骨质疏松性骨折愈合与骨量、骨结构及力学性能相关性的实验研究

目的探明骨质疏松性骨折愈合程度与骨量、骨结构与力学性能的相互关系,以期能为临床治疗提供科学指导与理论依据.方法选择8月龄雌性SPF级SD大鼠130只,随机分为2组：骨质疏松性骨折组（OPFM）与一般性骨折组（CFM）,每组各65只.手术方法建立骨质疏松性骨折与一般性骨折的实验模型,于术后1、2、4、6、8、12、16周作骨痂组织形态计量学、骨密度与力学性能测试等观察.结果①骨痂组织骨组织形态计量学结果发现：OPFM组成熟小梁骨占骨痂面积比CFM组小,且小梁骨厚度变薄、小梁骨间距较宽;同时骨小梁动力学参数显示：OPFM组骨小梁表面荧光标记百分比（LS）较CFM组低,而骨矿化沉积率（MAR）却较高.②骨密度（BMD）测定显示：两组BMD值8周时均达到高峰（P＞0.5）,随后均降低,OPFM组下降尤为明显;12周时两组间差异有显著性（P＜0.05）.③骨痂组织扭转力学强度测试结果表明：8、12周OPFM组扭转强度均较CFM组低.结论在骨质疏松性骨折修复过程中,骨痂组织的有机成份组成、显微结构、骨矿代谢与骨量的异常改变导致了其力学强度乃至骨折愈合质量的降低,是再次骨折发生的主要原因.     

戊酸雌二醇对去势大鼠骨折愈合影响的实验研究

目的 探讨戊酸雌二醇在骨质疏松性骨折愈合过程中的作用,为绝经后骨质疏松性骨折的治疗提供理论依据.方法 选用6月龄雌性Sprague-Dawley(SD)大鼠54只,实验分为SHAM组(假手术组)、OVX组(去势组)、补佳乐组.除SHAM组外,其余各组均切除双侧卵巢建立骨质疏松动物模型.去势后8周各组行右股骨骨折建立骨折模型,同时补佳乐组按0.104(mg·kg-1·d-1)灌胃.3组均在骨折后第2、4、6、8周处死大鼠后行放射学观察骨痂变化,骨痂HE染色及成骨细胞、破骨细胞计数.结果 ①放射学:OVX组骨痂密度影低,8周时OVX组骨折线仍然存在,SHAM组和补佳乐组骨折线模糊甚至消失.②骨痂组织学:OVX组骨小梁表面破骨细胞明显增多,成骨细胞也较多,呈骨高转换状态.8周时骨小梁变细、中断,软骨成分仍较多,软骨性骨痂向骨性骨痂转化缓慢;SHAM组和补佳乐组随骨折愈合骨小梁逐渐增加成熟,小梁骨粗大,排列紧密,骨小梁表面成骨细胞体积大,胞浆丰富,破骨细胞减少.③成骨、破骨细胞指数:2、4周OVX组破骨细胞指数大于补佳乐组和SHAM组.成骨细胞指数在3组间差异无显著性.结论 戊酸雌二醇对于促进绝经后骨质疏松性骨折早期愈合有效.     

阿仑膦酸钠和强骨胶囊单用与合用对大鼠骨质疏松性骨折骨愈合影响的实验研究

目的通过骨质疏松性骨折动物模型,观察阿仑膦酸钠、强骨胶囊单用及合用对骨折愈合的影响,以探讨中西医结合治疗骨质疏松性骨折的意义。方法 70只SD大鼠给予维甲酸灌胃,制造骨质疏松性骨折模型成功后分别予以阿仑膦酸钠、强骨胶囊及两药合用,于2周、4周和6周处死5只试验鼠,进行骨痂大小的测量及组织学研究。结果 2周时合用组骨痂大小较其他组无显著差异;4周时合用组骨痂大小较阿仑膦酸钠组小,较强骨胶囊组大;6周时各组骨痂大小无异。组织学检测发现阿仑膦酸钠组破骨细胞数目最少,骨小梁成熟较其他组缓慢;强骨胶囊组成骨细胞数目最多,小梁骨成熟最快;强骨胶囊联合阿仑膦酸钠组与对照组无差别。结论强骨胶囊与阿仑膦酸钠联合使用治疗维甲酸所致大鼠骨质疏松性骨折疗效并不显著。     

