前交叉韧带切断对卵巢切除大鼠股骨骨折愈合的影响

目的观察前交叉韧带切断(OA动物模型)对双侧卵巢切除大鼠(OVX绝经后骨质疏松模型)股骨骨折愈合的影响。方法12周龄SD大鼠共70只，分成基础对照组(Basal)、假手术组(Sham)、双侧卵巢切除术组(OVX)、卵巢切除 前交叉韧带切断术组(OVX OA)、假手术 骨折组(Sham F)、卵巢切除术 骨折组(OVX F)、卵巢切除 前交叉韧带切断 骨折组(OA OVX F)，每组10只大鼠。所有受试大鼠在处死前第10d天和第4d天分别皮下注射盐酸四环素和钙黄绿素行双荧光标记。基础对照组在实验开始时杀死，其余6组在术后6W杀死，取大鼠右侧股骨标本。然后，分别进行CR摄片、组织形态学染色，以及应用Norland-XR36双能X线骨密度仪(DXA)测量右股骨远段骨密度和中段骨密度，并将股骨远段及骨折段骨痂进行硬组织包埋、切片，作骨组织形态计量学测量。结果①OVX OA组与OVX组比较，股骨远段。BMD和BWTV显著增加；②OVX F组与Sham F组比较，骨痂(股骨中段)BMD和BV／TV显著降低：③OVX OA F组与OVX F组比较，骨痂(股骨中段)BMD利BV／TV无统计学差异。结论①骨质疏松不仅延缓骨折愈合过程，而且降低骨折愈合质量；②在此动物模型中，骨性关节炎延缓股骨骨质疏松的发生，但是，对骨质疏松性骨折的愈合没有确切的促进作用。     

麝香乌龙丸对卵巢切除大鼠股骨骨折愈合的实验研究

目的研究麝香乌龙丸对卵巢切除大鼠股骨干骨折愈合的作用。方法将30只雌性、12周龄Sprague-Dawley大鼠分成3组假手术组(Sham F V)、卵巢切除 骨折 生理盐水对照组(OVX F V)、卵巢切除 骨折 麝香乌龙丸给药组(OVX F M),每组10只大鼠。所有需制造骨折的大鼠均采用右股骨中段横行骨折,髓内针固定;麝香乌龙丸给药组采用大鼠灌胃给药(1.2g.kg-1.d-1),于术后4周杀死,取大鼠右侧股骨标本;分别进行CR摄片、组织形态学染色,并应用双能X线骨密度仪(DEXA)测量右股骨整体骨密度(tBMD)、远段骨密度(dBMD)和中段骨密度(mBMD)以及BMP-2免疫组化观察,并应用病理图像分析仪对BMP-2免疫组化进行光密度测定。结果麝香乌龙丸给药组与OVX F V比较,前者骨痂mBMD和BMP-2的表达显著增高,骨小梁增宽、排列较整齐,板层骨形成,软骨组织可见。结论麝香乌龙丸对OVX大鼠股骨骨折有明显促进骨折愈合的作用,并加快编织骨向板层骨的演变过程,这与BMP-2的表达有明显相关性。     

