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

Exploring neuronal mechanisms of osteosarcopenia in older adults

Until recently, research on the pathogenesis and treatment of osteoporosis and sarcopenia has primarily focused on local and systemic humoral mechanisms, often overlooking neuronal mechanisms. However, there is a growing body of literature on the neuronal regulation of bone and skeletal muscle structure and function, which may provide insights into the pathogenesis of osteosarcopenia. This review aims to integrate these neuronal regulatory mechanisms to form a comprehensive understanding and inspire future research that could uncover novel strategies for preventing and treating osteosarcopenia. Specifically, the review explores the functional adaptation of weight-bearing bone to mechanical loading throughout evolutionary development, from Wolff's law and Frost's mechanostat theory to the mosaic hypothesis, which emphasizes neuronal regulation. The recently introduced bone osteoregulation reflex points to the importance of the osteocytic mechanoreceptive network as a receptor in this neuronal regulation mechanism. Finally, the review focuses on the bone myoregulation reflex, which is known as a mechanism by which bone loading regulates muscle functions neuronally. Considering the ageing-related regressive changes in the nerve fibres that provide both structural and functional regulation in bone and skeletal muscle tissue and the bone and muscle tissues they innervate, it is suggested that neuronal mechanisms might play a central role in explaining osteosarcopenia in older adults.

Macroscopic differences in adult human femora are linked to body mass index

Bone functional adaptation is routinely invoked to interpret skeletal morphology despite ongoing debate regarding the limits of the bone response to mechanical stimuli. The wide variation in human body mass presents an opportunity to explore the relationship between mechanical load and skeletal response in weight-bearing elements. Here, we examine variation in femoral macroscopic morphology as a function of body mass index (BMI), which is used as a metric of load history. A sample of 80 femora (40 female; 40 male) from recent modern humans was selected from the Texas State University Donated Skeletal Collection. Femora were imaged using x-ray computed tomography (voxel size ~0.5 mm), and segmented to produce surface models. Landmark-based geometric morphometric analyses based on the Coherent Point Drift algorithm were conducted to quantify shape. Principal components analyses were used to summarize shape variation, and component scores were regressed on BMI. Within the male sample, increased BMI was associated with a mediolaterally expanded femoral shaft, as well as increased neck-shaft angle and decreased femoral neck anteversion angle. No statistically significant relationships between shape and BMI were found in the female sample. While mechanical stimulus has traditionally been applied to changes in long bong diaphyseal shape it appears that bone functional adaptation may also result in fundamental changes in the shape of skeletal elements.

Changes in limb bone diaphyseal structure in chimpanzees during development

OBJECTIVES

This study tests if femoral and humeral cross-sectional geometry (CSG) and cross-sectional properties (CSPs) in an ontogenetic series of wild-caught chimpanzees (Pan troglodytes ssp.) reflect locomotor behavior during development. The goal is to clarify the relationship between limb bone structure and locomotor behavior during ontogeny in Pan.

MATERIALS AND METHODS

The latex cast method was used to reconstruct cross sections at the midshaft femur and mid-distal humerus. Second moments of area (SMAs) (Ix, Iy, Imax, Imin), which are proportional to bending rigidity about a specified axis, and the polar SMA (J), which is proportional to average bending rigidity, were calculated at section locations. Cross-sectional shape (CSS) was assessed from Ix/Iy and Imax/Imin ratios. Juvenile and adult subsamples were compared.

RESULTS

Juveniles and adults have significantly greater femoral J compared to humeral J. Mean interlimb proportions of J are not significantly different between the groups. There is an overall decreasing trend in diaphyseal circularity between the juvenile phase of development and adulthood, although significant differences are only found in the humerus.

DISCUSSION

Juvenile chimpanzee locomotion includes forelimb- and hindlimb-biased behaviors. Juveniles and adults preferentially load their hindlimbs relative to their forelimbs. This may indicate similar locomotor behavior, although other explanations including a diversity of hindlimb-biased locomotor behaviors in juveniles cannot be ruled out. Different ontogenetic trends in forelimb and hindlimb CSS are consistent with limb bone CSG reflecting functional adaptation, albeit the complex nature of bone functional adaptation requires cautious interpretations of skeletal functional morphology from biomechanical analyses.

Asymmetry in linear measurements and cross-sectional geometry in the humerus during ontogeny

OBJECTIVES

Adult upper limb asymmetry is used to reconstruct behavior. However, the developmental trajectory of asymmetry in bone length, cross-sectional geometry (CSG), and joint dimensions is poorly understood. This study examines the development trajectory of humeral asymmetry and if asymmetry in bone length, joint size, and CSG develop in concert.

MATERIALS AND METHODS

Linear measurements of bone length and metaphyseal/epiphyseal breadth, bending rigidity (Imax and Imin), and cross-sectional shape (Imax/Imin) at 30%, 50%, and 70% of bone length were acquired from 3D models of humeri from four skeletal samples of prehistoric hunter-gatherer populations (n = 82). Dental age cohorts were used to assess ontogenetic trends. Percent absolute (%AA) and directional (%DA) asymmetry were calculated for paired measures. Percentage of matching direction of asymmetry across variables and correlation analysis tested relationships between variables.

RESULTS

Within the total pooled sample, Imax shows the highest %AA and %DA, followed by shape and linear dimensions. Asymmetry is lowest in neonates and increases with age, particularly %DA of Imax in mid-proximal sections. Correlations among variables are low to moderate and strongest between Imax measures. Matching direction of asymmetry between variables is low and generally increases with age.

DISCUSSION

Higher correlations with age in CSG likely indicate greater responsiveness to mechanical loading. Low correlations in magnitude of asymmetry and side dominance suggest independence in the development of asymmetry between maximum rigidity, shape, and linear measures. Differences in how asymmetric loading affects the ontogeny of linear and CSG variables may account for the heterogeneous development of asymmetry.

Callus formation after total hip arthroplasty using a short tapered-wedge stem

OBJECTIVE

The incidence of periprosthetic fractures after total hip arthroplasty using a short tapered-wedge stem is high. Callus formation preceding this fracture, which indicates postoperative stress fracture around the stem, has been reported. However, previous studies on postoperative callus are limited. Hence, the current study aimed to evaluate the prevalence and risk factors of postoperative callus after total hip arthroplasty with a short tapered-wedge stem.

