羟基磷灰石晶体纤维增强磷酸钙骨水泥力学性能及生物相容性研究

目的将高长径比的羟基磷灰石(HA)晶体纤维添加入磷酸钙骨水泥(CPC)中,研究HA晶体纤维对CPC抗压力学性能增强的最佳配方及在体内的生物相容性。方法采用水热合成法制备高长径比HA晶体纤维,并验证其细胞毒安全性。将2.5%、5%及10%(wt%)HA晶体纤维添加入CPC中,分析并获取HA晶体纤维对CPC力学性能增强的最佳配方。使用最佳配方制备CPC+HA晶体纤维复合材料,植入大鼠胫骨近端骨缺损模型,4、8周组织学观察HA晶体纤维添加入CPC的成骨性能及生物相容性。对照组为单纯CPC实验组。结果成功制备高长径比HA晶体纤维,其细胞毒安全性为1级(RGR79%)。与对照组相比,2.5%及5%HA晶体纤维添加入CPC可以增强材料的抗压力学性能(P<0.05),其中5%HA晶体纤维对CPC抗压性能的增强效果最佳,10%HA晶体纤维略降低CPC的抗压性能,但无统计学差异(P>0.05)。大鼠体内研究结果显示:与对照组相比,5%HA晶体纤维添加入CPC复合材料植入后材料周围骨体积分数(BV/TV)无显著性差异(P>0.05),HA晶体纤维添加入CPC后材料周围成骨与材料接触好,生物相容性良好。结论水热合成法制备的HA晶体纤维作为添加剂,具有增强CPC抗压力学性能,减低CPC脆性,生物相容性良好的特点,可用作骨植入生物材料的添加剂。     

多孔载因子CPC促进骨缺损愈合的实验研究

[目的]探讨磷酸钙骨水泥复合rhBMP-2/明胶微球复合材料在治疗骨缺损时的降解、成骨性能。[方法]制备携载rhBMP-2的明胶微球(GMs),与磷酸钙骨水泥(CPC)复合,制备出rhBMP-2/GMs/CPC复合人工骨。取30只新西兰大白兔,在前臂桡骨中段制造人工骨缺损,随机分成3组,分别植入rhBMP-2/GMs/CPC/复合物(A组)、GMs/CPC(B组)、rhBMP-2/CPC(C组),术后6、12周分别进行X线检测、骨密度测定,术后12周处死动物,分别行生物力学测定,脱钙切片、HE染色,不脱钙切片进行荧光显微镜下观察双标间距,计算平均矿化率。[结果]与GMs/CPC、rhBMP-2/CPC组比较,复合材料植入后不同时间点的材料降解及成骨均高于对照组。12周A组标本生物力学实验测定结果表明指标接近正常,与B、C组比较有统计学差异。骨密度12周、新骨矿化率提示有统计学差异。[结论]rhBMP-2/GMs/CPC微球系统复合材料在体内易降解,具有良好成骨活性,是良好的骨修复材料。     