骨质疏松性骨折愈合的细胞学观察

目的为了解骨质疏松性骨折愈合的过程及期问的细胞学变化情况。方法切除成年雌犬双侧卵巢，造成绝经后骨质疏松症模型，并人为造成胫骨骨折用螺钉内固定，以观察骨折愈合情况。结果发现骨质疏松性骨折后两周左右，骨折骨小梁表面及周围有大量大小不等的圆形细胞增殖，骨吸收陷窝内有胶原纤维形成，但比较稀疏、紊乱。在骨折塑形改造期，破骨细胞性骨吸收活动显得异常活跃，而成骨细胞性骨形成显得异常微弱。结论骨质疏松性骨折的治疗，不但要使骨折良好复位，坚强固定，而且在骨折塑形改造期，更应该促进成骨细胞的活性，降低破骨细胞活性，使骨形成增加，骨吸收减少。     

甲状旁腺激素联合降钙素对大鼠骨质疏松性骨折骨生长因子的影响

目的探讨甲状旁腺素联合降钙素对大鼠骨质疏松性骨折骨相关生长因子及骨折愈合的影响。方法75只雌性SD大鼠随机分为:假手术组、去势组、甲状旁腺素组、降钙素组、联合用药组,15只/组,首先构建去卵巢大鼠骨质疏松性骨折动物模型。观察并评估骨折愈合,测定骨痂BMD和BMC,检测血清BMP-2、VEGF、TGF-β、IGF-1水平和骨痂蛋白表达,观察骨痂形态结构变化。结果去势组较假手术组骨折愈合评分、骨痂BMD和BMC、血清BMP-2、VEGF、TGF-β、IGF-1水平和骨痂蛋白表达均显著降低(P均<0.05),而联合用药组较去势组上述指标均显著升高(P均<0.05)。去势组骨痂骨小梁明显减少,生长稀疏,排列紊乱,大量间充质干细胞及纤维软骨细胞,成骨细胞及微血管少见;联合用药组骨痂大量骨小梁,生长旺盛,互相交错网状,排列致密有序,可见较多成熟的骨细胞及成骨细胞。结论甲状旁腺素联合降钙素通过介导提高相关骨生长因子表达,提高骨质疏松性骨折骨密度和矿物含量,改善骨组织形态学,加快骨折愈合。     

葛根素对去卵巢大鼠骨质疏松性骨折骨痂血管形成的影响

目的探讨葛根素对骨质疏松性骨折骨痂血管形成的影响及对骨折愈合的作用。方法60只雌性SD大鼠分为3组:假手术组、去势组、葛根素组,20只/组,去卵巢大鼠骨质疏松性骨折动物。观察评估骨折愈合情况,检测血清BMP-2和VEGF浓度,观察骨痂形态结构变化,检测骨痂BMP-2和VEGF表达。结果去势组较假手术组骨折愈合评分、血清BMP-2和VEGF浓度、骨痂BMP-2和VEGF表达、微血管数均显著降低(P<0.05),葛根素组较去势组上述指标均显著增高(P<0.05)。去势组骨痂组织可见少量骨小梁,生长稀疏,排列紊乱,大量纤维软骨细胞等纤维组织,成骨细胞及新生小血管少见;葛根素组骨痂可见较多骨小梁,生长较旺盛,排列有序,可见较多成熟的骨细胞,新生微小血管较多。结论葛根素通过介导去卵巢大鼠骨质疏松性骨折骨痂BMP-2和VEGF表达,促进骨痂血管形成,改善骨组织形态学,加快骨折愈合。     