MATERIALS AND METHODS

This retrospective study included 127 patients who underwent total hip arthroplasty using a cementless short tapered-wedge stem. The depth of stem insertion was measured as the distance from the lateral corner of the stem to the most medial point of the lesser trochanter along the body axis. Postoperative callus was defined as a bridging callus on the lateral femoral cortex at the distal end of the porous coating of the stem. Plain radiography was performed before surgery and immediately and at 1, 3, and 6 months after surgery to assess postoperative callus. Univariate and multivariate logistic regression analyses were performed to identify the risk factors for PC.

RESULTS

In total, 60 (47.2%) of 127 patients presented with postoperative callus. Multivariate logistic regression analysis with postoperative callus as the dependent variable revealed that the stem depth at 1 month after total hip arthroplasty (odds ratio, 1.14; 95% confidence interval, 1.04-1.24, p = 0.002) was a significant and independent risk factor of postoperative callus.

CONCLUSION

Deep insertion of a short tapered-wedge stem is a risk factor for postoperative callus.

Increased Risk of Fracture after Traumatic Amputation: A Nationwide Retrospective Cohort Study

The physiological changes and alterations in gait following amputation may increase the risk of fractures. However, there is insufficient research on fracture risk in amputees. Therefore, this study intended to analyze whether the risk of new fractures increases after traumatic amputations. This population-based, retrospective cohort study used data from the Korean National Health Insurance System database. The study included 19,586 participants who had undergone an amputation and 76,645 matched controls. The incidence of any fracture and site-specific fractures (vertebral, hip, and others) according to amputation site(s) and severity of disability due to amputation were evaluated using Cox proportional hazard regression analysis. During the mean follow-up of 4.2 years, amputees had a higher incidence rate (IR) of any fracture (adjusted HR [aHR] 1.47, 95% CI 1.36-1.60), vertebral fracture (aHR 1.63, 95% CI 1.44-1.85), hip fracture (aHR 1.85, 95% CI 1.39-2.46), and other fracture (aHR 1.34, 95% CI 1.20-1.49) compared to that of controls. In the presence of disability, the risks were further increased and were highest among amputees with severe disabilities. All fracture risks were higher in amputees than they were in controls, regardless of lower limb or upper limb amputation. This cohort study demonstrated that traumatic amputees experienced higher incidence of all fractures than did individuals without amputations, and this risk increases with severity of disability. This finding underscores the importance of early screening and lifestyle interventions to address fracture risk in traumatic amputees.

Quantifying the relationship between bone and soft tissue measures within the rhesus macaques of Cayo Santiago

OBJECTIVES

Interpretations of the primate and human fossil record often rely on the estimation of somatic dimensions from bony measures. Both somatic and skeletal variation have been used to assess how primates respond to environmental change. However, it is unclear how well skeletal variation matches and predicts soft tissue. Here, we empirically test the relationship between tissues by comparing somatic and skeletal measures using paired measures of pre- and post-mortem rhesus macaques from Cayo Santiago, Puerto Rico.

MATERIALS AND METHODS

Somatic measurements were matched with skeletal dimensions from 105 rhesus macaque individuals to investigate paired signals of variation (i.e., coefficients of variation, sexual dimorphism) and bivariate codependence (reduced major axis regression) in measures of: (1) limb length; (2) joint breadth; and (3) limb circumference. Predictive models for the estimation of soft tissue dimensions from skeletons were built from Ordinary Least Squares regressions.

RESULTS

Somatic and skeletal measurements showed statistically equivalent coefficients of variation and sexual dimorphism as well as high epiphyses-present ordinary least square (OLS) correlations in limb lengths (R2 >0.78, 0.82), joint breadths (R2 >0.74, 0.83) and, to a lesser extent, limb circumference (R2 >0.53, 0.68).

CONCLUSION

Skeletal measurements are good substitutions for somatic values based on population signals of variation. OLS regressions indicate that skeletal correlates are highly predictive of somatic dimensions. The protocols and regression equations established here provide a basis for reliable reconstruction of somatic dimension from catarrhine fossils and validate our ability to compare or combine results of studies based on population data of either hard or soft tissue proxies.

Trabecular architecture of the distal femur in extant hominids

Extant great apes are characterized by a wide range of locomotor, postural and manipulative behaviours that each require the limbs to be used in different ways. In addition to external bone morphology, comparative investigation of trabecular bone, which (re-)models to reflect loads incurred during life, can provide novel insights into bone functional adaptation. Here, we use canonical holistic morphometric analysis (cHMA) to analyse the trabecular morphology in the distal femoral epiphysis of Homo sapiens (n = 26), Gorilla gorilla (n = 14), Pan troglodytes (n = 15) and Pongo sp. (n = 9). We test two predictions: (1) that differing locomotor behaviours will be reflected in differing trabecular architecture of the distal femur across Homo, Pan, Gorilla and Pongo; (2) that trabecular architecture will significantly differ between male and female Gorilla due to their different levels of arboreality but not between male and female Pan or Homo based on previous studies of locomotor behaviours. Results indicate that trabecular architecture differs among extant great apes based on their locomotor repertoires. The relative bone volume and degree of anisotropy patterns found reflect habitual use of extended knee postures during bipedalism in Homo, and habitual use of flexed knee posture during terrestrial and arboreal locomotion in Pan and Gorilla. Trabecular architecture in Pongo is consistent with a highly mobile knee joint that may vary in posture from extension to full flexion. Within Gorilla, trabecular architecture suggests a different loading of knee in extension/flexion between females and males, but no sex differences were found in Pan or Homo, supporting our predictions. Inter- and intra-specific variation in trabecular architecture of distal femur provides a comparative context to interpret knee postures and, in turn, locomotor behaviours in fossil hominins.

Trabecular bone variation in the gorilla calcaneus

OBJECTIVES

Calcaneal external shape differs among nonhuman primates relative to locomotion. Such relationships between whole-bone calcaneal trabecular structure and locomotion, however, have yet to be studied. Here we analyze calcaneal trabecular architecture in Gorilla gorilla gorilla, Gorilla beringei beringei, and G. b. graueri to investigate general trends and fine-grained differences among gorilla taxa relative to locomotion.

