Comparative Three‐Dimensional Structure of the Trabecular Bone in the Talus of Primates and Its Relationship to Ankle Joint Loads Generated During Locomotion

The trabecular structure of the ankle bone in small to medium‐bodied (60–5000 g) primates of distinct locomotor types was analyzed using high‐resolution X‐ray computed tomography. There are large inter‐, intraspecific, and regional (medial vs. lateral) variations in the trabecular architecture of the talar body. Body mass has no effect on the bone volume fraction or on the fabric anisotropy. However, both the number and thickness of trabeculae seem to be body mass‐dependent. All taxa show anisotropic trabecular bone, but the degree of anisotropy and elongation values vary, notably across the locomotion categories. The fabric orientation in the talar body indicates that, practically, all taxa studied display a generally consistent pattern of orientation restricted primarily to a dorsoplantar direction. We have observed a mediolateral difference in the bone volume fraction in most primates who are proficient or frequent climbers. This could reflect a specific reinforcement of the trabecular structure in response to the loads engendered in habitually sustained foot inversion. In contrast, tali of primates who are proficient or frequent leapers rather exhibit a different three‐dimensional distribution of the material, which consists of a more anisotropic trabecular structure. This could reflect stronger unidirectional and stereotypical‐loading conditions generated at the ankle joints during a leap. Finally, it appears that the talar trabecular bone structure has a good potential for predicting locomotion in extinct species. We have analyzed the trabecular bone structure of the talus of some Eocene European primates (Adapis, Leptadapis, and Necrolemur) and compared the functional signal of the external versus internal talar anatomy in these fossils. Anat Rec, 2012. © 2012 Wiley Periodicals, Inc.     

Trabecular Bone Fraction Variation in Modern Humans,Fossil Hominins and Other Primates

Evidence suggests that recent modern humans (Holocene) have low trabecular bone density (i.e., trabecular bone fraction, TBF) compared with other extant primates and fossil hominins. However, the extent to which TBF in recent humans with varying subsistence strategies differs from that of fossil hominins, and in turn, how hominins differ from various extant catarrhines is unclear. This study tests the hypotheses that first, populations with subsistence strategies demanding high physical activity exhibit greater TBF than sedentary populations and are more similar to fossil Homo. Secondly, that, australopiths have TBF that is more similar to nonhuman primates because of the greater mechanical loading on their skeletons. The study quantifies TBF in the limb epiphyses of recent humans, hominoids, cercopithecines, and fossil hominins. The results show overall a significant decrease in TBF among recent humans, whereas hominins, hominoids, and cercopithecines have similar, high TBF values. In addition, active human populations display TBF that is more similar to fossil Homo. The results suggest that this TBF decline reflects a reduction in activity levels among sedentary populations, although a systemic decline cannot be ruled out. These findings support the recent evolution of low trabecular density because of a decline in activity levels and underscore the utility of comparing multiple skeletal elements across a diverse set of recent modern humans when drawing conclusions about changes in trabecular bone in the human skeleton. Anat Rec, 302:288–305, 2019. © 2018 Wiley Periodicals, Inc.     

基于Micro-CT的小鼠骨小梁LBF模型提取及特征分析

针对小鼠股骨Micro-CT切片图像,提出一种骨小梁形态与分布特征的定量分析方法。利用形态学与LBF模型结合方法提取股骨中的骨小梁,通过模拟骨质疏松症状与提取后的正常骨小梁进行几何形态参数测量的对比,同时利用灰度共生矩阵分析骨小梁的纹理分布特征参数进行实验对比。实验结果表明,骨小梁变细、断裂以及消失等状态,其对比度、熵、能量、相关性等参数会发生明显变化,为定量化分析骨质疏松提供了一种研究方法。     

Influence of Ovariectomy on Bone Turnover and Trabecular Bone Mass in Mature Cynomolgus Monkeys

Purpose

To examine the influence of ovariectomy (OVX) on bone turnover and trabecular bone mass at the 3 clinically important skeletal sites in mature cynomolgus monkeys.