异体脱钙骨基质明胶骨粒/骨水泥复合材料的生物力学性能研究

目的　研究不同质量比的部分脱钙骨基质明胶骨粒 /骨水泥复合材料的结构特征及生物力学性能 ,初步分析与复合比例的关系 ,为临床应用提供依据。方法　按 Urist等的方法制备异体部分脱钙骨基质明胶骨粒 ,再与骨水泥按不同比例混和制成含骨粒质量比分别为 0、4 0 0、5 0 0及 6 0 0 m g/ g的部分脱钙骨基质明胶骨粒 /骨水泥复合材料 ,对其进行扫描电镜观察和抗压极限强度、抗弯极限强度测定。结果　不同复合比例材料中骨粒与骨水泥均匀混合分布 ,呈多点面状接触 ,无序排列 ,其中骨水泥相互延续构成材料的骨架 ,不同大小的骨粒分布其间 ;材料间存在较多 10 0～ 4 0 0 μm不规则相互连通的自然裂隙 ,随材料中骨粒所占比例增加 ,骨水泥含量减少 ,自然裂隙增多。含部分脱钙骨基质明胶骨粒质量比为 0、4 0 0、5 0 0及 6 0 0 mg/ g的复合材料的抗压极限强度分别为 (71.1± 2 .0 ) MPa,(46 .9± 3.3) MPa,(39.8± 4 .1) MPa和 (32 .2± 3.4 ) MPa;抗弯极限强度分别为 (6 5 .0± 3.4 )MPa,(38.2± 4 .0 ) MPa,(33.1± 4 .3) MPa和 (2 5 .3± 4 .6 ) MPa。结论　部分脱钙骨基质明胶骨粒 /骨水泥复合材料具有良好的生物力学性能 ,且制备简便 ,易于塑形 ,其中以 10 0～ 4 0 0 μm自然裂隙有利于宿主骨的长入 ,是很好的     

Mechanical properties of the femur filled with calcium phosphate cement under torsional loading: a model in rabbits

 We conducted an experimental study using rabbits to determine the effect of injection of calcium phosphate cement (CPC) through a small cortical window on the torsional strength of the long bone. A drill hole created in the femoral shaft and medullary curettage before CPC injection simulates the clinical procedure for managing benign bone tumors. Torsional loading always produced a spiral fracture through the drill hole. The CPC-treated femurs, but not the polymethylmethacrylate-treated femurs, tolerated greater torsional loads and had greater energy absorption to failure at 24 h and 2 weeks postoperatively compared with the con-tralateral sham-operated femurs. These two parameters, however, were only 54% and 26%, respectively, of those in normal femurs at 24 h, but they were 71% and 51% of those in normal femurs at 12 weeks. Histologic sections demonstrated progressive covering of the drill hole by new bone in the CPC-treated specimens and invagination by newly formed cortical bone into the medullary cavity following sham operation. CPC increases the torsional strength of the long bones immediately after injection, although not sufficiently to preclude the need for external fixation in clinical applications. Better management of the cortical defect is needed to further improve torsional strength. Received: February 21, 2002 / Accepted: May 8, 2002     

The benefit of bone marrow concentrate in addition to a glass‐reinforced hydroxyapatite for bone regeneration: An in vivo ovine study

This study evaluates the ability of a Glass Reinforced Hydroxyapatite Composite (GRHC), in a new microporous pellet formulation with autologous bone marrow concentrate (BMC), to enhance bone regeneration and new bone formation. Ninety non‐critical sized bone defects were created in the femurs of nine Merino breed sheep and randomly left unfilled (group A), filled with GRHC pellets alone (group B) or filled with GRHC pellets combined with BMC (group C). The sheep were sacrificed at 3 weeks (three sheep), 6 weeks (three sheep) and 12 weeks (three sheep) and histological analysis (Light Microscopy‐LM), scanning electron microscopy (SEM) and histomorphometric analysis (HM) were performed. At 3, 6, and 12 weeks, HM revealed an average percentage of new bone of 48, 72, 83%; 25, 73, 80%, and 16, 38, 78% for Groups C, B and A respectively (significantly different only at 3 weeks p < 0.05). LM and SEM evaluation revealed earlier formation of well‐organized mature lamellar bone in Group C. This study demonstrates that the addition of a bone marrow concentrate to a glass reinforced hydroxyapatite composite in a pellet formulation promotes early bone healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1176–1182, 2017.