MATERIALS AND METHODS

Calcanei were micro-CT scanned. A three-dimensional geometric morphometric sliding semilandmark analysis was carried out and the final landmark configurations used to position 156 volumes of interest. Trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), and bone volume fraction (BV/TV) were calculated using the BoneJ plugin for ImageJ and MATLAB. Non-parametric MANOVAs were run to test for significant differences among taxa in parameter raw values and z-scores. Parameter distributions were visualized using color maps and summarized using principal components analysis.

RESULTS

There are no significant differences in raw BV/TV or Tb.Th among gorillas, however G. b. beringei significantly differs in z-scores for both parameters (p = <0.0271). All three taxa exhibit relatively lower BV/TV and Tb.Th in the posterior half of the calcaneus. This gradation is exacerbated in G. b. beringei. G. b. graueri significantly differs from other taxa in Tb.Sp z-scores (p < 0.001) indicating a different spacing distribution.

DISCUSSION

Relatively higher Tb.Th and BV/TV in the anterior calcaneus among gorillas likely reflects higher forces associated with body mass (transmitted through the subtalar joint) relative to forces transferred through the posterior calcaneus. The different Tb.Sp pattern in G. b. graueri may reflect proposed differences in foot positioning during locomotion.

New insights into patterns of integration in the femur and pelvis among catarrhines

OBJECTIVES

Integration reflects the level of coordinated variation of the phenotype. The integration of postcranial elements can be studied from a functional perspective, especially with regards to locomotion. This study investigates the link between locomotion, femoral structural properties, and femur-pelvis complex morphology.

MATERIALS AND METHODS

We measured (1) morphological integration between femoral and pelvic morphologies using geometric morphometrics, and (2) covariation between femoral/pelvic morphologies and femoral diaphyseal cross-sectional properties, which we defined as morpho-structural integration. Morphological and morpho-structural integration patterns were measured among humans (n = 19), chimpanzees and bonobos (n = 16), and baboons (n = 14), whose locomotion are distinct.

RESULTS

Baboons show the highest magnitude of morphological integration and the lowest of morpho-structural integration. Chimpanzees and bonobos show intermediate magnitude of morphological and morpho-structural integration. Yet, body size seems to have a considerable influence on both integration patterns, limiting the interpretations. Finally, humans present the lowest morphological integration and the highest morpho-structural integration between femoral morphology and structural properties but not between pelvic morphology and femur.

DISCUSSION

Morphological and morpho-structural integration depict distinct strategies among the samples. A strong morphological integration among baboon's femur-pelvis module might highlight evidence for long-term adaptation to quadrupedalism. In humans, it is likely that distinct selective pressures associated with the respective function of the pelvis and the femur tend to decrease morphological integration. Conversely, high mechanical loading on the hindlimbs during bipedal locomotion might result in specific combination of structural and morphological features within the femur.

Main morphological characteristics and sexual dimorphism of hominin adult femora from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain)

The excellent fossil record from Sima de los Huesos (SH) includes three well-known complete adult femora and several partial specimens that have not yet been published in detail. This fossil record provides an opportunity to analyze the morphology of European pre-Neandertal adult femur and its variation with different evolution patterns. Currently, there are a minimum of five adult individuals (males or females). In this study, we compiled previously published basic anatomical and biometric characteristics of SH adult femora, emphasizing the most relevant features compared to other recent and fossil hominins. The SH femora exhibited a primitive morphological pattern common to all non-Homo sapiens femora, as well as most of the Neandertal traits. Therefore, the complete Upper Pleistocene Neandertal pattern was well-established in Middle Pleistocene ancestors long before the proper Neandertals appeared. Additionally, we highlight that the SH and Neandertal femora share some morphological traits and proportions with modern humans that hold sexual significance in our species, regardless of size. Keeping this in mind, we discussed the sex determination of the complete SH specimens and re-evaluated sex allocation in two of them.

Cortical bone architecture of hominid intermediate phalanges reveals functional signals of locomotion and manipulation

OBJECTIVES

Reconstruction of fossil hominin manual behaviors often relies on comparative analyses of extant hominid hands to understand the relationship between hand use and skeletal morphology. In this context, the intermediate phalanges remain understudied. Thus, here we investigate cortical bone morphology of the intermediate phalanges of extant hominids and compare it to the cortical structure of the proximal phalanges, to investigate the relationship between cortical bone structure and inferred loading during manual behaviors.

MATERIALS AND METHODS

Using micro-CT data, we analyze cortical bone structure of the intermediate phalangeal shaft of digits 2-5 in Pongo pygmaeus (n = 6 individuals), Gorilla gorilla (n = 22), Pan spp. (n = 23), and Homo sapiens (n = 23). The R package morphomap is used to study cortical bone distribution, cortical thickness and cross-sectional properties within and across taxa.

RESULTS

Non-human great apes generally have thick cortical bone on the palmar shaft, with Pongo only having thick cortex on the peaks of the flexor sheath ridges, while African apes have thick cortex along the entire flexor sheath ridge and proximal to the trochlea. Humans are distinct in having thicker dorsal shaft cortex as well as thick cortex at the disto-palmar region of the shaft.

DISCUSSION

Variation in cortical bone distribution and properties of the intermediate phalanges is consistent with differences in locomotor and manipulative behaviors in extant great apes. Comparisons between the intermediate and proximal phalanges reveals similar patterns of cortical bone distribution within each taxon but with potentially greater load experienced by the proximal phalanges, even in knuckle-walking African apes. This study provides a comparative context for the reconstruction of habitual hand use in fossil hominins and hominids.

Enhancing the contemporary human and water isotope reference database for the Netherlands: New insights from Sr-O-C-N-H isotope data

The determination of an individual's geographic origin is an essential aspect of forensic investigations. When primary identifiers cannot be used to make a positive identification, isotope analysis can be utilized to provide new leads. Modern reference data are essential for accurate interpretation of human isotopic data in terms of diet and origin. This article presents Sr-O-C-N-H isotope data of modern individuals (hair, dental enamel, and dentine collagen) and drinking water from the Netherlands. The δ15N values of human hair fall within the range of values observed worldwide and cannot be utilized to differentiate from other countries. Distinct disparities in the hair δ13C are evident between European countries and other regions, making it possible to exclude the Netherlands as a region of origin. Comparing Dutch dental isotope data to those of other nations has proven difficult due to the limited availability of reference data. The same limitation applies to tap water δ2H data.

