Haversian Canal Area Research Articles

The effect of caponization on tibia bone histomorphometric properties of crossbred roosters

The negative effect of caponization on the structural, geometric and mechanical parameters of femur and tibia has been shown in a few studies. Nevertheless, its influence on tibia bone microarchitecture is still largely unknown. Therefore, this study aimed to assess the effect of castration on the microstructural parameters of the trabecular and compact bone of tibia bone in crossbred chickens. The experiment involved 96 roosters derived from crossing Yellowleg Partridge hens (Z˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\dot{\ ext{Z}}}$$\\end{document}-33) and Rhode Island Red cockerels (R-11) fattened until the 16th, 20th and 24th week of life. Animals were randomly divided into 2 groups of 48 each. Group I (control) consisted of intact roosters and group II (experimental) consisted of birds subjected to caponization at the 8th week of age. The castration surgery had no influence on some properties within compact bone such as osteon diameter On.Dm, osteon perimeter On.Pm, osteon area On.Ar, osteocyte lacunar number Ot.Lc.N, osteon bone area On.B.Ar, osteon wall thickness On.W.Th as well as thick-mature collagen content in all analyzed age groups of animals. Nevertheless, our results demonstrate that castration caused a decrease of Haversian canal area Hc.Ar, osteocyte lacunar area Ot.Lc.Ar and osteocyte lacunar porosity Ot.Lc.Po among the 16-week-old birds, decrease of Haversian canal perimeter Hc.Pm and increase of fraction of bone area On.B.Ar/On.Ar among 16- and 24-week-old individuals and also an increase of osteocyte lacunar density Ot.Lc.Dn in the osteons of the oldest roosters. Additionally, some microstructural parameters of trabecular bone show the negative effect of caponization. The youngest 16-week-old capons were characterized by thinnin the trabecular in the epiphysis part of tibia. Moreover, in the case of 24-week-old, there is an increase in the trabecular separation Tb.Sp with simultaneous decrease of trabecular number Tb.N compared to roosters, which may suggest the increase of the bone resorption among the oldest individuals. The increased bone turnover in the epiphysis part of the tibia bone also indicates changes in the collagen fibers distribution, where among 20-week-old animals there is a decrease in the content of immature thin collagen fibers with simultaneous increase in the content of mature thick collagen fibers. Furthermore, among the oldest 24-week-old individuals we can observe the increased thick-to-thin collagen ratio, which may be a sign of slowing down in bone formation.

Age-dependent change and intraskeletal variability in secondary osteons of elderly Australians.

There is a need to fully understand intra-skeletal variability within different populations to develop and improve age-at-death estimation methods. This study evaluates age-related histomorphometric changes in three different bones intra-individually in a modern Australian sample. Four female and 13 male elderly Australian adult donors (67-93 years) were examined for osteon population density (OPD), osteon area (On.Ar), and Haversian canal area (H.Ar) of secondary osteons to compare between femora, ribs, and humeri and assess against age. In the pooled sex sample, no statistically significant correlations were observed between age and each histological variable. In the males, OPD of the femur increased significantly with age, as did porosity in the rib. In the male humeri, OPD increased moderately with age, while H.Ar was decreased moderately with age. Intra-bone comparisons showed that males had significantly higher osteon counts in their ribs compared to their femora, while their ribs showed statistically significantly less porosity than their humeri. When bone size was accounted for, by adjusting the femur and humerus histology data by robusticity indices, histology values were found to be similar between bones within the same individual. This is despite the upper and lower limbs receiving different ranges and types of biomechanical load. Our findings demonstrate that bone size influences histomorphometry, and this could confound age-at-death estimations that have not been adjusted for robusticity. Future studies would benefit from examining bone histomorphometry within a larger sample size and incorporating bone robusticity measures into histology analyses.

Heat-induced changes in the histomorphometry of human femur bone

ABSTRACT Background: Skeletal remains are often subjected to unexpected and adverse conditions which can eventually distort evidence. Therefore, understanding the factors that alter skeletal remains is crucial. Methods: A total of human femur fragments obtained from the gross anatomy laboratory of the University of Port Harcourt were used. Bone samples were divided into four groups. Group 1 is the control sample comprising bone fragments not exposed to heat, Group 2 had bones exposed to heat at 20°C, Group 3 had bones exposed to heat at 100°C, and Group 4 had bones exposed to heat at 200°C. Ground bone sections were prepared using Modified Frost’s manual method of bone preparation. Morphometric analysis of the micrographs was performed using the ImageJ software. Results: Data were analyzed using the SPSS software. The mean values of the Haversian canal area and diameter demonstrated a nonsignificant increase in the bone samples exposed to heat compared to the samples not exposed to heat. The osteon count was slightly higher, but the difference was not statistically significant (P > 0.05). Conclusion: The results demonstrated that histomorphometric features of bones are not altered at the temperature of 200°C. This information is useful in forensic investigations.