Materials and Methods

Six female cynomolgus monkeys, aged 17-21 years, were randomized into 2 groups by the stratified weight: the OVX and sham-operation groups (n = 3 in each group). The experimental period was 16 months. Lumbar bone mineral density (BMD) in vivo and serum and urinary bone turnover markers were longitudinally measured, and peripheral quantitative computed tomographic and bone histomorphometric analyses were performed on trabecular bone of the lumbar vertebra, femoral neck, and distal radius at the end of the experiment.

Results

OVX induced in a reduction in lumbar BMD compared with the sham controls and the baseline, as a result of increased serum levels of bone-specific alkaline phosphatase and urinary levels of cross-lined N- and C-terminal telopeptides of type I collagen. Furthermore, OVX induced reductions in trabecular volumetric BMD and trabecular bone mass compared with the sham controls, with increased bone formation rate at the lumbar vertebra, femoral neck, and distal radius.

Conclusion

The results indicated that OVX in mature cynomolgus monkeys (17-21 years of age) increased bone turnover and induced trabecular bone loss at the three skeletal sites compared with the sham controls. Thus, mature cynomolgus monkeys could be utilized for preclinical studies to examine the effects of interventions on bone turnover and trabecular bone mass at the 3 clinically important skeletal sites.     

The Effect of the Achilles Tendon on Trabecular Structure in the Primate Calcaneus

Humans possess the longest Achilles tendon relative to total muscle length of any primate, an anatomy that is beneficial for bipedal locomotion. Reconstructing the evolutionary history of the Achilles tendon has been challenging, in part because soft tissue does not fossilize. The only skeletal evidence for Achilles tendon anatomy in extinct taxa is the insertion site on the calcaneal tuber, which is rarely preserved in the fossil record and, when present, is equivocal for reconstructing tendon morphology. In this study, we used high‐resolution three‐dimensional microcomputed tomography (micro‐CT) to quantify the microstructure of the trabecular bone underlying the Achilles tendon insertion site in baboons, gibbons, chimpanzees, and humans to test the hypothesis that trabecular orientation differs among primates with different tendon morphologies. Surprisingly, despite their very different Achilles tendon lengths, we were unable to find differences between the trabecular properties of chimpanzee and human calcanei in this specific region. There were regional differences within the calcaneus in the degree of anisotropy (DA) in both chimpanzees and humans, though the patterns were similar between the two species (higher DA inferiorly in the calcaneal tuber). Our results suggest that while trabecular bone within the calcaneus varies, it does not respond to the variation of Achilles tendon morphology across taxa in the way we hypothesized. These results imply that internal bone architecture may not be informative for reconstructing Achilles tendon anatomy in early hominins. Anat Rec, 296:1509–1517, 2013. © 2013 Wiley Periodicals, Inc.     

仿骨小梁力学性能的多孔结构拓扑优化设计

目的基于动物骨小梁结构设计多孔植入物,阐述骨小梁结构的力学性能特点,说明使用仿骨小梁多孔结构植入物在临床治疗中的重要意义。方法基于动物骨小梁结构的各向异性力学性能,利用拓扑优化技术进行多孔结构设计。根据骨功能原理提出分区、分块重建原则,利用Micro-CT图像重建动物骨小梁模型结构;根据代表体元法对模型施加边界约束和外载荷,以求解的力学性能作为优化的目标函数,利用拓扑优化中的变密度法和均匀化方法进行多孔结构设计及优化。结果骨小梁结构具有各向异性的力学特点。求解发现,松质骨的体积分数在同一截面的边缘到中间主压力位置呈现递增趋势;泊松比无明显变化规律,均匀分布在0. 17～0. 30之间;而弹性模量和剪切模量在松质骨主压力位置明显大于其他位置;基于上述结果进行拓扑优化设计,结果显示,优化后模型的泊松比分布在0. 17～0. 30,弹性模量误差在14%以下,最小的仅为3%,剪切模量误差范围在8%以下,基本符合最初的设计目标。结论利用拓扑优化方法设计的多孔结构具有与动物松质骨相同的各向异性特点,同时减少应力集中现象,可以实现特定性能的多孔结构设计,为后续设计临床应用的多孔植入物提供一种合理有效的方法。     