Consideration of the thoracic phenotype of cerebro-costo-mandibular syndrome

Cerebro-costo-mandibular syndrome (CCMS) is a congenital condition with skeletal and orofacial abnormalities that often results in respiratory distress in neonates. The three main phenotypes in the thorax are posterior rib gaps, abnormal costovertebral articulation and absent ribs. Although the condition can be lethal, accurate diagnosis, and subsequent management help improve the survival rate. Mutations in the causative gene SNRPB have been identified, however, the mechanism whereby the skeletal phenotypes affect respiratory function is not well-studied due to the multiple skeletal phenotypes, lack of anatomy-based studies into the condition and rarity of CCMS cases. This review aims to clarify the extent to which the three main skeletal phenotypes in the thorax contribute to respiratory distress in neonates with CCMS. Despite the posterior rib gaps being unique to this condition and visually striking on radiographic images, anatomical consideration, and meta-analyses suggested that they might not be the significant factor in causing respiratory distress in neonates. Rather, the increase in chest wall compliance due to the rib gaps and the decrease in compliance at the costovertebral complex was considered to result in an equilibrium, minimizing the impact of these abnormalities. The absence of floating ribs is likely insignificant as seen in the general population; however, a further absence of ribs or vestigial rib formation is associated with respiratory distress and increased lethality. Based on these, we propose to evaluate the number of absent or vestigial ribs as a priority indicator to develop a personalized treatment plan based on the phenotypes exhibited.

Facing the facts: adaptive trade-offs along body size ranges determine mammalian craniofacial scaling

The mammalian cranium (skull without lower jaw) is representative of mammalian diversity and is thus of particular interest to mammalian biologists across disciplines. One widely retrieved pattern accompanying mammalian cranial diversification is referred to as 'craniofacial evolutionary allometry' (CREA). This posits that adults of larger species, in a group of closely related mammals, tend to have relatively longer faces and smaller braincases. However, no process has been officially suggested to explain this pattern, there are many apparent exceptions, and its predictions potentially conflict with well-established biomechanical principles. Understanding the mechanisms behind CREA and causes for deviations from the pattern therefore has tremendous potential to explain allometry and diversification of the mammalian cranium. Here, we propose an amended framework to characterise the CREA pattern more clearly, in that 'longer faces' can arise through several kinds of evolutionary change, including elongation of the rostrum, retraction of the jaw muscles, or a more narrow or shallow skull, which all result in a generalised gracilisation of the facial skeleton with increased size. We define a standardised workflow to test for the presence of the pattern, using allometric shape predictions derived from geometric morphometrics analysis, and apply this to 22 mammalian families including marsupials, rabbits, rodents, bats, carnivores, antelopes, and whales. Our results show that increasing facial gracility with size is common, but not necessarily as ubiquitous as previously suggested. To address the mechanistic basis for this variation, we then review cranial adaptations for harder biting. These dictate that a more gracile cranium in larger species must represent a structural sacrifice in the ability to produce or withstand harder bites, relative to size. This leads us to propose that facial gracilisation in larger species is often a product of bite force allometry and phylogenetic niche conservatism, where more closely related species tend to exhibit more similar feeding ecology and biting behaviours and, therefore, absolute (size-independent) bite force requirements. Since larger species can produce the same absolute bite forces as smaller species with less effort, we propose that relaxed bite force demands can permit facial gracility in response to bone optimisation and alternative selection pressures. Thus, mammalian facial scaling represents an adaptive by-product of the shifting importance of selective pressures occurring with increased size. A reverse pattern of facial 'shortening' can accordingly also be found, and is retrieved in several cases here, where larger species incorporate novel feeding behaviours involving greater bite forces. We discuss multiple exceptions to a bite force-mediated influence on facial proportions across mammals which lead us to argue that ecomorphological specialisation of the cranium is likely to be the primary driver of facial scaling patterns, with some developmental constraints as possible secondary factors. A potential for larger species to have a wider range of cranial functions when less constrained by bite force demands might also explain why selection for larger sizes seems to be prevalent in some mammalian clades. The interplay between adaptation and constraint across size ranges thus presents an interesting consideration for a mechanistically grounded investigation of mammalian cranial allometry.

The Effect of Diet Composition on the Post-operative Outcomes of Roux-en-Y Gastric Bypass in Mice

PURPOSE

Roux-en-Y gastric bypass (RYGB) leads to the improvement of many obesity-associated conditions. The degree to which post-operative macronutrient composition contributes to metabolic improvement after RYGB is understudied.

METHODS

A mouse model of RYGB was used to examine the effects of diet on the post-operative outcomes of RYGB. Obese mice underwent either Sham or RYGB surgery and were administered either chow or HFD and then monitored for an additional 8 weeks.

RESULTS

After RYGB, reductions to body weight, fat mass, and lean mass were similar regardless of diet. RYGB and HFD were independently detrimental to bone mineral density and plasma vitamin D levels. Independent of surgery, HFD accelerated hematopoietic stem and progenitor cell proliferation and differentiation and exhibited greater myeloid lineage commitment. Independent of diet, systemic iron deficiency was present after RYGB. In both Sham and RYGB groups, HFD increased energy expenditure. RYGB increased fecal energy loss, and HFD after RYGB increased fecal lipid content. RYGB lowered fasting glucose and liver glycogen levels but HFD had an opposing effect. Indices of insulin sensitivity improved independent of diet. HFD impaired improvements to dyslipidemia, NAFLD, and fibrosis.

CONCLUSION

Post-operative diet plays a significant role in determining the degree to which RYGB reverses obesity-induced metabolic abnormalities such as hyperglycemia, dyslipidemia, and NAFLD. Diet composition may be targeted in order to assist in the treatment of post-RYGB bone mineral density loss and vitamin D deficiency as well as to reverse myeloid lineage commitment. HFD after RYGB continues to pose a significant multidimensional health risk.