     

载骨髓间充质干细胞的磷酸钙骨水泥的制备

[目的]观察载骨髓间充质干细胞(Bone marrow mesenchymal stem cells,MSCs)明胶微球磷酸钙骨水泥(Calcium phosphate cement,CPC)的理化性质,探究新型CPC的制备。[方法]制备载MSCs的明胶微球后,分别以0%(A),2.5%(B),5%(C),10%(D)的质量比(w/w)与CPC复合。测定其抗压强度、初凝时间、孔隙率和大孔率等理化性质,进一步检测MSCs在CPC中的成长情况。[结果]在各组CPC中MSCs均生长良好,且与空白对照组比较,随着明胶微球比例的增大,各组CPC的抗压强度逐步降低,初凝时间延长,孔隙率增大,大孔率增高(P<0.05)。[结论]载MSCs的明胶微球与CPC的质量比为5%时,CPC的理化性质最为理想,细胞生长良好,此结果为下一步体内实验奠定了坚实的基础。     

磷酸钙骨水泥作为骨形成蛋白载体修复节段性骨缺损及相关研究

目的 制备CPC/BMP复合人工骨，通过动物实验研究其对骨缺损的修复作用及相关问题，探讨临床应用的可能性。方法 参考有关文献方法合成CPC，并将其作为BMP的载体制成CPC/BMP复合物，植入兔桡骨15mm骨缺损处，术后不同时间处死动物。通过生物力学测定，组织学染色分析，电镜扫描及X射线电子能谱分析。X线摄片，无机质含量测定以及骨密度测定等手段观察新骨形成和材料降解情况。同时以单纯的CPC及空白组作为对照研究。综合评价CPC/BMP对骨缺损的修复能力及对机体的影响。结果 术后CPC/BMP和CPC两组动物均无毒性反应。随着时间的延长，血清中碱性磷酸酶浓度逐渐升高，尤以CPC/BMP组显著，提示CPC/BMP复合物和单纯的CPC均可以促进新骨形成，前者新骨形成量大，骨修复能力明显好于后者。CPC/BMP植入2周时可见大量间充质细胞分化，在材料与骨端之间出现一层软骨细胞。4周时软骨细胞向编织骨分化，16周时板骨层骨长人材料并与之相互分割包裹，24周时骨缺损初步修复，新骨密度明显高于CPC组，说明BMP的加入不仅有效地促进了新骨的形成，同时也加速了新骨的钙化。24周组标本生物力学测定结果表明，新骨形成的同时伴随材料的降解，CPC组材料降解速度缓慢，CPC/BMP组降解速度优于CPC组，但24周时仍有部分材料残存。在新骨形成和材料降解过程中可出现血清钙浓度的一过性升高。结论 CPC是BMP的理想载体。CPC/BMP生物活性人工骨对骨缺损有较强的修复能力，可望成为新型的骨缺损修复材料。     

明胶微球/rhBMP-2/CPC的制备及其异位成骨效应研究

目的：制备多孔复合材料明胶微球／rhBMp-2／CPC并研究其异位成骨效应。方法：双相乳化冷凝聚合法制备明胶微球,京尼平进行交联,喷金后电镜观察。交联微球携载rhBMP-2,以2．5％的比例掺入磷酸钙骨水泥（calcium phosphate cements,CPC）固化,制成实验用多孔明胶微球／rhBMP-2／CPC,rhBMP-2／CPC作为对照组．两组材料固化后分别浸入生理盐水,1、3周后进行生物力学压缩实验,扫描电镜观察材料断面：ELISA法测定不同时间点生理盐水中rhBMP-2浓度,计算rhBMP-2的累积释放量。材料植入小鼠大腿肌袋,术后3周处死小鼠,切取材料及周围组织,HE染色后进行组织学观察,同时测定材料周围组织中碱性磷酸酶及钙含量。结果：交联的明胶微球呈规则圆形,粒径（62±18）um,分散性好。1、3周后实验组材料断面可见大量大孔形成,对照组未见明显大孔,实验组的总孔径率、大孔率及rhBMP-2的累积释放量均高于对照组：3周后实验组最大压缩强度（7．8±1．2）MPa,较对照组（11.2±1．6）MPa稍低。HE染色两组均可见软骨形成,但实验组更多,碱性磷酸酶及钙含量测定实验组分别为（4.33±0．52）IU／g和（6．12±1.22）ug／mg,高于对照组的（2．67±0．23）IU／g和（3．12±0．41）ug／mg。结论：明胶微球／rhBMp-2／CPC在微球降解后形成多孔磷酸钙复合材料,使rhBMp2的释放量增加,具有强大的异位成骨性能,是一种优秀的骨组织工程材料。     

