Response of the osteocyte syncytium adjacent to and distant from linear microcracks during adaptation to cyclic fatigue loading

Colopy, Sara A.; Benz-Dean, J.; Barrett, Jennifer G.; Sample, Susannah J.; Lu, Yunkai; Danova, Nichole A.; Kalscheur, Vicki L.; Vanderby, Ray; Markel, Mark D.; Muir, Peter

doi:10.1016/j.bone.2004.05.024

Cited by 82 publications

(90 citation statements)

References 41 publications

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“…In addition, total woven bone area (summed over five histology slides from P5 to D7) was reduced 94, 59 and 27% compared to fatigued loaded ulnae for low, medium and high displacement groups, respectively. By day 14 the mechanical properties of ulnae loaded in creep had recovered, similar to the response to fatigue loading [9,15,28], indicating a functional repair of the structural damage in both cases. There are two possible explanations for the relatively greater woven bone formation after fatigue loading compared to creep.…”

Section: Discussionmentioning

confidence: 66%

“…Our motivation for examining the response of bone to damaging creep loading was to follow up on previous studies that showed woven bone formation after damaging fatigue loading [9,15,25,28]. Consistent with fatigue loading [28], there is a dose-response in woven bone formation after creep loading whereby woven bone area increases with increasing damage.…”

Section: Discussionmentioning

confidence: 99%

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In vivo static creep loading of the rat forelimb reduces ulnar structural properties at time-zero and induces damage-dependent woven bone formation

Lynch

Silva

2008

Bone

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Periosteal woven bone forms in response to stress fractures and pathological overload. The mechanical factors that regulate woven bone formation are poorly understood. Fatigue loading of the rat ulna triggers a woven bone response in proportion to the level of applied fatigue displacement. However, because fatigue produces damage by application of cyclic loading it is unclear if the osteogenic response is due to bone damage (injury response) or dynamic strain (adaptive response). Creep loading, in contrast to fatigue, involves application of a static force. Our objectives were to use static creep loading of the rat forelimb to produce discrete levels of ulnar damage, and subsequently to determine the bone response over time. We hypothesized that 1) increases in applied displacement during loading correspond to ulnae with increased crack number, length and extent, as well as decreased mechanical properties; and 2) in vivo creep loading stimulates a damage-dependent dose-response in periosteal woven bone formation. Creep loading of the rat forelimb to progressive levels of sub-fracture displacement led to progressive bone damage (cracks) and loss of whole-bone mechanical properties (especially stiffness) at time-zero. For example, loading to 60% of fracture displacement caused a 60% loss of ulnar stiffness and a 25% loss of strength. Survival experiments showed that woven bone formed in a dose-dependent manner, with greater amounts of woven bone in ulnae that were loaded to higher displacements. Furthermore, after 14 days the mechanical properties of the loaded limb were equal or superior to control, indicating functional repair of the initial damage. We conclude that bone damage created without dynamic strain triggers a woven bone response, and thus infer that the woven bone response reported after fatigue loading and in stress fractures is in large part a response to bone damage.

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Section: Discussionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 99%

In vivo static creep loading of the rat forelimb reduces ulnar structural properties at time-zero and induces damage-dependent woven bone formation

Lynch

Silva

2008

Bone

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“…Bone, for example, JA 2013 Colopy et al (2004), showing a section of bone containing a network of osteocytes (small white dots and lines). A fatigue microcrack (top, centre, arrowed) is about to be repaired by a resorption cavity (large white object).…”

Section: The Benefits Of Being Alivementioning

confidence: 99%

Structural materials: What can we learn from nature?