雷洛昔芬对OVX大鼠骨质疏松性骨折愈合的影响

目的 探讨骨质疏松性骨折愈合的特点以及雷诺昔芬对骨质疏松性骨折愈合的影响.方法 健康12 周龄雌性SD大鼠54只,随机分成假手术组(SHAM),卵巢切除+生理盐水组(OVX),卵巢切除+雷诺昔芬组(OVX+RAL),每组18只大鼠.卵巢切除术后8周,骨密度检测确认大鼠骨质疏松模型成功.选择开放性右侧股骨中段骨折模型,以克氏针行髓内固定股骨;骨折后8周,CR片记录大鼠骨痂的连续性以及骨折愈合情况,三点弯曲试验检测股骨的最大弯曲应力和最大弯曲载荷.取骨折术后4周和8周时骨痂,行HE染色,并记录骨小梁或小梁状骨所占体积比(BV/TV)表示.免疫组化染色检测骨痂中血管内皮生长因子(VEGF)表达.结果 CR摄片显示骨折后8周各组大鼠骨折连续性都较好,骨折对位对线好.大鼠骨折8周时最大弯曲应力和最大弯曲载荷,SHAM组和OVX+RAL组都明显优于OVX组,差异显著,有统计学意义.骨折4周时骨痂的HE染色中,OVX组原始小梁状骨中新生软骨细胞较多.OVX+RAL组和SHAM组8周时骨痂中BV/TV值明显高于OVX组.骨折4周时骨痂VEGF染色中,各组大鼠的骨痂内软骨细胞或骨细胞上存在一定量的VEGF表达,SHAM组和OVX+RAL组的细胞上VEGF表达量略高于OVX组;骨折8周时各组骨痂中的VEGF几乎无明显表达.结论 OVX大鼠骨痂成熟缓慢和早期骨痂内VEGF低表达,可能是骨折愈合能力下降的重要因素.雷诺昔芬可以促进骨痂成熟和早期骨痂中VEGF的表达,有利于OVX大鼠骨折愈合.     

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.     

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。     

骨硬化蛋白单克隆抗体对于有去卵巢大鼠骨折愈合影响的实验研究

目的探索骨硬化蛋白单克隆抗体(Scl-Ab)对去势大鼠股骨干骨折愈合影响的实验研究。方法 30只健康雌性SD大鼠随机行假手术(Sham,n=5)和切除双侧卵巢(OVX,n=25)手术12w后每组各取5只大鼠处死取股骨行双能X线仪检测确保骨质疏松的建立,随后OVX组大鼠建立左侧股骨干中段骨折模型随机的分成2组:OVX组及骨硬化蛋白单克隆抗体治疗(Scl-Ab)组。术后第1天Scl-Ab组开始给予药物治疗:Scl-Ab皮下注射(剂量25 mg/kg,每周2次)直至8 w,8 w时所有大鼠处死取股骨行Micro-CT、硬组织切片检测及HE组织切片检测。结果 Micro-CT结果显示:Scl-Ab组和OVX组相比,骨折端有较多的新生骨形成,且有较高BV/TV、Tb.Th、Tb.N和较低的Tb.Sp值,比较有明显的统计学意义。HE结果表明Scl-Ab组骨折端有更多的骨痂形成,且骨痂更加成熟。硬组织切片观察结果表明:Scl-Ab组骨折端骨痂矿化速度更快,和OVX组表明有统计学意义。结论 Scl-Ab通过增加骨折端骨量及促进骨组织矿化来治疗去卵巢大鼠股骨中段骨折的愈合。     

仙灵骨葆胶囊对骨质疏松性骨折大鼠骨生长因子及骨折愈合的影响

目的 探讨仙灵骨葆胶囊对骨质疏松性骨折大鼠骨生长因子BMP-2、IGF-1表达及骨折愈合的影响。方法 48只雌性SD大鼠随机分为：假手术组、模型组、雌二醇组、仙灵骨葆组，12只/组，采用“双侧卵巢切除术+右侧股骨干骨折髓内固定术”构建骨质疏松性骨折大鼠模型，评估骨折愈合情况，检测股骨骨痂BMD、股骨骨生物力学指标和血清骨代谢相关指标，检测骨痂BMP-2、IGF-1蛋白表达。结果 模型组较假手术组骨折愈合评分、股骨痂BMD、股骨骨生物力学指标（最大载荷、最大应力、最大位移）、骨痂BMP-2和IGF-I阳性表达均显著降低（P<0.05），雌二醇组、仙灵骨葆组较模型组骨折愈合评分、股骨痂BMD、股骨骨生物力学指标、骨痂BMP-2和IGF-I阳性表达均显著升高（P<0.05），均以仙灵骨葆组最高。模型组较假手术组血清骨代谢指标（BGP、PICP、TRACP-5b）均显著升高（P<0.05），雌二醇组、仙灵骨葆组较模型组血清骨代谢指标均显著降低（P<0.05），以仙灵骨葆组最低。结论 仙灵骨葆胶囊可能通过介导提高骨质疏松性骨折大鼠骨生长因子BMP-2和IGF-1表达，改善骨代谢，加速骨痂形成，增加骨密度，提高骨生物力学，促进骨折愈合。     