聚磷酸钙纤维/磷酸钙骨水泥/微小颗粒骨修复骨缺损的实验研究

目的探讨聚磷酸钙纤维(calcium polyphosphate fibers,CPPF)、磷酸钙骨水泥(calcium phosphate cement,CPC)、自体微小颗粒骨复合材料修复骨缺损的能力。方法选用新西兰大白兔72只,双侧桡骨制成1.5cm骨缺损模型,随机分成6组分别植入。A组:CPPF/CPC/微小颗粒骨复合材料;B组:CPC/微小颗粒骨复合材料;C组:单纯微小颗粒骨;D组:CPPF/CPC复合材料;E组:单纯CPC;F组:空白对照组,不植入任何物质。在2、4、8、12周各时相点,分别进行大体观察、X线照片、组织学切片、扫描电镜观察及力学测试。结果A组在12周可使骨缺损修复,在骨缺损修复各时期,其成骨速度及成骨量均好于其他各组。结论CPPF/CPC/微小颗粒骨复合材料有良好的成骨能力、力学特性和生物相容性,有望成为骨组织工程中修复骨缺损的理想材料。     

Preparation and degradation characteristic study of bone repair composite of DL—polylactic acid／hydroxyapatite／decalcifying bone matrix

Objective:To explore the preparative method and study the degradation characteristics of bone repair composite of DL-polyactic acid(PDLLA) /hydroxyapatite(HA)/decalcifying bone matrix(DBM) in vitro.Methods:An emulsion blend method was developed to prepare the composite of PDLLA/HA/DBM in weight ratio of PDLLA:HA:DBM=1.2-2:1.5:1.The dynamic changes of weight,biomechanical property and pH value of PDLLA/HA/DBM and PDLLA in phosphate buffered saline(PBS,pH7.4)were studied respectively through degradation tests in vitro.Results:Without being heated,PDLLA,HA and DBM could be synthesized with the emulsion blend method as bone composite of PDLLA/HA/DBM,wich had both osteoconductive and osteoinductive effects.The diameter of the aperture was 100-400μm and the gap rate was 71.3%.During degradation,the pH value of PDLLA solution decreased lightly within 2 weeks,but decreased obviously at the end of 4 weeks and the value was 4.0 .While the pH value of PDLLA/HA/DBM kept quite steady and was 6.4 at the end of 12 weeks.The weight of PDLLA changed little within 4 weeks,then changed obviously and was 50% of its initial weight at the end of 12 weeks.While the weight of PDLLA/HA/DBM changed little within 5 weeks ,then changed obviously and was 60% of the initial weight at the end of 12 weeks.The initial biomechanical strength of PDLLA was 1.33 MPa, decreased little within 3 weeks, then changed obviously and kept at 0.11 MPa at the end of 12 weeks.The initial biomechanical strength of PDLLA/HA/DBM was 1.7 MPa, decreased little within 4 weeks, then changed obviously and kept at 0.21 MPa at the end of 12 weeks.Conclusions:The emulsion blend method is a new method to prepare bone repair materials.As a new bone repair material,PDLLA/HA/DBM is more suitable for regeneration and cell implantation,and the environment during its degradation is advantageous to the growth of bone cells.     