Taylor

2013

MATEC Web of Conferences

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Abstract. The mechanical properties of materials are of vital importance in the natural world. Over millions of years of evolution, Nature has created materials capable of resisting mechanical forces, in our bodies and in those of other animals and plants. Throughout history human beings have created new materials; in particular many materials developed over the last 100 years have greatly surpassed natural materials in their mechanical properties and durability. So is there anything which Nature can still teach us about making and maintaining structural materials? This talk will consider some of the "tricks" which Nature uses, such as bottom-up fabrication processes, functionally graded structures and materials with the capacity for continual self-monitoring and repair. It will be shown that some of these tricks can be used by materials scientists, but some aspects of the behaviour of natural materials are not suitable for copying into manmade structures. NATURE'S MATERIALS ARE NOT VERY GOODFrom a mechanical point of view, the properties of natural, biological materials are quite poor. Any rational comparison on the basis of properties such as strength, toughness, ductility or energy absorption shows that engineering materials developed in the 20 th century -especially metal alloys and fibre composites -far outperform natural materials. So do we really have anything to learn from nature? I believe we do, because (thanks to evolution) nature has been able to make the best possible use of the rather poor-quality materials available. By looking at how nature optimises material use we can learn lessons that we can apply to future materials development. Figure 1 shows a beautiful picture taken by Mueller et al (2006) of a section cut through a tree, revealing the structure near a branch. This image reveals several important aspects of natural materials which are worthy of consideration. Firstly, the material is essentially a fibre composite, in which the fibres have been arranged to alter their orientations in the vicinity of the joint between the main trunk and the side branch to achieve a smooth transition and follow lines of force. This is very difficult (though not impossible) for us to achieve in engineering structures made from fibre composites. This illustrates an important fact which recurs often in natural materials: there is no clear distinction between the material and the structure. Material properties gradually change from place to place within the structure, improving overall performance (e.g. stiffness/weight) and eliminating sudden transitions which are always points of weakness. Similar structure/material interactions can be found in the human body, for example at bone/tendon junctions and in cartilage. Our attempts to replicate this kind of transition, for example using functionally graded materials, is beginning to bear fruit, but we have a long way to go. MATERIAL VERSUS STRUCTUREThe second feature of interest in figure 1 is that the insertion of the branch does not occur only on the surface but ...

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“…O osteócito é o tipo celular presente em maior número no tecido ósseo maduro (11) e se encontra alojado em lacunas no seu interior (5,11) . Essas células se comunicam entre si e com os osteoblastos por meio de uma rede de conexões formada por processos intracanaliculares (4,9,11) . Essas conexões têm a função de promover a passagem de metabólitos, íons e moléculas sinalizadoras intracelulares importantes para a manutenção da matriz óssea (3) .…”

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“…Outra função importante e que vem sendo amplamente estudada é a participação do osteócito como célula responsável por traduzir a força mecânica imposta ao osso em sinais bioquímicos que regulam o turnover ósseo (3,6) . Por ser considerada uma célula multifuncional envolvida nos processos que regulam tanto a formação quanto a reabsorção ósseas, o osteócito tem ganho cada vez mais importância na osteologia (1,4,8,11) . Mas por ser uma célula que se localiza no interior do tecido ósseo mineralizado, a avaliação in situ de sua morfologia, atividade e característi-cas de suas conexões é difícil (11) e vem sendo realizada por técnicas mais avançadas, como a microscopia eletrônica (8) , o que requer o preparo do material a ser analisado de forma específica.…”

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Técnica histoquímica aplicada ao tecido ósseo desmineralizado e parafinado para o estudo do osteócito e suas conexões

Ocarino¹,

Gomes²,

Melo³

et al. 2006

J. Bras. Patol. Med. Lab.

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Response of the osteocyte syncytium adjacent to and distant from linear microcracks during adaptation to cyclic fatigue loading

Cited by 82 publications

References 41 publications

In vivo static creep loading of the rat forelimb reduces ulnar structural properties at time-zero and induces damage-dependent woven bone formation

In vivo static creep loading of the rat forelimb reduces ulnar structural properties at time-zero and induces damage-dependent woven bone formation

Structural materials: What can we learn from nature?

Técnica histoquímica aplicada ao tecido ósseo desmineralizado e parafinado para o estudo do osteócito e suas conexões

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