The aging of Wolff's ?law?: Ontogeny and responses to mechanical loading in cortical bone

The impact of stroke on bone properties and muscle-bone relationship: a systematic review and meta-analysis

To systematically review available evidence related to the characteristics of bone changes post-stroke and the relationship between various aspects of muscle function (e.g., strength, spasticity) and bone properties after stroke onset. An extensive online database search was undertaken (last search in January 2019). Articles that examined the bone properties in stroke patients were included. The quality of the studies was evaluated with the National Institutes of Health (NIH) Study Quality Assessment Tools. Publication bias of meta-analyses was assessed using the Egger's regression asymmetry test. The selection and evaluation of the articles were conducted by two independent researchers. Fifty-nine studies were identified. In subacute and chronic stroke studies, the skeletal sites in the paretic limbs sustained a more pronounced decline in bone quality than did their counterparts in the non-paretic limbs. The rate of changes showed a decelerating trend as post-stroke duration increased, but the timing of achieving the steady rate differed across skeletal sites. The magnitude of bone changes in the paretic upper limb was more pronounced than the paretic lower limb. There was a strong relationship between muscle strength/mass and bone density/strength index. Muscle spasticity seemed to have a negative impact on bone integrity in the paretic upper limb, but its influence on bone properties in the paretic lower limb was uncertain. Substantial bone changes in the paretic limbs occurred particularly in the first few months after stroke onset. Early intervention, muscle strength training, and long-term management strategies may be important to enhance bone health post-stroke. This review has also revealed the knowledge gaps which should be addressed in future research.

Morphological consequences of artificial cranial deformation: Modularity and integration

The cranium is an anatomically complex structure. One source of its complexity is due to its modular organization. Cranial modules are distinct and partially independent units that interact substantially during ontogeny thus generating morphological integration. Artificial Cranial Deformation (ACD) occurs when the human skull is intentionally deformed, through the use of different deforming devices applied to the head while it is developing. Hence, ACD provides an interesting example to assess the degree to which biomechanical perturbations of the developing neurocranium impact on the degree of morphological integration in the skull as a whole. The main objective of this study was to assess how ACD affects the morphological integration of the skull. This was accomplished by comparing a sample of non-deformed crania and two sets of deformed crania (i.e. antero-posterior and oblique). Both developmental and static modularity and integration were assessed through Generalized Procrustes Analysis by considering the symmetric and asymmetric components of variation in adults, using 3D landmark coordinates as raw data. The presence of two developmental modules (i.e. viscero and neurocranium) in the skull was tested. Then, in order to understand how ACD affects morphological integration, the covariation pattern between the neuro and viscerocranium was examined in antero-posterior, oblique and non-deformed cranial categories using Partial Least-Squares. The main objective of this study was to assess how ACD affects the morphological integration of the skull. This was accomplished by comparing a sample of deformed (i.e. antero-posterior and oblique) and non-deformed crania. Hence, differences in integration patterns were compared between groups. The obtained results support the modular organization of the human skull in the two analyzed modules. The integration analyses show that the oblique ACD style differentially affects the static morphological integration of the skull by increasing the covariance between neuro and viscerocranium in a more constrained way than in antero-posterior and non-deformed skulls. In addition, the antero-posterior ACD style seems to affect the developmental integration of the skull by directing the covariation pattern in a more defined manner as compared to the other cranial categories.

Sex differences in the patterning of age-related bone loss in the human hallucal metatarsal in rural and urban populations

OBJECTIVES

Age-degenerative features of the metatarsals are poorly known despite the importance of metatarsal bone properties for investigating mobility patterns. We assessed the role of habitual activity in shaping the patterning and magnitude of sexual dimorphism in age-related bone loss in the hallucal metatarsal.

MATERIALS AND METHODS

Cross-sections were extracted at midshaft from micro-computed tomography scan models of individuals from medieval rural (Abingdon Vineyard) and early industrial urban (Spitalfields) settings (n = 71). A suite of cross-sectional geometry dimensions and biomechanical properties were compared between populations.

RESULTS

The rural group display generally stronger and larger metatarsals that show a greater capacity to resist torsion and that have comparatively greater bending strength along the medio-lateral plane. Men in both groups show greater values of cortical area than women, but only in the urban group do men show lower magnitudes of age-related decline compared to females. Women in rural and urban populations show different patterns of age-related decline in bone mass, particularly old women in the urban group show a marked decline in cortical area that is absent for women in the rural group.

DISCUSSION

Lifetime exposure to hard, physical activity in an agricultural setting has contributed to the attainment of greater bone mass and stronger bones in young adults. Furthermore, over the life-course, less of this greater amount of bone is lost, such that sustained activity levels may have acted to buffer against age-related decline, and this is most pronounced for women, who are expected to experience greater bone loss later in life than men.

Evaluation of a bone groove geometry for fixation of a cochlear implant electrode

PURPOSE

Electrode migration is a rare, but relevant complication in cochlear implant (CI) surgery. An effective countermeasure is to create a bone groove in the facial recess to secure the electrode lead. We use this method routinely since 2013, but still experienced sporadic electrode migration events most likely due to an improper surgical execution. The aim of this study was to determine the optimum groove geometry.

METHODS

Grooves of defined geometry were created in specimens of fresh porcine femur compacta by use of a CNC milling machine. Electrode dummies were fixed in the groove and then exposed to tensile stress. Force measurements were carried out to examine the effect of groove diameter and opening width on the holding force. The mechanical impact on the electrode cable during insertion into the groove was recorded and the electrode lead was examined under microscopic magnification to assess potential structural damage.

RESULTS

Optimum groove geometry (diameter 1.10 mm, opening width 0.90 mm) ensured an average holding force of 830 mN which is equivalent to the established fixation by use of a titanium clip. None of the microscopic inspections revealed any morphological deterioration of the electrode lead.

CONCLUSION

The fixation of a CI electrode in a bone groove in the facial recess appears to be effective and safe. Furthermore, this method does not require additional costs or foreign material. The optimum geometry defined in this study helped us to refine our surgical standard produce and to generate more consistent results.

Osteoarthritis: A problematic disease in past human populations. A dependence between entheseal changes, body size, age, sex, and osteoarthritic changes development

Osteoarthritis is a problematic trait in terms of etiology and interpretation in past human populations. The relationships between osteoarthritic changes (osteophytes, porosity, and eburnation) and entheseal changes, body mass, stature, bone massiveness, sex, and age on the basis of skeletal material from Łekno (Poland) are analyzed here. Entheses were the strongest contributor to the prediction of osteophyte expression and when all types of changes and all joints were taken together. Stature demonstrates a negative dependence on porosity. When each joint was analyzed separately, entheses were the strongest contributor to the prediction of arthritis expression in the wrist and hip. Age was the strongest contributor to the prediction of arthritis expression in the elbow. Body mass, stature, bone massiveness, and sex had no effect on osteoarthritic changes in any of the examined joints. The results of the present study suggest an important dependence between entheses and osteoarthritic changes. Other factors had little to no effect on differences in OA severity. These results do not dispel all doubts but enrich knowledge about the effect of etiological factors on osteoarthritic change formation. This knowledge is essential for proper, reliable interpretation of osteoarthritic changes in the context of past human biology, ecology, and behavior.