The Effects of Prolonged Treatment with Cemtirestat on Bone Parameters Reflecting Bone Quality in Non-Diabetic and Streptozotocin-Induced Diabetic Rats.

Cemtirestat, a bifunctional drug acting as an aldose reductase inhibitor with antioxidant ability, is considered a promising candidate for the treatment of diabetic neuropathy. Our study firstly examined the effects of prolonged cemtirestat treatment on bone parameters reflecting bone quality in non-diabetic rats and rats with streptozotocin (STZ)-induced diabetes. Experimental animals were assigned to four groups: non-diabetic rats, non-diabetic rats treated with cemtirestat, diabetic rats, and diabetic rats treated with cemtirestat. Higher levels of plasma glucose, triglycerides, cholesterol, glycated hemoglobin, magnesium, reduced femoral weight and length, bone mineral density and content, parameters characterizing trabecular bone mass and microarchitecture, cortical microarchitecture and geometry, and bone mechanical properties were determined in STZ-induced diabetic versus non-diabetic rats. Treatment with cemtirestat did not affect all aforementioned parameters in non-diabetic animals, suggesting that this drug is safe. In diabetic rats, cemtirestat supplementation reduced plasma triglyceride levels, increased the Haversian canal area and slightly, but insignificantly, improved bone mineral content. Nevertheless, the insufficient effect of cemtirestat treatment on diabetic bone disease does not support its use in the therapy of this complication of type 1 diabetes mellitus.

The Effects of Experimental Whole-Body Burning on Histological Age-at-Death Estimation from Human Cortical Bone and Dental Cementum.

Whole-body donations (n = 6) were placed in various experimental fire-death scenarios to understand the histological effects of thermal alteration on bones and teeth. Midshaft samples of the femur, 6th rib, and metatarsal were removed from each donor pre- and post-burning to examine histomorphometric differences and test established age-at-death estimation methods. Dental samples were taken post-burning to test the applicability of dental cementum analysis for age-at-death estimation. Significant differences in osteon area or Haversian canal area between some pre- and post-burn samples were found although no patterns related to temperature or element were observable. The femoral age estimates across pre- and post-burn samples were 91% accurate across all donors. The point age estimates from the ribs compared to known age were significantly different (t(10) = 6.88, p < 0.001) with an average difference of -18.53 years. Dental age estimates of post-burn samples were not significantly different from the known donor age (t(3) = -0.74, p = 0.512) with an average difference of -3.96 years. Overall, the results of this study show that thermally altered remains can be used for histologic age-at-death analysis of cortical bone and dental cementum, within certain burning parameters.

Sex Estimation From Histomorphometric Analysis of Cortical Bone: A Hospital-based Study

Estimation of the sex of unknown skeletal remains is a daunting challenge, when only fragmented bones are available. For this reason, there is a need to study population specific histomorphometric features of bones to provide useful data for the process of identification. The purpose of this study was to estimate sex from six histomorphometric parameters of cortical bones in a cohort of Nigerian patients. The samples comprised non-pathologic bones collected from 29 patients (12 females and 17 males) between the ages of 35 to 85 years during orthopaedic procedures. The modified Frost’s manual method was used to prepare the histological sections of the cortical bones. The parameters evaluated were number of primary osteons (Os-p), number of secondary osteons (Os-s), osteon fragments (Os-f), non-Haversian canal (N-Hc), area of Haversian canal (Area Hc), and Haversian canal diameter (HCD). The data obtained were analyzed using SPSS version 23.0. Tests for sex differences were done using student t-test and stepwise discriminant function was used to formulate a predictive model for sex estimation. The mean Os-p, Os-s, Os-f, N-hc, Area HC, and HCD were 2.85 ± 0.86,3.92 ± 1.26,6.08 ± 1.37, 2.23 ± 0.66, 53.43 ± 5.55, and 7.85 ± 0.41 for males and 1.11 ± 0.56, 0.33 ± 0.17, 2.44 ± 0.67, 54.37 ± 6.04 and 7.426 ± 0.35 for females, respectively. The mean value of Os-s was significantly different in males and females (p=0.04). Stepwise discriminant function analysis showed Os-s could be used to estimate sex. 71.4% of our samples were correctly predicted based on sex. Discriminant function values of 0.418 and -0.626 were predictive values for males and females, respectively, using the DFA predictive model. Our study shows that the number of secondary osteons (Os-s) could be used to estimate sex in Nigerian patients.

