Comparison between Different Methods for Biomechanical Assessment of Ex Vivo Fracture Callus Stiffness in Small Animal Bone Healing Studies

For ex vivo measurements of fracture callus stiffness in small animals, different test methods, such as torsion or bending tests, are established. Each method provides advantages and disadvantages, and it is still debated which of those is most sensitive to experimental conditions (i.e. specimen alignment, directional dependency, asymmetric behavior). The aim of this study was to experimentally compare six different testing methods regarding their robustness against experimental errors. Therefore, standardized specimens were created by selective laser sintering (SLS), mimicking size, directional behavior, and embedding variations of respective rat long bone specimens. For the latter, five different geometries were created which show shifted or tilted specimen alignments. The mechanical tests included three-point bending, four-point bending, cantilever bending, axial compression, constrained torsion, and unconstrained torsion. All three different bending tests showed the same principal behavior. They were highly dependent on the rotational direction of the maximum fracture callus expansion relative to the loading direction (creating experimental errors of more than 60%), however small angular deviations (<15°) were negligible. Differences in the experimental results between the bending tests originate in their respective location of maximal bending moment induction. Compared to four-point bending, three-point bending is easier to apply on small rat and mouse bones under realistic testing conditions and yields robust measurements, provided low variation of the callus shape among the tested specimens. Axial compressive testing was highly sensitive to embedding variations, and therefore cannot be recommended. Although it is experimentally difficult to realize, unconstrained torsion testing was found to be the most robust method, since it was independent of both rotational alignment and embedding uncertainties. Constrained torsional testing showed small errors (up to 16.8%, compared to corresponding alignment under unconstrained torsion) due to a parallel offset between the specimens’ axis of gravity and the torsional axis of rotation.     

Prediction of the Time Course of Callus Stiffness as a Function of Mechanical Parameters in Experimental Rat Fracture Healing Studies - A Numerical Study

Numerous experimental fracture healing studies are performed on rats, in which different experimental, mechanical parameters are applied, thereby prohibiting direct comparison between each other. Numerical fracture healing simulation models are able to predict courses of fracture healing and offer support for pre-planning animal experiments and for post-hoc comparison between outcomes of different in vivo studies. The aims of this study are to adapt a pre-existing fracture healing simulation algorithm for sheep and humans to the rat, to corroborate it using the data of numerous different rat experiments, and to provide healing predictions for future rat experiments. First, material properties of different tissue types involved were adjusted by comparing experimentally measured callus stiffness to respective simulated values obtained in three finite element (FE) models. This yielded values for Young’s moduli of cortical bone, woven bone, cartilage, and connective tissue of 15,750 MPa, 1,000 MPa, 5 MPa, and 1 MPa, respectively. Next, thresholds in the underlying mechanoregulatory tissue differentiation rules were calibrated by modifying model parameters so that predicted fracture callus stiffness matched experimental data from a study that used rigid and flexible fixators. This resulted in strain thresholds at higher magnitudes than in models for sheep and humans. The resulting numerical model was then used to simulate numerous fracture healing scenarios from literature, showing a considerable mismatch in only 6 of 21 cases. Based on this corroborated model, a fit curve function was derived which predicts the increase of callus stiffness dependent on bodyweight, fixation stiffness, and fracture gap size. By mathematically predicting the time course of the healing process prior to the animal studies, the data presented in this work provides support for planning new fracture healing experiments in rats. Furthermore, it allows one to transfer and compare new in vivo findings to previously performed studies with differing mechanical parameters.     

