Bone Cross-sectional Properties Research Articles

Intraindividual variation in the cross‐sectional geometry of the first metatarsal, femur, and tibia

Objectives The examination of cross-sectional properties (CSP) of long bones can inform about differential activity patterns and levels of mobility. Typically, these analyses have focused on the femur and tibia, but metatarsals might also be informative. This study examines femora, tibiae, and first metatarsals to evaluate the relationships between long bone CSP within the lower limb and how this might improve our interpretations of metatarsal variability. Materials and Methods The study includes protohistoric Andaman Islanders (n = 26) and Later Stone Age (LSA) Southern Africans (n = 25) from approximately 10,000–500 BP. Skeletal data were acquired from past studies of these groups. Correlations were used to evaluate the relationships between CSP of lower limb bones within individuals. Principal component analyses were used to evaluate how each lower limb bone contributed to variation in CSP among individuals. Results The correlations between the CSP in the femur and tibia were always strong, but the correlations with the first metatarsal are variable. Variation in femoral loading largely drove PCAs, with less influence by the first metatarsal, or loading in the opposite direction. Discussion The femur and tibia experience similar patterns of mechanical loading, specifically in compression and tension, but the first metatarsal does not reflect the same biomechanical patterns as the femur and tibia. Similarly, the first metatarsal often drove variation in the opposite direction as the femur, indicating differences in the mechanical loading pattern between the two bones.

A morphometric analysis of early Eocene Euprimate tarsals from Gujarat, India

Early Eocene primate postcranial bones from the Vastan lignite mine of Gujarat, India, have proven useful for understanding the haplorhine and strepsirrhine divergence. Previous analyses of material assigned to Asiadapidae supported interpretations that these primates were generalized arboreal quadrupeds, while the omomyid Vastanomys was likely to have been more proficient leaper than asiadapids. More recent examinations of long bone cross-sectional properties and calcaneal elongation have complicated the behavioral interpretations of these fossils. This study examines whole talar and calcaneal morphology of the Vastan material to refine the locomotor reconstructions of these fossils. A comparative sample of extant primate species representing various locomotor behaviors was obtained by accessing surface models from MorphoSource.org. Surface models of fossil specimens attributed to Asiadapis cambayensis, Marcgodinotius indicus, and Vastanomys major were generated from micro-computed tomography scans. A morphological analysis was carried out using weighted spherical harmonics, a Fourier-based method that represents surfaces using coefficients associated with a common set of spherical harmonic functions. The coefficients describing each surface were then used as shape variables in a principal components analysis. Significant differences between locomotor groups were assessed using nonparametric tests. Results from extant comparative samples show that locomotor behavior can be predicted from both talar and calcaneal morphology when phylogenetic relationships are known. Consistent with previous analyses, our results indicate that Asiadapis cambayensis and Marcgodinotius indicus were likely arboreal quadrupeds with some leaping capabilities. Vastanomys major is reconstructed as an arboreal quadruped with greater leaping proficiency than its asiadapid counterparts based on its talar morphology.

Cross-sectional properties of reindeer long bones and metapodials allow identification of activity patterns

Habitual loading patterns of domesticated animals may differ due to human influence from their wild counterparts. In the early stages of human-reindeer interaction, cargo and draft use was likely important, as well as corralling tame reindeer. This may result to changes in loading as increased (working) or decreased (captive) loading, as well as foraging patterns (digging for lichen from under the snow versus fed working and/or captive reindeer). Our aim is to study whether differences in activity modify variation in bone cross-sectional properties and external dimensions. Our material consists of donated skeletons of modern reindeer: 20 working reindeer (19 racing and one draft), 24 zoo reindeer, and sample of 78 free-ranging/wild reindeer as a reference group. We used general linear modelling to first establish the total variation in cross-sectional properties among wild and free-ranging reindeer, and then to infer how differences in loading modify observed variation among zoo and working reindeer. According to our results, direction of greater bone quantity as well as external dimensions in of radioulna of female reindeer differs from female reference group, likely relating to foraging behavior. External dimensions of humerus differ in working and zoo male reindeer compared to male reference group. Increased robusticity of long bones, especially of tibia among working male reindeer, may indicate increased loading, and increased cortical area of long bones may indicate sedentary lifestyle among female reindeer. The results of this study can be used to understand early stages of reindeer domestication by observing reindeer activity patterns from archaeological material.