Rat bone properties and their relationship to gait during growth

Allometric relationships have been studied over different Orders of mammals to understand how bone accommodates the mechanical demands associated with increasing mass. However, less attention has been given to the scaling of bone within a single lifetime. We aimed to determine how bone morphology and tissue density are related to (1) bending and compressive strength, and (2) gait dynamics. Longitudinal in vivo computed tomography of the hindlimbs and gait data were collected from female rats (n=5, age 8-20 weeks). Cross-sectional properties and tissue density were measured at the diaphysis, distal and proximal regions of the tibia and scaling exponents were calculated. Finite element models of the tibia were used to simulate loading during walking using joint forces from inverse dynamics calculation to determine the strain energy density and longitudinal strain at the midshaft. Second moment of area at the diaphysis followed strain similarity-based allometry, while bone area trended towards positive allometry. Strain energy in the diaphysis under transverse loading was lower than axial loading throughout growth. While both axial and transverse loading resulted in bending, tensile strains were mitigated by a change in the neutral axis and resulted in overall lower longitudinal tensile strains. The tissue density and cross-sectional properties initially increased and converged by 11 weeks of age and were correlated with changes in ground reaction forces. The scaling analyses imply that rodent tibia is (re)modeled in order to sustain bending at the midshaft during growth. The finite element results and relatively constant density after 10 weeks of age indicate that structural parameters may be the primary determinant of bone strength in the growing rodent tibia. The correlations between bone properties and joint angles imply that the changes in posture may affect bone growth in specific regions.

Differences in Trabecular Bone, Cortical Shell, and Endplate Microstructure Across the Lumbar Spine

Background

The quality of the vertebral body structures such as endplate, cortex, and trabecular bone is important for understanding the performance of implants, particularly at the bone-implant interface. Although vertebral body structures have been analyzed separately in the literature, there is no comprehensive study to assess these anatomical measurements along with their interrelationships in the lumbar spine. Therefore, the purpose of this study was to assess variations in trabecular microstructure, vertebral endplate thickness and concavity, and vertebral body cortex thickness within the lumbar spine.

Methods

A total of 80 lumbar vertebrae (L1-L5) were dissected from 16 human cadaver specimens and imaged with microcomputed tomography to determine trabecular microstructure, vertebral cortex thickness, endplate thickness, and maximum endplate concavity depth. A paired t test and regression analysis were used to determine significant differences (P < .05) between different vertebral levels and correlations between the analyzed anatomical parameters.

Results

L1 vertebra had significantly better (P < .02) trabecular bone microstructure (eg, trabecular bone volume fraction) than all other lumbar vertebrae. However, L1 vertebra also had significantly thinner (P ≤ .02) anterior, left, and right cortices compared to all other vertebral levels. Within L3-L5 intervertebral disc spaces, cranial endplates had significantly greater (P ≤ .03) thickness and maximum concavity depth compared to their respective caudal endplates. No strong correlations were observed between trabecular bone microstructure, maximum endplate concavity depth, vertebral cortex, and endplate thickness parameters.

Conclusions

Detailed reference data of these anatomical parameters for each lumbar vertebral body can aid in improved understanding of bone quality, particularly when assessing different implant designs and fixation approaches. Moreover, such anatomical knowledge may help clinicians with optimal implant design selection and surgical placement of these devices into their respective locations.

Error in the estimation of periosteal and endosteal contours from micro-CT scans for nonadult tibiae and humeri

OBJECTIVES

This article summarized errors obtained by diverse techniques used for the derivation of cross-sectional contours in nonadult humeri and tibiae.

MATERIALS AND METHODS

We analyzed cross-sectional contours in a total sample of 62 humeral and 75 tibial diaphyses in the age between birth and 12 years divided into three age groups. Long bone 35% (humeri) and midshaft (tibiae) cross-sections were taken on micro-CT images and analyzed by EPJMacro in FIJI. Properties were extracted from contours derived by manual, automatic, spline, and ellipse techniques. Agreement between techniques was assessed using manually extracted properties such as the true value using percent prediction error (%PE), reduced major axis regression, and ±95% limits of agreement.

RESULTS

The lowest measurement errors were obtained for total areas, moderate errors for cortical areas and section moduli, and the highest errors for medullary areas for both bones. Derivation of humeral nonadult cross-sectional properties is less sensitive to the technique used for derivation of periosteal and endosteal contours, reaching mean %PEs below 5%. In contrast, tibial nonadult cross-sectional properties are more sensitive to the technique used and exceed 5% for some combinations.

DISCUSSION

Automatic techniques provide reasonably high agreement with manually extracted contours for nonadult humeri but low agreement for tibiae. Semiautomatic approaches-spline and ellipse techniques-may reduce the error for all studied properties in tibiae, especially when combined with manually traced periosteal contours. The positive effect of the semiautomatic technique on measurement error is low for humeri.

Femoral neck and shaft structure in Homo naledi from the Dinaledi Chamber (Rising Star System, South Africa)

The abundant femoral assemblage of Homo naledi found in the Dinaledi Chamber provides a unique opportunity to test hypotheses regarding the taxonomy, locomotion, and loading patterns of this species. Here we describe neck and shaft cross-sectional structure of all the femoral fossils recovered in the Dinaledi Chamber and compare them to a broad sample of fossil hominins, recent humans, and extant apes. Cross-sectional geometric (CSG) properties from the femoral neck (base of neck and midneck) and diaphysis (subtrochanteric region and midshaft) were obtained through CT scans for H. naledi and through CT scans or from the literature for the comparative sample. The comparison of CSG properties of H. naledi and the comparative samples shows that H. naledi femoral neck is quite derived with low superoinferior cortical thickness ratio and high relative cortical area. The neck appears superoinferiorly elongated because of two bony pilasters on its superior surface. Homo naledi femoral shaft shows a relatively thick cortex compared to the other hominins. The subtrochanteric region of the diaphysis is mediolaterally elongated resembling early hominins while the midshaft is anteroposteriorly elongated, indicating high mobility levels. In term of diaphyseal robusticity, the H. naledi femur is more gracile that other hominins and most apes. Homo naledi shows a unique combination of characteristics in its femur that undoubtedly indicate a species committed to terrestrial bipedalism but with a unique loading pattern of the femur possibly consequence of the unique postcranial anatomy of the species.