应力叩击仪促进胫骨骨折外固定架术后骨折愈合的临床观察

目的:探讨应力叩击仪促进胫骨骨折外固定架术后骨折愈合的临床价值。方法:选取132例胫骨骨折患者为研究对象,随机抽样法分成研究组和对照组两组,各66例。对照组采用术后常规干预方案,研究组予以术后应力叩击仪叩击治疗方案。比对两组患者的骨不愈合率、骨延迟愈合率、骨折愈合时间、完全负重时间、骨折6个月时Lane-Sandhu X线评分及Johner-wruh评估情况。结果:1研究组骨不愈合率及骨延迟愈合率分别为4.5%和7.6%,均显著低于对照组的19.7%和22.7%(P0.05);2研究组骨折愈合时间及完全负重时间分别为(82.6±9.2)d和(101.5±10.5)d,均显著短于对照组的(105.9±10.3)d和(122.4±10.3)d,(P0.05);对照组骨折6个月时Lane-Sandhu X线评分为(2.2±0.5)分,显著低于研究组的(3.0±0.5)分,(P0.05);3研究组骨折6个月时Johner-wruh优良率为90.1%,显著高于对照组的75.8%(P0.05)。结论:应力叩击仪应用于胫骨骨折患者外固定架手术后的康复治疗中,可有效缩短骨折愈合时间、提高骨折愈合率,对加快骨痂生长速度、促进病情转归有利。     

Callus Formation and Mineralization after Fracture with Different Fixation Techniques: Minimally Invasive Plate Osteosynthesis versus Open Reduction Internal Fixation

Minimally invasive plate osteosynthesis(MIPO) has been considered as an alternative for fracture treatment. Previous study has demonstrated that MIPO technique has the advantage of less soft tissue injury compared with open reduction internal fixation (ORIF). However, the comparison of callus formation and mineralization between two plate osteosynthesis methods remains unknown. In this experiment, ulna fracture model was established in 42 beagle dogs. The fractures underwent reduction and internal fixation with MIPO or ORIF. Sequential fluorescent labeling and radiographs were applied to determine new callus formation and mineralization in two groups after operation. At 4, 8 and 12 weeks postoperatively, the animals were selected to be sacrificed and the ulna specimens were analyzed by Micro-CT. The sections were also treated with Masson staining for histological evaluation. More callus formation was observed in MIPO group in early stage of fracture healing. The fracture union rate has no significant difference between two groups. The results indicate that excessive soft tissue stripping may impact early callus formation. As MIPO technique can effectively reduce soft tissue injury with little incision, it is considered to be a promising alternative for fracture fixation.     

Systemic Inhibition of Canonical Notch Signaling Results in Sustained Callus Inflammation and Alters Multiple Phases of Fracture Healing

The Notch signaling pathway is an important regulator of embryological bone development, and many aspects of development are recapitulated during bone repair. We have previously reported that Notch signaling components are upregulated during bone fracture healing. However, the significance of the Notch pathway in bone regeneration has not been described. Therefore, the objective of this study was to determine the importance of Notch signaling in regulating bone fracture healing by using a temporally controlled inducible transgenic mouse model (Mx1-Cre;dnMAML^f/-) to impair RBPjκ-mediated canonical Notch signaling. The Mx1 promoter was synthetically activated resulting in temporally regulated systemic dnMAML expression just prior to creation of bilateral tibial fractures. This allowed for mice to undergo unaltered embryological and post-natal skeletal development. Results showed that systemic Notch inhibition prolonged expression of inflammatory cytokines and neutrophil cell inflammation, and reduced the proportion of cartilage formation within the callus at 10 days-post-fracture (dpf) Notch inhibition did not affect early bone formation at 10dpf, but significantly altered bone maturation and remodeling at 20dpf. Increased bone volume fraction in dnMAML fractures, which was due to a moderate decrease in callus size with no change in bone mass, coincided with increased trabecular thickness but decreased connectivity density, indicating that patterning of bone was altered. Notch inhibition decreased total osteogenic cell density, which was comprised of more osteocytes rather than osteoblasts. dnMAML also decreased osteoclast density, suggesting that osteoclast activity may also be important for altered fracture healing. It is likely that systemic Notch inhibition had both direct effects within cell types as well as indirect effects initiated by temporally upstream events in the fracture healing cascade. Surprisingly, Notch inhibition did not alter cell proliferation. In conclusion, our results demonstrate that the Notch signaling pathway is required for the proper temporal progression of events required for successful bone fracture healing.     