胶原膜联合自体骨髓基质细胞及富血小板血浆修复牙槽骨缺损的实验研究

目的初步探讨胶原膜与骨髓基质细胞（bone marrow stromal cells,BMSCs）、富血小板血浆（plateletrich plasma,PRP）复合后修复牙槽骨缺损的应用潜能。方法将犬BMSCs与BME-10X胶原膜复合培养。取3只雄性杂种犬,拔除双侧上下颌第1、2前磨牙,保留唇舌侧牙槽嵴,制备一近远中向15mm×5mm,冠根向8mm的骨内缺损,随机分为四组。A组（空白对照组）：直接缝合牙龈;B组：缺损区上覆盖Bio-Gide胶原膜;C组：缺损区植入BMSCs胶原膜复合物后覆盖Bio-Gide胶原膜;D组：缺损区注入PRP,覆盖Bio-Gide胶原膜。分别于术后4、8、12周进行大体、X线片和组织学观察。结果BMSCs与胶原膜复合培养1d,细胞近似圆形或短梭形,3d左右可见多数细胞有突起,呈多边形及长梭形。大体观察：术后4周A组见骨缺损中央有明显凹陷,骨缺损区内见明显血肿机化物;B、C及D组骨缺损区主要为新生骨样组织充填,间杂少量血肿机化物。8周A组见骨缺损区凹陷基本长平,骨缺损顶部为纤维组织,血肿机化物被新生骨组织所取代;B、C及D组膜边缘破裂,与深面组织稍粘连,针头均不能刺入骨缺损表面。12周各组骨缺损区凹陷完全长平,A组牙槽嵴顶部纤维组织较其他组厚。X线片观察：各组骨质均长满骨缺损区;A、B、C及D组灰度值,4周分别为68、50、56及49,8周时为46、30、24及30,12周时为24、17、15及20。组织学观察：术后4周,A组缺损区可见大量纤维结缔组织及及新生血管形成的肉芽组织,未见明显新骨生成;B、C及D组膜的胶原结构均存在,其内侧面有新骨生成。8周A组缺损区新生骨小梁呈团灶状、网状;B、C及D组膜的胶原结构不完整,多个骨岛和少量纤维结缔组织连接整个骨缺损区。12周各组骨缺损区均被新生骨充填。结论使用胶原膜引导骨再生（guided boneregeneration,GBR）技术可促进牙槽骨缺损区成骨,将骨修复时间缩短为8周,但单独应用GBR的成骨作用与胶原膜复合BMSCs或PRP的成骨作用差异不明显,提示二者与GBR的联合应用还有待进一步研究。     

磷酸钙人工骨结合骨髓基质干细胞移植修复骨缺损的实验研究

目的制备磷酸钙人工骨(calcium phosphats artifieal bone, CPC)与骨髓基质干细胞(bone mesenchymal stem cells, BMSCs)复合物，通过动物实验研究其对骨缺损的修复作用。方法分离、扩增兔的BMSCs，并以CPC为载体制备cPc／BMSCs复合物，植入兔桡骨15mm骨缺损处。于术后不同时间处死动物，通过X线摄片、组织学染色分析和放射性核素监测，观察新骨形成和材料降解情况。同时以单纯的CPC及空白对照组作为对照研究，评价CPC／BMSCs复合物对骨缺损的修复能力。结果CPC／BMSCs复合物可再生新骨组织并完好地修复桡骨缺损，且其修复能力明显优于单纯的CPC。结论以CPC为载体的自体骨髓细胞移植能有效的修复骨缺损。     

骨显像诊断股骨头缺血性坏死

目的　了解三相骨显像对于股骨头缺血性坏死的诊断价值。方法　出院诊断为股骨头缺血性坏死患者 31例 (36个坏死股骨头 ) ,多次门诊后确诊为股骨头缺血性坏死患者 17例 (2 0个坏死股骨头 ) ,共计 4 8例 5 6个缺血性坏死股骨头 ,对其进行99　TCm MDP三相骨显像。其中 31例 36个坏死股骨头有近期X线片检查结果 ,列表与骨显像结果作了对照。结果　 5 6个缺血性坏死股骨头静态骨显像均有相关坏死征象 ,血流相 37个有改变 (6 6 1% ) ,血池相 4 0个有改变 (71 4 % )。 36个坏死股骨头X线片结果为正常者 10个 (2 7 8% ) ,早期坏死 7个 (19 4 % ) ,坏死 19个 (5 2 8% ) ,诊断灵敏性低于骨显像。结论　三相骨显像对诊断股骨头缺血性坏死是一个准确、灵敏而简便的方法 ,可作为常规应用     

