Microanatomical Record of Cortical Bone Remodeling and High Vascularity in a Fossil Giant Rat Midshaft Femur

Rat cortical bone does not typically undergo secondary (Haversian) remodeling. Haversian organization of rat bone has been mainly observed in experimental settings following biomechanical or dietary manipulation. Here, we report an observation of cortical secondary osteons within a histological femur cross-section from an extinct (late Quaternary) form of Timorese giant rat (Murinae gen. et sp. indet). The medio-lateral midshaft diameter of its femur, used as a measure of bone size, is 6.15 mm and indicates a heavier than normal skeletal frame. We compare this sample to bone histology in a small rat's midshaft femur of 2.33 mm diameter. A complete lack of Haversian bone remodeling characteristics is noted for the smaller sample, which is dominated by radial vascular canals. The giant rat shows clear secondary osteons and diffuse vascularity mainly composed of tightly packed longitudinal canals across its cortex. It appears that rat cortical bone can undergo bone remodeling, and is organized in a highly vascularized manner, in insular giant cases. Our findings from Timor align with results reported in experimental rat model skeletal biology literature and other insular fossil rat material. Where macroanatomical examination is limited, histological observations on fossil rat limb bones have the potential to aid reconstructions of life history and skeletal growth aspects in these rodents. Anat Rec, 302:1934–1940, 2019. © 2019 American Association for Anatomy     

Growth and the Modeling/Remodeling of the Alveolar Bone of the Rat Incisor

The modeling and remodeling of the rat incisor alveolar bone was followed as the animals grew. The weight of the hemimandible, the length of the socket, and the width of the lower incisor were measured. Osteoclasts and resorption areas were identified by tartrate‐resistant acid phosphatase staining. Fluorochrome markers were used to detect and measure osteogenic activities. In the socket related to the periodontal ligament, osteoclasts appeared in scattered sites as well as isolated sites of osteogenic activity, apparently without any variation related to the age of the animals. At the socket facing the dental follicle of young rats, the inner surface was lined with osteoclasts. The number of osteoclasts decreased steadily as the rats grew. In 1‐year‐old rats, in addition to a few scattered osteoclasts, the internal aspect of the labial wall showed some sites lined with osteoblasts and cement lines indicative of prior bone formation. In young rats, there was a continuous osteogenic activity at the external surface of this wall. The thickness of the labial wall of the socket remained apparently constant; therefore, bone resorption must have occurred at the internal side of the wall. Such osteogenic activity was not observed in old rats. The main forces acting on rat incisors, biting and eruption, are continuous through the life of the animals. Thus, these results indicate that the modeling of the alveolar bone related to the dental follicle, in young rats, can only be associated with another force, specifically, the growth of the incisor. Anat Rec, 291:827‐834, 2008. © 2008 Wiley‐Liss, Inc.     

基于自适应网格技术方法的牙齿移动骨改建过程模拟

目的 建立一种可以高效模拟正畸牙槽骨重建的方法。 方法 建立单颗门牙和磨牙的完整牙及牙周模型,模拟位移控制和力控制加载远中平移,基于外部重建理论和牙周膜应变理论,实现基于利用 ABAQUS 子程序UMESHMOTION 结合自适应网格技术(ALE),模拟牙槽骨重建过程。 结果 位移控制能够将初始远中位移加载量50 μm 通过骨重建算法实现,达到远中移动牙槽骨重建位移量 50 μm;力控制模式在施加 1 N 初始远中方向力并考虑最终衰减到 50% 初始力水平情况下,单、双根牙最终位移量分别为 67. 5、23. 77 μm。 两种模式均实现骨重建后牙周膜上绝对值最大主应力恢复到 0 应力水平,牙周膜达到新的力学平衡。 该算法可以在很短时间内很好模拟单、双根牙槽骨的重建过程。 控制成骨和破骨速率比为 7 ∶5时,单次迭代位移移动量控制在 0. 1 μm 能够得到稳定的重建过程。 结论 本方法首次实现了双根牙槽骨重建模拟,在位移和衰减力控制下均可以很好模拟牙槽骨重建的过程,为无托槽和有托槽正畸力系的设计提供有效工具。     