Yeast-Incorporated Gallium Promotes Fracture Healing by Increasing Callus Bony Area and Improving Trabecular Microstructure on Ovariectomized Osteopenic Rats

The purpose of this study was to analyze the impact of yeast-incorporated gallium on fracture healing in ovariectomized osteopenic rats. Forty Wistar female rats used were divided into three groups: sham-operated rats (SHAM), ovariectomized (OVX) rats, and ovx rats treated with yeast-bound gallium (YG). A standardized fracture-healing model with stable plate fixation was established for rat femoral. After 4-week stable fixation, animals were killed to prepare bones for Micro-CT, biomechanical testing, and histomorphometry. In addition, bone samples were obtained to evaluate the content of mineral substances in bones. Quantitative analysis of the bones from animals in the organic gallium group revealed significantly increased mineral contents compared to bones from OVX and SHAM groups. Micro-CT showed that treatment with yeast-incorporated gallium increased BV/TV and trabecular thickness and decreased trabecular separation in ovx animals. Histomorphometric evaluation demonstrated that YG increased callus area and callus bone formation. Yeast-bound gallium also improved the biomechanical properties of bone healing. In conclusion, this study suggests that yeast-incorporated gallium could promote fracture healing in ovariectomized rats.     

孝顺竹愈伤组织增殖培养基优化研究

为筛选适宜孝顺竹愈伤组织继代增殖培养基,控制褐变发生,提高再生体系效率,对培养基组成如5种基本培养基、6种有机添加物、7种糖类和5种大量元素等因子进行试验分析。结果表明：培养20 d,基本培养基以MS效果较好,愈伤组织增殖2.8倍,白至淡黄色,致密;有机添加物以1.0 g·L^-1脯氨酸效果较显著,愈伤组织增殖3.64倍,淡黄色,致密均一;碳源以30 g·L^-1麦芽糖效果较好,愈伤组织增殖2.96倍,白至淡黄色,致密。5种大量元素中NH₄NO₃对孝顺竹愈伤组织增殖的影响达到显著水平,以825 mg·L^-1为较佳浓度,培养29 d愈伤组织增殖可达5倍以上,部分出现根分化;适宜孝顺竹愈伤组织培养的大量元素组合为：KNO₃ 475 mg·L^-1+NH₄NO₃ 825 mg·L^-1+MgSO₄·7H₂O 185 mg·L^-1+KH₂PO₄ 340 mg·L^-1+CaCl₂·7H₂O 440 mg·L^-1。     

髓腔内固定联合低强度脉冲超声对兔股骨中段骨折愈合作用研究

摘要 目的：针对髓腔内固定联合低强度脉冲超声对兔股骨中段骨折愈合作用进行研究。方法：选择成年兔股骨中段骨折40只,作为本次的研究对象,将其平均分为对照组和观察组。所有兔子,在手术前禁水、禁食,对其右后肢进行备皮,称重、麻醉,对照组实施髓腔内固定治疗,观察组实施髓腔内固定联合低强度脉冲超声治疗。治疗后1、2、3、4周对兔子的骨折部位进行影像学检查确定兔子的骨折线模糊情况,并在各周采集样品进行组织学检查。治疗4周后对骨折愈合情况进行检查。结果：观察组愈合程度I级、II级、II级比例均低于对照组相应比例,差异具有统计学意义（P＜0.05）,观察组IV级、V级比例分别为35.0 %、55.0 %,均高于对照组的5.0 %、5.0 %,差异具有统计学意义（P＜0.05）;观察组兔子的在1 w、2 w、3 w、4 w骨折线模糊程度评分高于对照组相应时间评分,差异具有统计学意义（P＜0.05）。结论：在兔股骨中断骨折治疗中,实施髓腔内固定联合低强度脉冲超声,可以提高骨折的愈合速度,加速骨折修复,整体治疗效果显著,可以在临床上进行推广实施。     