Lower limb coronal malalignment correction by percutaneous osteotomy and schanz screws fixation

Pediatric knee deformities are common, and the classic treatment is corrective osteotomy. The aim of this study to assess the safety and efficacy of percutaneous low-energy osteotomy and casting with shanz screws fixation in treatment of Genu varum in children equal or younger than 7 years. This is a prospective nonrandomized case series study was conducted. A total of 38 patients (total of 60 limbs: 36 varus and 24 valgus) were treated by percutaneous low-energy osteotomy and casting with shanz screws fixation and observed over 2-5 years. Clinical and radiological outcomes were evaluated at the end of follow-up period by standing scanogram which enabled tibiofemoral angles and the mechanical axis to be measured and the rate of complications. There was a statistically significant improvement of the radiographic parameters in the form of tibiofemoral angle and MAD. Clinically, all the cases were completely corrected just one patient (two limbs) complicated by over-correction but statically non-significant and. pin tract infection in shanz screws fixation was noticed in one Patient. Percutaneous low-energy osteotomy and casting with shanz screws fixation is a simple, safe, and effective method in dealing with 7 years and younger children with pathological knee deformities. Level of evidence: Therapeutic level IV.

Sex differences in workload in medieval Poland: Patterns of asymmetry and biomechanical adaptation in the upper limb at Giecz

OBJECTIVES

This study characterizes sexual dimorphism in skeletal markers of upper limb mechanical loading due to lateralization as evidence of division of labor in medieval Giecz, Poland.

METHODS

Twenty-six dimensions for paired humeri, clavicles, and radii representing adult males (n = 89) and females (n = 53) were collected from a skeletal sample from the cemetery site Gz4. Percent directional asymmetry (DA) and absolute asymmetry (AA) for each dimension were compared among bones, osteometric subcategories, and sex. Additionally, side bias and sex differences were assessed in degenerative joint disease (DJD) and entheseal changes (ECs).

RESULTS

Nearly all measurements revealed significant asymmetry favoring the right side. Asymmetry was most pronounced in midshaft dimensions with few sex differences. There were more correlations among dimensions within elements than between elements, mainly in the midshaft. No laterality in DJD frequencies was noted for either sex, but females demonstrated significantly lower odds of having DJD than males in most joints. Most ECs demonstrated a right-bias and association with DA with no sex-specific patterns except the biceps brachii insertion, where females were ~5 times more likely to be scored "right" than males.

DISCUSSION

The general lack of sex differences in asymmetry and ECs suggests similarly demanding workloads for females and males, with the exception of sex-specific functional loading differences in the forearm. Further, DJD data suggest males engaged in more intensive activities involving the upper limb. These results enhance understanding of workload in this important historical period and provide a comparison for asymmetry in past populations.

The frequency and presentation of upper thoracic spinous process deviations, their relationship to articular morphology, and the potential influence on static palpation techniques

BACKGROUND

Static palpation of vertebral spinous process deviations from the midline are often utilized by manual therapists as a means to determine area for treatment of manipulable lesions. Previous research has discussed the diagnostic validity of this technique, but no correlation to vertebral morphology has been presented.

AIM

To evaluate the frequency and presentation of vertebral spinous process deviations and their relationship with articular morphology, and the impact this may have in terms of static palpation techniques in the upper thoracic spine.

SETTING

This study was conducted on human T1-T6 vertebrae.

METHOD

A skeletal sample consisting of 58 humans T1-T6 vertebrae were photographed and linear and angular measurements taken utilizing ImageJ software and non-metric visual observations.

RESULTS

Spinous process deviations in the entire sample group (n = 348) were found to occur in a frequency ranging from 19% (n = 11) at T1 to 41.4% (n = 24) at T3. However, when evaluated in terms of frequency within an individual's T1-T6, 83.3% (n = 25) of males and 67.86% (n = 19) of females demonstrated this feature, with an overall incidence of 77.59% (n = 45). Age of individuals did not show an increase in frequency, and no clear pattern could be identified regarding metric measurements and its presence.

CONCLUSION

Spinous process deviations in the upper thoracic spine are most probably the result of random normal variations between individuals and are more frequent in males. Static palpation without pain criteria is not a reliable diagnostic technique to determine areas needing manual treatment, as these may be considered normal osseous anatomical variations.

Biomechanical and taxonomic diversity in the Early Pleistocene in East Africa: Structural analysis of a recently discovered femur shaft from Olduvai Gorge (bed I)

Recent Plio-Pleistocene hominin findings have revealed the complexity of human evolutionary history and the difficulties involved in its interpretation. Moreover, the study of hominin long bone remains is particularly problematic, since it commonly depends on the analysis of fragmentary skeletal elements that in many cases are merely represented by small diaphyseal portions and appear in an isolated fashion in the fossil record. Nevertheless, the study of the postcranial skeleton is particularly important to ascertain locomotor patterns. Here we report on the discovery of a robust hominin femoral fragment (OH 84) at the site of Amin Mturi Korongo dated to 1.84 Ma (Olduvai Bed I). External anatomy and internal bone structure of OH 84 were analyzed and compared with previously published data for modern humans and chimpanzees, as well as for Australopithecus, Paranthropus and Homo specimens ranging from the Late Pliocene to Late Pleistocene. Biomechanical analyses based on transverse cross-sections and the comparison of OH 84 with another robust Olduvai specimen (OH 80) suggest that OH 84 might be tentatively allocated to Paranthropus boisei. More importantly, the identification of a unique combination of traits in OH 84 could indicate both terrestrial bipedalism and an arboreal component in the locomotor repertoire of this individual. If interpreted correctly, OH 84 could thus add to the already mounting evidence of substantial locomotor diversity among Early Pleistocene hominins. Likewise, our results also highlight the difficulties in accurately interpreting the link between form and function in the human fossil record based on fragmentary remains, and ultimately in distinguishing between coeval hominin groups due to the heterogeneous pattern of inter- and intraspecific morphological variability detected among fossil femora.