Dental macrowear and cortical bone distribution of the Neanderthal mandible from Regourdou (Dordogne, Southwestern France)

Tooth wear is an important feature for reconstructing diet, food processing and cultural habits of past human populations. In particular, occlusal wear facets can be extremely useful for detecting information about diet and non-masticatory behaviors. The aim of this study is to reconstruct the diet and cultural behavior of the Neanderthal specimen Regourdou 1 (Dordogne, Southern France) from the analysis of the macrowear pattern, using the occlusal fingerprint analysis method. In addition, we have also examined whether there is any association between the observed dental macrowear and mandibular bone distribution and root dentine thickness. The posterior dentition of Regourdou 1 is characterized by an asymmetric wear pattern, with the right side significantly more worn than the left. In contrast, the left lower P₃ shows a more advanced wear than the right premolar, with unusual semicircular enamel wear facets. The results from occlusal fingerprint analysis of this unique pattern suggest tooth-tool uses for daily task activities. Moreover, the left buccal aspect of the mandibular cortical bone is thicker than its right counterpart, and the left P₃ has a thicker radicular dentine layer than its antimere. These results show a certain degree of asymmetry in cortical bone topography and dentine tissue that could be associated with the observed dental macrowear pattern. The molar macrowear pattern also suggests that Regourdou 1 had a mixed diet typical of those populations living in temperate deciduous woodlands and Mediterranean habitats, including animal and plant foods. Although this study is limited to one Neanderthal individual, future analyses based on a larger sample may further assist us to better understand the existing relationship between mandibular architecture, occlusal wear and the masticatory apparatus in humans.

Trabecular architecture of the great ape and human femoral head

Studies of femoral trabecular structure have shown that the orientation and volume of bone are associated with variation in loading and could be informative about individual joint positioning during locomotion. In this study, we analyse for the first time trabecular bone patterns throughout the femoral head using a whole-epiphysis approach to investigate how potential trabecular variation in humans and great apes relates to differences in locomotor modes. Trabecular architecture was analysed using microCT scans of Pan troglodytes (n = 20), Gorilla gorilla (n = 14), Pongo sp. (n = 5) and Homo sapiens (n = 12) in medtool 4.1. Our results revealed differences in bone volume fraction (BV/TV) distribution patterns, as well as overall trabecular parameters of the femoral head between great apes and humans. Pan and Gorilla showed two regions of high BV/TV in the femoral head, consistent with hip posture and loading during two discrete locomotor modes: knuckle-walking and climbing. Most Pongo specimens also displayed two regions of high BV/TV, but these regions were less discrete and there was more variability across the sample. In contrast, Homo showed only one main region of high BV/TV in the femoral head and had the lowest BV/TV, as well as the most anisotropic trabeculae. The Homo trabecular structure is consistent with stereotypical loading with a more extended hip compared with great apes, which is characteristic of modern human bipedalism. Our results suggest that holistic evaluations of femoral head trabecular architecture can reveal previously undetected patterns linked to locomotor behaviour in extant apes and can provide further insight into hip joint loading in fossil hominins and other primates.

Postmortem change in bone biomechanical properties: Loss of plasticity

Bone is a hierarchical composite material composed primarily of collagen molecules, mineral crystals, and water. The mineral phase confers strength and stiffness while the organic matrix provides toughness. As a result, living bone is very capable of absorbing energy and resisting fracture. After death, the bone often becomes dehydrated and the collagen degrades causing greater stiffness and reduced toughness. These changes in mechanical properties are augmented due to the combined effects of water loss and collagen degradation. As a result, bone becomes more brittle postmortem, which causes the changes in fracture characteristics that are commonly used to estimate the timing of the fracture. However, because the loss of moisture and collagen degradation are influenced by taphonomic conditions, anthropologist must use caution when interpreting the timing of fractures based solely on fracture characteristics. As part of this special volume on hard tissue alterations associated with trauma, the aim of this article is to provide an overview of the mechanical changes that occur in bone postmortem and summarize major works in bone biology and anthropology examining the cause and timing of plasticity loss in bone after death.

Trauma in the upper limb of an Upper Paleolithic female from Caviglione cave (Liguria, Italy): Etiology and after-effects in bone biomechanical properties

The impact of injury on the health and activities of human foragers is of great interest for understanding the adaptability of past populations to their environments. For the Gravettian female of Caviglione 1, a violent blow has been suggested as the origin of the left radial fracture, and abnormal body asymmetry has been observed. Access to high resolution CT-scans of the upper limb allows us to address new etiologic considerations and assess the after-effects of trauma on bone biomechanical properties by focusing on cortical and trabecular bones and conducting a comparative analysis of cross-sectional geometric properties in an Upper Paleolithic context. This originally right-dominant female, who became left-handed, was mainly affected by severe bone modifications on the proximal right humerus due to secondary changes following a traumatic event. The left radial fracture is very well consolidated with thick and homogeneous cortical bone. Etiological considerations point to a Galeazzi fracture for the left forearm occurring during a fall. The bone structure and robusticity of the left arm probably prove the lack of strong and enduring dependency of this female on her group for the usual cultural tasks despite the strongly limited function of the right arm.

Do Exostoses Correlate with Contact Disfunctions? A Case Study of a Maxillary Exostosis

A maxillary exostosis is a benign overgrowth of bone that occurs on the outer or facial surface of the maxilla and is usually located near the premolar or molar teeth. This paper investigates the correlation between the presence and growth of jaw exostoses and the oral mechanics of contact. For this purpose, a case study of an upper jawbone exostosis of a female patient was considered. 3D models of the patient’s cranial bones were extracted from 2D computerized tomography (CT) data and were analyzed by proper software. A contact congruence evaluation based on the Winkler contact model was performed, and results were presented in terms of indentation maps and load distributions. Results were correlated with the theory of bone remodelling by Wolff.

Limb- and tendon-specific Adamtsl2 deletion identifies a role for ADAMTSL2 in tendon growth in a mouse model for geleophysic dysplasia

Geleophysic dysplasia is a rare, frequently lethal condition characterized by severe short stature with progressive joint contractures, cardiac, pulmonary, and skin anomalies. Geleophysic dysplasia results from dominant fibrillin-1 (FBN1) or recessive ADAMTSL2 mutations, suggesting a functional link between ADAMTSL2 and fibrillin microfibrils. Mice lacking ADAMTSL2 die at birth, which has precluded analysis of postnatal limb development and mechanisms underlying the skeletal anomalies of geleophysic dysplasia. Here, detailed expression analysis of Adamtsl2 using an intragenic lacZ reporter shows strong Adamtsl2 expression in limb tendons. Expression in developing and growing bones is present in regions that are destined to become articular cartilage but is absent in growth plate cartilage. Consistent with strong tendon expression, Adamtsl2 conditional deletion in limb mesenchyme using Prx1-Cre led to tendon anomalies, albeit with normal collagen fibrils, and distal limb shortening, providing a mouse model for geleophysic dysplasia. Unexpectedly, conditional Adamtsl2 deletion using Scx-Cre, a tendon-specific Cre-deleter strain, which does not delete in cartilage, also impaired skeletal growth. Recombinant ADAMTSL2 is shown here to colocalize with fibrillin microfibrils in vitro, and enhanced staining of fibrillin-1 microfibrils was observed in Prx1-Cre Adamtsl2 tendons. The findings show that ADAMTSL2 specifically regulates microfibril assembly in tendons and that proper microfibril composition in tendons is necessary for tendon growth. We speculate that reduced bone growth in geleophysic dysplasia may result from external tethering by short tendons rather than intrinsic growth plate anomalies. Taken together with previous work, we suggest that GD results from abnormal microfibril assembly in tissues, and that ADAMTSL2 may limit the assembly of fibrillin microfibrils.