髓内钉及其骨折内固定的力学研究

“Ｖ”形和梅花形髓内钉是常用的长管骨骨折髓内固定材料。目前临床上梅花形髓内钉有代替“Ｖ”形髓内钉的趋势,本文从力学角度对其进行研究包括、．髓内钉及其髓内固定骨折模型弯曲试验显示,梅花形髓内钉抗弯强度和承受载荷系数均大于“Ｖ”形髓内钉;２．抗弯截面惯性矩研究显示,新型双冠形髓机钉优于梅花形髓内钉优于“Ｖ”形髓内钉;３．髓内钉设计成双冠形截面将大大改进其力学原理。     

椎弓根系统治疗胸腰椎骨折的临床探讨

目的:探讨对椎弓根系统治疗胸腰椎骨折的临床疗效。方法:本组98例均采用后路减压、植骨及椎弓根系统内固定。结果:术中C臂及术后x摄片见植入椎弓根螺钉平行于椎体上下终板95例,3例有4°-6°的成角。伤前后突畸形平均25°,术后矫正至平均4°。术前伤椎压缩50%-75%,术后恢复至89%-95%。获随访1-3年,内固定松动2例,拔钉3例,断钉2例,椎体高度及Cobb角丢失5°-9°有6例。慢性腰痛12例。神经功能除A级有7例未恢复外,其余病例均有1-3级的恢复。结论:后路手术较完善,适应范围广,创伤小,对屈曲压缩型、骨折脱位型的整复及下腰椎的固定优于前路手术。特别强调准确的椎弓根植入技术及有效的植骨融合是保证后路手术脊柱稳定和防止远期并发症的主要手段。     

板栗愈伤组织瞬时转化体系的优化与应用

愈伤组织瞬时转化体系可初步快速地验证基因功能和鉴定相关表型。为提高板栗愈伤组织瞬时转化体系的转化效率和稳定性,并鉴定板栗淀粉合成酶基因的功能,该研究以板栗‘燕山红栗’幼胚胚芽诱导形成的愈伤组织为材料,通过不同状态的愈伤组织和表达载体优化板栗愈伤组织瞬时转化体系;并构建板栗淀粉合成关键酶基因CmSSⅠ沉默载体,验证CmSSⅠ基因在板栗中的功能。结果表明:(1)愈伤组织可按照体细胞胚起动难易程度划分为胚性愈伤组织(EC_E)和胚性愈伤组织早期阶段(EC_DⅠ、Ⅱ、Ⅲ),且白色、外表相对分散的胚性早期阶段愈伤(EC_DⅢ)更适合板栗瞬时转化体系。(2)转化材料为胚性愈伤早期阶段(EC_DⅢ)时,RNAi沉默载体pK7GWIWG2(Ⅱ)RR-277的瞬时转化效率高达87.67%。(3)通过最适愈伤组织瞬时转化体系,基因CmSSⅠ在转基因愈伤组织中表达显著下调,且沉默CmSSⅠ阳性愈伤组织的总淀粉和支链淀粉含量显著降低,直链淀粉变化差异不显著。该研究提高了板栗愈伤组织瞬时转化体系的转化效率和稳定性,证明基因CmSSⅠ正调控板栗淀粉的合成,这为板栗基因功能的研究奠定了基础,进一步为分子辅助育种提供了技术平台。     

