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American Journal of Physical... Sep 1998In order to preserve whole bone integrity and minimize destruction, paleohistologists often rely on histomorphometric data obtained from small areas (1.5-50 mm2) sampled...
In order to preserve whole bone integrity and minimize destruction, paleohistologists often rely on histomorphometric data obtained from small areas (1.5-50 mm2) sampled within the anterior mid-diaphyseal femur. Because bone exhibits significant histological variation, the validity of results based on such sampling is questionable. The accuracy of various subareas (columns, rows, squares approximating dimensions and locations assessed by paleohistologists) in predicting total osteon density in the anterior mid-diaphyseal femur is assessed in the present study. Thirty-five specimens (12.7 mm wide, 100 microm thick, average area 56.7 mm2) were chosen at random from a skeletal population of 94 Inuits and Pueblo agriculturists. The specimens were photographed and enlarged; an acetate grid (12 columns, 10 rows, 120 squares, square = 1 mm2 of bone surface) was superimposed over the photograph; and secondary osteons and fragments were identified. Alternate columns (50% total area, T.Ar) predicted over 98% of entire section total osteon density. Two column combinations (15% T.Ar), separated by at least one column, predicted 91 to 95% of total osteon density. Individual column (8% T.Ar) predictability ranged from 48 to 86%. Two row combination (32 to 40% T.Ar) predictability values ranged from 86 to 95%. Individual rows (<1 to 20% T.Ar) predicted from 45 to 92% of total variation. Combinations of squares approximating areas and locations assessed by other paleohistologists ranged in predictability values from 80 to 94%. The results demonstrate that subareas of as little as 15% predict 95% of variation in total osteon density in the entire anterior mid-diaphyseal femoral section. A minimization of histological area evaluated without the loss of accuracy allows for a minimization of time invested in data collection and the utilization of partially damaged specimens.
Topics: Adolescent; Adult; Bone Density; Bone Remodeling; Diaphyses; Femur; Haversian System; Humans; Indians, North American; Inuit; Middle Aged; Paleontology
PubMed: 9740298
DOI: 10.1002/(SICI)1096-8644(199809)107:1<13::AID-AJPA2>3.0.CO;2-E -
Journal of Biomechanics 1989A mathematical model for streaming potentials in an osteon is proposed, taking into account the microstresses in the vicinity of the Haversian Canal. With the help of...
A mathematical model for streaming potentials in an osteon is proposed, taking into account the microstresses in the vicinity of the Haversian Canal. With the help of the finite element method, a boundary problem for the fluid pressure amplitude in the osteon is investigated when the bone sample is subjected to harmonic loading. A numerical analysis of the intra-osteonal potential is performed. It is found that there exists an azimuthal asymmetry which increases with the enlargement of the Haversian Canal. The results of the numerical modeling of the intra-osteonal potential are in accordance with the available experimental data.
Topics: Action Potentials; Animals; Extracellular Space; Haversian System; Humans; Mathematics; Models, Biological; Pressure; Stress, Mechanical
PubMed: 2808436
DOI: 10.1016/0021-9290(89)90002-x -
Bone May 2012There is little information on the distribution of osteocytes within the individual cortical osteon, but using direct 3-D imaging in a single subject, Hannah et al....
Osteocyte recruitment declines as the osteon fills in: interacting effects of osteocytic sclerostin and previous hip fracture on the size of cortical canals in the femoral neck.