The merit of sintered PDLLA/TCP composites in management of bone fracture internal fixation

Polyesters based on lactic acid have been reported in terms of safety and biodegradation in human beings for 2 decades. The greatest advantage of such material is its degradation conducted only by hydrolysis, whereby the ester backbones are supposed to be unchained in the aqueous condition. The final degradable products are carbon dioxide and water which can be metabolized and digested in the physiological environment. The goal of this study was aimed at developing a composite sintered with poly-DL-lactide (PDLLA) and tricalcium phosphate (TCP) ceramic particles for orthopedic application. The TCP particles in a range of 30-60 wt% with 5 wt% increments were doped into the PDLLA matrix which was prepared by melting and hot pressing techniques for the reinforcement. The basic mechanical strength, biodegradable behavior, and biological response of the composites were investigated in the study. Various techniques such as pH meter, UV, Fourier-transform infrared, and x-ray diffractometer were used to examine and record the degradable process of the composites soaked in saline for 1-16 weeks. The rabbit femur condyle fracture fixation test was used to evaluate tissue compatibility and the effects of bone fracture fixation on the composites. Histological observation and x-ray photography were used for investigating assistance. The mechanical strength of the composites initially increased with TCP additions up to 50wt%, but thereafter they showed no significant difference (p < 0.05). The composite with 50 wt% TCP addition showed greater mechanical strength and had good agreement with cortical bone in terms of its elastic modulus of 30-40 GPa. The weight loss of the pure PDLLA soaked in the saline started at 4 weeks and reached 95% after 16 weeks. The composites compared with pure PDLLA, however, showed no apparent evidence of degradation after soaked for 12 weeks. The possible mechanisms for the delayed degradation of the composites in saline might have been solution penetration retardation by the ceramic particles and chemical bonds formed between the interface of the TCP particles and the PDLLA matrix. In the histological evaluation of the rabbit femur condyle fracture fixation test, the surface of the composite with 50 wt% TCP addition was attached by the newly generated bone without fibrous tissue around 8 weeks after implantation. The fractured bone was gradually healed and the composite firmly and properly fixed on the fracture area during the implanted period, which provided a breeding environment for normal bone remodeling. The developed composite was thought to be an alternative material for orthopedic application in the future, especially for bone screws and bone plates.     

Calcium Phosphate Cement with BMP-2-loaded Gelatin Microspheres Enhances Bone Healing in Osteoporosis: A Pilot Study

Background

The capacity for bone healing reportedly is limited in osteoporosis with a less than ideal environment for healing of bone grafts. We therefore developed a composite bone substitute with rhBMP-2 loaded gelatin microsphere (GM) and calcium phosphate cement (CPC) to use in osteoporosis.

Questions/purposes

We asked whether (1) controlled release of rhBMP-2 could be improved in this composite bone substitute and (2) increasing factors released from the bone substitute could accelerate osteoporotic bone healing.

Methods

We soaked rhBMP-2/GM/CPC and rhBMP-2/CPC composites in simulated body fluid for 28 days and then determined the amount of rhBMP-2 released. Both composites were implanted in bone defects of osteoporotic goats and left in place for 45 and 140 days; the specimens then were evaluated mechanically (pushout test) and morphologically (CT scanning, histology).

Results

The in vitro study showed the new composite released more rhBMP-2 compared with rhBMP-2/CPC. CT showed the defects healed more quickly with new grafts. The bone mineralization rate was greater in rhBMP-2/GM/CPC than in rhBMP-2/CPC after 45 days of implantation and the pushout test was stronger after 45 and 140 days of implantation.