骨质疏松性骨折愈合过程中PDGF-A与PDGF-αR的表达

目的观察骨质疏松性骨折愈合的不同阶段血小板衍生生长因子A(platelet-derivedgrowthfactorA,PDGF-A)与PDGF-αR的表达,进一步探讨两者对骨折愈合的作用及作用机制。方法采用免疫组织化学的方法(ABC法),检测大鼠骨质疏松性骨折愈合的不同阶段(5、7、14、28、42d)骨痂组织中的PDGF-A与PDGF-αR的表达与变化。结果在骨质疏松性骨折愈合的不同阶段,骨痂组织内软骨细胞、成骨细胞、骨细胞与血管内皮细胞等可呈现不同程度的PDGF-A与PDGF-αR的表达。结论PDGF-A参与调节骨质疏松性骨折的愈合,骨质疏松性骨折修复能力的降低可能与PDGF-A分泌水平异常有关。     

骨质疏松性骨折实验模型的设计与建立

目的：建立较理想的骨质疏松性骨折实验模型，方法：SD大鼠60只，8月龄，雌性，手术方法：切除双侧卵巢；术后3个月，手术造成股骨中段骨折，进行骨圆针髓腔内固定。模型建立前后双能X线骨密度仪（DEXA），组织学、放射学等动态观察。结果：卵巢切除3个月后DEXA检测结果与术前比较：全身骨密度明显降低（P＜0．02）；子宫内膜组织萎缩变薄，内膜内腺体消失或萎缩，变性呈空泡状；软骨内成骨与膜内成骨共同参与了骨质疏松性骨折的修复，且以软骨内成骨为主，与一般骨折愈合方式相似，模型动物骨折愈合过程中，软骨内成骨延缓，骨性骨痂改建（骨吸收＞骨形成）加速，骨痂内胶原纤维疏松，排列紊乱，与主应力方向不一致，放射学观察模型动物骨折位置，类型统一，内固定后骨折断端稳定。结论：本实验建立的骨质疏松性骨折动物模型模型其方法，易于复制，可应用于骨质疏松林骨折的相关研究。     

骨质疏松对卵巢切除大鼠骨折愈合影响的超微结构研究

目的 探讨骨质疏松对骨折愈合的影响。方法 选择8个月龄雌性SD大鼠24只,随机分为假手术组和卵巢切除骨质疏松组,每组12只,分别行假性手术和双侧卵巢切除术;3个月后,于股骨中部制造骨折模型,采用透射电镜对两组骨折后3、7、14、21、28和42d骨痂进行观察。结果 两组骨折愈合早期（21d前）参与修复细胞类型,超微结构变化及细胞功能状态几乎相同;术后28d,卵巢切除组钙化软骨骨痂仍未完全吸收和被新的纺织骨取代,可见大量坏死软骨细胞包埋于钙化的软骨基质中,此后,破骨细胞性骨吸收逐渐加剧,伴骨细胞发现肝溶解现象。结论 骨质疏松对卵巢切除大鼠骨折愈合影响主要发生在骨折愈合后期,表现为软骨内化骨迟缓,骨改建过程中破骨细胞性骨吸收增加;骨细胞性骨溶解现象加剧了这一骨吸收过程。     

骨松安激活Runx 2/Osterix途径促进骨质疏松性骨折愈合的机制研究

目的初步探索骨松安促进骨质疏松性骨折愈合的机制。方法建立骨质疏松性骨折大鼠模型,采用骨松安进行治疗,分别于7、14、21 d取出骨折端骨痂,通过HE染色观察骨痂生长情况,采用免疫组化、RT-qPCR检测Runx 2、Osterix的表达。结果 HE染色结果显示,骨松安治疗可在早期促进骨质疏松性骨折大鼠骨折端软骨细胞增生、成骨细胞成熟分化及编织骨形成。免疫组化、RT-qPCR结果显示,骨质疏松性骨折组大鼠Runx 2与Osterix的表达一直处于较低水平,在骨松安持续治疗下,Runx 2与Osterix的表达得到明显改善。结论骨松安可激活Runx 2/Osterix途径,加速前成骨细胞向成骨细胞分化,促进骨质疏松性骨折大鼠的骨折愈合。     