There is little information on the distribution of osteocytes within the individual cortical osteon, but using direct 3-D imaging in a single subject, Hannah et al. found a gradient with a two-fold higher density of cells adjacent to the cement line compared to near the canal. Since a limiting factor for bone formation might be the availability of osteoblasts due to their recruitment as osteocytes, we studied distributions of osteonal osteocytes in frozen sections of the femoral neck cortex. Osteocytes were stained with an anti-sclerostin antibody and counter-stained with toluidine blue. Adjacent sections were stained for alkaline phosphatase (ALP). Each osteonal osteocyte was categorised as being sclerostin-positive (scl+) or negative (scl-). ImageJ was used to measure the perimeter and area of each osteon and canal, while special purpose routines were used to measure the minimum distances of each osteocyte from the cement line and the canal. Canal area was strongly correlated with osteon area. Osteocytes were most dense close to the cement line; and their areal density within the matrix declined up to three-fold between the cement line and the canal, depending on osteon diameter. Large and small osteons had similar densities of osteocytes close to the cement line, but fractured neck of femur cases had significantly lower densities of osteocytes close to the canal. Higher osteocyte density close to the canal was associated with ALP expression. It is concluded that entombment of osteocytes newly drawn from the osteoblast pool into the mineralising matrix is independent of preceding bone resorption depth. As osteonal infilling proceeds, osteocyte formation declines more rapidly than matrix formation, leading to a progressive reduction in osteocyte density. A shrinking supply of precursor osteoblasts due to previous osteocyte recruitment, apoptosis, or both could produce this effect. In a statistically significant contrast, sclerostin negative osteocytes adjacent to the canal had the expected effect of reducing canal size in controls but this was not seen in hip fracture. This demonstrated the failure of osteonal osteoblasts to sustain bone formation through a complete remodelling cycle in osteoporosis, perhaps due to insufficient osteoblasts remaining capable of mineralized matrix formation. The failure of osteocytic sclerostin suppression to associate with bone formation in these osteons might alternatively be explained by downstream interference with sclerostin's effect on wnt signalling.
Topics: Adaptor Proteins, Signal Transducing; Aged; Bone Morphogenetic Proteins; Cell Count; Cell Death; Female; Femur Neck; Genetic Markers; Haversian System; Hip Fractures; Humans; Male; Microscopy, Polarization; Models, Biological; Organ Size; Osteocytes
PubMed: 22353552
DOI: 10.1016/j.bone.2012.01.016 -
Journal of Anatomy May 2016Intracortical remodeling, and the osteons it produces, is one aspect of the bone microstructure that is influenced by and, in turn, can influence its mechanical...
Intracortical remodeling, and the osteons it produces, is one aspect of the bone microstructure that is influenced by and, in turn, can influence its mechanical properties. Previous research examining the spatial distribution of intracortical remodeling density across the femoral midshaft has been limited to either considering only small regions of the cortex or, when looking at the entirety of the cortex, considering only a single individual. This study examined the spatial distribution of all remodeling events (intact osteons, fragmentary osteons, and resorptive bays) across the entirety of the femoral midshaft in a sample of 30 modern cadaveric donors. The sample consisted of 15 males and 15 females, aged 21-97 years at time of death. Using geographic information systems software, the femoral cortex was subdivided radially into thirds and circumferentially into octants, and the spatial location of all remodeling events was marked. Density maps and calculation of osteon population density in cortical regions of interest revealed that remodeling density is typically highest in the periosteal third of the bone, particularly in the lateral and anterolateral regions of the cortex. Due to modeling drift, this area of the midshaft femur has some of the youngest primary tissue, which consequently reveals that the lateral and anterolateral regions of the femoral midshaft have higher remodeling rates than elsewhere in the cortex. This is likely the result of tension/shear forces and/or greater strain magnitudes acting upon the anterolateral femur, which results in a greater amount of microdamage in need of repair than is seen in the medial and posterior regions of the femoral midshaft, which are more subject to compressive forces and/or lesser strain magnitudes.