Conclusions

The new graft composite released more loaded factors and appeared to repair osteoporotic bone defects.

Clinical Relevance

These preliminary data suggest the new composite can be used as a bone substitute to accelerate healing of fractures and bone defects in osteoporosis.     

一种新型生物活性人工骨的制备及成骨活性的研究

目的：研制CPC/BMP复合人工骨,检测其成骨活性。方法：制备CPC/BMP及CPC骨块,扫描电子显微镜观察表面结构。用小鼠肌袋植入实验观察材料的成骨活性。结果：BMP在CPC中呈微球状均匀分布。CPC植入小鼠肌袋内不能诱导,CPC/BMP植入后1周有软骨细胞出现,2周有编织骨,4周以后小梁骨生成,16周出现成熟的板层骨。同时材料出现降解迹象。有机质含量、碱性磷酸酶浓度在CPC/BMP组出现升高,扫描电镜结果同样证实有新骨形成。结论：CPC/BMP生物活性人工骨可异位诱导成骨,可望成为新型的骨缺损修复材料。     

Osteogenic evaluation of glutaraldehyde crosslinked gelatin composite with fetal rat calvarial culture model

The cytotoxicity of the synthetic bone substitute composed of tricalcium phosphate and glutaraldehyde crosslinked gelatin (GTG) were evaluated by osteoblast cell culture. In a previous study, the GTG composites were soaked in distilled water for 1, 2, 4, 7, 14, 28, and 42 days, and then the solutions (or extracts) were cocultured with osteoblasts to evaluate the cytotoxicity of GTG composites by alive cell counting. In this study, the extracts were cocultured with the osteoblasts; thereafter, the concentration of transforming growth factor-beta (TGF-beta1) and prostaglandin E2 (PGE2) in the medium was analyzed to strictly reflect the biological effects of GTG composites on the growth of osteoblasts. In order to investigate the osteoconductive potential of the GTG composites on new bone formation in a relative short term, a model of neonatal rat calvarial organ culture was designed prior to animal experiments. Three experimental materials of 4, 8, and 12% GTG composites were evaluated by fetal rat calvarial organ culture for their ability for bone regeneration. Deproteinized bovine and porcine cancellous bone matrixes were used as the controlled materials. All the organ culture units were maintained in cultured medium for 5 weeks. Following the culture period, the morphology of tissue was observed under an optical microscope, and the quantitative evaluation of the new generation bone was determined by using a semiautomatic histomorphometeric method. Except in the initial 4 days, the concentration of TGF-beta1 of 4% and 8% GTG composites was higher than that of the blank group for all the other experimental time periods. The PGE2 concentration for 4% and 8% GTG composites was lower than that of the blank group. It revealed that the 4% and 8% GTG composites would not lead to inflammation and would promote osteoblast growth. The morphology and activity of the osteoblasts were not transformed or changed by the 2 GTG composites. For the 12% GTG composite, the performance of the in vitro condition was inferior to the blank group and the other 2 GTG composites. Although the concentration of TGF-beta1 and PGE2 was gradually back to normal after 14 days, the morphology of the osteoblasts was abnormal with features such as contracted cytoplast structures. The osteoblast was damaged perhaps in the initial stage. We suggested that the 4% and 8% GTG composites should be soaked in distilled water at least for 4 days before medical applications. The 12% GTG composite and the composites with a concentration of glutaraldehyde solution higher than 12% were not recommended as a medical prostheses in any condition. The fetal rat calvaria culture also showed the same results with the analysis of TGF-beta1 and PGE2. From the study, we could predict the results of animal experiments in the future.     