Prospective associations of osteosarcopenia and osteodynapenia with incident fracture and mortality over 10 years in community-dwelling older adults

AIM

To determine whether older adults with low muscle mass (sarcopenia) and strength (dynapenia), in the presence of osteoporosis/osteopenia, have an increased risk of fracture and mortality over 10 years, compared to those with low muscle or low bone mass alone or with neither condition.

METHODS

1032 participants (52% women; mean age 62.9 ± 7.4 years) were prospectively followed for 10 years. Mortality was ascertained from the death registry and fractures were self-reported. Baseline appendicular lean mass (ALM) was assessed using dual-energy X-ray absorptiometry and normalised to body mass index (BMI). Hand grip strength (HGS) was assessed by dynamometer. Osteosarcopenia and osteodynapenia were defined as having T-scores of the total hip and/or lumbar spine bone mineral density (BMD) < -1 combined with being in the lowest 20% of the sex-specific distribution for ALM/BMI or HGS respectively.

RESULTS

Incident fracture risk was significantly higher in participants who were osteodynapenic (RR = 2.07, 95% CI: 1.26-3.39), dynapenic alone (RR = 1.74, 95% CI: 1.05-2.87), and osteopenic alone (RR = 1.63, 95% CI: 1.15-2.31), compared to those without dynapenia or osteopenia. Mortality risk was significantly higher only in participants with osteosarcopenia (RR = 1.49, 95% CI: 1.01-2.21) compared to those without sarcopenia or osteopenia. However, osteosarcopenia and osteodynapenia did not lead to a significantly greater fracture or mortality risk compared to having these conditions on their own.

CONCLUSION

These findings suggest that the combined effect of osteopenia and sarcopenia or dynapenia on fracture and mortality risk, respectively, may not be greater than that of each individual condition.

Morphometric, anatomic and radiographic study of the scapula in the white-footed tamarin (Saguinus leucopus): report of scapular cartilage and one variation in cranial (superior) transverse scapular ligament

The white-footed tamarin (Saguinus leucopus) is an endangered endemic primate of Colombia, mainly due to the deforestation of its habitat and illegal trade, which generates a high incidence of these animals in wildlife care centres. Musculoskeletal system disorders in S. leucopus are one of the most common diseases and therefore the aim of this study was to contribute to the morphologic studies with a morphometric, anatomic and radiographic description of the scapula in this species to provide a basis for medical interventions, surgical approaches, radiologic diagnoses and comparative functions of this bone. Gross dissections of each scapular region were made in eight specimens without a diagnosis of osteomuscular disease. These specimens died from natural cases in the wildlife care centres of the Corporación Autónoma Regional de Caldas (CORPORCALDAS); after necropsy their carcasses were fixed with 10% formaldehyde, 5% mineral oil and 1% phenic acid in these centres over the course of at least 1 week. X-rays of the scapula were taken in the small animal clinic of the Universidad del Tolima, and morphometric data of the scapulae were obtained with a digital calliper. The scapula of the white-footed tamarin was a flat triangular bone with a deep scapular notch in its cranial margin, where there was a cranial transverse scapular ligament that was absent in two specimens. The coracoid process was highly developed, medially covering the humeral joint. The dorsal margin was covered by the scapular cartilage, which was highly developed in the caudal angle. In the dorsal fourth of the caudal margin, there was a surface from which the m. teres major originated. The lateral surface had a scapular spine with a long hamatus process of the acromion until the lateral part of the humeral joint. The infraspinatus fossa was wider than the supraspinous fossa. On the costal surface, the subscapular fossa was formed by three subscapular lines and one subscapular ridge, the latter helping to form the surface for the m. teres major. In the two radiographic views, caudocranial to the scapula and dorsoventral to the thorax, the scapular spine, acromion, coracoid process, scapular incisura, supraglenoid tubercle, caudal margin, subscapular ridge, and the joints with the clavicle and the humerus could be observed. The scapula of the white-footed tamarin presented bony reliefs that share characteristics with other primates but also with domestic mammals due to its quadrupedal locomotion, which allowed us to correlate its morphologic adaptation with its quadrupedal arboreal displacement.

Histomorphometry and cortical robusticity of the adult human femur

Recent quantitative analyses of human bone microanatomy, as well as theoretical models that propose bone microstructure and gross anatomical associations, have started to reveal insights into biological links that may facilitate remodeling processes. However, relationships between bone size and the underlying cortical bone histology remain largely unexplored. The goal of this study is to determine the extent to which static indicators of bone remodeling and vascularity, measured using histomorphometric techniques, relate to femoral midshaft cortical width and robusticity. Using previously published and new quantitative data from 450 adult human male (n = 233) and female (n = 217) femora, we determine if these aspects of femoral size relate to bone microanatomy. Scaling relationships are explored and interpreted within the context of tissue form and function. Analyses revealed that the area and diameter of Haversian canals and secondary osteons, and densities of secondary osteons and osteocyte lacunae from the sub-periosteal region of the posterior midshaft femur cortex were significantly, but not consistently, associated with femoral size. Cortical width and bone robusticity were correlated with osteocyte lacunae density and scaled with positive allometry. Diameter and area of osteons and Haversian canals decreased as the width of cortex and bone robusticity increased, revealing a negative allometric relationship. These results indicate that microscopic products of cortical bone remodeling and vascularity are linked to femur size. Allometric relationships between more robust human femora with thicker cortical bone and histological products of bone remodeling correspond with principles of bone functional adaptation. Future studies may benefit from exploring scaling relationships between bone histomorphometric data and measurements of bone macrostructure.