Topics: Adaptation, Physiological; Adult; Aged; Aged, 80 and over; Bone Remodeling; Female; Femur; Haversian System; Humans; Image Processing, Computer-Assisted; Male; Middle Aged; Stress, Mechanical; Young Adult
PubMed: 26708961
DOI: 10.1111/joa.12433 -
Anatomical Record (Hoboken, N.J. : 2007) Sep 2011An important hypothesis is that the degree of infilling of secondary osteons (Haversian systems) is controlled by the inhibitory effect of osteocytes on osteoblasts,... (Comparative Study)
Comparative Study
An important hypothesis is that the degree of infilling of secondary osteons (Haversian systems) is controlled by the inhibitory effect of osteocytes on osteoblasts, which might be mediated by sclerostin (a glycoprotein produced by osteocytes). Consequently, this inhibition could be proportional to cell number: relatively greater repression is exerted by progressively greater osteocyte density (increased osteocytes correlate with thinner osteon walls). This hypothesis has been examined, but only weakly supported, in sheep ulnae. We looked for this inverse relationship between osteon wall thickness (On.W.Th) and osteocyte lacuna density (Ot.Lc.N/B.Ar) in small and large osteons in human ribs, calcanei of sheep, deer, elk, and horses, and radii and third metacarpals of horses. Analyses involved: (1) all osteons, (2) smaller osteons, either ≤150 μm diameter or less than or equal to the mean diameter, and (3) larger osteons (>mean diameter). Significant, but weak, correlations between Ot.Lc.N/B.Ar and On.W.Th/On.Dm (On.Dm = osteon diameter) were found when considering all osteons in limb bones (r values -0.16 to -0.40, P < 0.01; resembling previous results in sheep ulnae: r = -0.39, P < 0.0001). In larger osteons, these relationships were either not significant (five/seven bone types) or very weak (two/seven bone types). In ribs, a negative relationship was only found in smaller osteons (r = -0.228, P < 0.01); this inverse relationship in smaller osteons did not occur in elk calcanei. These results do not provide clear or consistent support for the hypothesized inverse relationship. However, correlation analyses may fail to detect osteocyte-based repression of infilling if the signal is spatially nonuniform (e.g., increased near the central canal).
Topics: Adult; Animals; Bone Remodeling; Bone and Bones; Deer; Extremities; Haversian System; Horses; Humans; Male; Osteocytes; Ribs; Sheep; Young Adult
PubMed: 21809466
DOI: 10.1002/ar.21452 -
American Journal of Physical... Jun 2013Studies of secondary osteons in ribs have provided a great deal of what is known about remodeling dynamics. Compared with limb bones, ribs are metabolically more active...
Studies of secondary osteons in ribs have provided a great deal of what is known about remodeling dynamics. Compared with limb bones, ribs are metabolically more active and sensitive to hormonal changes, and receive frequent low-strain loading. Optimization for calcium exchange in rib osteons might be achieved without incurring a significant reduction in safety factor by disproportionally increasing central canal size with increased osteon size (positive allometry). By contrast, greater mechanical loads on limb bones might favor reducing deleterious consequences of intracortical porosity by decreasing osteon canal size with increased osteon size (negative allometry). Evidence of this metabolic/mechanical dichotomy between ribs and limb bones was sought by examining relationships between Haversian canal surface area (BS, osteon Haversian canal perimeter, HC.Pm) and bone volume (BV, osteonal wall area, B.Ar) in a broad size range of mature (quiescent) osteons from adult human limb bones and ribs (modern and medieval) and various adult and subadult non-human limb bones and ribs. Reduced major axis (RMA) and least-squares (LS) regressions of HC.Pm/B.Ar data show that rib and limb osteons cannot be distinguished by dimensional allometry of these parameters. Although four of the five rib groups showed positive allometry in terms of the RMA slopes, nearly 50% of the adult limb bone groups also showed positive allometry when negative allometry was expected. Consequently, our results fail to provide clear evidence that BS/BV scaling reflects a rib versus limb bone dichotomy whereby calcium exchange might be preferentially enhanced in rib osteons.
Topics: Adult; Aged; Animals; Anthropology, Physical; Anthropometry; Bone Remodeling; Bone and Bones; Female; Haversian System; Humans; Linear Models; Male; Middle Aged
PubMed: 23633395
DOI: 10.1002/ajpa.22270 -
Zeitschrift Fur Orthopadie Und Ihre... 1983In a previous study the biochemical data of 45 metacarpal and 36 phalangeal bones of 21 male cadavers (24-69 years of age) were obtained by fracturing in a bending test....