Soil pH effect on bone degradation: Implications in forensic investigation

Background: Skeletal remains have become the mainstay in forensic investigations. Hence, it is imperative to study bone degradation and some influencers as to guide forensic practices. The purpose of this study was to determine the effect of soil pH on bone degradation. Methods: One-centimeter diameter sections of the mid-shaft of the femur of a male cadaver were buried for the duration of 6 weeks in soils of different pH: 2.98 for the acidic soil, 7.10 for the neutral soil, and 11.58 for the alkaline soil. Histological sections of the exhumed bones were prepared using Frost’s rapid manual method. Four fields of view at 12 o’clock, 3 o’clock, 6 o’clock, and 9 o’clock positions were obtained for each section. Results: Quantitative analysis showed that there was a reduction in the mean Haversian canal area (HCA) and Haversian canal diameter (HCD) in the samples of bone fragments buried in the acidic and alkaline soil when compared with control. The acidic soil sample showed a mean HCA and HCD of 130.58 μm and 12.24 μm as against 136.83 μm and 12.48 μm of the control, whereas the alkaline soil sample showed a mean HCA and HCD of 122.70 μm and 11.70 μm, respectively. Statistical analysis showed a significant difference in the HCA and HCD (P ≤ 0.05). Conclusion: The result of this study suggests that the extreme of soil pH can cause the weathering of bone, which can distort the histomorphometry. The study focused on the extremes of pH and not various scales. This should help guide forensic investigations.

HISTOMORPHOMETRIC ESTIMATION OF AGE FROM BONE SAMPLES OF NIGERIANS

Background. Age estimation is crucial in creating the biological profile of unknown skeletal remains and recently there is emphasis on the need to develop population specific forensic baseline data for easy identification of these remains. Objective. The aim of this study is to estimate age from the histomorphometric features of the bones of Nigerians. Methods. Fragments of non-pathologic bone samples were collected during orthopaedic procedures. Ground sections were prepared using Modified Frost’s manual method of bone preparation to determine the following histologic parameters; haversian canal diameter (HCD), primary and secondary osteons, number of osteon fragments and non-haversian canal as well as haversian canal area (HCA). 29 subjects aged 35 to 85 years old were used for the study. Bone fragments included samples from the femur, tibia, humerus, and the vertebrae. Data obtained were subjected to descriptive statistics, Pearson’s correlation, bivariate regression equation, Student t-test and analysis of variance (ANOVA). Results. The mean age for our population was 58.86 years old. ANOVA showed significant variation in the average HCD for the various regions: humerus=8.45±2.48, femur=7.09±4.06, tibia=8.70±2.52 and verte­brae=3.69±0.73. There was a strong inverse relationship between age and primary osteons. The total number of osteon fragments increased with age while total number of primary osteons and average HCD decreased with age. The HCA, though statistically insignificant, also decreased with age. Conclusion. Our findings show that three histomorphometric parameters showed significant correlation with age: osteon fragments (OS-f), primary osteons (OS-p) and HCD. The histomorphometric parameters were therefore relevant in age estimation. Objective: The aim of this study is to estimate age from the histologic features of the bones of Nigerians. Methods: Fragments of non-pathologic bone samples were collected during orthopaedic procedures. Ground sections were prepared using Modified Frost’s manual method of bone preparation to determine the following histologic parameters; haversian canal diameter (HCD), primary and secondary osteons, number of osteon fragments and non haversian canal as well as haversian canal area (HCA). 29 subjects aged 35 to 85 years were used for the study. Bone fragments included samples from the femur, tibia, humerus, and the vertebrae. Data obtained were subjected to descriptive statistics, Pearson’s correlation, bivariate regression equation, student t-test and Analysis of variance (ANOVA). Results: The mean age for our population was 58.86 years. ANOVA shows significant variation in the average HCD for the various regions: humerus=8.45±2.48, femur=7.09±4.06, tibia=8.70±2.52 and vertebrae=3.69±0.73. There is a strong inverse relationship between age and primary osteons. The total number of osteon fragments increased with age while total number of primary osteons and average HCD decreased with age. The HCA though statistically insignificant, also decreased with age. Conclusion: Our findings show that three histomorphometric parameters showed significant correlation with age: osteon fragments (OS-f), primary osteons (OS-p) and HCD. The histomorphometric parameters are therefore relevant in age estimation. Key words: Age estimation, Histomorphometric parameters, Nigerians, Forensics

Secondary osteon variants and remodeling in human bone.