Differences in the Cortical Structure of the Whole Fibula and Tibia Between Long-Distance Runners and Untrained Controls. Toward a Wider Conception of the Biomechanical Regulation of Cortical Bone Structure

The cortical structure of human fibula varies widely throughout the bone suggesting a more selective adaptation to different mechanical environments with respect to the adjacent tibia. To test this hypothesis, serial-pQCT scans of the dominant fibulae and tibiae of 15/15 men/women chronically trained in long-distance running were compared with those of 15/15 untrained controls. When compared to controls, the fibulae of trained individuals had similar (distally) or lower (proximally) cortical area, similar moments of inertia (MI) for anterior-posterior bending (xMI) and lower for lateral bending (yMI) with a lower "shape-index" (yMI/xMI ratio) throughout, and higher resistance to buckling distally. These group differences were more evident in men and independent of group differences in bone mass. These results contrast with those observed in the tibia, where, as expected, structural indicators of bone strength were greater in trained than untrained individuals. Proximally, the larger lateral flexibility of runners' fibulae could improve the ability to store energy, and thereby contribute to fast-running optimization. Distally, the greater lateral fibular flexibility could reduce bending strength. The latter appears to have been compensated by a higher buckling strength. Assuming that these differences could be ascribed to training effects, this suggests that usage-derived strains in some bones may modify their relative structural resistance to different kinds of deformation in different regions, not only regarding strength, but also concerning other physiological roles of the skeleton.

The Dynamic Baropodometric Profile of Children with Idiopathic Toe-Walking A Cross-Sectional Study

BACKGROUND

Idiopathic toe-walking (ITW) gait may present in children older than 3 years and in the absence of a medical condition known to cause or be associated with toe-walking gait. It is unknown how this gait type changes pressure distribution in the growing foot. We sought to determine whether children with ITW gait exhibit different plantar pressures and temporal gait features than typically developing children.

METHODS

Children aged 3 to 6 years were recruited who had either a typical heel-toe gait pattern or a diagnosis of ITW. The ITW diagnosis was reported by the parent/caregiver and confirmed through history and physical examination. Temporal gait measures, peak pressures, and impulse percentages were measured. A minimum of ten unshod footprints were collected. Data were compared with unpaired t tests.

RESULTS

The study included 40 children with typical gait and 56 with ITW gait. The ITW group displayed lower peak pressures at the hallux, midfoot, and hindfoot ( P < .05) and higher and lower pressure impulse percentages at the forefoot ( P < .001) and hindfoot ( P < .001), respectively. The ITW group spent a higher percentage of contact time at all areas of the forefoot and less at the midfoot and rearfoot ( P < .05). There were no significant differences in total step duration and foot progression angle between groups ( P > .05).

CONCLUSIONS

There were differences in pressure distributions between groups. Understanding these differences may help us better understand the compensations or potential long-term impact that ITW gait may have on a young child's foot. Podiatric physicians may also consider the use of this equipment in the clinical setting to measure outcomes after treatment for ITW.

Getting into Shape: Limb Bone Strength in Perinatal Lemur catta and Propithecus coquereli

Functional studies of skeletal anatomy are predicated on the fundamental assumption that form will follow function. For instance, previous studies have shown that the femora of specialized leaping primates are more robust than those of more generalized primate quadrupeds. Are such differences solely a plastic response to differential loading patterns during postnatal life, or might they also reflect more canalized developmental mechanisms present at birth? Here, we show that perinatal Lemur catta, an arboreal/terrestrial quadruped, have less robust femora than perinatal Propithecus coquereli, a closely related species specialized for vertical clinging and leaping (a highly unusual locomotor mode in which the hindlimbs are used to launch the animal between vertical tree trunks). These results suggest that functional differences in long bone cross-sectional dimensions are manifest at birth, belying simple interpretations of adult postcranial form as a direct record of loading patterns during postnatal life. Despite these significant differences in bone robusticity, we find that hindlimb bone mineralization, material properties, and measures of whole-bone strength generally overlap in perinatal L. catta and P. coquereli, indicating little differentiation in postcranial maturity at birth despite known differences in the pace of craniodental development between the species. In a broader perspective, our results likely reflect evolution acting during prenatal ontogeny. Even though primates are notable for relatively prolonged gestation and postnatal parental care, neonates are not buffered from selection, perhaps especially in the unpredictable and volatile environment of Madagascar. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 303:250-264, 2020. © 2018 American Association for Anatomy.

Fibula: The Forgotten Bone-May It Provide Some Insight On a Wider Scope for Bone Mechanostat Control?

The human fibula responds to its mechanical environment differently from the tibia accordingly with foot usage. Fibula structure is unaffected by disuse, and is stronger concerning lateral bending in soccer players (who evert and rotate the foot) and weaker in long-distance runners (who jump while running) with respect to untrained controls, along the insertion region of peroneus muscles. These features, strikingly associated to the abilities of the fibulae of predator and prey quadrupeds to manage uneven surfaces and to store elastic energy to jump, respectively, suggest that bone mechanostat would control bone properties with high selective connotations beyond structural strength.

Cancellous bone and theropod dinosaur locomotion. Part I-an examination of cancellous bone architecture in the hindlimb bones of theropods

This paper is the first of a three-part series that investigates the architecture of cancellous ('spongy') bone in the main hindlimb bones of theropod dinosaurs, and uses cancellous bone architectural patterns to infer locomotor biomechanics in extinct non-avian species. Cancellous bone is widely known to be highly sensitive to its mechanical environment, and has previously been used to infer locomotor biomechanics in extinct tetrapod vertebrates, especially primates. Despite great promise, cancellous bone architecture has remained little utilized for investigating locomotion in many other extinct vertebrate groups, such as dinosaurs. Documentation and quantification of architectural patterns across a whole bone, and across multiple bones, can provide much information on cancellous bone architectural patterns and variation across species. Additionally, this also lends itself to analysis of the musculoskeletal biomechanical factors involved in a direct, mechanistic fashion. On this premise, computed tomographic and image analysis techniques were used to describe and analyse the three-dimensional architecture of cancellous bone in the main hindlimb bones of theropod dinosaurs for the first time. A comprehensive survey across many extant and extinct species is produced, identifying several patterns of similarity and contrast between groups. For instance, more stemward non-avian theropods (e.g. ceratosaurs and tyrannosaurids) exhibit cancellous bone architectures more comparable to that present in humans, whereas species more closely related to birds (e.g. paravians) exhibit architectural patterns bearing greater similarity to those of extant birds. Many of the observed patterns may be linked to particular aspects of locomotor biomechanics, such as the degree of hip or knee flexion during stance and gait. A further important observation is the abundance of markedly oblique trabeculae in the diaphyses of the femur and tibia of birds, which in large species produces spiralling patterns along the endosteal surface. Not only do these observations provide new insight into theropod anatomy and behaviour, they also provide the foundation for mechanistic testing of locomotor hypotheses via musculoskeletal biomechanical modelling.