Estimation of body mass in white-tailed deer (Odocoileus virginianus) using cross-sectional geometry of the metapodial

Zooarchaeologists have developed and used several techniques for estimating the body mass of individual prey animals. Many of these are based on skeletal variables such as minimum number of individuals, weight of remains, or linear dimensions of long bone articular ends. All of these techniques fail to account for individual variability in body mass across the lifespan driven by the primary productivity of the landscape, sex, ontogeny, and season of individual death. Because skeletons are weight-bearing, they constantly remodel in response to changes in body mass, making long bone cross-sectional properties an ideal metric for predicting body mass. Cross-sectional geometric properties of distal limb bones and body mass of white-tailed deer (Odocoileus virginianus) were measured in a sample of 64 recently harvested individuals. Best-fit regressions between cross-sectional skeletal dimensions and dressed body weight produce higher R-squared values and lower standard errors of the estimate than regressions between dressed body weight and linear dimensions of long bone articular ends. Cross-sectional geometry can provide new useful line of evidence for estimating body mass of prey animals, when available.

Covariation between entheseal changes and cross-sectional properties of reindeer long bones – Considering bone functional adaptation as partial contributing factor

Entheseal changes and bone cross-sectional properties are used as skeletal activity markers for different animal species, although most studies are targeted on humans. While there is compelling evidence on the association between activity and bone cross-sectional properties, studies on association of entheseal changes to activity have presented more contradictory results. In previous research, covariation between entheseal changes and bone cross-sectional properties is considered a possible result of common underlying factor. However, these studies are performed predominantly on human material. We provide beyond-species scope by studying this covariation in reindeer skeleton. The results will provide platform for discussing bone functional adaptation pathway in which activity modifies entheseal appearance. The material are wild forest reindeer, domesticated free-ranging reindeer and zoo reindeer of Northern and North-East Finland. We found that bone formation in most studied entheses (25 out of 27) were associated with increased values in bone cross-sectional properties and proxies of bone/body size. Features of bone resorption, when significant, were also associated with increased values in bone cross-sectional properties and bone/body size. We conclude that as entheseal changes were associated with bone cross-sectional properties and bone/body size, the observed variation at reindeer entheses likely reflects skeletal robusticity. While causal factors resulting in association between skeletal robusticity and entheseal appearance cannot be evidenced, bone functional adaptation can be hypothesized as at least a partial contributing mechanism to entheseal appearance.

The effect of diet and sociopolitical change on physiological stress and behavior in late Roman-Early Byzantine (300-700 AD) and Islamic (902-1,235 AD) populations from Ibiza, Spain.

This study evaluated chronological changes in physiological stress and levels of habitual loading of Ibizan populations from the Late Roman-Early Byzantine (LREB) to the Islamic period (300-1,235 AD) using measures of body size and bone cross-sectional properties to compare Urban LREB, Urban Medieval Islamic, and Rural Medieval Islamic groups. It also explored the effect of diet, modeled using stable isotopes, on physiological stress levels and behavior. The sample comprised individuals from three archeological populations: Urban Late Roman- Early Byzantine (LREB) (300-700 AD), Medieval Urban Islamic (902-1,235 AD), and Medieval Rural Islamic. Bone lengths, femoral head dimensions, and cross-sectional properties, diaphyseal products and circumferences, were compared to assess differences in body size and habitual loading in 222 adult individuals. Ordinary least squares regression evaluated the correlations between these measures and carbon (δ13 C) and nitrogen (δ15 N) stable isotope ratios in 115 individuals for whom both isotope values and osteological measures are available. The Medieval Rural Islamic group had shorter stature and reduced lower limb cross-sectional properties compared to the two urban groups. Limb shape differs between Urban LREB and Urban Medieval Islamic groups. Measures of body size length were positively correlated with δ13 C values in all individuals and separately in the Urban LREB and Rural Medieval Islamic groups. δ15 N showed a positive correlation with left humerus shape in the Urban LREB sample. The low stature and cross-sectional properties of the Medieval Rural Islamic group may be an indicator of greater physiological stress, potentially due to poorer diet. Positive correlations between measures of body size and δ13 C values further suggest that greater access to C4 resources improved diet quality. Alternatively, this relationship could indicate greater body size among migrants from areas where individuals consumed more C4 resources.