维生素K2对去卵巢大鼠股骨干骨折愈合影响的实验研究

目的探讨维生素K2能否促进卵巢切除骨质疏松(OVX)大鼠骨折愈合。方法将30只雌性大鼠随机分为3组(每组10只):假手术组(SHAM)、去卵巢组(OVX)、OVX+维生素K2组。大鼠卵巢切除术后3个月,在右侧股骨干制作单侧股骨干骨折。然后在通过维生素K2治疗8周后处死动物,行X线片检测;对骨折的股骨进行生物力学检测并观察血清骨钙素(BGLAP)、碱性磷酸酶(ALP)、抗酒石酸酸性磷酸酶(TRACP)和雌二醇水平的变化。结果与OVX组相比,OVX+维生素K2组观察到更多骨痂组织形成和更好的骨愈合,并且BGLAP、ALP和TRACP水平降低,但是血液雌二醇水平没有观察到显著增加。与OVX组相比,OVX+维生素K2组显示出骨强度、最大负荷和弹性显著增加。结论维生素K2具有作为绝经后骨质疏松症骨折愈合新型替代治疗剂的潜力。     

降钙素对卵巢切除大鼠股骨骨折愈合的影响

目的观察降钙素对卵巢切除大鼠股骨骨折愈合的作用，为临床上治疗骨质疏松性骨折提供实验依据。方法50只雌性、14周龄SD大鼠共分成5组，每组10只。分成假手术组（Sham，G1），双侧卵巢切除术组（OVX，G2），假手术＋骨折组（Sham＋F，G3），卵巢切除术＋骨折组（OVX＋F，G4），卵巢切除＋骨折＋降钙素药物组（OVX＋F＋CT，G5），骨折组大鼠均采用右股骨中段横行骨折，髓内针固定；降钙素采用皮下给药，隔日1次（16IU·kg^-1）。所有大鼠于术后4周杀死，取右侧股骨标本。然后，分别进行CR摄片、组织形态学观察，并应用双能X线骨密度仪（DEXA）测量右股骨整体、远段和中段骨密度以及BMP-2免疫组化观察，并应用病理图像分析仪对BMP-2免疫组化进行光密度测量。结果（1）OVX组与Sham组比较，BMD显著下降。（2）OVX＋F＋CT组与OVX＋F组比较：骨痂mBMD显著增高；BMP-2的表达无显著性差异。结论降钙素对OVX大鼠股骨骨折具有明显促进骨折愈合的作用，加速编织骨向板层骨的演变过程。     

Micro-CT动态观察骨质疏松骨折的愈合

目的通过Micro-CT探讨骨质疏松大鼠股骨干骨折愈合过程中骨痂的体积、骨矿物密度、骨 小梁结构等的动态变化规律。方法将清洁级4月龄雌性Wistar大鼠40只,体重300 g±20g,行双 侧卵巢切除术（OVX),3个月后形成骨质疏松模型。进行股骨干中段骨折造模,髓内钉固定。骨折固 定术后,分别于术后4周,6周,8周,12周进行骨折端显微CT观察,并进行骨结构和骨矿物密度 (BMD)的定量分析。术后12周取材进行组织学观察。结果骨质疏松大鼠骨折后8周骨折区骨痂 总体积（Total Volume,TV)、骨痂中高矿化组织出现下降趋势,但无统计学差异。骨组织占骨痂总体 积的比率（Bone Volume Fraction,BVF)随时间点有明显上升趋势,且12周后显著大于4周。骨痂中 总体矿物密度（Bone Mineral Density, BMD),12周明显高于4周。矿化组织自身的密度（Tissue Mineral Density,TMD) ,12周高于4周,8周于6周比较,均有显著性差异。骨小梁厚度（Tb. Th)和骨 小梁间隙（Tb.SP) ,12周与4周、6周比较均有显著性差异,且Tb. SP在12周出现下降,12周时改建 塑型基本完成。组织学观察显示,术后12周,骨折断端板层骨改建形成骨小梁,恢复骨结构的完整 性。结论对于骨质疏松骨折大鼠早期,Micro-CT分析显示骨痂数量因损伤而增加,但软骨性骨痂至 骨痂演变过程较慢。骨折后期,矿化诱导新骨生成,且骨折大鼠在12周基本完成矿化,从而促进骨折 修复D     