Trabecular Bone Structural Variation in the Proximal Sacrum Among Primates

The sacrum occupies a functionally important anatomical position as part of the pelvic girdle and vertebral column. Sacral orientation and external morphology in modern humans are distinct from those in other primates and compatible with the demands of habitual bipedal locomotion. Among nonhuman primates, however, how sacral anatomy relates to positional behaviors is less clear. As an alternative to evaluation of the sacrum's external morphology, this study assesses if the sacrum's internal morphology (i.e., trabecular bone) differs among extant primates. The primary hypothesis tested is that trabecular bone parameters with established functional relevance will differ in the first sacral vertebra (S1) among extant primates that vary in positional behaviors. Results for analyses of individual variables demonstrate that bone volume fraction, degree of anisotropy, trabecular number, and size-corrected trabecular thickness differ among primates grouped by positional behaviors to some extent, but not always in ways consistent with functional expectations. When examined as a suite, these trabecular parameters distinguish obligate bipeds from other positional behavior groups; and, the latter three trabecular bone variables further distinguish knuckle-walking terrestrial quadrupeds from manual suspensor-brachiators, vertical clingers and leapers, and arboreal quadrupeds, as well as between arboreal and terrestrial quadrupeds. As in other regions of the skeleton in modern humans, trabecular bone in S1 exhibits distinctively low bone volume fraction. Results from this study of extant primate S1 trabecular bone structural variation provide a functional context for interpretations concerning the positional behaviors of extinct primates based on internal sacral morphology. Anat Rec, 302:1354-1371, 2019. © 2018 Wiley Periodicals, Inc.

Differential Adaptive Response of Growing Bones From Two Female Inbred Mouse Strains to Voluntary Cage-Wheel Running

The phenotypic response of bones differing in morphological, compositional, and mechanical traits to an increase in loading during growth is not well understood. We tested whether bones of two inbred mouse strains that assemble differing sets of traits to achieve mechanical homeostasis at adulthood would show divergent responses to voluntary cage‐wheel running. Female A/J and C57BL6/J (B6) 4‐week‐old mice were provided unrestricted access to a standard cage‐wheel for 4 weeks. A/J mice have narrow and highly mineralized femora and B6 mice have wide and less mineralized femora. Both strains averaged 2 to 9.5 km of running per day, with the average‐distance run between strains not significantly different (p = 0.133). Exercised A/J femora showed an anabolic response to exercise with the diaphyses showing a 2.8% greater total area (Tt.Ar, p = 0.06) and 4.7% greater cortical area (Ct.Ar, p = 0.012) compared to controls. In contrast, exercised B6 femora showed a 6.2% (p < 0.001) decrease in Tt.Ar (p < 0.001) and a 6.7% decrease in Ct.Ar (p = 0.133) compared to controls, with the femora showing significant marrow infilling (p = 0.002). These divergent morphological responses to exercise, which did not depend on the daily distance run, translated to a 7.9% (p = 0.001) higher maximum load (ML) for exercised A/J femora but no change in ML for exercised B6 femora compared to controls. A consistent response was observed for the humeri but not the vertebral bodies. This differential outcome to exercise has not been previously observed in isolated loading or forced treadmill running regimes. Our findings suggest there are critical factors involved in the metabolic response to exercise during growth that require further consideration to understand how genotype, exercise, bone morphology, and whole‐bone strength interact during growth. © 2018 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Exploring bone volume and skeletal weight in the Middle Pleistocene humans from the Sima de los Huesos site (Sierra de Atapuerca, Spain)

Body mass estimation in fossil human species is a crucial topic in paleoanthropology as it yields information about ecologically relevant characteristics. Nevertheless, variables crucial to body mass estimation such as bone volume and skeletal weight have never before been calculated in a fossil human species. The exceptional state of preservation of several fossil human long bones from the Sima de los Huesos (SH) Middle Pleistocene site, in the Sierra de Atapuerca, makes it possible to calculate for the first time the absolute bone volume in five complete long bones (two femora and three humeri) of a fossil human species, an approach not possible in fragmentary or poorly preserved fossils. We have relied on computed tomography scans and 3D reconstructions to calculate bone volume. A sample of 62 complete bones of robust recent humans was also used for comparative purposes. The male SH femora (weight-bearing bones) and humeri (non-weight-bearing bones) have, relative to their size, greater bone volume (volume of bone tissue over total bone volume) than the equivalent bones in our recent human sample. As mass is volume × density, and bone tissue density (as a material) is similar across mammals, we calculate bone mass, and our results show that the SH hominins had on average heavier long bones than extant humans of the same size. From the femoral weight at hand, we have estimated the total skeletal weight in two SH individuals, which is about 36% heavier than in the recent humans of the equivalent body size. Using different methods and skeletal variables, including skeletal weight, to estimate body mass in these two SH humans, we highlight the considerable differences in body mass estimates we obtained, and that the largest body mass estimate is the one based on the skeletal weight. Our results suggest that we cannot assume the same relative proportion of bone volume and bone and skeletal weight characterized the entire genus Homo. Given that skeletal weight has a significant influence on body mass, current body mass estimates of fossil Homo specimens could be systematically underestimated. Thus, the significantly larger bone volume and heavier bones, probably throughout the entire skeleton, of SH humans could have had consequences for many biological parameters in this Pleistocene population and considerable importance for studies focusing on adaptive and ecologically relevant characteristics. Although more recent human samples should be analyzed, in our view, the high skeletal robusticity of the SH sample, including larger bone volume and skeletal weight, is part of their adaptive body type selected for throughout the Pleistocene to support different mechanical and activity regimes and formed under tight genetic control, including control over bone formative and regulatory processes.

Inferring locomotor behaviours in Miocene New World monkeys using finite element analysis, geometric morphometrics and machine-learning classification techniques applied to talar morphology

The talus is one of the most commonly preserved post-cranial elements in the platyrrhine fossil record. Talar morphology can provide information about postural adaptations because it is the anatomical structure responsible for transmitting body mass forces from the leg to the foot. The aim of this study is to test whether the locomotor behaviour of fossil Miocene platyrrhines could be inferred from their talus morphology. The extant sample was classified into three different locomotor categories and then talar strength was compared using finite-element analysis. Geometric morphometrics were used to quantify talar shape and to assess its association with biomechanical strength. Finally, several machine-learning (ML) algorithms were trained using both the biomechanical and morphometric data from the extant taxa to infer the possible locomotor behaviour of the Miocene fossil sample. The obtained results show that the different locomotor categories are distinguishable using either biomechanical or morphometric data. The ML algorithms categorized most of the fossil sample as arboreal quadrupeds. This study has shown that a combined approach can contribute to the understanding of platyrrhine talar morphology and its relationship with locomotion. This approach is likely to be beneficial for determining the locomotor habits in other fossil taxa.