A Morphometric Analysis of Early Eocene Euprimate Calcanei from Gujarat, India

Postcrania dating back to the early Eocene from the Cambay Shale Formation of Gujarat, India, provide a unique window for understanding early primate behavior. Previous metric analyses of postcrania assigned to Asiadapinae indicate that these primates were generalized arboreal quadrupeds. Examination of long bone cross‐sectional properties, however, complicates the initial behavioral interpretations because it shows that these fossils overlap with primates of differing locomotor behaviors. The purpose of this study is to re‐examine calcaneal morphology of the Indian material in order to refine the locomotor reconstructions of these fossils.Surface models of fossil calcanei (n=6) were generated from micro‐computed tomography scans while those (n=73) representing 23 extant primate species were downloaded from MorphoSource. A weighted spherical harmonics analysis was carried out on the total sample. This morphological analysis represents genus‐zero surfaces using a common set of spherical harmonic functions. The harmonic coefficients associated with each calcaneus serve as shape descriptors that can be summarized via principal components (PC) analysis. Bivariate plots and models representing plus and minus two standard deviations of each PC were created to visualize morphological differences.The first three PCs explain 52.4%, 9.7%, and 9.3% of the morphological variation in the sample respectively (71.4% combined). The first PC differentiates primates with elongated calcanei that are more likely to engage in vertical clinging and leaping, from more quadrupedal primates. The second PC distinguishes calcanei of slow climbers from primates that engage in other forms of locomotion (e.g., leaping and quadrupedalism). Extant primate morphology seems to follow a continuum in which relative anteroposterior calcaneal elongation negatively correlates with slow climber calcaneal morphology. As expected, the calcaneal morphology of Marcgodinotius indicus aligns with that of extant lemuriforms, and most closely resembles that of a generalized arboreal quadruped with some leaping ability. There are two fossils tentatively attributed to Asiadapis cambayensis included in the analysis. One groups with other generalized arboreal quadrupeds, while the other falls outside the range of calcaneal variation observed in extant primates. The outlier does not follow the general pattern of calcaneal morphology observed in extant primates; instead it is characterized by some aspects of slow climber morphology, but with a relative anteroposterior calcaneal elongation. These results may reflect the generalized morphology of this fossil, and consequently the behavior of this primitive euprimate.Support or Funding InformationSupported by NSF DGE‐1746891, National Geographic Society, Leakey Foundation

Increased Cellular Presence After Sciatic Neurectomy Improves the Bone Mechano-adaptive Response in Aged Mice

The mechano-adaptive response of bone to loading in the murine uniaxial tibial loading model is impaired in aged animals. Previous studies have shown that in aged mice, the amount of bone formed in response to loading is augmented when loads are applied following sciatic neurectomy. The synergistic effect of neurectomy and loading remains to be elucidated. We hypothesize that sciatic neurectomy increases cellular presence, thereby augmenting the response to load in aged mice. We examined bone adaptation in four groups of female C57BL/6J mice, 20-22months old: (1) sham surgery + 9N loading; (2) sciatic neurectomy, sacrificed after 5days; (3) sciatic neurectomy, sacrificed after 19days; (4) sciatic neurectomy + 9N loading. We examined changes in bone cross sectional properties with micro-CT images, and static and dynamic histomorphometry with histological sections taken at the midpoint between tibiofibular junctions. The response to loading at 9N was not detectable with quantitative micro-CT data, but surface-specific histomorphometry captured an increase in bone formation in specific regions. 5days following sciatic neurectomy, the amount of bone in the neurectomized leg was the same as the contralateral leg, but 19days following sciatic neurectomy, there was significant bone loss in the neurectomized leg, and both osteoclasts and osteoblasts were recruited to the endosteal surfaces. When sciatic neurectomy and loading at 9N were combined, 3 out of 4 bone quadrants had increased bone formation, on the endosteal and periosteal surfaces (increased osteoid surface and mineralizing surface respectively). These data demonstrate that sciatic neurectomy increases cellular presence on the endosteal surface. With long-term sciatic-neurectomy, both osteoclasts and osteoblasts were recruited to the endosteal surface, which resulted in increased bone formation when combined with a sufficient mechanical stimulus. Controlled and localized recruitment of both osteoblasts and osteoclasts combined with appropriate mechanical loading could inform therapies for mechanically-directed bone formation.

The evolution of femoral cross-sectional properties in sciuromorph rodents: Influence of body mass and locomotor ecology.