Trabecular Bone Structural Variation in the Proximal Sacrum Among Primates

The sacrum occupies a functionally important anatomical position as part of the pelvic girdle and vertebral column. Sacral orientation and external morphology in modern humans are distinct from those in other primates and compatible with the demands of habitual bipedal locomotion. Among nonhuman primates, however, how sacral anatomy relates to positional behaviors is less clear. As an alternative to evaluation of the sacrum's external morphology, this study assesses if the sacrum's internal morphology (i.e., trabecular bone) differs among extant primates. The primary hypothesis tested is that trabecular bone parameters with established functional relevance will differ in the first sacral vertebra (S1) among extant primates that vary in positional behaviors. Results for analyses of individual variables demonstrate that bone volume fraction, degree of anisotropy, trabecular number, and size-corrected trabecular thickness differ among primates grouped by positional behaviors to some extent, but not always in ways consistent with functional expectations. When examined as a suite, these trabecular parameters distinguish obligate bipeds from other positional behavior groups; and, the latter three trabecular bone variables further distinguish knuckle-walking terrestrial quadrupeds from manual suspensor-brachiators, vertical clingers and leapers, and arboreal quadrupeds, as well as between arboreal and terrestrial quadrupeds. As in other regions of the skeleton in modern humans, trabecular bone in S1 exhibits distinctively low bone volume fraction. Results from this study of extant primate S1 trabecular bone structural variation provide a functional context for interpretations concerning the positional behaviors of extinct primates based on internal sacral morphology. Anat Rec, 302:1354–1371, 2019. © 2018 Wiley Periodicals, Inc.     

骨小梁Micro-CT图像形态计量学参数计算方法综述

骨质疏松症是骨科领域的研究热点之一,研究发现,除骨密度(骨量)改变的因素外,骨小梁的结构变化也是患病的重要影响因素。骨小梁形态计量学分析是研究骨小梁结构形态变化的一种重要方法。基于骨小梁的Micro-CT图像介绍部分骨小梁形态学参数的计算方法,主要包括骨小梁各向异性、连通性、结构模型指数以及纹理等不同特征,同时列举部分相关研究实例,总结上述形态学参数的适用性以及优缺点,为更加有效地评价骨质疏松状态以及药物治疗效果提供依据。     

老龄对腰椎松质骨冲击力学特性的影响

目的腰椎松质骨的冲击力学特性对治疗骨质疏松、骨重建、骨再造以及人工关节置换术等具有重要的临床意义,本文对正常国人青年和老年新鲜尸体腰椎松质骨进行冲击试验,通过分析确定老年腰椎松质骨和青年尸体腰椎松质骨是否具有不同的冲击力学特性。方法死后1h之内解剖取出青年和老年死者腰椎L1-L5标本,并将标本沿纵向切成长30mm、宽5mm、高5mm的试样共40个,按年龄分青年和老年组各20个样本。以能量释放方法对2组样本进行冲击实验,根据试验机显示出的样本承受的冲击功,利用材料力学中的数学公式计算出每个样本的冲击韧性。结果青年组腰椎松质骨承受的冲击功为(35.92±3.26)N·mm,冲击韧性为(1.44±0.13)N·cm/mm2;老年组的冲击功为(28.2±2.94)N·mm,冲击韧性为(1.14±0.11)N·cm/mm2。结论老年组腰椎松质骨的冲击力学特性因老年性骨质疏松发生一定变化,其冲击力学性能显著降低。     

小梁网弹性变化与青光眼发病的关系

青光眼是一种以眼内压异常升高为主要危险因素的致盲性眼病,小梁网组织作为房水流出的主要通道,对于调节眼内压十分重要。研究表明,青光眼患者小梁网组织弹性较正常人小梁网组织明显升高,眼内压升高可能与小梁网弹性增加之间存在关联。本文在简要叙述小梁网细胞特性的基础上,着重对小梁网组织弹性与青光眼的关系、细胞外基质弹性对小梁网细胞的影响进行综述,为研究青光眼的发病机制以及预防和治疗提供参考。     