The relationship of age, activity, and body size on osteoarthritis in weight-bearing skeletal regions

This study examined the simultaneous impact of multiple underlying factors on OA expression in weight-bearing joints of the vertebrae and lower limb of a modern European skeletal sample (Lisbon and Sassari). OA was evaluated using standard ranked categorical scoring; composite OA scores derived through principal component analysis. Body size was calculated from postcranial measurements; torsional strength (J) of the femoral midshaft was calculated from three-dimensional surface models, size standardized and used as a proxy for activity. A standard multiple regression was applied. In all regions, the linear combination of age, body mass, stature, and J was significantly related to differences in OA. Across all joints, age was the strongest predictor; neither body size, nor activity variables demonstrated a statistical relationship with OA at the lumbar or knee; J demonstrated a negative correlation with pelvic OA. Variation in OA can be explained by age, stature, body mass, and structural adaptation related to habitual use. The negative correlation between femoral torsional strength with OA suggests that long-term, repetitive physical work capacity in childhood may be protective against OA development later in life. The multifactorial aetiology of OA requires incorporating multiple lines of evidence to interpret individual or population health from bone samples.

Trabecular bone patterning in the hominoid distal femur

BACKGROUND

In addition to external bone shape and cortical bone thickness and distribution, the distribution and orientation of internal trabecular bone across individuals and species has yielded important functional information on how bone adapts in response to load. In particular, trabecular bone analysis has played a key role in studies of human and nonhuman primate locomotion and has shown that species with different locomotor repertoires display distinct trabecular architecture in various regions of the skeleton. In this study, we analyse trabecular structure throughout the distal femur of extant hominoids and test for differences due to locomotor loading regime.

METHODS

Micro-computed tomography scans of Homo sapiens (n = 11), Pan troglodytes (n = 18), Gorilla gorilla (n = 14) and Pongo sp. (n = 7) were used to investigate trabecular structure throughout the distal epiphysis of the femur. We predicted that bone volume fraction (BV/TV) in the medial and lateral condyles in Homo would be distally concentrated and more anisotropic due to a habitual extended knee posture at the point of peak ground reaction force during bipedal locomotion, whereas great apes would show more posteriorly concentrated BV/TV and greater isotropy due to a flexed knee posture and more variable hindlimb use during locomotion.

RESULTS

Results indicate some significant differences between taxa, with the most prominent being higher BV/TV in the posterosuperior region of the condyles in Pan and higher BV/TV and anisotropy in the posteroinferior region in Homo. Furthermore, trabecular number, spacing and thickness differ significantly, mainly separating Gorilla from the other apes.

DISCUSSION

The trabecular architecture of the distal femur holds a functional signal linked to habitual behaviour; however, there was more similarity across taxa and greater intraspecific variability than expected. Specifically, there was a large degree of overlap in trabecular structure across the sample, and Homo was not as distinct as predicted. Nonetheless, this study offers a comparative sample of trabecular structure in the hominoid distal femur and can contribute to future studies of locomotion in extinct taxa.

Estimating body mass and composition from proximal femur dimensions using dual energy x-ray absorptiometry

Body mass prediction from the skeleton most commonly employs femoral head diameter (FHD). However, theoretical predictions and empirical data suggest the relationship between mass and FHD is strongest in young adults, that bone dimensions reflect lean mass better than body or fat mass and that other femoral measurements may be superior. Here, we generate prediction equations for body mass and its components using femoral head, neck and proximal shaft diameters and body composition data derived from dual-energy x-ray absorptiometry (DXA) scans of young adults (n = 155, 77 females and 78 males, mean age 22.7 ± 1.3 years) from the Andhra Pradesh Children and Parents Study, Hyderabad, India. Sex-specific regression of log-transformed data on femoral measurements predicted lean mass with smaller standard errors of estimate (SEEs) than body mass (12-14% and 16-17% respectively), while none of the femoral measurements were significant predictors of fat mass. Subtrochanteric mediolateral shaft diameter gave lower SEEs for lean mass in both sexes and for body mass in males than FHD, while FHD was a better predictor of body mass in women. Our results provide further evidence that lean mass is more closely related to proximal femur dimensions than body or fat mass and that proximal shaft diameter is a better predictor than FHD of lean but not always body mass. The mechanisms underlying these relationships have implications for selecting the most appropriate measurement and reference sample for estimating body or lean mass, which also depend on the question under investigation.

Interpreting the three-dimensional orientation of vascular canals and cross-sectional geometry of cortical bone in birds and bats

Cortical bone porosity and specifically the orientation of vascular canals is an area of growing interest in biomedical research and comparative/paleontological anatomy. The potential to explain microstructural adaptation is of great interest. However, the determinants of the development of canal orientation remain unclear. Previous studies of birds have shown higher proportions of circumferential canals (called laminarity) in flight bones than in hindlimb bones, and interpreted this as a sign that circumferential canals are a feature for resistance to the torsional loading created by flight. We defined the laminarity index as the percentage of circumferential canal length out of the total canal length. In this study we examined the vascular canal network in the humerus and femur of a sample of 31 bird and 24 bat species using synchrotron micro-computed tomography (micro-CT) to look for a connection between canal orientation and functional loading. The use of micro-CT provides a full three-dimensional (3D) map of the vascular canal network and provides measurements of the 3D orientation of each canal in the whole cross-section of the bone cortex. We measured several cross-sectional geometric parameters and strength indices including principal and polar area moments of inertia, principal and polar section moduli, circularity, buckling ratio, and a weighted cortical thickness index. We found that bat cortices are relatively thicker and poorly vascularized, whereas those of birds are thinner and more highly vascularized, and that according to our cross-sectional geometric parameters, bird bones have a greater resistance to torsional stress than the bats; in particular, the humerus in birds is more adapted to resist torsional stresses than the femur. Our results show that birds have a significantly (P = 0.031) higher laminarity index than bats, with birds having a mean laminarity index of 0.183 in the humerus and 0.232 in the femur, and bats having a mean laminarity index of 0.118 in the humerus and 0.119 in the femur. Counter to our expectation, the birds had a significantly higher laminarity index in the femur than in the humerus (P = 0.035). To evaluate whether this discrepancy was a consequence of methodology we conducted a comparison between our 3D method and an analogue to two-dimensional (2D) histological measurements. This comparison revealed that 2D methods significantly underestimate (P < 0.001) the amount of longitudinal canals by an average of 20% and significantly overestimate (P < 0.001) the laminarity index by an average of 7.7%, systematically mis-estimating indices of vascular canal orientations. In comparison with our 3D results, our approximated 2D measurement had the same results for comparisons between the birds and bats but found significant differences only in the longitudinal index between the humerus and the femur for both groups. The differences between our 3D and pseudo-2D results indicate that differences between our findings and the literature may be partially based in methodology. Overall, our results do not support the hypothesis that the bones of flight are more laminar, suggesting a complex relation between functional loading and microstructural adaptation.

