.     

Evaluation of a highly-radiopaque iodine-containing acrylic bone cement for use in augmentation of vertebral compression fractures

Vertebroplasty and balloon kyphoplasty are widely used for the augmentation of osteoporosis-induced vertebral compression fractures. Almost invariably, an injectable poly(methyl methacrylate) (PMMA) bone cement that contains a large amount of BaSO(4) particles is used in these procedures. The deleterious effects of this radiopacifier on various properties of PMMA cement have been detailed in the literature. The objective of the present study was therefore to avoid such high levels of inorganic contrast agent and thus to develop an all-polymeric bone cement, for which radiopacity was provided by 60 wt % of an iodine-containing methacrylic copolymer, incorporated into the powder (IO cement), ultimately leading to 6.6 wt % of iodine in the cement. A large array of properties of this cement were determined, ranging from setting time and injectability to fatigue life under fully-reversed tension-compression loading and cytotoxicity, and a comprehensive comparison with a cement containing 30 wt % BaSO(4) in the powder component (BA cement) has been made (11 wt % of Ba in the cement). Statistical analyses of the results showed that, for the majority of the properties, the difference between the means for the two cements was not significant. It is therefore suggested that the IO cement is a suitable alternative to the BA cement for use in the aforementioned procedures.     

骨水泥充填治疗多节段骨质疏松性压缩性骨折的病例分析

背景：椎体骨质疏松性压缩骨折多发生于骨质钙丢失严重的老年人群,轻微的外力就可以引起椎体骨折,近年来发展起来的经皮椎体成形治疗骨质疏松性压缩性骨折效果较好。 目的：探讨骨水泥充填治疗多节段骨质疏松性压缩性骨折的疗效及材料的特性。 方法：采用骨水泥充填材料经皮椎体成形治疗多椎体骨质疏松性压缩骨折患者32例,共158个椎体。治疗后复查X 射线、CT等辅助检查,了解骨折椎体复位情况、椎体的容量变化、骨水泥分布及外漏情况,用CT容量分析法检测治疗前后椎体的容积变化,观察疼痛强度评价的目测类比评分变化,分析发生骨水泥渗漏的原因。 结果与结论：纳入结果分析32例,158个椎体。注射骨水泥后无神经根及脊髓损伤,无肺栓塞及心脑血管系统急性反应。①治疗后随访6-16个月,平均随访10个月,无严重并发症和椎体塌陷。②治疗前椎体体积为(22.2±8.6) cm³,治疗后增至(24.8±6.9) cm³,体积变化差异有统计学意义(P < 0.05)。③6个椎体发生骨水泥渗漏,分别为椎管内硬膜外2个、椎旁静脉4个,可能与椎体后缘爆裂、骨水泥黏度过低以及注射速度过快有关。④治疗后48 h目测类比评分为(2.2±3.7)分,较治疗前(8.3±1.6)分显著下降(t=25.2,P < 0.05)。作者认为,对于多节段骨质疏松性压缩性骨折,采用充分的治疗前准备和恰当的方法,选择合适的骨水泥充填材料,一期行经皮椎体成形治疗是安全可行的,可明显缓解患者的疼痛症状,治疗中操作要注意防止骨水泥渗漏。     

A proposed specification for acrylic bone cement.

A proposed specification covering handling characteristics and physical and chemical properties of bone cement composed primarily of methyl methacrylate has been prepared on the basis of data from the authors' studies and from various other sources. Under handling characteristics, requirements included relate to dough, handling and setting time, proper plasticity for insertion and temperature rise on setting. Mechanical properties specified include compressive strength and indentation and recovery characteristics. Maximum limits are proposed for water sorption and solubility. Suggested packaging requirements are also included.     