颗粒骨的制备及修复骨缺损的研究

目的 观察聚磷酸钙纤维(CPPF)磷酸钙骨水泥(CPC)、微小颗粒骨复合物体外降解特性及体内修复骨缺损的能力.方法 将CPPF、CPC、微小颗粒骨按质量比1∶4∶4制成复合人工骨,通过PH值、重量、抗压强度的变化,观察人工骨在pH7.4的37℃磷酸盐缓冲液(PBS)中的降解性能.通过大体、X光片、组织学观察及力学测试来检测复合人工骨的体内修复骨缺损的能力.结果 体外实验证实:CPPF/CPC/颗粒骨复合材料孔隙率为72.1%,CPC/颗粒骨孔隙率为58.2%;扫描电镜显示CPPF/CPC/颗粒骨复合材料的孔径为100～400 μm,CPC/颗粒骨为50～300 μm;两组样品溶液pH值在12周内基本维持恒定;CPPF/CPC/颗粒骨复合材料0～4周重量变化较小,4～8周下降较快,12周为初始重量50%,CPC/颗粒骨复合材料在0～6周变化较小,6周后重量下降较快,12周时为初始重量70%;CPPF/CPC/颗粒骨复合材料初始抗压强度9.28 MPa,CPC/颗粒骨复合材料初始抗压强度6.21 Mpa,两者有统计学意义.CPPF/CPC/颗粒骨强度在0～4周下降较慢,4周后下降较快,12周时为0.1,8 MPa,CPC/颗粒骨强度均匀下降,12周时为0.24 MPa.体内实验:CPPF/CPC/颗粒骨复合材料修复骨缺损效果优于其他各组,且差异有统计学意义(P＜0.05).结论 复合材料以其优良的生物学性能有望成为理想的骨替代材料.     

Microbiological and pharmacological tests on new antibiotic-loaded PMMA-based composites for the treatment of osteomyelitis

Local antibiotic diffusion in rabbit femurs from two new PMMA-based and nail-shaped composites, enriched with β-tricalcium phosphate (P-TCP) and BaSO(4) or only with BaSO(4) (P-BaSO(4) ), and soaked in a solution of gentamicin (G) and vancomycin (V) was studied. Nails were implanted into the intramedullary cavity of healthy and osteomyelitic femurs to study the resolution of infection and to quantify the antibiotic penetration into bone by microbiological, pharmacological, and histological tests. A significant progression of osteomyelitis was recorded 7 weeks after MRSA inoculation, whereas no bacteria were found in animals treated with antibiotic-loaded nails as confirmed by microbiology and histology (Smeltzer score). The release of both antibiotics from composites was high and prompt both in healthy and infected bone; the amount of V was higher than that of G in all bone samples. Antibiotics of both composites were still present in bone 3 weeks after nail implantation. The P-BaSO4 composite released a lower amount of antibiotics than did P-TCP. The G-V combination in vivo exerted a synergistic bactericidal effect, which was confirmed by microbiological, histological, and clinical results (no infection). These new porous PMMA composites, soaked in G-V solution in the operating room, might be an effective and useful drug delivery system for osteomyelitis treatment.     

Basic fibroblast growth factor may improve devascularized sternal healing

BACKGROUND: We have shown that a gelatin sheet incorporating basic fibroblast growth factor enhanced bone regeneration of the devascularized sternum. The purpose of this study was to determine if topical use of the gelatin sheet accelerated normal sternal regeneration and bone remodeling. METHODS: Thirty Wistar rats had median sternotomy and were divided into 3 groups: 10 had the bilateral internal thoracic arteries removed and basic fibroblast growth factor sheet applied on the sternum (group A), 10 had just the bilateral internal thoracic arteries removed (group B), and 10 had intact bilateral internal thoracic arteries (group C). RESULTS: Four weeks later the peristernal blood flow significantly increased and marked angiogenesis was seen around the sternum in group A. Histologically, the sternum was almost completely healed only in group A. In group A the bone mineral content was highest, but the bone mineral density was similar to that in other groups. The osteoclast index in group A was highest at the border zone of bone formation and remained high in regenerated bone. CONCLUSIONS: The basic fibroblast growth factor sheet offset sternal ischemia and accelerated normal sternal bone regeneration and remodeling, not only by callus formation but also by callus resorption.