In several groups of mammals, adaptation to differing functional demands is reflected in long bone cross-sectional properties (CSP), which relate to the resistance to compression and to bending loads in the craniocaudal and mediolateral directions. Members of the Sciuromorpha ("squirrel-like" rodents) display a diversity of locomotor ecologies and span three orders of magnitude in terms of body size. The availability of robust phylogenies is rendering them a suitable group to further substantiate the relationship of long bone CSP with locomotor ecology and body mass while taking the phylogenetic non-independence among species into account. Here, we studied 69 species of Sciuromorpha belonging to three lifestyle categories, "arboreal," "fossorial," and "aerial" (i.e., gliding). We hypothesized locomotor category specific loading regimes that act on femora during predominant or, in terms of gliding, critical locomotor behaviors of each category. High resolution computed tomography scans of the specimens' femora were obtained and cross-sections in 5% increments were analyzed. Cross-sectional area, the craniocaudal second moment of area (SMAcc ), and the mediolateral second moment of area were quantified. Further, a scaling analysis was conducted for each bone cross-section to examine how the CSP scale with body mass. Body mass accounted for variances in CSP with mainly positive allometry. The aerial sciuromorphs showed lower values of CSP compared to the arboreal and fossorial species in the distal epiphysis for all quantified parameters and along the bone for SMAcc . In contrast to previous studies on other mammalian lineages, no differences in CSP were found between the fossorial and the arboreal lifestyles.

Bone adaptation compensates resorption when sciatic neurectomy is followed by low magnitude induced loading.

The uniaxial tibial loading model is commonly used to promote bone formation through mechanoadaptation in mice. Sciatic neurectomy on the other hand recruits osteoclasts, which results in bone loss. Previous studies have shown that combining sciatic neurectomy with high magnitude loading increases the amount of bone formed. Here we determine whether low-intensity loading (low magnitude and few cycles) is sufficient to maintain bone mass after sciatic neurectomy, either by promoting bone formation (balance between concurrent resorption and formation), or by preventing bone resorption altogether. We examined bone adaptation in 4 groups of female C57BL/6J mice, 19-22 weeks old: (1) sham surgery +10 N loading; (2) sham surgery +5 N loading; (3) sciatic neurectomy; (4) sciatic neurectomy +5 N loading. Left legs were kept intact as internal controls. We examined changes in bone cross sectional properties and marrow area with micro-CT images, and histomorphometric measures with histological sections at the midpoint between tibiofibular junctions. Loading at 10 N caused a significant increase in the amount of bone, but bone formation after 5 N of loading was not detectable in micro-CT images. There was significant bone loss in mice with sciatic neurectomy alone, but when combined with loading there was no significant bone loss. Histomorphometric analyses showed that loading at 5 N augmented bone formation periosteally on the lateral and posterior-medial surfaces, and reduced the number of endosteal osteoclasts on the posterior-medial surface compared to the contralateral leg. Combining sciatic neurectomy and loading at 5 N promoted faster mineral apposition on the periosteal lateral surface and augmented bone resorption on the endosteal posterior surface compared to the contralateral leg. These data demonstrate that low-intensity loading is sufficient to maintain bone mass after sciatic neurectomy, both by preventing recruitment of osteoclasts on the endosteal surface and by compensating endosteal resorption caused by disuse with periosteal formation promoted by loading. This has implications for the loading required to maintain bone mass after injury or prolonged bedrest.

Asymmetry in the Cortical and Trabecular Bone of the Human Humerus During Development.

Many studies have noted that the bones of the human upper limb display bilateral asymmetry, commonly linking this asymmetry in external and internal morphology to handedness and lateralization. Few studies, however, have attempted to track asymmetry throughout ontogeny. This study assesses the ontogenetic development of cortical and trabecular bone asymmetry in the humerus. We predict that directional asymmetry in structural properties will emerge in concert with hand preference and increased activity levels during the juvenile period. Paired humeri from 57 individuals from the Norris Farms #36 archaeological skeletal collection ranging in age from neonate to adult were used in the current study. Cortical bone cross-sectional properties and three-dimensional trabecular bone structure were quantified from microcomputed tomography data. The results indicate significant absolute asymmetry in all measured cortical and trabecular bone variables across all ages. Trabecular bone displays significantly higher absolute asymmetry than cortical bone. Contrary to expectations, however, this study found very little evidence for significant directional asymmetry in humeral length and cortical or trabecular bone variables, except in adults. The presence of significant absolute asymmetry in all age groups, and the lack of significant directional asymmetry in almost all variables at all ages, suggests that structural differences due to higher levels of habitual loading in the dominant arm are overlain on a template of potentially significant existing asymmetry. Anat Rec, 301:1012-1025, 2018. © 2017 Wiley Periodicals, Inc.