Effects of selective breeding for high voluntary wheel-running behavior on femoral nutrient canal size and abundance in house mice

Bone modeling and remodeling are aerobic processes that entail relatively high oxygen demands. Long bones receive oxygenated blood from nutrient arteries, epiphyseal-metaphyseal arteries, and periosteal arteries, with the nutrient artery supplying the bulk of total blood volume in mammals (~ 50-70%). Estimates of blood flow into these bones can be made from the dimensions of the nutrient canal, through which nutrient arteries pass. Unfortunately, measuring these canal dimensions non-invasively (i.e. without physical sectioning) is difficult, and thus researchers have relied on more readily visible skeletal proxies. Specifically, the size of the nutrient artery has been estimated from dimensions (e.g. minimum diameters) of the periosteal (external) opening of the nutrient canal. This approach has also been utilized by some comparative morphologists and paleontologists, as the opening of a nutrient canal is present long after the vascular soft tissue has degenerated. The literature on nutrient arteries and canals is sparse, with most studies consisting of anatomical descriptions from surgical proceedings, and only a few investigating the links between nutrient canal morphology and physiology or behavior. The primary objective of this study was to evaluate femur nutrient canal morphology in mice with known physiological and behavioral differences; specifically, mice from an artificial selection experiment for high voluntary wheel-running behavior. Mice from four replicate high runner (HR) lines are known to differ from four non-selected control (C) lines in both locomotor and metabolic activity, with HR mice having increased voluntary wheel-running behavior and maximal aerobic capacity (VO₂ max) during forced treadmill exercise. Femora from adult mice (average age 7.5 months) of the 11th generation of this selection experiment were μCT-scanned and three-dimensional virtual reconstructions of nutrient canals were measured for minimum cross-sectional area as a skeletal proxy of blood flow. Gross observations revealed that nutrient canals varied far more in number and shape than prior descriptions would indicate, regardless of sex or genetic background (i.e. HR vs. C lines). Canals adopted non-linear shapes and paths as they traversed from the periosteal to endosteal borders through the cortex, occasionally even branching within the cortical bone. Additionally, mice from both HR and C lines averaged more than four nutrient canals per femur, in contrast to the one to two nutrient canals described for femora from rats, pigs, and humans in prior literature. Mice from HR lines had significantly larger total nutrient canal area than C lines, which was the result not of an increase in the number of nutrient canals, but rather an increase in their average cross-section size. This study demonstrates that mice with an evolutionary history of increased locomotor activity and maximal aerobic metabolic rate have a concomitant increase in the size of their femoral nutrient canals. Although the primary determinant of nutrient canal size is currently not well understood, the present results bolster use of nutrient canal size as a skeletal indicator of aerobically supported levels of physical activity in comparative studies.

Bilateral asymmetry of the humerus in Neandertals, Australian aborigines and medieval humans

OBJECTIVES

Bilateral asymmetry of diaphyseal shape and size may be a reflection of relative activity levels and patterns of habitual biomechanical stress in the upper arms of Neandertals and Homo sapiens. The main purpose of our study was to assess the level of directional asymmetry of humeral cross sections in Neandertals, recent Australian aborigines, and medieval farmers.

MATERIALS AND METHODS

Indices of directional and absolute asymmetry (%DA and %AA) of humeral cross-sectional properties in Neandertals and recent Homo sapiens were calculated. Evenly distributed semilandmarks around the external and internal borders of cortical bone were digitized in the course of computed tomography for analysis of shape differences between sides of the body.

RESULTS

The medieval farmers were characterized by significant %DA and %AA for polar second moment of area (J), ratio of maximum to minimum second moments of area, and ratio of antero-posterior to medio-lateral bending strength. In Australian aborigines, only J in males shows significant %DA and %AA, while Neandertals exhibit no significant asymmetry of any cross-sectional properties. Differences in cross-sectional shape between sides of the body were established in all three analyzed groups.

DISCUSSION

High levels of directional asymmetry of cross-sectional shape and properties in medieval farmers may be caused by the performance of more physically demanding tasks using one side of the body from an early age in that population. Various patterns of asymmetry in Neandertals and modern humans may be caused by different habitual behaviors during growth, eco-geographic patterns in body proportions, genetic factors, and differences in ontogeny.

Relationship between body mass, lean mass, fat mass, and limb bone cross-sectional geometry: Implications for estimating body mass and physique from the skeleton

OBJECTIVES

Estimating body mass from skeletal dimensions is widely practiced, but methods for estimating its components (lean and fat mass) are poorly developed. The ability to estimate these characteristics would offer new insights into the evolution of body composition and its variation relative to past and present health. This study investigates the potential of long bone cross-sectional properties as predictors of body, lean, and fat mass.

MATERIALS AND METHODS

Humerus, femur and tibia midshaft cross-sectional properties were measured by peripheral quantitative computed tomography in sample of young adult women (n = 105) characterized by a range of activity levels. Body composition was estimated from bioimpedance analysis.

RESULTS

Lean mass correlated most strongly with both upper and lower limb bone properties (r values up to 0.74), while fat mass showed weak correlations (r ≤ 0.29). Estimation equations generated from tibial midshaft properties indicated that lean mass could be estimated relatively reliably, with some improvement using logged data and including bone length in the models (minimum standard error of estimate = 8.9%). Body mass prediction was less reliable and fat mass only poorly predicted (standard errors of estimate ≥11.9% and >33%, respectively).

DISCUSSION

Lean mass can be predicted more reliably than body mass from limb bone cross-sectional properties. The results highlight the potential for studying evolutionary trends in lean mass from skeletal remains, and have implications for understanding the relationship between bone morphology and body mass or composition.

Smaller long bone cross-sectional size in people who died of tuberculosis: Insights on frailty factors from a 19th and early 20th century Finnish population

There is little research on how individuals suffering from tuberculosis may differ from those not infected in terms of overall skeletal morphology. Tuberculosis was endemic in 19th and early 20th century Finland making documented skeletal collections of Finns ideal to study effects of the disease on bone. The present study compares long bone cross-sectional total area between individuals who died of tuberculosis and those with another recorded cause of death in a Finnish sample. Adult male individuals (N = 105) were selected for analysis. Complete humeri (N = 56), femora (N = 66) and tibiae (N = 64) were 3D scanned using a laser scanner and total cross-sectional areas calculated with AsciiSection software. Individuals who died of tuberculosis (N = 24, 15 humeri, 14 femora, 13 tibiae) had, when standardized for body size, significantly smaller total cross-sectional femoral and humeral, but not tibial, areas. The mechanisms behind the observed relationship may reflect a combination of biological 'frailty' in terms of susceptibility to infection, reduced childhood activity and/or vitamin D deficiency, which possibly influenced both subperiosteal development during adolescence and, later, susceptibility to contracting and dying of TB. Due to the relatively small sample future studies are needed to further investigate the relationship between TB and bone cross-sectional size.