Trabecular architecture

Dicarboxymethyl chitosan and 6-oxychitin sodium salt, applied to femoral surgical defects for 3 weeks produced a good histoarchitectural order in the newly formed bone tissue. The spongious trabecular architecture was restored in the defect site. The association of the chitin derivatives with the osteoblasts seemed to be the best biomaterial in terms of bone tissue recovery [128]. 

On the other hand, Fukada et al.[5] found piezoelectricity properties in bone which was stressed. There are several reports [11,20,21] which are based on evidence that bone demonstrates a piezoelectric effect. This is used to explain the concept of stress- or strain-induced bone remodelling which is often refered to as Wolfs law[3]. Thus, bone converts mechanical stress to an electrical potential that influences the activity of osteoclasts and osteoblasts[l]. It is also known that the interior structure of bone(trabecular architecture) is arranged in compressive and tensile systems corresponding to the principal stress directions[4]. The role of the voltage signals induced in bamboo and palm we found may also be similar to the piezoelectric effect in bone. 

Spatially, the relatively high porosity of trabecular bone is in the form of a networic of interconnected pores filled with bone marrow. The trabecular tissue forms an irregular lattice of small rods and plates that are called trabeculae (Fig. 8.3). Typical thicknesses of individual trabeculae are in the range 100 to 300 /u.m, and t)rpical intertrabecular spacing is on the order of 500 to 1500 /u.m. The spatial arrangement of the trabeculae is referred to as the trabecular architecture. Architectural type varies across anatomic site and with age. Bone from the human vertebral body tends to be more rodlike, whereas bone from the bovine proximal tibia consists almost entirely of... 

McCalden, R. W., McGeough, J. A., and Court-Brown, C. M. (1997), Age-related changes in the compressive strength of cancellous bone The relative importance of changes in density and trabecular architecture, J. Bone Joint Surg. 79A(3) 421-427. 

The relationships between the static mechanical properties of trabecular bone and apparent density vary for the different types of trabecular bone because of the anatomic site-, age-, and disease-related variations in trabecular architecture. Both linear and power-law relationships can be used to describe the dependence of modulus and compressive strength on apparent density (Tables A2.2, A2.3), with typical coefficients of determination (r values) in the range 0.5-0.9. Differences in the predictive... 

Fig. 12.26 Threshold plot showing the strain magnitude (equivalent micro strains) disbibution within the bone micro architecture an open view of the implant-bone complex showing the local displacements (micromotions of the bone with respect to the implant) of the trabecular architecture right) [33]...

Figure 7.1. Early diagrams showing the relationship between stresses created by forces on bones and the internal architecture of the skeleton (a) Culmann s calculation of the stress trajectories in a crane, (b) Wolff s drawing of the trabecular orientation in the upper part of the femur, and (c) a photograph of the cross-section of the upper part of the femur.

Dysplasia This condition is defined as variably large, differentshaped hepatocytes, mostly in locahzed groups, with enlarged, pleomorphic and hyperchromatic nuclei as well as enlarged nucleoli. These dysplastic hepatocytes may often be polyploid. Dysplasia can occur as a macrocellular (with eosinophilic cytoplasm) or microcellular (with basophilic cytoplasm and increased proliferation) variant. The latter is considered to be a precancerous stage. Dysplastic foci with a diameter of l(-2) mm consist of enriched, predominantly small-cellular dysplastic hepatocytes. Dysplastic nodes with a diameter of 0.3-1.0 cm contain an atypical architecture and cellular atypias trabecular or pseudo-glandular structures are evident. Atypical hepatocytes are often clear-cellular, basophilic or steatotic. Fluent transition into HCC is seen occasionally. (87, 95)... 

Hepatocellular carcinoma (HCC) is the single most common histologic type of epithelial primary liver tumor. Architecturally, HCC may have a number of different patterns, the most common being a trabecular or plate-like pattern. Other patterns include acinar, pseudoglandular, scirrhous, clear cell, spindle cell, and pleomorphic. ... 

Figure 71.6 Distal femoral metaphysis and epiphysis (a) of a selenium-deficient rat 74 days old and (b) of selenium-adequate rats. The selenium-defioient rat shows a deteriorated trabecular bone architecture with fewer and thinner trabeculae in the epiphysis and metaphysis (Von Kossa stain magnifioation X11 bar = 1 mm). Reproduced with permission from Moreno-Reyes etai, (2001). The American Society for Bone and Mineral Research.

Chappard, D., Legrand, E., Haettich, N., Chales, G., Auvinet, B., Eschard, J.P., Hamelin, J.P., Basle, M.F. and Audran, M. (2001). Fractal dimension of trabecular bone comparison of three histomorphometric computed techniques for measuring the architectural two-dimensional complexity. J. Pathol., 195(4), 515-521. 

FIGURE 8.1 The four levels of bone microstructure, from the level of mineralized collagen fibrils to cortical and trabecular bone. It is generally assumed that at the former level, all bone is equal, although there may be subtle differences in the nature of the lamellar architecture and degree of mineralization between cortical and trabecular bone. Adaptedfrom Ref. 145.)... 

Majumdar, S., Kotharl, M., Augat, P., Newitt, D. C., Link, T. M Lin, J. C., Lang, T., Lu, Y., and Genant, H. K. (1998), High-resolution magnetic resonance imaging three-dimensional trabecular bone architecture and biomechanical properties. Bone 22(5) 445-454. 

Mosekilde, L. (1988) Age-related changes in vertebral trabecular bone architecture - Assessed by a new model. Bone, 9, 247-250. 

Trabecular or cancellous bone is spongy in nature and occupies about 20% of the total bone. Cancellous bone is lighter, less dense, has higher porosity (pores diameter varies from a few micrometers to millimeters), and a higher concentration of blood vessels than compact bone (also called cortical or dense bone) (Fig. 2). The porous architecture of cancellous bone is easily visible under the microscope or even with the naked eye because it contain very large pores. Cortical bone, which has less porosity and thus a lower concentration of blood vessels, occupies about 80% of the total bone. Due to its lower porosity, its porous architecture is not visible to the naked eye. The diameters of pores are 10-20 pm and mostly separated by 200-300 pm intervals. Spongy bone acts mainly in compression, whereas compact bone acts mechanically in torsion, tension, and compression. 

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