Notch信号通路在骨重建中的作用

Notch信号通路在胚胎发育、神经系统、血管系统、内分泌系统及肿瘤等领域具有广泛的影响。近年来的研究表明,Notch对于骨组织代谢尤其是骨重建有着重要的调控作用,而骨重建的调节紊乱和骨质疏松、骨关节炎等疾病的进展密切相关。Notch信号通路可以通过调控骨组织不同细胞的功能从而影响骨重建过程,但其在不同细胞中具体的参与方式仍然未知。综述近年来Notch信号通路在骨重建中的作用研究进展。     

阻塞性睡眠呼吸暂停低通气综合征模型鼠软腭的力学重建

目的　研究阻塞性睡眠呼吸暂停低通气综合征 (OSAHS)咽腔呼吸压力对软腭力学特性的影响。方法　用SD鼠建立OSAHS动物模型 ,对动物模型的软腭进行单轴拉伸实验 ,离体检测软腭的弹性。结果　通过对照正常生理状态下SD鼠的实验结果 ,比较研究与OSAHS有关的软腭力学特性的变化规律和软腭重建现象。结论　实验研究表明 ,类似OSHAS发病情形的咽腔呼吸压力可引起软腭发生易于OSAHS形成和发展的重建     

基于损伤修复的骨重建数值模拟

目的 研究不同损伤情况下的骨重建行为.方法 提出一种疲劳机制作用下的骨重建模型,通过建立股骨近端三维有限元模型,并结合有限元法,分别模拟3种载荷工况下的骨重建情况,分析股骨近端的力学性能及密度变化.结果 通过增加载荷循环次数,使损伤不断增加.在不同损伤情况下,骨展现出不同的骨重建行为.骨重建作为一种修复机制,在一定范围...     

活骨组织应力与重建适应模型的研究现状与展望

“应力与生长是生物力学的活的灵魂”。对于21世纪生物力学的发展来说,生物活体组织的应力与生长关系是一个新的研究前沿,在这方面,骨的应力与生长（或应力与重建）关系的研究已有开端。我们将根据文献,对活骨组织的应力与重建适应模型的研究现状予以简单的评估与综述,并对活骨组织应力与重建适应模型的未来研究方向予以展望。     

骨骼肌通过力学刺激对骨重建的影响

骨骼与骨骼肌作为运动系统最重要的组织,两者之间存在密切的联系。骨肌单元的概念提出已久,运动产生的力学负荷将两者紧密地联系在一起。骨骼为骨骼肌施力提供力学支撑,而骨骼肌收缩带动机体的运动。在机体运动过程中,骨骼肌充当力学负荷与骨骼之间的中间媒介,并通过内分泌因子以及力学信号调节骨骼的代谢活动,与机体内持续不断的骨重建密切相关,并维持骨骼良好的结构和功能。主要综述近年来骨骼肌通过对骨骼施加力学刺激影响骨重建作用的研究进展,为预防和治疗骨代谢疾病提供新的思路。     

骨功能适应性重建模型及数值模拟

骨骼会受到力学因素的影响和调控,发生骨功能适应性重建。建立模拟骨重建的数值模型,定量地研究骨重建过程,有着重要的临床应用价值。目前,骨功能适应性重建模型可分为两大类：力学模型和生理模型。对这两类重建模型的原理、算法和应用等做详细论述。力学模型通过假设力学环境与骨结构之间的函数关系来预测骨重建,但不考虑其真实的生物学过程。基于不同的重建激励主要有两种力学模型：骨力学稳态模型和骨损伤修复模型。生理模型则试图从微观层次阐明骨重建的力学-生物学机制,骨重建是由破骨细胞、成骨细胞等各种骨组织细胞完成,有以基本多细胞单位的形式作用或细胞独立分开作用两种观点。这些重建模型结合有限元法应用在许多有关骨重建问题的数值计算中。通过比较分析多个数值应用的模拟结果,还讨论了重建控制方程中各参数值的设置对重建结果的影响。     