Sr-Pb isotope differences in pre- and post-burial human bone, teeth, and hair keratin: implications for isotope forensics

The isotopic signatures of human tissues can provide valuable information on geographic origin for medicolegal investigations involving unidentified persons. It is important to understand the impact of diagenetic processes on isotopic signatures, as alterations could result in incorrect estimation of geographic origin. This study examines alterations in isotope signatures of different tissues of five human body donors studied throughout decomposition at the Forensic Anthropology Research Facility (FARF), San Marcos, TX. Two body donors were buried, two were placed in open pits, and one was first allowed to naturally mummify and then buried. Remains were recovered after a period of 7-34 months. The preplacement and post-recovery Sr-Pb isotope data of scalp hair, bone (iliac and tibia), and tooth enamel and dentine were compared. The hair samples record significant shifts in Sr-Pb isotope compositions, with hair keratin Pb isotope composition shifting towards the Pb signature of local soil samples. Hair keratin Sr isotope compositions were altered by the burial environment and possibly also by the lab sample cleaning method. The spongy iliac bone samples show inconsistencies in the recoverability of the preplacement Sr-Pb isotope signatures. The post-placement signatures of the buried donors show slight elevation over preplacement signatures. The post-placement signatures of donors placed in open pits are significantly elevated. The tibia and dental samples record the most consistent isotopic data with the least alteration. These more densely mineralised elements show good recoverability of the preplacement isotope signatures in burials and open pits and are thus deemed better targets for forensic investigative purposes.

Surface-based anthropomorphic bone structures for use in high-resolution simulated medical imaging

Objective.Virtual imaging trials enable efficient assessment and optimization of medical image devices and techniques via simulation rather than physical studies. These studies require realistic, detailed ground-truth models or phantoms of the relevant anatomy or physiology. Anatomical structures within computational phantoms are typically based on medical imaging data; however, for small and intricate structures (e.g. trabecular bone), it is not reasonable to use existing clinical data as the spatial resolution of the scans is insufficient. In this study, we develop a mathematical method to generate arbitrary-resolution bone structures within virtual patient models (XCAT phantoms) to model the appearance of CT-imaged trabecular bone.Approach. Given surface definitions of a bone, an algorithm was implemented to generate stochastic bicontinuous microstructures to form a network to define the trabecular bone structure with geometric and topological properties indicative of the bone. For an example adult male XCAT phantom (50th percentile in height and weight), the method was used to generate the trabecular structure of 46 chest bones. The produced models were validated in comparison with published properties of bones. The utility of the method was demonstrated with pilot CT and photon-counting CT simulations performed using the accurate DukeSim CT simulator on the XCAT phantom containing the detailed bone models.Main results. The method successfully generated the inner trabecular structure for the different bones of the chest, having quantiative measures similar to published values. The pilot simulations showed the ability of photon-counting CT to better resolve the trabecular detail emphasizing the necessity for high-resolution bone models.Significance.As demonstrated, the developed tools have great potential to provide ground truth simulations to access the ability of existing and emerging CT imaging technology to provide quantitative information about bone structures.

Intramedullary nailing vs. open reduction-internal fixation for humeral shaft fractures: a meta-analysis of randomized controlled trials

BACKGROUND

The purpose of this study was to perform a meta-analysis of randomized controlled trials (RCTs) to compare outcomes following intramedullary nailing (IMN) vs. open reduction-internal fixation (ORIF) for humeral shaft fractures.

METHODS

A literature search of 3 databases was performed based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. RCTs comparing IMN and ORIF for humeral shaft fractures were included. Clinical outcomes were compared using RevMan. P < .05 was considered statistically significant.

RESULTS

Ten RCTs with 512 patients were included. Overall, 8.4% of patients treated with IMN and 6.4% of patients treated with ORIF had nonunion (P = .57, I2 = 0%), with a significantly faster time to union with IMN (10 weeks vs. 11.9 weeks, P < .05). There was no significant difference in the rate of reoperation (11.6% in IMN group vs. 7.6% in ORIF group, P = .26) or radial nerve palsy (2.8% in IMN group vs. 4.2% in ORIF group, P = .58). A lower rate of infection was noted with IMN (1.2% vs. 5.3%, P < .05). Additionally, there was a lower operative time with IMN (61 minutes vs. 88 minutes, P < .05).

CONCLUSIONS

The Level I evidence in the literature does not show a significant difference in rates of union, reoperation, or radial nerve palsy between IMN and ORIF for humeral shaft fractures. Overall, treatment with IMN results in a lower infection rate, less operative time, and a modestly quicker time to union. The optimal treatment strategy for humeral shaft fractures may be best informed by fracture pattern and surgeon preference.

Cortical bone distribution of the proximal phalanges in great apes: implications for reconstructing manual behaviours

Primate fingers are typically in direct contact with the environment during both locomotion and manipulation, and aspects of external phalangeal morphology are known to reflect differences in hand use. Since bone is a living tissue that can adapt in response to loading through life, the internal bone architecture of the manual phalanges should also reflect differences in manual behaviours. Here, we use the R package Morphomap to analyse high-resolution microCT scans of hominid proximal phalanges of digits 2-5 to determine whether cortical bone structure reflects variation in manual behaviours between bipedal (Homo), knuckle-walking (Gorilla, Pan) and suspensory (Pongo) taxa. We test the hypothesis that relative cortical bone distribution patterns and cross-sectional geometric properties will differ both among extant great apes and across the four digits due to locomotor and postural differences. Results indicate that cortical bone structure reflects the varied hand postures employed by each taxon. The phalangeal cortices of Pongo are significantly thinner and have weaker cross-sectional properties relative to the African apes, yet thick cortical bone under their flexor sheath ridges corresponds with predicted loading during flexed finger grips. Knuckle-walking African apes have even thicker cortical bone under the flexor sheath ridges, as well as in the region proximal to the trochlea, but Pan also has thicker diaphyseal cortices than Gorilla. Humans display a distinct pattern of distodorsal thickening, as well as relatively thin cortices, which may reflect the lack of phalangeal curvature combined with frequent use of flexed fingered hand grips during manipulation. Within each taxon, digits 2-5 have a similar cortical distribution in Pongo, Gorilla and, unexpectedly, Homo, which suggest similar loading of all fingers during habitual locomotion or hand use. In Pan, however, cortical thickness differs between the fingers, potentially reflecting differential loading during knuckle-walking. Inter- and intra-generic variation in phalangeal cortical bone structure reflects differences in manual behaviours, offering a comparative framework for reconstructing hand use in fossil hominins.