Early period of fracture healing in ovariectomized rats

Objective. To evaluate the effect of osteoporosis on fracture healing through observing the hlstomorphological changes, bone mineral density of callus and expression and distribution of transforming growth factor beta 1 (TGF-β1 ), basic fibroblast growth factor (bFGF)and bone morphogenetic protein.2 (BMP-2) in ovariectomized rats. Methods. Sixty female Sprague-Dawley rats ( aged 12 weeks and weighing 235 g on average ) were randomly divided into an ovariectomized (OVX) group (n =30) anda sham-operated (SO) group ( n = 30). Ovariectomy was performed in the OVX rats and same incision was made in the SO rats. Three months later, fracture of femoral shaft was made on all the rats. Then they were killed at different time points. Callus formation was observed with histological and imethods. Results: A reduction in callus and bone mineral density in the healing femur and a decrease of osteoblasts expressing TGF-β1 near the bone trabecula were observed in the OVX rats 3-4 weeks after fracture.Histomorphological analysis revealed a higher content of soft callus in the OVX rats than that in the SO rats.Immunohistochemistry results showed that no remarkable difference in expression and distribution of BMP-2 and bFGF between the OVX and SO groups was found. Conclusions: Osteoporosis influences the quantity and quality of callus during the early period of fracture healing. The effect of osteoporosis on fracture healing has no relationship with the expression of BMP-2 or bFGF. The decreased expression of TGF-I31 in osteoblasts may cause a decrease in quality of facture healing after osteoporosis.     

Strontium Ranelate Enhances Callus Strength More Than PTH 1-34 in an Osteoporotic Rat Model of Fracture Healing

Treatment of an underlying disease is often initiated after the occurrence of an osteoporotic fracture. Our aim was to investigate whether teriparatide (PTH 1-34) and strontium ranelate affect fracture healing in ovariectomized (OVX) rats when provided for the first time after the occurrence of an osteoporotic fracture. We combined the model of an OVX rat with a closed diaphyseal fracture. Sixty Sprague Dawley rats were randomly assigned to four groups. Fracture healing in OVX rats after treatment with pharmacological doses of strontium ranelate and PTH 1-34 was compared with OVX and sham-treated control groups. After 28 days, the femur was excised and scanned by micro computed tomography and the callus evaluated, after which biomechanical torsional testing was performed and torque and toughness until reaching the yield point were analyzed. Only treatment with strontium ranelate led to a significant increase in callus resistance compared to the OVX control rats, whereas both PTH 1-34 and strontium ranelate increased the bone volume/tissue volume ratio of the callus. The PTH 1-34–increased trabecular bone volume within the callus was even higher compared to sham. As for the callus tissue volume, the increase induced by strontium ranelate was significant, contrary to the changes induced by PTH. Callus in strontium ranelate–treated animals is more resistant to torsion compared with OVX control rats. To our knowledge, this is the first report of the enhancement of fracture healing by strontium ranelate. Because both treatments enhance bone and tissue volume within the callus, there may be a qualitative difference between the calluses of PTH 1-34– and strontium ranelate–treated OVX rats. The superior results obtained with strontium ranelate compared to PTH in terms of callus resistance could be the consequence of a better quality of the new bone formed within the callus.     