In a previous study the biochemical data of 45 metacarpal and 36 phalangeal bones of 21 male cadavers (24-69 years of age) were obtained by fracturing in a bending test. The present study attempts of correlate these data with the compacta area, the number of osteons, and the cross sectional area of the osteons. The relative and absolute number of osteons increase significantly with increasing age, whereas the average thickness of the compacta decreases significantly. The calibre of the bone marrow cavity increases with age. There is no correlation between age and osteon diameter. Ultimate bending deflection, bending breaking load, and breaking energy decrease following a reduction in compacta thickness or in the cross sectional area of the compacta. Bending tests on whole bones indicate that it is not so much bone tissue morphology, but rather the relationship of the marrow area to the total cross sectional area which is the significant factor in the bending behaviour of the whole bone.
Topics: Adult; Age Factors; Aged; Biomechanical Phenomena; Bone and Bones; Fingers; Haversian System; Humans; Male; Metacarpus; Middle Aged; Tensile Strength
PubMed: 6666243
DOI: 10.1055/s-2008-1053293 -
American Journal of Physical... Aug 2003At the microstructural level, bones remodel throughout life. This process is recorded in bone cortex as osteons. A more comprehensive understanding of the interaction... (Comparative Study)
Comparative Study
At the microstructural level, bones remodel throughout life. This process is recorded in bone cortex as osteons. A more comprehensive understanding of the interaction between genetic regulation and environmental factors in osteon remodeling will increase the value of this skeletal record and enable more accurate reconstruction of individual life histories. The purpose of this study was to examine the contribution of maternal lineage to normal age and sex variation in osteon remodeling dynamics in Macaca mulatta. Femoral cross sections from 57 Cayo Santiago-derived rhesus macaques representing five matrilines were examined to evaluate the effect of genetic relatedness on osteon remodeling dynamics. Analysis of variance revealed an effect of maternal lineage on osteon area and Haversian canal area. The other variables did not differ significantly among matrilines. Analysis of covariance revealed no significant interactions among age, sex, and matriline for any of the microstructural variables.
Topics: Age Factors; Analysis of Variance; Animals; Bone Remodeling; Female; Femur; Haversian System; Inheritance Patterns; Macaca mulatta; Male; Sex Factors
PubMed: 12884317
DOI: 10.1002/ajpa.10208 -
Anatomical Science International Sep 2011The collagen architecture of secondary osteons was studied with scanning electron microscopy (SEM) employing the fractured cortex technique and osmic maceration....
The collagen architecture of secondary osteons was studied with scanning electron microscopy (SEM) employing the fractured cortex technique and osmic maceration. Fibrillar orientation and the change in their direction in sequential lamellae was documented where lamellar formation was ongoing, as well as in resorption pits where osteoclasts had exposed the collagen organisation of the underlying layers. Applying an adaptive stereo matching technique, the mean thickness of matrix layers removed by osteoclasts was 1.36 ± 0.45 μm. It was also documented that osteoclasts do not attack the cellular membrane of the exposed osteocytes. The mean linear osteoblast density in fractured hemicanals was assessed with SEM and no significant differences were observed comparing larger with smaller central canal osteons. These findings suggested a balance between the differentiated osteoblasts that have aligned on the surface of the cutting cone and those that are transformed into osteocytes, because the canal surface is progressively reduced as the lamellar apposition advances.
Topics: Animals; Bone Remodeling; Fibrillar Collagens; Haversian System; Male; Microscopy, Electron, Scanning; Rabbits
PubMed: 21213094
DOI: 10.1007/s12565-010-0099-x -
Computer Methods in Biomechanics and... 2014
Topics: Biomechanical Phenomena; Computer Simulation; Elasticity; Haversian System; Humans; Models, Biological
PubMed: 25074146
DOI: 10.1080/10255842.2014.931078