Relationship among bone mineral density, collagen composition, and biomechanical properties of callus in the healing of osteoporotic fracture

Objective： To study the change and relationship among bone mineral density （BMD）, collagen composition and biomechanical properties of the callus in the healing process of osteoporotic fracture. Methods： The osteoporotic rat model and fracture model were established through bilateral ovariectomy （OV＇X） and osteotomy of the middle shaft of the right hind tibiae, respectively. Ninety female SD rats were randomly divided into OVX group and sham group. With the samples of blood and callus, roentgenoraphic and histological observation were performed for the assessment of the healing progress of the fracture, and the serum concentration of TRAP-5b, proportion of type I collagen, BMD and biomechanical properties of the callus were measured. Results： The OVX group experienced a significant delay of fracture healing. The mean serum concentration of TRAP-5b of rats in the OVX group was much higher than that in the sham group after the operation （P 〈 0.05）, but the difference at the same time point after fracture was smaller than that before fracture （P 〈 0.05）. The BMD of the callus in both groups reached the peak value at the 6 th week after fracture while the proportion of the type I collagen and the biomechanical strength reached the peak at the 8th week. Conclusions. The deficiency of estrogen after the ovariectomy could induce the up-regulation of the osteoclasts activities, whereas the potency of further activation after fracture was depressed. Although the synthesis of collagen together with its mineralization determines the biomechanical properties of new bone, the accumulation of collagen could be assessed as an index in the prediction of biomechanical strength of bones independent of the bone mineral deposition.     

Experimental study of effect of stress-relaxation bone plate on fracture healing

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振动力学刺激对骨质疏松性骨折愈合的影响

目的本研究旨在探讨高频率低能量的振动力学刺激对骨质疏松性骨折愈合的影响。方法59只大鼠建立大鼠卵巢切除骨质疏松模型,建模成功后构建股骨骨折模型,并随机分为振动力学刺激组和对照组。骨折后第5天开始对振动组使用高频率低能量振动平台(35Hz,峰振幅0.3重力加速度)行每天20min的振动力学刺激,对照组则行假治疗。每周摄X线片观察骨折愈合的情况,并采用显微计算机断层扫描和生物力学测试评估骨痂生成的情况及其力学属性。结果 X线随访显示,振动组的骨折愈合速度和愈合率均优于对照组。前者新生矿化骨痂的体积在治疗后第2周和第4周时均显著高于后者。第8周时,振动组成熟骨痂的体积以及整体的力学强度均显著优于对照组。结论高频率低能量振动力学刺激可促进骨质疏松性骨折的愈合。     

仙灵骨葆胶囊联合阿仑膦酸钠对骨质疏松骨折大鼠骨痂血管形成的影响

目的探讨仙灵骨葆胶囊联合阿仑膦酸钠对骨质疏松性骨折大鼠骨痂血管形成及VEGF、BMP-2表达的影响。方法50只雌性SD大鼠随机分为假手术组(SHAM组)、模型组(MODEL组)、仙灵骨葆组(XLGB组)、阿仑膦酸钠组(ALLSN组)、联合药物组(LHYW组),10只/组,构建骨质疏松性骨折大鼠模型,放射性X线观察评估骨折愈合,双能X线检测骨密度,Mirco-CT检测骨结构形态学参数,番红O固绿染色观察骨痂组织形态学,免疫组化检测骨痂VEGF和BMP-2蛋白表达。结果所有实验大鼠均进入结果分析。与SHAM组比较,MODEL组大鼠骨折愈合评分、骨密度、骨组织形态学参数、骨痂VEGF和BMP-2表达均显著降低(P0.05),与MODEL组比较,XLGB组、ALLSN组和LHYY组骨折愈合评分、骨密度、骨组织形态学参数、骨痂VEGF和BMP-2表达均显著升高(P0.05),尤以LHYY组最高。SHAM组骨小梁结构正常,几乎均为骨性骨痂。MODEL组骨小梁明显稀疏、断裂,未见明显骨性骨痂。XLGB组和ALLSN组骨小梁增多,排列稍紊乱,大部分为骨性骨痂。LHYW组骨小梁明显增多,排列密集整齐,大量骨性骨痂。结论仙灵骨葆胶囊联合阿仑膦酸钠可能通过介导提高骨质疏松性骨折大鼠骨生长因子VEGF和BMP-2表达,促进骨痂血管形成,加速骨痂形成,增加骨密度,改善骨结构形态,促进骨折愈合。     