锁骨骨折内固定失效的原因分析及对策

目的：探讨锁骨骨折切开复位内固定术后内固定失效的原因,并寻找补救方案。方法：选择我院2007年5月~2010年5月收治的184例锁骨骨折患者,其中男性123例,女性61例,年龄24~76岁,对手术切开复位内固定失败病例的内固定方法进行对比,分析内固定失效的原因,并选取记忆合金环抱器或天鹅型记忆接骨器作为再次手术的内固定器械,分析其临床疗效。结果：本组所有病例均获得6~24个月随访,所有患者首次手术均行钢板内固定治疗,其中应用重建钢板治疗48例,解剖钢板治疗86例,锁骨钩钢板治疗50例,3例术后发生钢板或螺钉断裂患者选用记忆合金环抱器重新手术内固定治疗,2例痊愈,1例记忆合金环抱器再次发生断裂,改用天鹅型记忆接骨器治疗获得痊愈。3例骨不连患者均选择天鹅型记忆接骨器配合植骨内固定治疗,术后恢复良好。结论：锁骨骨折切开复位内固定术后内固定失败的原因主要与所使用内固定技术不合理及患者早期不正确的功能锻炼有关。记忆合金环抱器和天鹅型记忆接骨器均可作为钢板内固定失败术后的补救方案,但天鹅型记忆接骨器较记忆合金环抱器可提供更好的纵向加压作用,治疗钢板断裂及骨不连患者更为可靠。     

Microstructures of External Periosteal Callus of Repaired Femoral Fracture in Children

In order to understand further the mechanism of bone fracture repair, and thus to innovate better operative treatment for bone fracture and to design new implant materials for bone repair, microstructures of external periosteal callus (EPC) of repaired femoral fracture in both children and adults were investigated by using a scanning electron microscope, transmission electron microscopy, and an X-ray microdiffractometer. The repair time after the fractures in children and adults is on average 155 and 370 days, respectively. Collagen fibrils making up children's EPC (CEPC) are underdeveloped and insufficiently mineralized by hydroxyapatite (HA), while those from adults' EPC (AEPC) are similar to normal bone. A lot of particles loaded by brushite (DCPD) minerals were found among the collagen fibrils of CEPC. The main mineral phases in CEPC consist of DCPD and HA, while only HA exists in AEPC. Deposition of DCPD minerals could have compensated for the insufficient mineralization of the collagen fibrils of CEPC, thereby making fractured bone repair more rapidly in children than in adults.     

均匀设计法优化黄芩愈伤组织培养基

目的:优化黄芩愈伤组织培养条件。方法:采用均匀设计法,以黄芩甙含量为主要考察指标,对黄芩愈伤组织生长的MS培养基成分进行多因素多水平考察。结果:最佳培养基为MS附加0.25mg/L NAA、0.5mg/L 6-BA、17g/L葡萄糖和35g/L蔗糖。最佳培养基黄芩甙含量为27.44mg/gDW。结论:用均匀设计法优化愈伤组织培养基省时、方便,且最佳培养基黄芩甙含量与预测值相近,且明显高于均匀设计实验方案中的黄芩甙含量。经SAS软件分析得出的优化方程拟合度很好。     

Numerical Simulation and Structural Optimization of the Inclined Oil/Water Separator

Improving the separation efficiency of the inclined oil/water separator, a new type of gravity separation equipment, is of great importance. In order to obtain a comprehensive understanding of the internal flow field of the separation process of oil and water within this separator, a numerical simulation based on Euler multiphase flow analysis and the realizable k-ε two equation turbulence model was executed using Fluent software. The optimal value ranges of the separator’s various structural parameters used in the numerical simulation were selected through orthogonal array experiments. A field experiment on the separator was conducted with optimized structural parameters in order to validate the reliability of the numerical simulation results. The research results indicated that the horizontal position of the dispenser, the hole number, and the diameter had significant effects on the oil/water separation efficiency, and that the longitudinal position of the dispenser and the position of the weir plate had insignificant effects on the oil/water separation efficiency. The optimal structural parameters obtained through the orthogonal array experiments resulted in an oil/water separation efficiency of up to 95%, which was 4.996% greater than that realized by the original structural parameters.     