低载荷下耦合电刺激的骨重建数值模拟

目的 考虑电场影响的同时研究骨在低载荷刺激频率下的废用行为。方法 提出一个废用模型并通过参数激活频率来描述力学刺激与电刺激对骨重建过程的影响。通过建立股骨近端有限元模型,结合有限单元法,模拟低载荷刺激频率下耦合电刺激的骨重建过程,并分析骨密度的流失情况。结果 降低日载荷刺激频率会显著降低骨密度。电刺激可以在一定程度上抵抗由于低载荷刺激频率导致的密度流失,其主要影响区域分布在股骨头部与股骨颈部。电刺激持续时长会显著影响骨皮质与骨松质的密度流失情况。结论 模型可以模拟由于日载荷刺激频率降低导致的废用过程;同时,纳入了电场影响表现其抵抗密度流失的现象。     

Priming the Surface of Orthopedic Implants for Osteoblast Attachment in Bone Tissue Engineering

The development of better orthopedic implants is incessant. While current implants can function reliably in the human body for a long period of time, there are still a significant number of cases for which the implants can fail prematurely due to poor osseointegration of the implant with native bone. Increasingly, it is recognized that it is extremely important to facilitate the attachment of osteoblasts on the implant so that a proper foundation of extracellular matrix (ECM) can be laid down for the growth of new bone tissue. In order to facilitate the osseointegration of the implant, both the physical nanotopography and chemical functionalization of the implant surface have to be optimized. In this short review, however, we explore how simple chemistry procedures can be used to functionalize the surfaces of three major classes of orthopedic implants, i.e. ceramics, metals, and polymers, so that the attachment of osteoblasts on implants can be facilitated in order to promote implant osseointegration.     

钛植入物促骨整合及抗感染涂层的研究进展

钛及其合金具有稳定的化学性质和良好的人体亲和性,常被作为骨科植入材料,但未经处理的钛植入物易发生骨整合不良和植入物周围感染导致植入失败。近年来,人口老龄化加剧带动植入材料使用量增加,亟需性能更好的钛表面修饰方法以降低植入失败率。理想的骨科植入物应同时具备促成骨和抗菌特性,但目前大量表面改性策略只解决其中一种问题,导致植入物无法达到预期效果。因此,植入材料涂层需满足这两种特性或在两者间寻找平衡点。综述近几年来解决钛植入物无菌性松动或感染问题的最新策略,如表面形貌改善和生物分子涂层等促进成骨,抗菌药物负载和光热治疗等防治感染措施,并通过双因素整合和三因素整合进一步介绍了同时解决这两个问题的研究进展。     

LncRNA在骨重建及骨相关疾病中的作用

骨重建可保持骨生物力学特性稳定,对维持骨强度具有重要意义。正常骨骼的生长和发育需要转录调控网络、信号传导通路、力学生物学及生物力学因素的紧密协调,而力学环境的改变,多种信号途径失调,影响骨的发育。长链非编码RNA(long non-coding RNA, lncRNA)是一类长度大于200 nt、生物来源广泛、2级及3级结构高度保守的RNA分子。研究显示,许多lncRNA参与骨骼系统的正常发育或平衡,调控成骨细胞的分化,以及参与骨肉瘤的发生。LncRNA表达失调与关节炎、骨质疏松症和骨癌等多种骨疾病密切相关,有望作为预测骨疾病的生物标志物。综述lncRNA的特征、参与骨重塑的lncRNA及其可能的作用机理,并讨论lncRNA作为生物标志物应用于治疗包括骨关节炎、骨质疏松症、骨癌等骨骼系统疾病的可能性,旨在为更好地理解和研究lncRNA在生物体内的作用提供参考。     