Histomorphometric analysis of human cortical bone has documented the occurrence of secondary osteon variants. These include drifting osteons which form tails as they move erratically through the cortex and Type II osteons which show partial resorption and redeposition within the cement line of the osteon. Little is known about the biological significance of these variants. Prior studies suggested correlations with age, biomechanics, diet, and mineral homeostasis. No study has yet tested for osteon variant associations with static measures of bone remodeling. In this study, thin sections (n= 112) of the posterior femur representing a late English Medieval adult human osteological collection, subdivided by age, sex, and socio-economic status, were examined to determine whether remodeling indicators reconstructed from osteon parameters (area, diameter, area ratios) and densities differed between categories of presence or absence of Type II and drifting osteon variants. Of the 112 sections, 33 presented with Type II osteons, and 38 had drifting osteons. Sporadic statistically significant results were identified. Haversian canal:osteon area ratio differed (p= 0.017) with Type II osteon presence, Type II osteons were more prevalent in males than females (p= 0.048), and drifting osteons were associated with smaller osteon (p= 0.049) and Haversian canal area (p= 0.05). These results may be explained through some biological (sex) and social (status) processes such as a period of physiological recovery (e.g., following lactation, malnutrition). However, the general lack of consistent relationships between osteon variants and remodeling indicators suggests they occur as a result of natural variation.

An examination of histomorphometric relationships in the anterior and posterior human femoral cortex.

Static cortical bone histomorphometry utilised in forensic age-at-death estimation generally examines only the anterior femoral mid-shaft, as biomechanical strain at the posterior femur is thought to result in increased bone remodelling, osteon density and adversely affect age-at-death estimates. As osteon density increases there is a corresponding decrease in geometric variables, such as osteon area and Haversian canal diameter. The present study tests whether the inverse relationship between osteon density and osteon geometry is reflected in a modern documented Australian sample, and if this relationship differs between the anterior and posterior femoral mid-shaft. The study sample comprises 215 femoral microradiographs (117♂ 98♀) of recorded age (18‒97years) from the Melbourne Femur Reference Collection (MFRC). The following variables were measured in Image J across six 1mm2 regions of interest (ROIs) from the anterior and posterior; mean intact and fragmentary secondary osteon count, osteon population density, osteon and Haversian canal area, perimeter, and diameter. Osteon area was positively correlated with Haversian canal size and shape metrics, and negatively correlated with osteon density. Chronological age was significantly correlated with most variables. There were significant between-group effects between the youngest (18‒34years) and all other age groups (35‒49, 50-74 and 75 + years) for both regions. Our findings support an increased rate of remodelling associated with decreases in osteon geometry in the anterior and posterior femur. Future studies should examine static osteon histomorphometry using anterior and posterior measurements in larger samples of documented age and sex.

Using histomorphometry for human and nonhuman distinction: A test of four methods on fresh and archaeological fragmented bones

Positive identification of human remains is the very first step in anthropological analysis, and the task may be particularly difficult in the case of fragmented bones. Histomorphometry methods have been developed to discriminate human from nonhuman bones, based on differences in the size and shape of Haversian systems between the two groups. Those methods all focus on a very specific type of bone, section, and zone. Therefore, the objective of this study was to test the efficiency of four histomorphometric methods on a sample of fragmented bones. The sample is composed of 37 archaeological and fresh specimens, 25 nonhumans (Bos taurus, Equus caballus, Sus scrofa, Capreolus, Canis familiaris, Cervus elaphus, Ovis, and Capra) and 12 humans (Homo sapiens). Eight histomorphometric criteria were collected from all intact osteons visible on each fragment and then inserted into the corresponding discriminate function of each method. The results were compared with the real origin to establish rates of correct classification for each method. The methods of Martiniaková et al. (2006) and Crescimanno and Stout (2012) obtained very low percentages of good classification (32 % and 67 %). Those of Cattaneo et al. (1999) obtained 94 % correct classification, but only after a correction of the units of measurement for Haversian canal area in their formula. The methods of Dominguez and Crowder (2012) obtained an 86 % rate for well-classified specimens. Some of the methods tested here contain errors in the original publication that make them unusable in their current state. Plus, it seems that histomorphometric methods developed from specific areas are more difficult to apply to fragments. A reduced number of intact osteons analyzed may partially affect the reliability of the method by being unrepresentative of the entire microstructure. Therefore, this study demonstrates that one should be cautious with the use of histomorphometric methods to distinguish human and nonhuman fragmented bone until further research can refine these methods to achieve greater reliability.