Inferring the mobility of a middle Upper Paleolithic female skeleton from Caviglione (Liguria, Italy): Impact of trauma and mountainous terrain

Mobility and territory occupation, the participation of injured individuals in group activities, and the role of women in early human groups are crucial issues in human evolution. Previously, a biomechanical study showed evidence of several traumas to the upper limb of the well-preserved middle Upper Paleolithic (UP) female skeleton from Caviglione (Caviglione 1, Liguria, Italy) but did not characterize their impact on locomotor behavior. Furthermore, mobility in the European UP context is thoroughly documented in males but not in females. Therefore, we examined whether this trauma-affected female skeleton shows bone adaptation to high mobility, as expected in UP groups, and to frequent foot eversion and inversion, as expected, given the mountainous area in which it was discovered. This study investigated the structural properties of the femur, tibia, fibula, and first metatarsal to infer the mobility level and pattern of Caviglione 1. We analyzed the diaphyseal 'shape', robusticity, fibular cortical distribution, and relative robusticity (fibula versus tibia). No substantial findings were derived from the first metatarsal. The fibular cortical distribution can discriminate 'active' (nomadic or settled) and recent sedentary human groups; these findings indicated Caviglione 1 belonged to the former. Interestingly, compared with ancient and recent sedentary humans and some UP individuals, Caviglione 1 had femurs with strong relative anteroposterior rigidity and robust tibias and fibulas reflecting an adaptation to extremely high levels of mobility. The very high relative fibular robusticity of Caviglione 1, higher than that of Middle UP males, is consistent with bone adaptation to frequent travel through mountainous terrain. Such fibular robusticity may also be a consequence of imbalance, due to upper limb traumas, when traveling downhill. These findings indicate that injured individuals may have participated in subsistence activities in past populations and describe an UP female with bone adaptations to habitual high mobility, notably in mountainous terrain.

Utility of HR-pQCT in detecting training-induced changes in healthy adult bone morphology and microstructure

Healthy bone adjusts its traits in an exceptionally coordinated, compensatory process. Recent advancements in skeletal imaging via High-Resolution Peripheral Quantitative Computed Tomography (HR-pQCT) allows for the in vivo 3-dimensional and longitudinal quantification of bone density, microarchitecture, geometry, and parameters of mechanical strength in response to varying strain stimuli including those resulting from exercise or military training. Further, the voxel size of 61 microns has the potential to capture subtle changes in human bone in as little as 8 weeks. Given the typical time course of bone remodeling, short-term detection of skeletal changes in bone microstructure and morphology is indicative of adaptive bone formation, the deposition of new bone formation, uncoupled from prior resorption, that can occur at mechanistically advantageous regions. This review aims to synthesize existing training-induced HR-pQCT data in three distinct populations of healthy adults excluding disease states, pharmacological intervention and nutritional supplementation. Those included are: 1) military basic or officer training 2) general population and 3) non-osteoporotic aging. This review aims to further identify similarities and contrasts with prior modalities and cumulatively interpret results within the scope of bone functional adaptation.

The multifactor pelvis: An alternative to the adaptationist approach of the obstetrical dilemma

The obstetrical dilemma describes the competing demands that a bipedally adapted pelvis and a large-brained neonate place on human childbirth and is the predominant model within which hypotheses about the evolution of the pelvis are framed. I argue the obstetrical dilemma follows the adaptationist program outlined by Gould and Lewontin in 1979 and should be replaced with a new model, the multifactor pelvis. This change will allow thorough consideration of nonadaptive explanations for the evolution of the human pelvis and avoid negative social impacts from considering human childbirth inherently dangerous. First, the atomization of the pelvis into discrete traits is discussed, after which current evidence for both adaptive and nonadaptive hypotheses is evaluated, including childbirth, locomotion, shared genetics with other traits under selection, evolutionary history, genetic drift, and environmental and epigenetic influences on the pelvis.

Multivariate assessments of activity-related skeletal changes: Interpreting Bell Beaker specialized male archery and social organization in Central Europe

OBJECTIVES

The Bell Beaker period witnessed the rise of individual inhumations with "wealthy" burial contexts containing archery-related grave goods, leading archaeologists to label the individuals in these tombs as "archers." This study looks to (1) compare the skeletons from male "archer" burials with those from male "non-archer" burials-those not having archery-related grave goods-in order to assess a possible link between burial context and physical activity, and (2) apply a biomechanics profile to evaluate whether the individuals associated with these "archer" burials practiced specialized archer activity.

MATERIALS AND METHODS

The corpus (males only) included 46 "archers" and 40 "non-archers" from Bell Beaker individual inhumations. Osteological data included measurements, scores of entheseal changes, and a diagnosis of certain pathologies. Data analyses involved visual observations, hypothesis tests, dimension reduction, and MANOVA, with approaches aimed at exploring the treatment of data missingness.

RESULTS

Measurement data revealed no differences between the two groups. Evaluations of entheseal changes found that "non-archers" had consistently more instances of bone surface modifications than "archers." Individual assessments of specialized archer occupation identified 11 possible specialized archers.

DISCUSSION

These findings indicate a possible labor differentiation represented through the presence of a probably prestigious "archer" burial context. This suggests a link between grave good presence and labor, but not between a Bell Beaker archery occupation and an "archer" burial context. Data analyses support the application of biomechanics to osteological analyses in order to assess specialized activity on the skeleton.

Human remains from Arma di Nasino (Liguria) provide novel insights into the paleoecology of early Holocene foragers in northwestern Italy

We report the discovery and analysis of new Mesolithic human remains-dated to ca. 10,200-9000 cal. BP-from Arma di Nasino in Liguria, northwestern Italy, an area rich in Upper Paleolithic and Neolithic attestations, but for which little information on Early Holocene occupation was available. The multi-proxy isotopic profile of the two individuals reveals that-despite the proximity of the site to the Mediterranean seashore and the use of shellfish as decorative elements in burials-the ecology of these foragers was based on the exploitation of high-altitude resources, presumably in the nearby western Alps. This constitutes the first direct evidence in northwestern Italy of a significant ecological shift towards higher altitudes following deglaciation, especially when compared to isotopic data of the Late Pleistocene hunter-gatherers from the nearby site of Arene Candide Cave, who exploited terrestrial resources nearer to the coast and at lower altitudes. While the biochemistry of Nasino's skeletal assemblage revealed new details on Early Holocene lifeways in the area, the osteobiography of one individual offers glimpses into the life experience of a specific female forager, depicting a scenario of early skeletal trauma, developmental disturbances, long-term impairments, and resilience amongst the last European hunter-gatherers.