Experimental osteoporosis induced by ovariectomy and vitamin D deficiency does not markedly affect fracture healing in rats

BACKGROUND: The question of whether fracture healing and mechanical properties of the callus are influenced by osteoporosis (OP) is still not settled. We therefore studied this issue in vitamin D-depleted ovariectomized (OVX) rats, an OP model previously shown to induce weakening of the femoral neck, and thus thought to be closer to the human condition than the classic OVX rat model. METHODS: 72 female Wistar rats were randomized into two groups: ovariectomy and vitamin D-deficient diet (Ovx-D group) or sham operation and normal rat chow (Sham group). After 12 weeks, a closed tibial midshaft fracture was performed on the right side and fixed with an intramedullary nail. Bone loss and callus formation were monitored with DXA; serum levels of estradiol and vitamin D3 were measured and histomorphometric analyses were performed. Mechanical properties of callus, tibia, femoral shaft, and femoral neck were examined in 3-point cantilever bending 6 weeks after fracture. RESULTS: The Ovx-D group showed reduced BMD in the spine and femoral neck, and reduced trabecular bone volume in the femoral head. There were no differences in BMD and mechanical properties of callus between the groups. Except for reduced stiffness of the right femoral neck in the Ovx-D group (p = 0.02), no differences in the mechanical strength of long bones were detected. INTERPRETATION: Our results suggest that the systemic effects of estrogen and vitamin D deficiency are not crucial for fracture healing or mechanical properties of the callus.     

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.     

Effect of weight manipulation on bone loss due to ovariectomy and the protective effects of estrogen in the rat

Summary While characterizing the effects of estrogen on an ovariectomized (OVX) rat model of bone loss, we examined several weight-matching regimens e.g.,ad libitum (feed bins continually full), weight matched (rate of weight gain for OVX and Sham-OVX groups was equalized), and weight restricted (weight gain rates for all groups were equalized to that of estrogen-treated OVX rats) for possible effects. Bone loss following ovariectomy is primarily the result of an increase in bone resorption and is extremely sensitive to the effects of estrogens. Thus, in all of our analyses, treatment with 170-estradiol served as a positive control for the prevention of bone loss. Each weight-matching study had three groups: control (Sham-OVX), OVX, and OVX + 170 estradiol (0.1 mg/kg/day), and lasted for either 2, 4, or 6 weeks. Throughout the study, each Sprague Dawley rat was weighed every other day, and following sacrifice, a femur was removed for bone mineral density (BMD) analysis at the distal metaphysis by single photon absorptiometry. Following 2 weeks of dietary modifications, no significant differences were detected in BMD among thead lib or weight matched groups. However, an estradiol-preventable reduction in BMD in restricted OVX rats was detected at 2 weeks postovariectomy. Additionally, OVX rats in all three dietary regimens displayed an estrogen-preventable reduction in proximal femur BMD at 4 and 6 weeks postovariectomy. These results indicate that a 4-week rat ovariectomized model of bone loss, under conditions of ad libitum feeding, shows great potential for pharmacologic manipulation.     

Role of dual energy X-ray absorptiometry in monitoring fracture healing in a rat femoral fracture model

Earlymobilizationandweightbearingplayimportantrolesinminimizingtheamountofbonelosstoachievegoodhealingafterbonefracture.1Areliableandnoninvasivemethodforevaluatingfracturehealingcannotonlyhelpdecidewhentostarweightbearing, butalsohelpdetecttheimpairedboneunionearlytopreventdelayedunionsornonunions.However, objectivequantitativemethodsforearlyevaluationoffracturehealinghavenotbeendevelopedyet. DualenergyX rayabsorptiometry(DEXA)isoneofthemostaccuratemethodsformeasuringbonemassinvivo. Itismain…     

密骨方对去卵巢大鼠骨折的影响

目的 采用卵巢切除法建立原发性骨质疏松及骨折动物模型,观察中药密骨方对去势大鼠骨痂组织的影响.方法 将90只雌性Wistar大鼠随机分为对照组(sham),模型组(OVX)与密骨方治疗组(MGF),模型组及治疗组行卵巢摘除术,同时3组大鼠均致其右侧股骨上1/3处骨折.MGF组按每日100mg/kg体重的剂量灌胃给药,Sham组和OVX组给予同体积的生理盐水,每日1次,疗程分别为2、4、6周,用SABC免疫组织化学方法检测骨折端转化生长因子(TGF-β1)的表达.结果 在骨折端MGF组软骨细胞的阳性表达率较高;TGF-β1的表达在时间的变化上呈显著升高趋势;第4、6周TGF-β1表达显著高于OVX组和Sham组.结论 密骨方对骨质疏松性骨折的愈合有一定的促进作用.     