高黏度骨水泥与传统骨水泥治疗骨质疏松性椎体压缩性骨折的疗效比较

目的比较高黏度骨水泥与传统聚甲基丙烯酸甲酯(PMMA)骨水泥治疗骨质疏松性椎体压缩性骨折的疗效,探讨高黏度骨水泥在临床应用中的优势。方法选择2009年7月~2013年7月治疗并获得随访160例骨质疏松性椎体压缩性骨折患者,其中男性64例,女性96例;年龄61~88岁,平均年龄69.1岁。分高黏度骨水泥组[91例(112个椎体)]和传统骨水泥组[69例(86个椎体)]。高黏度骨水泥组,采用以色列Disc-O-Tech公司Confidence骨水泥,施行经皮椎体成形术(PVP);传统骨水泥组,采用PMMA骨水泥,施行PVP。术后对比两组患者视觉疼痛模拟评分(VAS)、责任椎Cobb角的恢复情况及术后骨水泥渗漏情况,并随访观察。结果高黏度骨水泥组与传统骨水泥组VAS评分(1.5±0.8vs1.4±0.9)比较差异无统计学意义(P0.05);高黏度骨水泥组Cobb角恢复优于传统骨水泥组(13.6°±3.1°vs 19.8°±3.0°),差异有统计学意义(P0.05);高黏度骨水泥组渗漏率远低于传统骨水泥组(19.6%vs 41.9%),差异有统计学意义(P0.05)。所有患者术后获得3~48个月(平均16个月)随访,其中3例出现神经根症状,所有患者未出现感染、肺栓塞等并发症。结论高黏度骨水泥与传统PMMA骨水泥相比,在纠正椎体Cobb角及降低骨水泥渗漏发生率方面效果更佳,明显提高了PVP的安全性及有效性。     

Properties of an injectable low modulus PMMA bone cement for osteoporotic bone

The use of polymethylmethacrylate (PMMA) cement to reinforce fragile or broken vertebral bodies (vertebroplasty) leads to extensive bone stiffening. Fractures in the adjacent vertebrae may be the consequence of this procedure. PMMA with a reduced Young's modulus may be more suitable. The goal of this study was to produce and characterize stiffness adapted PMMA bone cements. Porous PMMA bone cements were produced by combining PMMA with various volume fractions of an aqueous sodium hyaluronate solution. Porosity, Young's modulus, yield strength, polymerization temperature, setting time, viscosity, injectability, and monomer release of those porous cements were investigated. Samples presented pores with diameters in the range of 25-260 microm and porosity up to 56%. Young's modulus and yield strength decreased from 930 to 50 MPa and from 39 to 1.3 MPa between 0 and 56% porosity, respectively. The polymerization temperature decreased from 68 degrees C (0%, regular cement) to 41 degrees C for cement having 30% aqueous fraction. Setting time decreased from 1020 s (0%, regular cement) to 720 s for the 30% composition. Viscosity of the 30% composition (145 Pa s) was higher than the ones received from regular cement and the 45% composition (100-125 Pa s). The monomer release was in the range of 4-10 mg/mL for all porosities; showing no higher release for the porous materials. The generation of pores using an aqueous gel seems to be a promising method to make the PMMA cement more compliant and lower its mechanical properties to values close to those of cancellous bone.     

Mechanical properties of oligomer-modified acrylic bone cement

The aim of this study was to determine the mechanical properties of acrylic bone cement modified with an experimental oligomer filler, based on an amino acid of trans-4-hydroxy-L-proline synthesized in the laboratory. The test specimens were tested either dry, or after being stored in distilled water or in simulated body fluid (SBF) for 1 week and then tested in distilled water. The three-point bending test was used to measure the flexural strength and flexural modulus of the cement, and the compression tests were used to measure the compression strength and modulus. One test specimen from each group was examined under a scanning electron microscope (SEM) to determine the nature of the oligomer filler in the polymethylmethacrylate-polymethylacrylate copolymer-based (PMMA-PMA/PMMA) polymer blend. In dry conditions, the flexural strength of the test specimens tested in air was 66 MPa, and the compression strength was 93 GPa (p<0.001) for the plain bone cement. For the test specimens including 20 wt% of oligomer filler, the flexural strength was 37 MPa, and the compression strength was 102 MPa(p<0.001) in dry conditions. The storage in wet conditions (in distilled water and the SBF) decreased the flexural strength of the test specimens with 20 wt% of oligomer filler (p<0.001) by 60% and the flexural modulus by 44% compared to the plain bone cement specimens stored in the same conditions. The reduction in compression strength in wet conditions was 32%, and that of the compression modulus was 30% (p<0.001). No significant differences were found between test specimens stored in distilled water or SBF (ANOVA, p<0.001). In the SEM examinations, random voids were observed in the oligomer-PMMA-PMA/PMMA polymer blend after water or SBF storage. The results suggest that both water and SBF storage decrease the mechanical properties of the PMMA-PMA/PMMA bone cement modified with oligomer, while at the same time, there was porous formation in the bone cement structure.     