废用对松质骨结构的影响

正常骨结构形态的变化总是与力学环境相适应的，废用状态可引起松质骨结构的较大改变。本研究将有限元分析与带有调整目标的骨再造方程相结合，模拟废用对松质骨结构的影响。数值模拟表明，当某方向载荷变小时，此方向的骨小梁变细，结构质量下降；当某方向载荷急剧变小(严重废用，如长期卧床)时，此方向很多骨小梁消失，废用破坏了松质骨结构的完整性；当从废用状态恢复到正常活动时，消失的骨小梁不能恢复。这种废用状态引起的结构完整性变化是不可逆的。废用引起的松质骨孔隙变大，可能是老年人骨质疏松发生的原因之一。     

Comparison of the Effect of Vitamin K2 and Risedronate on Trabecular Bone in Glucocorticoid-Treated Rats: A Bone Histomorphometry Study

Purpose

To compare the effect of vitamin K₂ and risedronate on trabecular bone in glucocorticoid (GC)-treated rats.

Materials and Methods

Forty-eight Sprague-Dawley female rats, 3 months of age, were randomized by the stratified weight method into 5 groups according to the following treatment schedule: age-matched control, GC administration, and GC administration with concomitant administration of vitamin K₂, risedronate, or vitamin K₂ + risedronate. GC (methylprednisolone sodium succinate, 5.0 mg/kg) and risedronate (10 µg/kg) were administered subcutaneously three and five times a week, respectively. Vitamin K₂ (menatetrenone, 30 mg/kg) was administered orally three times a week. At the end of the 8-week experiment, bone histomorphometric analysis was performed on trabecular bone of the tibial proximal metaphysis.

Results

GC administration decreased trabecular bone mass compared with age-matched controls because of decreased bone formation (mineralizing surface, mineral apposition rate, and bone formation rate) and increased bone erosion. Vitamin K₂ attenuated GC-induced trabecular bone loss by preventing GC-induced decrease in bone formation (mineralizing surface) and subsequently reducing GC-induced increase in bone erosion. Risedronate prevented GC-induced trabecular bone loss by preventing GC-induced increase in bone erosion although it also suppressed bone formation (mineralizing surface, mineral apposition rate, and bone formation rate). Vitamin K₂ mildly attenuated suppression of bone formation (mineralizing surface) and bone erosion caused by risedronate without affecting trabecular bone mass when administered in combination.

Conclusion

The present study showed differential effect of vitamin K₂ and risedronate on trabecular bone in GC-treated rats.     

A Comparative Study of Trabecular Bone Mass Distribution in Cursorial and Non‐Cursorial Limb Joints

Skeletal design among cursorial animals is a compromise between a stable body that can withstand locomotor stress and a light design that is energetically inexpensive to grow, maintain, and move. Cursors have been hypothesized to reduce distal musculoskeletal mass to maintain a balance between safety and energetic cost due to an exponential increase in energetic demand observed during the oscillation of the distal limb. Additionally, experimental research shows that the cortical bone in distal limbs experiences higher strains and remodeling rates, apparently maintaining lower mass at the expense of a smaller safety factor. This study tests the hypothesis that the trabecular bone mass in the distal limb epiphyses of cursors is relatively lower than that in the proximal limb epiphyses to minimize the energetic cost of moving the limb. This study utilized peripheral quantitative computed tomography scanning to measure the trabecular mass in the lower and upper limb epiphyses of hominids, cercopithecines, and felids that are considered cursorial and non‐cursorial. One‐way ANOVA with Tukey post hoc corrections was used to test for significant differences in trabecular mass across limb epiphyses. The results indicate that overall, both cursors and non‐cursors exhibit varied trabecular mass in limb epiphyses and, in certain instances, conform to a proximal–distal decrease in mass irrespective of cursoriality. Specifically, hominid and cercopithecine hind limb epiphyses exhibit a proximal–distal decrease in mass irrespective of cursorial adaptations. These results suggest that cursorial mammals employ other energy saving mechanisms to minimize energy costs during running. Anat Rec, 298:797–809, 2015. © 2014 Wiley Periodicals, Inc.     