关节置换法与内固定法治疗老年骨质疏松合并股骨粗隆间骨折的临床对比分析

目的:探讨关节置换法和内固定法对老年骨质疏松合并股骨粗隆间骨折患者的治疗效果。方法:选择2011年12月到2014年12月在我院收治的96例老年骨质疏松合并股骨粗隆间骨折患者,随机分为对照组和实验组,分别采用内固定法和关节置换法进行治疗,对比两组临床疗效、并发症发生率和骨密度值。结果:实验组患者下地时间和并发症发生率均明显小于对照组(P0.05)。实验组的优良率(95.83%)明显高于对照组(70.83%),具有显著性差异(P0.05)。治疗后,两组患者骨密度值均明显高于治疗前(P0.05),实验组骨密度值明显高于对照组(P0.05)。结论:关节置换法治疗老年骨质疏松合并股骨粗隆间骨折的临床效果优于内固定法,能明显降低并发症发生率,增强骨密度,改善患者预后。     

L-羟脯氨酸用于小鼠骨折愈合的实验研究

让骨折的小白鼠饮用L 羟脯氨酸水溶液 ,然后通过X线拍片观察其骨折的愈合情况 ,并与对照组进行比较 ,结果表明 :L 羟脯氨酸有促进骨折愈合的作用 ,而且安全、无毒。     

经骨折椎体椎弓根螺钉短节段固定治疗胸腰段骨折疗效

目的:评估和分析经骨折椎体椎弓根螺钉短节段固定治疗胸腰段单椎体粉碎性骨折的临床疗效。方法:选取胸腰段单椎体粉碎性骨折30例患者,分为两组,甲组20例,采用经骨折椎体椎弓根螺钉短节段固定治疗,均行骨折椎体及骨折椎体上下相邻椎体的椎弓根螺钉+双侧连接杆固定;乙组10例,只行骨折椎体的上下相邻椎体的椎弓根螺钉+连接杆固定术。术后随访。测定两组患者手术前后的椎体后凸畸形角和骨折椎体前方高度,评估其临床疗效。结果:术前平均后凸畸形角纠正:甲组15°,乙组11°,P0.05。术后骨折椎体前方的平均高度(和正常椎体前方高度比):甲组89%,乙组81%,P0.05;术后3个月随访:平均后凸畸形角纠正丢失,甲组2°,乙组6°,P0.05;骨折椎体前方的平均高度(和正常椎体前方高度比):甲组87%,乙组73%,P0.05。结论:经骨折椎体椎弓根螺钉短节段固定治疗胸腰段单椎体粉碎性骨折能提供更好的生物力学稳定性,更有利于骨折的复位和后凸畸形的纠正。     

新型可降解锌合金内固定系统用于犬下颌骨骨折固定的研究

目的:探讨新型可降解锌合金内固定系统用于犬下颌骨骨折固定的可行性。方法:选择比格犬12只,并将其随机分为两组,其中6只为锌合金实验组,6只为钛合金对照组。每只比格犬的下颌作左右两个骨折内固定模型,每侧骨折模型使用一套小型四孔直连内固定产品。分别于术后即刻、术后4周、12周拍X片。于术前、术后4周、12周、24周抽血检测微量元素锌。于术后12周、24周分批次将动物安乐死,取下颌骨块行Micro-CT检测,取动物重要脏器和内固定周围软组织做病理切片。结果:全程动物无脱落,实验组与对照组骨折均临床愈合。X线图像及Micro-CT显示实验组与对照组的内固定效果比较差异无统计学意义(P0.05)。锌合金表面有明显的降解产物,Micro-CT测量锌合金的板钉初始体积为155.8±1.536 mm~3,12周体积为147.1±0.9893 mm~3,24周体积为137±5.365 mm~3,降解率12.07%,随着植入后时间的延长显著下降(P0.05),而钛合金板钉体积无显著变化。实验组及对照组心、肝、肾及植入物板周软组织均未见异常。血清锌离子浓度在正常范围内略有上升,各时间节点比较差异无统计学意义(P0.05)。结论:可降解锌合金内固定系统可以对犬下颌骨骨折提供稳固的固定,可降解锌合金在下颌骨部位具有一定的降解性能,血液中锌离子未见明显异常升高,对心、肝、肾及植入物周围软组织无毒性作用。