Relation between cross-sectional bone geometry and double zonal osteon frequency and morphology.

While double-zonal osteons (DZ) are characterized by a hyper-mineralized ring inside their lamellae, recent findings suggest that this ring is also defined by a change in the collagen fibers' orientation. Collagen and minerals are essential components to the maintenance of adequate bone strength and their alteration can modify the mechanical properties of the bone tissue. Consequently, the aim of this study is to explore the effect of past loads, as estimated from cross-sectional geometric properties, on the formation of DZ osteons compared to type I (common) osteons. The sample consists of paired humerus and femur midshaft sections (n = 23) of Eurocanadian settlers from the historical St. Matthew cemetery, Quebec City (1771-1860). Histomorphometric variables included in this study are osteon density for DZ and type I osteons (DZD; OPD), osteon area (DZOn.Ar; On. Ar), Haversian canal area (DZH.Ar; H.Ar), and the area within the hypermineralized ring (HR. Ar). Loading history is estimated from cross-sectional properties including the following variable: cortical and total area (CA, TA), maximum and minimum second moment of area (Imax , Imin ) and polar moment of area (J). When the humerus and femur of the same individuals are compared, the femur has a higher OPD, DZD, and relative DZD (DZD/OPD). DZ osteons have a smaller area and Haversian canal area compared to type I osteons. The area within the hypermineralized ring in DZ is higher than the Haversian canal area of the type I osteons. Correlations between the residual scores of the regression of histomorphometric variables and cross-sectional properties of the humerus on the femur were not significant. Based on the analysis of the entire cross-section, the lack of correlation between variations in cross-sectional properties and remodeling combined with the significant differences between humeri and femura suggests that the creation of DZ or type I osteons in the bone tissue might be due to a bone specific response, possibly related to differences in bone tissue age that needs to be further investigated. Definitive conclusion regarding biomechanical loads still seem to be premature as regional variations associated with mechanical properties remain to be explored.

Microscopic markers of an infradian biorhythm in human juvenile ribs

Recent studies have indicated that there may be an infradian systemic biorhythm that coordinates aspects of human hard tissue growth and influences adult body size. Here we investigate if evidence of this biorhythm retained in human teeth as the periodicity of Retzius lines (RP) corresponds with the microstructural growth of a non-weight bearing bone, the rib, in a sample of 50 human juvenile skeletons. Using static histomorphometric methods, the RP of one permanent tooth from each skeleton was calculated and combined with measures of bone remodeling in a rib from the same individual. Results provide the first evidence that the infradian biorhythm is linked to bone remodeling in children. Retzius periodicity was negatively correlated with relative osteon area (r = -0.563, p = 0.008) and positively related to Haversian canal area (r = 0.635, p = 0.002) and diameter (r = 0.671, p = 0.001) in children between the age of 8 to 12 years. There was also a negative correlation between RP and the relative cortical area of ribs (r = -0.500, p = 0.048). Relationships between bone remodeling and the biorhythm were much more variable in younger children. Results imply that as the biorhythm speeds up there is increased bone deposition during remodeling of the rib, leading to the larger osteonal lamellar bone areas and smaller Haversian canals in children between 8 and 12 years of age. Our results support the idea that there is an infradian biorhythm that coordinates aspects of human hard tissue growth.