ERK5在小鼠骨质疏松性骨折愈合过程中作用的实验研究

目的通过构建小鼠骨质疏松骨折模型,研究ERK5在骨质疏松性骨折愈合过程中的作用。方法将108只6周龄雌性昆明小鼠随机分成4组,通过手术切除小鼠双侧卵巢及小鼠股骨离断分别构建骨质疏松(OVX)和骨折模型(Fracture),然后给实验组小鼠每日腹腔注射ERK5特异性阻断剂XMD8-92,于1 w、2 w、4 w后分别处死一定数量的小鼠,取术侧股骨标本,行X线片检查、股骨骨痂Micro-CT、HE染色及免疫组织化学染色检查,观察骨折端骨小梁生长情况,骨痂内成骨相关蛋白及ERK5表达情况。结果给予实验小鼠注射XMD8-92后第2周及第4周,Fracture组小鼠骨痂生长较快,骨小梁数目较多,厚度较大,成骨相关蛋白ALP、Runx2的表达相对较多(P0.05),而Fracture+XMD8-92组小鼠骨痂生长则相对缓慢,骨小梁稀少且绯薄,结构相对较乱,碱性磷酸酶(alkaline phosphatase,ALP)、Runx2表达较少(P0.05);且OVX+Fracture+XMD8-92组小鼠与OVX+Fracture组小鼠相比,骨小梁生成更少且紊乱,骨痂生长明显延迟,ALP、Runx2表达量显著减少(P0.05)。结论 ERK5影响骨折端骨痂形成的速度和质量,在促进骨质疏松性骨折愈合过程中起着十分重要的生理作用。     

The fate of soft callus chondrocytes during long bone fracture repair.

Following fracture, the cartilaginous tissue of the soft callus is eventually replaced by bone. Removal of the cartilage is a critical part of the bone healing process but information concerning the changes in chondrocytes during this process is sparse. The aim of the study was to investigate the fate of chondrocytes in the soft callus during the bone repair process using a rabbit tibial fracture model. Fracture tissue was processed for collagen I-III and keratan sulphate immunohistochemistry to study changes in matrix composition and the TUNEL technique (terminal deoxynucleotidyl transferase medicated dUTP nick-end labelling) to identify death of soft callus chondrocytes. Transmission electron microscopy (TEM) was also carried out to investigate the ultrastructure of chondrocytes within the soft callus. Results showed that the size of the cartilage area decreased over time and that cartilage matrix was replaced with new matrix rich in collagen I and III. Chondrocytes became engulfed in the new matrix and appeared to stop producing cartilage matrix. Chondrocyte cell death was seen at the border of the soft callus, just within the newly produced matrix. TEM revealed that these dying/dead cells were not typically apoptotic in appearance. In conclusion, results indicate that chondrocytes of the soft callus die as a result of the progressive production of bone matrix which eventually engulfs them and leads to the remodelling of the area and eventual bone repair.     

