Osteonal bone

This may have no consequence in vivo but the observation of this phenomenpn has led to methods of clinical treatment of bone healing . The potentials produced may be of several milli-volts and are precisely associated with microscopical structural units of bone (osteons) so that it is not unreasonable to suppose some biological effect arising from them. It is known from blood compatibility studies that blood components are attracted to charged surfaces and in a similar way these strain generated potentials could influence macromolecular orientations in growing bone. ... 

Fig. 1 Hierarchical structural oigamzadon of bone (lefi to right) cortical and cancellous bone osteons with Haversian systems lamellae collagen fibre assemblies of collagen fibrils bone mineral crystals, collagen molecules and non-coUagenous proteins. Reprinted from [12] with permission from Elsevier...

Kazanci, M. et al (2006) Bone osteonal tissues by Raman spectral mapping orientation-composition. / Struct Biol, 156 (3), 489 -496. 

Most bones of the human skeleton are composed of two structurally distinct types of tissue compact (dense) and trabecular (cancellous, spongy) bone. Both types contain the same elements cells ( osteocytes) embedded in a mineralised matrix and connected by small canals ( canaliculi ). In compact bone, which makes up 85% of the skeleton, these components form elongated cylinders of concentric lamellae surrounding a central blood vessel (called osteon or Haversian system). Cancellous bone, in contrast, forms thin,... 

The geometry and structure of a bone consist of a mineralised tissue populated with cells. This bone tissue has two distinct structural forms dense cortical and lattice-like cancellous bone, see Figure 7.2(a). Cortical bone is a nearly transversely isotropic material, made up of osteons, longitudinal cylinders of bone centred around blood vessels. Cancellous bone is an orthotropic material, with a porous architecture formed by individual struts or trabeculae. This high surface area structure represents only 20 per cent of the skeletal mass but has 50 per cent of the metabolic activity. The density of cancellous bone varies significantly, and its mechanical behaviour is influenced by density and architecture. The elastic modulus and strength of both tissue structures are functions of the apparent density. 

Parfitt AM (1994) Osteonal and hemi-osteonal remodeling the spatial and temporal framework for signal traffic in adult human bone. J Cell Biochem 55 273-286... 

A section through a human toe bone (fifth metatarsal, amputated by Roger Gundle who took the pictures in 1.3) is shown in Fig. 9.18. The circular patterns relate to the Haversian system responsible for blood flow in the bone. The regions around the holes are osteons. The osteons appear with different contrast in this picture. As always this relates to different mechanical properties. In this case it enables you to distinguish the different ages of osteons, because the variation in contrast is related to different degrees of mineralization. 

Fig. 14.1. Raman spectrum of osteonal bone tissue. Major band assignments are marked. Reprinted with permission from [1]...

Fig. 14.3. (a) Bone section under polarized light, black line outlines where Raman images were acquired. Polarized Raman images of (b) phosphate V2/amide III, (c) phosphate Vi/amide I, and (d) carbonate/phosphate V2 band ratios at the interface between osteon and interstitial bone, (e and f) Three-dimensional view of phosphate Vi/amide I ratio for different polarization directions. Reprinted with permission from [1]... 

Figure 7. Strain amplification A plot of the strain amplification ratio er as a function of the load frequency for different load magnitudes. Strain amplification ratio is defined as the ratio of the hoop strain in the cell process membrane to the bone surface strain at the osteonal lumen, e is the strain on the whole bone s is the load on the whole bone. Previously published in You et al. (2001).

Zhang, D., Cowin, S.C., and Weinbaum, S. (1997) Electrical signal transmission and gap junction regulation in bone cell network a cable model for an osteon. Annals of Biomedical Engineering 25 357-374... 

Researchers are also exploring ways of using inorganic materials, especially those closely related to natural hone material, for artificial bone filling. Interpore International of Irvine, California, for example, received approval in 1992 for its hydroxyapatite-based hone substitute called Pro Osteon. The material is made from coral that has been heated to temperatures of about 2000°C to obtain hydroxyapatite (a primary component of coral) of 95 percent purity. The material is then formed into a scaffolding resembling natural bone, and this final product is irradiated with gamma rays to sterilize it. 

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