Evaluation of the effect of adipose tissue-derived stem cells on the quality of bone healing around implants

Purpose/Aim: This study evaluates the efficacy of grafted adipose-derived stem cells (ADSCs) on blade-type implants in improving osseointegration in rat femurs using a low-densitybone model. Materials and Methods: After isolating and expanding ADSCs, twice-passaged cells were seeded on blade-type implants on culture plates. Osteogenic induction of grafted cells began after attaching cells to the prepared titanium surfaces and it continued for 4 days. The scaffolds were then implanted in the femurs of Wistar rats. Osteogenic differentiation of these cells was confirmed using polymerase chain reaction (PCR) and alizarin red staining ofthe mineralized extracellular matrix. After 8 weeks, histological and histomorphometric evaluations of undecalcified resin sections (bone–implant contact [BIC] % and bone mineral index [BMI]) were performed using light microscopy and scanning electron microscopy. Results: Alizarin red staining in conjunction with gene expression results confirmed osteogenic differentiation. Histomorphometric assessment using scanning electron microscopy demonstrated improved BIC% and BMI near the treated surface compared with the untreated surface. Conclusions: The complex of differentiated grafted ADSCs and extracellular matrix and the macrodesign and microdesign of the implant can improve osseointegration in low-density bone.     

Intracortical Remodeling Parameters Are Associated With Measures of Bone Robustness

Prior work identified a novel association between bone robustness and porosity, which may be part of a broader interaction whereby the skeletal system compensates for the natural variation in robustness (bone width relative to length) by modulating tissue‐level mechanical properties to increase stiffness of slender bones and to reduce mass of robust bones. To further understand this association, we tested the hypothesis that the relationship between robustness and porosity is mediated through intracortical, BMU‐based (basic multicellular unit) remodeling. We quantified cortical porosity, mineralization, and histomorphometry at two sites (38% and 66% of the length) in human cadaveric tibiae. We found significant correlations between robustness and several histomorphometric variables (e.g., % secondary tissue [R² = 0.68, P < 0.004], total osteon area [R² = 0.42, P < 0.04]) at the 66% site. Although these associations were weaker at the 38% site, significant correlations between histological variables were identified between the two sites indicating that both respond to the same global effects and demonstrate a similar character at the whole bone level. Thus, robust bones tended to have larger and more numerous osteons with less infilling, resulting in bigger pores and more secondary bone area. These results suggest that local regulation of BMU‐based remodeling may be further modulated by a global signal associated with robustness, such that remodeling is suppressed in slender bones but not in robust bones. Elucidating this mechanism further is crucial for better understanding the complex adaptive nature of the skeleton, and how interindividual variation in remodeling differentially impacts skeletal aging and an individuals' potential response to prophylactic treatments. Anat Rec, 297:1817–1828, 2014. © 2014 Wiley Periodicals, Inc.     

力学刺激通过microRNA调控骨重建的研究进展

骨骼结构完整性和骨量的维持需要一定的力学刺激。研究表明,力学刺激可通过调控多种调节因子(例如激素、转录因子和信号分子等)参与骨重建过程。力学刺激可以通过调控微小RNA(microRNA,miRNA)表达在骨重建过程中起着至关重要的作用。然而,受力学刺激调控的miRNA在骨重建过程中的作用和机制尚不完全清楚。本文综述受力学刺激调控的miRNA在骨重建过程中的作用及其机制,并强调其在治疗骨质疏松中的潜在应用。     