股骨头坏死松质骨生物力学特征的空间分布规律

目的 探究股骨头坏死松质骨微观结构参数和力学性能的空间分布规律,为临床诊断中科学评估病灶对病情的影响提供理论依据。方法 结合影像学测量和数值模拟方法,定量分析不同区域松质骨的微观结构参数和力学性能,分别从冠状面、矢状面和水平面投影方向上探究松质骨生物力学特征的空间分布特点。结果 在股骨头冠状面和矢状面投影方向上,松质骨的微观结构特征与力学性能大致呈Y型分布,Y形区域内松质骨的力学性能高于其他区域,该分布特点与股骨头内的主压应力束的位置相吻合。结论 位于股骨头Y形区域内的坏死灶对股骨头内应力分布的影响程度会更大,更有可能导致病情恶化。临床诊断中应充分考虑坏死灶和Y形区域的位置关系。     

Mechanical Properties of the Hindlimb Bones of Bullfrogs and Cane Toads in Bending and Torsion

When compared with most vertebrates, frogs use a novel style of jumping locomotion powered by the hindlimbs. Hindlimb bones of frogs must withstand the potentially erratic loads associated with such saltatory locomotion. To evaluate the load bearing capacity of anuran limb bones, we used three‐point bending, torsion, and hardness tests to measure the mechanical properties of the femur and tibiofibula from adults of two species that use different jumping styles: explosively jumping bullfrogs (Rana (Lithobates) catesbeiana) and cyclically hopping cane toads (Bufo (Chaunus) marinus). Yield stress and strain values for R. catesbeiana and B. marinus hindlimb bones are within the range of values previously reported for other vertebrates. However, anuran hindlimb bones generally stand out as having higher yield stresses in bending than those of closely related, nonsaltatory salamanders, highlighting the importance of considering phylogenetic context in comparisons of bone functional capacity and adaptation. Stiffness values for both frog species tested were also high, which may facilitate efficient transmission of muscular forces while jumping. Elevated stiffness may also contribute to some discrepancies between determinations of bone properties via hardness versus bending tests. In comparisons between species, B. marinus bones showed significantly higher bending yield stresses than R. catesbeiana, whereas R. catesbeiana bones showed significantly higher torsional yield stresses than B. marinus. These differences may correlate with differences in jumping style and limb anatomy between ranid and bufonid frogs, suggesting that evolutionary changes in bone mechanical properties may help to accommodate new functional demands that emerge in lineages. Anat Rec, 292:935–944, 2009. © 2009 Wiley‐Liss, Inc.     

Postcranial Pneumaticity and Bone Structure in Two Clades of Neognath Birds

Most living birds exhibit some degree of postcranial skeletal pneumaticity, aeration of the postcranial skeleton by pulmonary air sacs and/or directly from the lungs. The extent of pneumaticity varies greatly, ranging from taxa that are completely apneumatic to those with air filling most of the postcranial skeleton. This study examined the influence of skeletal pneumatization on bone structural parameters in a sample of two size‐ and foraging‐style diverse (e.g., subsurface diving vs. soaring specialists) clades of neognath birds (charadriiforms and pelecaniforms). Cortical bone thickness and trabecular bone volume fraction were assessed in one cervical and one thoracic vertebra in each of three pelecaniform and four charadriiform species. Results for pelecaniforms indicate that specialized subsurface dive foragers (e.g., the apneumatic anhinga) have thicker cortical bone and a higher trabecular bone volume fraction than their non‐diving clademates. Conversely, the large‐bodied, extremely pneumatic brown pelican (Pelecanus occidentalis) exhibits thinner cortical bone and a lower trabecular bone volume fraction. Such patterns in bone structural parameters are here interpreted to pertain to decreased buoyancy in birds specialized in subsurface dive foraging and decreased skeletal density (at the whole bone level) in birds of larger body size. The potential to differentially pneumatize the postcranial skeleton and alter bone structure may have played a role in relaxing constraints on body size evolution and/or habitat exploitation during the course of avian evolution. Notably, similar patterns were not observed within the equally diverse charadriiforms, suggesting that the relationship between pneumaticity and bone structure is variable among different clades of neognath birds. Anat Rec, 296:867–876, 2013. © 2013 Wiley Periodicals, Inc.     