Age regression for Malaysian males using cortical bone Histomorphometry

Bone microstructures have the capability to record the variations in its structure that occur during the life span. These variations can be analysed to estimate human age at death. This study analysed 30 Malaysian male samples in order to create a regression equation for age estimation. Bone samples were collected from human long bones i.e humerus, radius, ulna, tibia, fibula and femur. Two morphological and five histological variables were selected for analysis. Cortical thickness and medullar cavity diameter did not show any significant relation with increasing age however haversian canal parameters and osteon count showed significant correlation with age. Regression equation with lowest SEE 7.2 was based on Haversian canal area, haversian canal radius and osteon count. The regression equation estimated age at death within 10 years of range for 85% samples. The mean value of the known ages was 39.8 years while the mean value of the estimated ages was 37.03 years. Increasing number of samples including female samples for further research might produce promising results.

Secondary osteons scale allometrically in mammalian humerus and femur.

Intra-cortical bone remodelling is a cell-driven process that replaces existing bone tissue with new bone tissue in the bone cortex, leaving behind histological features called secondary osteons. While the scaling of bone dimensions on a macroscopic scale is well known, less is known about how the spatial dimensions of secondary osteons vary in relation to the adult body size of the species. We measured the cross-sectional area of individual intact secondary osteons and their central Haversian canals in transverse sections from 40 stylopodal bones of 39 mammalian species (body mass 0.3–21 000 kg). Scaling analysis of our data shows that mean osteonal resorption area (negative allometry, exponent 0.23,R2 0.54,p<0.005) and Haversian canal area (negative allometry, exponent 0.31,R2 0.45,p<0.005) are significantly related to body mass, independent of phylogeny. This study is the most comprehensive of its kind to date, and allows us to describe overall trends in the scaling behaviour of secondary osteon dimensions, supporting the inference that the osteonal resorption area may be limited by the need to avoid fracture in smaller mammalian species, but the need to maintain osteocyte viability in larger mammalian species.

Differences in osteon structure histomorphometry between puppyhood and adult stages in the Golden Retriever.

Osteon structure has been widely studied in mammals, but osteon structure in dogs has received relatively little attention, especially in terms of whether aging has any effect on osteon structure. The aim of this study was to compare the osteon structure of both flat (scapula and os coxae) and long bones (humerus, radius, ulna, metacarpus, femur and tibia) of male puppy and adult Golden Retrievers. We examined five parameters: Haversian canal diameter, Haversian canal area, osteon diameter, osteon area, and number of lacunae per osteon. Our results show that the values for Haversian canal diameter were significantly higher in the os coxae and tibia, but significantly lower in the femur of adult dogs as compared to those of puppies. The Haversian canal diameter of the other bones investigated did not show any significant differences between puppies and adult dogs. The Haversian canal area was significantly greater in the os coxae, radius and femur of adult dogs than in those of puppies. The osteon diameter and area of every bone examined were significantly smaller in puppies than in adult dogs. Lastly, the number of lacunae per osteon showed the same trend as osteon diameter and area. Plexiform bone could be found in three bones in puppies, i.e. the femur, humerus and tibia. Overall, the results of this study should provide basic knowledge on the microanatomy of cortical bone in dogs and on the possible influence age.

Ancient Human Bone Microstructure in MedievalEngland: Comparisons between Two Socio‐Economic Groups

Understanding the links between bone microstructure and human lifestyle is critical for clinical and anthropological research into skeletal growth and adaptation. The present study is the first to report correspondence between socio-economic status and variation in bone microstructure in ancient humans. Products of femoral cortical remodeling were assessed using histological methods in a large human medieval sample (N = 450) which represented two distinct socio-economic groups. Osteonal parameters were recorded in posterior midshaft femoral sections from adult males (N = 233) and females (N = 217). Using univariate and multivariate statistics, intact, fragmentary, and osteon population densities, Haversian canal area and diameter, and osteon area were compared between the two groups, accounting for sex, age, and estimated femoral robusticity. The size of osteons and their Haversian canals, as well as osteon density, varied significantly between the socio-economic groups, although minor inconsistencies were observed in females. Variation in microstructure was consistent with historical textual evidence that describes differences in mechanical loading and nutrition between the two groups. Results demonstrate that aspects of ancient human lifestyle can be inferred from bone microstructure.

Investigating histomorphometric relationships at the human femoral midshaft in a biomechanical context.

