Adaptation of cancellous bone to overloading in the adult rat: A single photon absorptiometry and histomorphometry study

Jee, Webster S. S.; Li, Xiao Jian

doi:10.1002/ar.1092270405

Cited by 114 publications

(38 citation statements)

References 30 publications

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“…When the level of load is changed, the model predicted that the architecture adapts by changing the thickness of the struts while maintaining the same number of struts. This is consistent with the results from Jce and Li (26), who found that, in the overloaded limb of a in the bone, by which a local mechanical stimulus can rat, the trabecular number and separation remained affect the local area within a certain distance, is useful unchanged whereas the trabecular thickness increased for the regulation of the maximal local load. If, for instance, we compare the results from the model with the experimental finding that the trabec ular thickness of the iliac cancellous bone in normal significantly.…”

Section: ! ^ésupporting

confidence: 92%

Proposal for the regulatory mechanism of Wolff's law

Mullender

Huiskes

1995

Journal Orthopaedic Research

328

259

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Summary:It is currently believed that the trabecular structure in bone is the result of a dynamic remodeling process controlled bÿ mechanical loads. We propose a regulatory mechanism based on the hypothesis that osteocytes located within the bone sense mechanical signals and that these cells mediate osteoclasts and osteoblasts in their vicinity to adapt bone mass. A computer-simulation model based on these assumptions was used to investigate if the adaptation of bone, in the sense of Wolffs law, and remodeling phenomena, as observed in reality, can be explained by such a local control process. The model produced structures resem bling actual trabecular architectures. The architecture transformed after the external loads were changed, aligning the trabeculae with the actual principal stress orientation, in accordance with Wolffs trajectorial hypothesis. As in reality, the relative apparent density of the structure depended on the magnitude of the applied stresses. Osteocyte density influenced the remodeling rate, which also is consistent with experimental findings. Furthermore, the results indicated that the domain of influence of the osteocytes affects the refine ment of the structure as represented by separation and thickness of the struts. We concluded that the trabec ular adaptation to mechanical load, as described by Wolff, can be explained by a relatively simple regulatory model. The model is useful for investigating the effects of physiological parameters on the development, maintenance, and adaptation of bone.

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Section: ! ^ésupporting

confidence: 92%

Proposal for the regulatory mechanism of Wolff's law

Mullender

Huiskes

1995

Journal Orthopaedic Research

328

259

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“…The periosteal mineral apposition rate (MAR) was 76% higher and intracortical MAR was 23% higher in the trained sows. Jee and Li (1990) observed changes in cellular activity of adult rats after 18 and 26 weeks of increased loading. The proximal tibia of loaded animals had overall higher bone density and significantly higher trabecular number, thickness, and density than the tibia in control rats.…”

Section: Mechanical Straw Homeostasismentioning

confidence: 90%

Exercise: A Prevention and Treatment for Osteoporosis and Injurious Falls in the Older Adult

Smith¹,

Tommerup²

1995

Journal of Aging and Physical Activity

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Osteoporosis is a major public health problem in persons over the age of 65, and it leads to approximately 250,000 hip fractures per year. Contributing risk factors for osteoporosis and hip fractures in the aging population include insufficient nutrient intake, inadequate dietary calcium, muscular weakness, decreased physical activity, and changes in hormonal homeostasis. Physical activity especially plays an important role in the prevention of falls and fractures. Physically active older adults with greater muscular strength experience fewer and less injurious falls than older people who are inactive. The effects of physical activity on bone strength and metabolism have only recently been investigated. When bone is mechanically stimulated, the cells respond by producing many local hormones and growth factors, including prostaglandin E, (PGE$), a mediator of bone modeling and remodeling. Current research continues to show that physical activity significantly affects the geometry and architecture of bone as well as increasing bone mineral density, all of which contribute to an increase in bone strength.Key Words: physical activity, osteoporosis, bone, mechanical loading Osteoporosis and fractures resulting from falls are a major public health hazard for older adults. Evidence is beginning to emerge that physical exercise can both strengthen bone integrity and reduce risk factors for falls (such as muscle weakness, poor balance, and slow gait velocity). This review will discuss current knowledge in the following areas: (a) general bone metabolism, (b) prevalence of and risk factors for falls and fractures, (c) the effects of exercise on risk factors for falls and fractures, especially bone mineral density, and (d) cellular hypotheses for the mechanisms of the bone response to exercise. Overview of Bone MetabolismThe skeleton not only provides structural support but also serves as a mineral reservoir. Skeletal architecture, geometry, and bone mineral content respond to hormonal and mechanical homeostatic mechanisms through the processes of The authors are with the

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“…Moreover, for all variables, adaptive behavior persisted, despite changes in loading magnitude and direction. Elevated external loads increased Tr.Th, 17,23 and reduced loads caused trabecular thinning and loss of connectivity. 26 Alternative loading directions caused trabeculae to realign accordingly.…”

Section: Discussionmentioning

confidence: 99%