Vertebral Osteoporosis and Trabecular Bone Quality

Vertebral fractures due to osteoporosis commonly occur under non-traumatic loading conditions. This problem affects more than 1 in 3 women and 1 in 10 men over a lifetime. Measurement of bone mineral density (BMD) has traditionally been used as a method for diagnosis of vertebral osteoporosis. However, this method does not fully account for the influence of changes in the trabecular bone quality, such as micro-architecture, tissue properties and levels of microdamage, on the strength of the vertebra. Studies have shown that deterioration of the vertebral trabecular architecture results in a more anisotropic structure which has a greater susceptibility to fracture. Transverse trabeculae are preferentially thinned and perforated while the remaining vertical trabeculae maintain their thickness. Such a structure is likely to be more susceptible to buckling under normal compression loads and has a decreased ability to withstand unusual or off-axis loads. Changes in tissue material mechanical properties and levels of microdamage due to osteoporosis may also compromise the fracture resistance of vertebral trabecular bone. New diagnostic techniques are required which will account for the influence of these changes in bone quality. This paper reviews the influence of the trabecular architecture, tissue properties and microdamage on fracture risk for vertebral osteoporosis. The morphological characteristics of normal and osteoporotic architectures are compared and their potential influence on the strength of the vertebra is examined. The limitations of current diagnostic methods for osteoporosis are identified and areas for future research are outlined.     

松质骨骨小梁的微观构筑对骨质力学强度影响的实验研究

目的　观察骨质疏松和非骨质疏松状态的松质骨的三维微观结构对其骨强度的影响。方法　16只雌性成年绵羊随机分为去势(OVX)组（8只）和假手术(Sham)组（8只）。OVX组行双侧卵巢切除术，假手术组仅显露双侧卵巢，术前测定腰椎竹密度(BMD)。术后12个月处死动物，测定腰椎的BMD，用环钻钻取椎体松质骨，并行MicroCT分析及生物力学测试。结果　去势12个月后，OVX组的BMD较Sham组显著降低。松质骨的骨体积分数(BV/TV)、骨小梁厚度(Tb.Th)、骨小梁数目(Tb.N)较Sham组显著降低，表面积体积比(BS/BV)和骨小梁分离度(Tb.Sp)较对照显著增高。生物力学测试表明，去势12个月后，OVX组松质骨的力学强度显著下降。骨小梁的力学强度与骨小梁厚度(r=0.945，R^2=0.886)、骨体积分数(r=0.783，R^2=0.586)及面积体积比(r=0.643，R^2=0.372)呈线性相关。结论　骨小梁的三维微观结构改变可以影响松质骨的力学强度，两者之间具有一定的线性关系。     

Variation of trabecular microarchitectural parameters in cranial, caudal and mid-vertebral regions of the ovine L3 vertebra

The lumbar vertebrae are major load-bearing structures within the spinal column. The current understanding of the microstructure of these bodies and their full role in load-bearing is incomplete. There is a need to develop our understanding of these issues to improve fracture prediction in musculoskeletal diseases such as osteoporosis. The lumbar vertebrae consist primarily of trabecular bone enclosed in a thin cortical shell, but little is known about how microstructural parameters vary within these structures, particularly in relation to the trabecular compartment. The specific aim of this study was to use micro-computed tomography to characterize the trabecular microarchitecture of the ovine L3 vertebra in cranial, mid-vertebra and caudal regions. The L3 vertebra was obtained from skeletally mature ewes ( n  = 18) more than 4 years old. Three-dimensional reconstructions of three pre-defined regions were obtained and microarchitectural parameters were calculated. Whereas there was no difference in bone volume fraction or structural model index between regions, trabecular number, thickness, spacing, connectivity density, degree of anisotropy and bone mineral density all displayed significant regional variations. The observed differences were consistent with the biomechanical hypothesis that in vivo loads are distributed differently at the endplates compared with the mid-vertebra. Thus, a more integrative approach combining biomechanical theory and anatomical features may improve fracture risk assessment in the future.