全髋关节置换术对股骨近端骨重建的影响

目的 采用Wolff骨重建理论分析全髋关节置换（total hip arthroplasty,THA）对股骨近端骨重建进程的影响。方法 根据骨重建控制方程,利用Python语言编写骨重建程序。在ABAQUS软件中分别建立术前股骨模型与术后股骨及假体有限元模型。对比THA手术前后骨重建进程,分析假体植入对THA术后中远期股骨力学性能的影响。结果 假体植入后,股骨近端应力持续降低,受力点由股骨头转移到假体,出现明显的应力遮挡现象。应力遮挡区域内骨丢失现象严重。股骨干皮质骨变薄,应力遮挡有所缓解。假体底端内侧受挤压,应力显著高于外侧,此处骨质分布不均。结论 THA术后股骨近端内侧出现明显的应力遮挡,导致骨丢失,造成假体松动;假体底端两侧应力水平存在差异,引起骨质分布不均,导致假体与股骨配合不紧密,造成术后患者大腿中段的疼痛。     

X-Ray Image Review of the Bone Remodeling Around an Osseointegrated Trans-femoral Implant and a Finite Element Simulation Case Study

The insertion of an implant into a bone leads to stress/strain redistribution, hence bone remodeling occurs adjacent to the implant. The study of the bone remodeling around the osseointegration implants can predict the long-term clinical success of the implant. The clinical medial–lateral X-rays of 11 patients were reviewed. To eliminate geometrical distortion of different X-rays, they were converted into a digital format and geometrical correction was carried out. Furthermore, the finite element (FE) method was used to investigate how the bone remodeling was affected by the stress/strain distribution in the femur. The review of clinical X-rays showed cortical bone growth around the proximal end of the implant and absorbtion at the distal end of the femur. The FE simulation revealed the stress/strain distribution in the femur of a selected patient. This provided a biomechanical interpretation of the bone remodeling. The existing bone remodeling theories such as minimal strain and strain rate theories were unable to offer satisfactory explanation for the cortical bone growth at the implant side of the proximal femur, where the stress/strain level was much lower than the one in the intact side of the femur. The study established the correlation between stress/strain distribution obtained from FE simulations and the bone remodeling of the clinical review. The cortical bone growth was initiated by the stress/strain gradient in the bone. Through the review of clinical X-rays and FE simulations, the study confirmed that the bone remodeling in a femur with an implant was influenced by the stress/strain redistribution. The strain level and stress gradient hypothesis is presented to offer an explanation for the implanted cortical bone remodeling observed in this study.     

应力环境对大鼠股骨生长与重建和力学性能的影响

通过创建一种新的动物模型，研究应力环境对生长期大鼠股骨生长与重建，以及对其力学性能的影响，并探讨其作用机理。切断6周大SD大鼠右后肢的坐骨神经，致使其右后肢残废，为废用组；左后肢过度负重，为过载组；正常大鼠为对照组。每天早午晚鼓励动物运动半小时，4周后结束实验观测。测量股骨中段的宏观几何学参数、物理学参数和生物力学参数。实验发现：与对照组相比，实验组股骨的若干几何及物理参数发生了明显变化，表明应力环境可以改变活骨组织的成份和结构并逐渐改变其力学性能。实验结果表明，本研究提出的实验模型实用且可靠。     

步态水平对髋关节假体周围骨重建的影响

目的 针对髋关节置换术后患者步态运动水平变化,研究假体周围骨密度（bone mineral density, BMD）变化率的变化趋势,揭示置换初期、长期运动变化对骨重建的影响规律。方法 基于自适应骨重建理论,建立股骨-假体有限元模型,以术后初期、长期步态水平作为重建参数计算假体周围BMD分布,采用Gruen分区方法量化BMD的变化。结果 术后初期,恒定步态组与变化步态组BMD存在明显差异,最大差异发生在低步态组中,造成大转子区域BMD减小41%;步态运动提高促进假体近端、中端BMD变化,显著影响发生在大转子区域,造成BMD增加47%;术后长期阶段,步态运动提高促进假体中端、末端区域BMD恢复,BMD增加2%～9%。结论 研究结果为髋关节置换后患者康复过程提供指导。