Bax deficiency in mice increases cartilage production during fracture repair through a mechanism involving increased chondrocyte proliferation without changes in apoptosis

This study sought to determine the role of the pro-apoptotic gene, Bax, in fracture healing by comparing femoral fracture healing in Bax knockout (KO) and wild-type C57BL/6J (background strain) mice. Bax KO fractures were larger, had more bone mineral content, had approximately 2-fold larger cartilage area per callus area in the first and second weeks of fracture healing, and showed an increased osteoclast surface area in the third and fourth weeks of fracture healing compared to C57BL/6J fractures. The increased cartilage area in the Bax KO fracture callus was due to increases in number of both pre-hypertropic and hypertropic chondrocytes. TUNEL analysis showed no significant differences in the number of either chondrocyte or non-chondrocyte apoptotic cells between Bax KO and C57BL/6J fractures at 7 or 14 days post-fracture, indicating that the increased number of chondrocytes in Bax KO fractures was not due to reduced apoptosis. Analysis of expression of apoptotic genes revealed that although the expression levels of Bcl-2 and Bcl-xL were not different between the Bax KO and C57BL/6J mice at 7 or 14 days post-fracture, the expression of BH3-domain only Bak and "Bik-like" pro-apoptotic gene increased approximately 1.5-fold and approximately 2-fold, respectively, in Bax KO fractures at 7 and 14 days post-fracture, compared to C57BL/6J fractures, suggesting that up-regulation of the Bak and Bik-like pro-apoptotic genes in Bax KO mice might compensate for the lack of Bax functions in the context of apoptosis. Analysis by in vivo incorporation of bromodeoxyuridine into chondrocytes within the fracture tissues indicated a highly significant increase in chondrocyte proliferation in Bax KO fractures compared to C57BL/6J fractures at day 7. The increased expression of collagen 2alpha1 and 9alpha1 gene in Bax KO fractures during early healing was consistent with an increased chondrocyte proliferation. In conclusion, this study demonstrates for the first time that Bax has an important role in the early stage of fracture healing, and that the increased callus size and cartilage area in Bax KO fractures was due to increased chondrocyte proliferation and not to reduced apoptosis or increased chondrocyte hypertrophy. The unexpected effect of Bax deficiency on chondrocyte proliferation implicates a novel regulatory function for Bax on chondrocyte proliferation during fracture repair.     

Effects of low-dose, intermittent treatment with recombinant human parathyroid hormone (1-34) on chondrogenesis in a model of experimental fracture healing

Recent studies have demonstrated that intermittent administration of parathyroid hormone (PTH) enhances osteogenesis (hard callus formation) and increases mechanical strength in experimental fracture healing. Thus far, however, effects of PTH on chondrogenesis (soft callus formation) during fracture healing have not been fully elucidated. In the present study, we analyzed the underlying molecular mechanism by which exogenous PTH would affect chondrogenesis in a model of experimental fracture healing. Unilateral femoral fractures were produced in 2-month-old Sprague-Dawley rats. Daily subcutaneous injections of 10 microg/kg of recombinant human PTH(1-34) [rhPTH(1-34)] were administered over a 28-day period of fracture healing. Control animals were injected with vehicle solution (normal saline) alone. The results showed that, on day 14 after fracture, cartilage area in the PTH-treated group was significantly increased (1.4-fold) compared with the controls, but this increase was not observed at days 21 and 28. In the early stage of chondrogenesis (days 4-7), cell proliferation, expressed as the rate of proliferating cell nuclear antigen-positive cells, was increased in mesenchymal (chondroprogenitor) cells but not chondrocytes in the PTH-treated group compared with controls. In addition, gene expression of SOX-9 was up-regulated in the PTH-treated group on day 4 (1.4-fold), and this was accompanied by enhanced expression of pro-alpha1 (II) collagen (1.8-fold). After 14 days, there were no significant differences between groups in either cell proliferation or the expression levels of cartilage differentiation-related genes (SOX-9, pro-alpha1 (II) collagen, pro-alpha1 (X) collagen and osteopontin). These results suggest that intermittent treatment with low-dose rhPTH(1-34) induces a larger cartilaginous callus but does not delay chondrocyte differentiation during fracture healing.