Cross-sectional analysis of long bones in a sample of ancient Egyptians

BackgroundAs diaphyseal shape is predominantly influenced by mechanical loading history, long bone cross-sections can be used to access activity patterns. The aim of this study was to evaluate long bone cross-sectional properties in a sample of ancient Egyptians from two socioeconomic classes with different habitual activities. Material and methodsThe material of the present study consisted of 174 skeletons, 71 Workers and 103 High Officials. Measurements of cross-sectional properties from CT images were taken for humerus, femur, and tibia. Cross-sectional images were obtained in the transverse plane of each bone, perpendicular to both coronal and sagittal planes. ResultsCross-sectional thickness and cortical areas of long bones were higher in male Workers than in male High Officials; the differences were significant in anterior thickness of the femur and total cross-sectional areas of both humerus and tibia, and the cortical area of the tibia. Moreover, female Workers had significantly higher values of humeral medullary area and femoral total and cortical areas than High Officials. ConclusionsWorkers had higher level of skeletal robusticity than High Officials which could reflect their higher levels of mobility and physical workload. The study suggests that different activity patterns can significantly affect the bone structure.

The relationship between musculoskeletal stress markers and biomechanical properties of the humeral diaphysis

Musculoskeletal stress markers (MSM) at entheses and bone biomechanical properties are used in activity reconstructions. The effect of physical activity on bone biomechanical properties is well established but the relative role of physical activity on MSM is less well known. In this article, it is hypothesized that the same causal mechanisms should affect MSM development as those responsible for bone biomechanical properties. Further, there should be a correlation between MSMs and bone cross-sectional properties as both are considered to reflect physical activity. This was tested using three skeletal samples: early 20th century Finnish (Helsinki) and two medieval English (Blackgate and York) populations. Torsional/average bending rigidity (J) for four cross-sectional locations at 80, 65, 50, and 35% of humeral length from the distal end was calculated and pectoralis major, teres major, and deltoid were scored for MSM. Correlations between MSM and size-standardized J were significant for many comparisons, although they were stronger in males than in females, especially on the right side. In ANOVAs, sample was found to be a significant influence on the right side in both sexes. Using an aggregated MSM score, covariance between J and high MSM scores was again stronger in males. Covariance between J and MSM was found both at cross-sectional locations under muscle insertions and at more distant locations, demonstrating both direct and general effects of muscular loadings applied to diaphyses. Thus, the two types of skeletal markers appear to be related to similar underlying mechanical factors, but effects may also be sex- and sample-specific.

Habitual throwing and swimming correspond with upper limb diaphyseal strength and shape in modern human athletes

Variation in upper limb long bone cross-sectional properties may reflect a phenotypically plastic response to habitual loading patterns. Structural differences between limb bones have often been used to infer past behavior from hominin remains; however, few studies have examined direct relationships between behavioral differences and bone structure in humans. To help address this, cross-sectional images (50% length) of the humeri and ulnae of university varsity-level swimmers, cricketers, and controls were captured using peripheral quantitative computed tomography. High levels of humeral robusticity were found in the dominant arms of cricketers, and bilaterally among swimmers, whereas the most gracile humeri were found in both arms of controls, and the nondominant arms of cricketers. In addition, the dominant humeri of cricketers were more circular than controls. The highest levels of ulnar robusticity were also found in the dominant arm of cricketers, and bilaterally amongst swimmers. Bilateral asymmetry in humeral rigidity among cricketers was greater than swimmers and controls, while asymmetry for ulnar rigidity was greater in cricketers than controls. The results suggest that more mechanically loaded upper limb elements--unilaterally or bilaterally--are strengthened relative to less mechanically loaded elements, and that differences in mechanical loading may have a more significant effect on proximal compared to distal limb segments. The more circular humerus in the dominant arm in cricketers may be an adaptation to torsional strain associated with throwing activities. The reported correspondence between habitual activity patterns and upper limb diaphyseal properties may inform future behavioral interpretations involving hominin skeletal remains.