矿化胶原改性骨水泥在骨质疏松性椎体压缩骨折中的应用

文题释义： 矿化胶原改性骨水泥：是在普通聚甲基丙烯酸甲酯骨水泥中加入适量人工骨修复材料。普通聚甲基丙烯酸甲酯骨水泥的主要成分是丙烯酸甲酯-甲基丙烯酸甲酯聚合物和为氧化锆,硬度较大,缺乏生物活性;人工骨修复材料的主要成分是Ⅰ型胶原和羟基磷灰石,它具有与天然骨相似的微结构,具有很好的传导成骨活性,利于新骨的形成。两者按照适当比例混合制成矿化胶原改性骨水泥。 经皮椎体成形：是一种微创脊柱外科技术,经皮通过椎弓根或椎弓根外侧向压缩椎体内注入骨水泥从而增加椎体强度和稳定性,防止进一步塌陷,恢复椎体部分高度,矫正后凸畸形,缓解腰背部疼痛。可用于治疗骨髓瘤、脊椎血管瘤、溶骨性转移瘤等癌性疼痛,但主要用于治疗老年椎体压缩性骨折,常见并发症有邻近椎体骨折、骨水泥渗漏、椎体坏死等。 背景：单纯骨水泥由于硬度较大,易造成邻近椎体再骨折,当前迫切需要一种能够降低邻近椎体骨折发生率的骨水泥材料。 目的：观察使用矿化胶原改性骨水泥行经皮椎体成形治疗骨质疏松性椎体压缩骨折的临床效果。 方法：选择行经皮椎体成形治疗的骨质疏松性椎体压缩骨折患者60例,均为新鲜单椎体骨折,随机分为2组,每组30例。单纯骨水泥组采用单纯聚甲基丙烯酸甲酯骨水泥,改性骨水泥组采用人工骨修复材料与单纯聚甲基丙烯酸甲酯骨水泥混合的矿化胶原改性骨水泥。所有患者对治疗方案均知情同意,且得到医院伦理委员会批准。随访时间6-12个月,于术前、术后2 d、术后末次随访时根据目测类比评分、Oswestry功能障碍指数、脊柱后凸局部Cobb角及椎体前缘高度百分比评定临床效果,并记录术后并发症的发生情况。 结果与结论：①所有患者手术均顺利完成,共发现4例患者出现不同程度的骨水泥渗漏,所有骨水泥渗漏患者均未出现明显临床不适症状;②2组患者术后2 d、末次随访与术前相比,目测类比评分、Oswestry功能障碍指数显著改善(P < 0.05),伤椎前缘高度、脊柱后凸局部Cobb角变化不明显(P > 0.05);以上指标2组间相同时间段比较差异均无显著性意义(P > 0.05);③单纯骨水泥组邻近椎体骨折发生例数多于改性骨水泥组,但2组邻近椎体骨折发生率相比,差异无显著性意义(P > 0.05);④提示矿化胶原改性骨水泥与单纯骨水泥相比无明显缺点,且在保证骨水泥支撑强度、减轻疼痛的同时,矿化胶原改性骨水泥可赋予其更好的生物学特性,降低邻近椎体骨折的发生率有待进一步研究。 ORCID: 0000-0002-5714-2566(姜文康) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Bone augmentation by bone marrow mesenchymal stem cells cultured in three-dimensional biodegradable polymer scaffolds

Poly-lactic-glycolic acid (PLGA) is a biocompatible as well as biodegradable polymer and used in various medical applications. In this study, we evaluated efficiency of the specially designed three-dimensional porous PLGA as a scaffold for bone augmentation. First, cell attachment/proliferation, differentiation, and mineralization of Fisher 344 rat marrow mesenchymal stem cells (MSCs) cultured on the PLGA scaffold were analyzed. Viable MSCs were impregnated into pore areas of the scaffold and a moderate increase of DNA contents was seen. High alkaline phosphatase, osteocalcin content, and calcium content of MSCs in PLGA scaffolds under osteogenic differentiation conditions were seen after 14 or 21 days of culture. Subsequently, we implanted the PLGA/MSCs composites on rat calvaria bone for 30 days. Newly formed bone was seen in only the composite PLGA/MSCs implantation group, which had been precultured under osteogenic condition. We also demonstrated that the newly formed bone originated from the donor composites. These results demonstrate that the three-dimensional PLGA scaffold can support osteogenic differentiation of MSCs, and the scaffold combined with osteogenic MSCs can be used for in vivo bone tissue augmentation.     