Age and ovariectomy impair both the normalization of mechanical properties and the accretion of mineral by the fracture callus in rats.

The impact of age and ovariectomy on the healing of femoral fractures was studied in three groups of female rats at 8, 32 and 50 weeks of age at fracture. In the two older groups, the rats had been subjected to ovariectomy or sham surgery at random at 26 weeks of age. At fracture, all rats received unilateral intramedullary pinning of one femur and a middiaphyseal fracture. Rigidity and breaking load of the femora were evaluated at varying times up to 24 weeks after fracture induction by three-point bending to failure. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry. In the youngest group, 8-week-old female rats regained normal femoral rigidity and breaking load by 4 weeks after fracture. They exceeded normal contralateral values by 8 weeks after fracture. In the middle group, at 32 weeks of age, fractures were induced, and the femora were harvested at 6 and 12 weeks after fracture. At 6 weeks after fracture there was partial restoration of rigidity and breaking load. At 12 weeks after fracture, only the sham-operated rats had regained normal biomechanical values in their fractured femora, while the fractured femora of the ovariectomized rats remained significantly lower in both rigidity and breaking load. In contrast, for the oldest group of rats, 50 weeks old at fracture, neither sham-operated nor ovariectomized rats regained normal rigidity or breaking load in their fractured femora within the 24 weeks in which they were studied. In all fractured bones, there was a significant increase in BMD over the contralateral intact femora due to the increased bone tissue and bone mineral in the fracture callus. Ovariectomy significantly reduced the BMD of the intact femora and also reduced the gain in BMD by the fractured femora. In conclusion, age and ovariectomy significantly impair the process of fracture healing in female rats as judged by measurements of rigidity and breaking load in three-point bending and by accretion of mineral into the fracture callus.     

中等强度跑台运动对去卵巢大鼠后肢骨骨矿物含量和骨密度的双重调节作用

目的 观察中等强度跑台运动对去卵巢大鼠后肢骨骨矿物含量(BMC)和骨密度(BMD)的影响.方法 将60只3月龄未经产雌性SD大鼠按体重随机分为假手术、去卵巢静止、去卵巢运动Ⅰ、去卵巢运动Ⅱ、去卵巢运动Ⅲ和去卵巢运动Ⅳ 6个组.各运动组经1周的跑台适应训练后,按实验设计分别进行为期14周的正式跑台训练.实验结束时,腹主动脉取血处死大鼠,双能χ-射线骨密度仪检测右侧游离股骨和胫骨的BMC和BMD.结果 ①与假手术组相比,去卵巢静止组股骨近端和远端以及胫骨近端BMC和BMD显著下降,但股骨中段以及胫骨中段和远端BMC和BMD无显著变化.②与去卵巢静止组相比,去卵巢运动Ⅰ组股骨近端和远端BMC显著增加,股骨中段以及胫骨3个部位BMC均无显著变化;去卵巢运动Ⅱ组和Ⅲ组股骨和胫骨3个部位BMC 均无显著变化;去卵巢运动Ⅳ组股骨3个部位BMC均无显著变化,而胫骨3个部位BMC均显著下降.③与去卵巢静止组相比,去卵巢运动Ⅰ组股骨近端和远端以及胫骨近端BMD 显著增加, 而股骨中段和胫骨中段和远端BMD无显著变化;去卵巢运动Ⅱ组和Ⅲ组股骨和胫骨任何部位BMD均没有显著变化;去卵巢运动Ⅳ组股骨3个部位BMD无显著变化,而胫骨3个部位BMD却显著下降.结论 较低中等强度跑台运动能减缓去卵巢大鼠股骨近端和远端骨矿物含量和骨密度的下降;而较高中等强度跑台运动却能加速去卵巢大鼠胫骨近端骨矿物含量和骨密度的下降.