Effect of Y2 Receptor Deletion on Whole Bone Structural Behavior in Mice

Recent evidence has shown that mice deficient in the NPY Y2 receptor have an increase in trabecular bone volume as well as cortical bone mass due to increased osteoblast activity. However, the mechanical phenotype of Y2 -/- bone has not yet been assessed. Thus, the aim of the present study was to examine the effect of Y2 deletion on murine cortical bone structural behavior, as well as to assess the material and geometric contributions to that behavior. The results of this study indicate that Y2 -/- mice on a 129 SV x Balb/c background strain are smaller in body mass and have smaller bones than wild-type controls. As expected based on smaller bone cross-sectional properties, cortical bone structural strength was lower in -/- animals. Surprisingly, the structural stiffness of -/- bones was comparable to that of +/+ bones despite their smaller cross-sectional geometry. Comparable structural stiffness appeared to be achieved by means of an elevated effective shear modulus, which was associated with a small, but statistically significant, higher ash content in Y2 -/- bones. These data represent the first comprehensive characterization of the effect of Y2 deletion on cortical bone structural and material behavior to date.

Cross-sectional geometrical properties of distal radius and ulna in large, medium and toy breed dogs

Fractures of the distal radius and the ulna are the third most common fractures in dogs. Toy and miniature breeds have a propensity to develop antebrachial fractures after falling or jumping. Most affect the distal third of both bones involving between 15% and 37% of the radial length. Larger dogs, instead, typically sustain hyperextension injuries to the carpus. The causative mechanisms for this fracture prevalence in toy dogs are unknown. Breed-related changes in bone geometry and/or mineral density have been suggested as possible etiologic factors. In a multifactorial study, the main etiological factors potentially responsible for determining susceptibility to fractures in toy breeds are considered. The aim of this first study is to evaluate the geometric bone features in different dog sizes. The cortical bone cross-sectional properties along the length of the right radius and the ulna of 28 dogs from three different size categories have been quantified by computerized tomographic scanning. Geometrical cross-sectional parameters were measured and normalized to radial length to allow intergroup comparisons. Discriminant analysis was used to classify the observations into different groups. Through statistical analysis of the normalized values, significant differences in cross-sectional properties of different bone sizes were found. The results suggest that, when proportionally loaded, the antibrachii of toy breed dogs are more susceptible to fracture than those of large breed dogs due to morphological differences.

Bone Cross-sectional Properties in the Five Species of Macaque Genera: Geometric Characters of Radius and Tibia

マカク属5種（ベニガオザル（Macaca arctoides），アッサムザル（Macaca assamensis），タイワンザル（Macaca cyclopis），ボンネットザル（Macaca radiata），ブタオザル（Macaca nemestrina））の橈骨と脛骨において，遠位部から骨幹にかけての骨断面をpQCT（peripheral Quantitative Computed Tomography, XCT Research SA; Norland-Stratec社製）により撮像し，その特性値を算出した。得られたデータから，橈骨と脛骨の同一計測パラメータの相関関係や，体重と骨長あるいは骨断面特性値との相関関係の回帰分析を行った。地上性四足歩行のマントヒヒ（Papio hamadryas）および樹上性四足歩行のフサオマキザル（Cebus apella）の分析結果と比較することによって，行動様式の観点からマカク属5種の骨形態特徴を検討・考察したところ，種ごとに特有な特徴が見出された。結果：(1)アッサムザルとボンネットザルは地上性と樹上性のモザイク的特徴を示し，従来どおり半地上性な骨形態特徴を持っていることがわかった。(2)従来，半地上性と言われているブタオザルは地上性的な骨形態特徴を示した。(3)地上性とされているベニガオザルは今回の分析から見ると，樹上性の特徴を強く示した。(4)タイワンザルは地上性とも樹上性とも言えない独自の骨形態パターンを示した。マカク属において，従来言われてきた行動様式と骨形態との関連性について再検討する必要性が示唆された。

A test of two methods of radiographically deriving long bone cross‐sectional properties compared to direct sectioning of the diaphysis