骨水泥强化治疗伴强直性脊柱炎的骨质疏松性椎体骨折

目的 探讨骨水泥强化治疗伴强直性脊柱炎的骨质疏松性椎体骨折的临床疗效。方法 回顾性分析2010年1月～2018年1月因骨质疏松性椎体骨折合并强直性脊柱炎接受椎体后凸成形33例手术患者的资料,其中男15例,女18例。年龄67～85岁,平均(73.3±4.6)岁。记录术前、术后1周和末次随访时疼痛模拟VAS(visual analog scale)评分和伤残ODI(Oswestry disability index)指数,分析比较各时间节点参数变化。结果 随访13～16个月,平均(13.9±1.1)个月。术后骨水泥渗漏13例,均未发生脊髓神经根压迫症状。所纳入患者术后腰背部疼痛明显减轻或消失,术后2 d下床活动无受限。VAS评分由术前(7.1±0.9)分降至术后1周(3.3±0.7)分(P=0.000);末次随访时(2.0±0.7)分(与术前比较P=0.000;与术后1周比较P=0.000)。ODI指数由术后1周(27.8±3.8)%降至末次随访(14.3±1.6)%(P=0.000)。结论 骨水泥强化治疗伴强直性脊柱炎的骨质疏松性椎体骨折可有效缓解腰背部疼痛,改善患者的生存质量。     

Crack initiation processes in acrylic bone cement

A major constraint in improving the understanding of the micromechanics of the fatigue failure process and, hence, in optimizing bone cement performance is found in the uncertainties associated with monitoring the evolution of the internal defects that are believed to dominate in vivo failure. The present study aimed to synthesize high resolution imaging with complementary damage monitoring/detection techniques. As a result, evidence of the chronology of failure has been obtained. The earliest stages of crack initiation have been captured and it is proposed that, in the presence of a pore, crack initiation may occur away from the pore due to the combined influence of pore morphology and the presence of defects within regions of stress concentration. Furthermore, experimental evidence shows that large agglomerations of BaSO(4) are subject to microcracking during fatigue, although in the majority of cases, these are not the primary cause of failure. It is proposed that cracks may then remain contained within the agglomerations because of the clamping effect of the matrix during volumetric shrinkage upon curing.     

Degree of polymerization of acrylic bone cement.

Self-curing powder-liquid admixed acrylic systems are used for internal fixation fo total hip and total knee prostheses. Gel permeation chromatography revealed that the polymer chain length distributions of set cements were basically unaffected by their curing pressures. However, a decrease of approximately 11% in porosity coupled with a measured increase in mechanical strengths could be induced through the use of high curing pressures well beyond those attainable by the surgeon in the current arthroplasties. The conclusion of the investigation was that, to improve such cements, attention should be focused on elimination of porosity rather than attempting to produce higher degree of polymerization.     

Microtomography assessment of failure in acrylic bone cement

Micromechanical studies of fatigue and fracture processes in acrylic bone cement have been limited to surface examination techniques and indirect signal analysis. Observations may then be mechanically unrepresentative and/or affected by the presence of the free surface. To overcome such limiting factors the present study has utilised synchrotron X-ray microtomography for the observation of internal defects and failure processes that occurred within a commercial bone cement during loading. The high resolution and the edge detection capability (via phase contrast imaging) have enabled clear microstructural imaging of both strongly and weakly absorbing features, with an effective isotropic voxel size of 0.7 microm. Detailed assessment of fatigue damage processes in in vitro fatigue test specimens is also achieved. Present observations confirm a link with macroscopic failure and the presence of larger voids, at which crack initiation may be linked to the mechanical stress concentration set up by adjacent beads at pore surfaces. This study does not particularly support the suggested propensity for failure to occur via the inter-bead matrix; however crack deflections at matrix/bead interfaces and the incidence of crack arrest within beads do imply locally increased resistance to failure and potential improvements in global crack growth resistance via crack tip shielding.     