Cortical bone histomorphometry utilised in human and animal bone biology studies has demonstrated that osteon densities and their geometric properties may be in a relationship with biomechanical load application. Further research is required to investigate mutual links between bone histological variables to elucidate their usefulness in future biomechanical studies. Here, a series of correlations exploring bone biology relationships at the human midshaft femur were performed using a large sample. Mean intact, fragmentary and total osteon population densities, Haversian canal diameter and area, osteon area, as well as osteocyte lacunae density were measured along the sub-periosteal cortex in sections removed from the posterior midshaft aspect of modern human male (n=233) and female (n=217) femora (total n=450). Parametric and non-parametric correlations between the histology variables were sought in the entire sample, as well as within age and sex sub-groups. Several significant positive and negative correlations explaining a large proportion of data variation were found. Haversian canal area, diameter, and osteon area were positively correlated. As the density of osteocyte lacunae increased, Haversian canals and osteons became smaller. As osteons increased in density, so did osteocyte lacunae, but Haversian canal and osteon area became smaller. Results were consistent across age and sex groups. Findings suggest that an increased rate of bone remodelling is associated with a decrease in geometrical properties of osteons. An increased density of osteocyte lacunae and osteons indicates the involvement of bone maintenance cells in remodelling potentially induced by mechanical stimuli. Future histomorphometry studies will benefit from examining multiple bone histology variables due to many mutual bone biology relationships that exist at the human midshaft femur.

Cortical bone histomorphometry in male femoral neck: the investigation of age-association and regional differences.

Low bone volume and changes in bone quality or microarchitecture may predispose individuals to fragility fractures. As the dominant component of the human skeleton, cortical bone plays a key role in protecting bones from fracture. However, histological investigations of the underlying structural changes, which might predispose to fracture, have been largely limited to the cancellous bone. The aim of this study was to investigate the age-association and regional differences of histomorphometric properties in the femoral neck cortical bone. Undecalcified histological sections of the femoral neck (n=20, aged 18-82years, males) were cut (15μm) and stained using modified Masson-Goldner stain. Complete femoral neck images were scanned, and cortical bone boundaries were defined using our previously established method. Cortical bone histomorphometry was performed with low (×50) and high magnification (×100). Most parameters related to cortical width (Mean Ct.Wi, Inferior Ct.Wi, Superior Ct.Wi) were negatively associated with age both before and after adjustment for height. The inferior cortex was the thickest (P<0.001) and the superior cortex was the thinnest (P<0.008) of all cortical regions. Both osteonal size and pores area were negatively associated with age. Osteonal area and number were higher in the antero-inferior area (P<0.002) and infero-posterior area (P=0.002) compared to the postero-superior area. The Haversian canal area was higher in the infero-posterior area compared to the postero-superior area (P=0.002). Moreover, porosity was higher in the antero-superior area (P<0.002), supero-anterior area (P<0.002) and supero-posterior area (P<0.002) compared to the infero-anterior area. Eroded endocortical perimeter (E.Pm/Ec.Pm) correlated positively with superior cortical width. This study describes the changes in cortical bone during ageing in healthy males. Further studies are needed to investigate whether these changes explain the increased susceptibility to femoral neck fractures.

Intracortical Bone Remodeling Variation Shows Strong Genetic Effects

Intracortical microstructure influences crack propagation and arrest within bone cortex. Genetic variation in intracortical remodeling may contribute to mechanical integrity and, therefore, fracture risk. Our aim was to determine the degree to which normal population-level variation in intracortical microstructure is due to genetic variation. We examined right femurs from 101 baboons (74 females, 27 males; aged 7–33 years) from a single, extended pedigree to determine osteon number, osteon area (On.Ar), haversian canal area, osteon population density, percent osteonal bone (%On.B), wall thickness (W.Th), and cortical porosity (Ct.Po). Through evaluation of the covariance in intracortical properties between pairs of relatives, we quantified the contribution of additive genetic effects (heritability [h 2]) to variation in these traits using a variance decomposition approach. Significant age and sex effects account for 9 % (Ct.Po) to 21 % (W.Th) of intracortical microstructural variation. After accounting for age and sex, significant genetic effects are evident for On.Ar (h 2 = 0.79, p = 0.002), %On.B (h 2 = 0.82, p = 0.003), and W.Th (h 2 = 0.61, p = 0.013), indicating that 61–82 % of the residual variation (after accounting for age and sex effects) is due to additive genetic effects. This corresponds to 48–75 % of the total phenotypic variance. Our results demonstrate that normal, population-level variation in cortical microstructure is significantly influenced by genes. As a critical mediator of crack behavior in bone cortex, intracortical microstructural variation provides another mechanism through which genetic variation may affect fracture risk.