AbstractNumerous studies have made use of cross‐sectional geometry to describe the distribution of cortical bone in long bone diaphyses. Several methods can be used to measure or estimate cross‐sectional contours. Direct sectioning (DSM) of the diaphysis is not appropriate in most curatorial contexts, and is commonly substituted with methods based upon bi‐planar radiography: a latex cast method (LCM) or an eccentric elliptical method (EEM). Previous studies have demonstrated that the EEM provides accurate estimates of area measurements, while providing less accurate estimates of second moments of area (Biknevicius & Ruff, 1992; Runestad et al., 1993; Lazenby, 1997). The LCM has been commonly employed, as a way to estimate section contours more accurately, yet the validity of this method has not been adequately documented. This study measures the agreement of these methods against DSM of long bone diaphyses using 21 sections of canine tibiae derived from a study of total hip arthroplasty. The accuracy and agreement of these methods is evaluated using reduced major axis regression, paired sample t‐tests and tests for agreement (Bland & Altman, 1986). The results illustrate that the LCM provides a reasonable estimate of cross‐sectional dimensions, producing cross‐sectional properties that are on average within 5% of properties derived from the DSM. The EEM is found to provide adequate estimates of true cross‐sectional areas, but poor estimates of second moments of area. The use of the LCM is supported for all cross‐sectional properties, but the EEM is only accurate in total area, cortical area and percent cortical area estimates. Copyright © 2002 John Wiley & Sons, Ltd.

A comparison of primate, carnivoran and rodent limb bone cross-sectional properties: are primates really unique?

The cross-sectional properties of mammalian limb bones provide an important source of information about their loading history and locomotor adaptations. It has been suggested, for instance, that the cross-sectional strength of primate limb bones differs from that of other mammals as a consequence of living in a complex arboreal environment (Kimura, 1991, 1995). In order to test this hypothesis more rigorously, we have investigated cross-sectional properties in samples of humeri and femora of 71 primate species, 30 carnivorans and 59 rodents. Primates differ from carnivorans and rodents in having limb bones with greater cross-sectional strength than mammals of similar mass. This might imply that primates have stronger bones than carnivorans and rodents. However, primates also have longer proximal limb bones than other mammals. When cross-sectional dimensions are regressed against bone length, primates appear to have more gracile bones than other mammals. These two seemingly contradictory findings can be reconciled by recognizing that most limb bones experience bending as a predominant loading regime. After regressing cross-sectional strength against the product of body mass and bone length, a product which should be proportional to the bending moments applied to the limb, primates are found to overlap considerably with carnivorans and rodents. Consequently, primate humeri and femora are similar to those of nonprimates in their resistance to bending. Comparisons between arboreal and terrestrial species within the orders show that the bones of arboreal carnivorans have greater cross-sectional properties than those of terrestrial carnivorans, thus supporting Kimura's general notion. However, no differences were found between arboreal and terrestrial rodents. Among primates, the only significant difference was in humeral bending rigidity, which is higher in the terrestrial species. In summary, arboreal and terrestrial species do not show consistent differences in long bone reinforcement, and Kimura's conclusions must be modified to take into account the interaction of bone length and cross-sectional geometry.

Cross-sectional geometrical properties and bone mineral contents of the human radius and ulna

The mechanical strength of the human radius and ulna depends on their geometrical and material properties. This study quantifies the cortical bone cross-sectional properties of the adult radius and ulna (cross-sectional area, thickness, centroids, area moments of inertia and section moduli) using computerized tomographic (CT) scanning coupled with image processing along the lengths of eight human cadaveric forearms. Bone mineral mass and apparent ash density were also quantified at serial locations. Sites of significant variation of selected geometric and mineral properties along the length of each forearm bone were determined. Our results show that interpolation of CT measurements made at 10 and 30% of the radial length in the radius and 30 and 90% of the radial length in the ulna can provide approximate geometric values over the 10–90% region. This information can be used to develop a protocol using the fewest sites to clinically assess changes in forearm bone geometry. Regression analyses did not show significant linear relationships between geometric properties and apparent cortical ash density. Thus, CT derived geometric properties are not helpful in estimating the extent of changes in bone density. Area moment of inertia results suggest that the junction of the middle and distal third of the radius, and the ulnar shaft region may have increased vulnerability to fractures. The former is likely due to the change in moment of inertia values, whereas the latter is due to the relatively small magnitude of cross-sectional moments along the ulnar shaft as compared to the proximal or distal ends. This is consistent with fracture patterns observed clinically when a single forearm bone is fractured: Galeazzi fracture of the radius and nightstick fracture of the ulna.