Variation of the mechanical properties of PMMA to suit osteoporotic cancellous bone

Poly(methyl methacrylate) (PMMA) is by far the most frequently used bone substitute material for vertebroplasty. However, there are serious complications, such as cement leakage and an increased fracture rate of the adjacent vertebral bodies. The latter may be related to the mechanical properties of the augmented segment within the osteoporotic spine. A possible counter-measure is prophylactic augmentation at additional levels, but this aggravates the risk for the patient. Introduction of pores is a possible method to reduce the inherent high stiffness of PMMA. This study investigates the effect of porosity on the mechanical properties of PMMA bone cement. Different fractions of a highly viscous liquid were mixed into the PMMA during preparation. An open-porous material with adjustable mechanical properties resulted after removal of the aqueous phase. Different radiopacifiers were admixed to investigate their suitability for vertebroplasty. The final material was characterized mechanically by compressive testing, microscopically and radiologically. In addition, the monomer release subsequent to hardening was measured by means of gas chromatography. The Young's modulus in compression could be varied between 2800 +/- 70 MPa and 120 +/- 150 MPa, and the compression ultimate strength between 170 +/- 5 MPa and 8 +/- 9 MPa for aqueous fractions ranging between 0 and 50% of volume. Only a slight decrease of the Young's modulus and small changes of ultimate strength were found when the mixing time was increased. An organic hydrophilic and lipophilic radiopacifier led to a higher Young's modulus of the porous material; however, the ultimate strength was not significantly affected by adding different radiopacifiers to the porous cement. The radiopacity was lost after washing the aqueous phase out of the pores. No separation occurred between the aqueous and the PMMA phase during injection into an open porous ceramic material. The monomer released was found to increase for increasing aqueous fractions, but remained comparable in magnitude to standard PMMA. This study demonstrates that a conventional PMMA can be modified to obtain a range of mechanical properties, including those of osteoporotic bone.     

骨水泥、钉道植骨强化动力髋螺钉固定修复老年骨质疏松性股骨转子间骨折

背景：对于老年骨质疏松性髋部骨折的动力髋螺钉固定,如能避免使用过程中造成的骨量丢失,或是采用其他手段增加固定螺钉把持力,将改善动力髋螺钉固定的治疗效果。 目的：对比研究3种固定方式修复老年骨质疏松性股骨转子间骨折的效果。   方法：回顾性分析近5年来采用常规动力髋螺钉内固定、骨水泥强化后动力髋螺钉固定及主钉道压配植骨配合动力髋螺钉固定3种固定方式治疗老年骨质疏松性股骨转子间骨折患者的资料,分别设为对照组、骨水泥组和植骨组。 结果与结论：经固定后2年随访,植骨组、骨水泥组和对照组Harris髋关节功能评分优良率分别为95%,80%,70%。植骨组骨折临床愈合时间明显缩短(P < 0.05),出现螺钉固定失败情况与骨水泥组相当。对照组较其他2组相对更多出现退钉等内固定失败情况。结果表明,与其他常规动力髋螺钉内固定、骨水泥强化后动力髋螺钉固定方式相比较,主钉道压配植骨配合动力髋螺钉内固定的疗效及安全性更好。中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

Microencapsulation of 2-octylcyanoacrylate tissue adhesive for self-healing acrylic bone cement

Here, we report the first phase of developing self-healing acrylic bone cement: the preparation and characterization of polyurethane (PUR) microcapsules containing a medical cyanoacrylate tissue adhesive. Capsules were prepared by interfacial polymerization of a toluene-2,4-diisocyanate-based polyurethane prepolymer with 1,4-butanediol to encapsulate 2-octylcyanoacrylate (OCA). Various capsule characteristics, including: resultant morphology, average size and size distribution, shell thickness, content and reactivity of encapsulated agent, and shelf life are investigated and their reliance on solvent type and amount, surfactant type and amount, temperature, pH, agitation rate, reaction time, and mode of addition of the oil phase to the aqueous phase are presented. Capsules had average diameters ranging from 74 to 222 μm and average shell thicknesses ranging from 1.5 to 6 μm. The capsule content was determined via thermogravimetric analysis and subsequent analysis of the capsules following up to 8 weeks storage revealed minimal loss of core contents. Mechanical testing of OCA-containing capsules showed individual capsules withstood compressive forces up to a few tenths of Newtons, and the contents released from crushed capsules generated tensile adhesive forces of a few Newtons. Capsules were successfully mixed into the poly(methyl methacrylate) bone cement, surviving the mixing process, exposure to methyl methacrylate monomer, and the resulting exothermic matrix curing. ? 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.