Effects of Development on Bone Mineral Density and Mechanical Properties in the Aquatic Frog, Xenopus Laevis, and a Terrestrial Frog, Lithobates Catesbianus

The limb bones of vertebrates have a critical role in supporting the weight of the body and transmitting forces that power locomotion. The loads that limb bones experience can vary in association with a range of factors, including locomotor environment or developmental stage. Limbed vertebrates that are habitually found in environments with low locomotor loads (e.g., water) might be predicted to also exhibit limb bones with less elevated mechanical properties, such as yield stiffness and yield stress. Frogs provide a distinctive case, in which these ideas can be tested as they experience changes in both locomotor style and habitat as they develop. However, while many frog taxa shift from aquatic to terrestrial habitats as they metamorphose, some lineages, such as pipids, maintain an aquatic lifestyle even after metamorphosis, providing a comparative framework for the effects of habitat shifts on developing limbs in vertebrates. This study compares the material composition and mechanical properties of the femur between frog species that are aquatic specialists (Xenopus laevis) vs generalists that spend considerable time both on land and in water (Lithobates catesbeianus) as they transition from metamorphic tadpoles to fully grown adults. MicroCT scanning was used to determine changes in bone density related to developmental stage and hindlimb use during swimming. Microindentation was then used to collect hardness values from the cortical bone of each femur, which was used to evaluate bone material properties. We found that aquatic frogs had less overall bone mineral density (BMD) than terrestrial frogs and that BMD was more elevated in the cortical region of the diaphysis than trabeculae and distal and proximal epiphyses. Despite its less elevated BMD, bone mechanical properties were not significantly different in aquatic specialist X. laevis than in more terrestrial L. catesbeianus. Our results suggest that the limb bones of aquatic frogs may experience compensatory effects through development to offset their lower BMD. Furthermore, changes in bone density and material properties across development may help to explain some of the differences in locomotor performance found between aquatic and terrestrial metamorphic frogs, providing insight into how environmental factors might correlate with bone ossification.

Intraspecific variation of long bone cross-sectional properties in Pan troglodytes troglodytes and Gorilla gorilla gorilla

OBJECTIVES

Morphological intraspecific variation is due to the balance between skeletal plasticity and genetic constraint on the skeleton. Osteogenic responses to external stimuli, such as locomotion, have been well documented interspecifically across the primate order, but less so at the intraspecific level. Here, we examine the differences in cross-sectional variability of the femur, humerus, radius, and tibia in Pan troglodytes troglodytes versus Gorilla gorilla gorilla. We investigate whether there are sex, species, bone, and trait differences in response to variable body size and locomotion.

MATERIALS AND METHODS

Adult male and female P. t. troglodytes and G. g. gorilla long bones from the Cleveland Museum of Natural History were scanned with a peripheral quantitative computer tomography system. Scans were taken at the midshaft of each bone according to functional bone length. Coefficients of variation were used to provide a size-independent measure of variation. We applied a Bonferroni correction to account for the multiple pairwise tests.

RESULTS

There were limited significant differences between males and females, however, females tended to be more variable than males. Variation in Gorilla, when significant, was greater than in Pan, although significant differences were limited. There were no differences between bone variability in male and female Gorilla, and female Pan.

DISCUSSION

Increased female variability may be due to more variable locomotor behavior, particularly during periods of pregnancy, lactation, and caring for an offspring compared to consistent locomotion over the life course by males. Body size may be a contributing factor to variability; more work is needed to understand this relationship.

Pathophysiological mechanism of acute bone loss after fracture

BACKGROUND

Acute bone loss after fracture is associated with various effects on the complete recovery process and a risk of secondary fractures among patients. Studies have reported similarities in pathophysiological mechanisms involved in acute bone loss after fractures and osteoporosis. However, given the silence nature of bone loss and bone metabolism complexities, the actual underlying pathophysiological mechanisms have yet to be fully elucidated.

AIM OF REVIEW

To elaborate the latest findings in basic research with a focus on acute bone loss after fracture. To briefly highlight potential therapeutic targets and current representative drugs. To arouse researchers' attention and discussion on acute bone loss after fracture.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Bone loss after fracture is associated with immobilization, mechanical unloading, blood supply damage, sympathetic nerve regulation, and crosstalk between musculoskeletals among other factors. Current treatment strategies rely on regulation of osteoblasts and osteoclasts, therefore, there is a need to elucidate on the underlying mechanisms of acute bone loss after fractures to inform the development of efficacious and safe drugs. In addition, attention should be paid towards ensuring long-term skeletal health.

Is the distribution of cortical bone in the mandibular corpus and symphysis linked to loading environment in modern humans? A systematic review

OBJECTIVE

The human mandible is a unique bone with specific external and internal morphological characteristics, influenced by a complex and challenging loading environment. Mandibular cortical thickness distribution in cross-sections is reported to be related to facial divergence patterns, cultural and dietary habits and more generally, specific loading environment. This review hypothesises that a process of environmental mechanical sensitivity is involved in the distribution of cortical bone in the mandibular corpus and symphysis in modern humans, and that loading regimes can influence this distribution pattern. Based on a review of the recent literature, this study aims to answer the following question: "Is the distribution of cortical bone in the mandibular corpus and symphysis linked to the loading environment in modern humans?"

DESIGN

A systematic review was undertaken using the PubMed/Medline, Scopus and Cochrane Library databases for publications from 1984 to 2022 investigating the relationship between cortical bone distribution in the mandibular corpus and the loading environment. A subgroup meta-analysis was performed to determine the overall effect of facial divergence on cortical thickness.

RESULTS

From a total of 2791 studies, 20 fulfilled the inclusion criteria. The meta-analyses were performed in eight studies using a randomised model, finding a significant overall effect of facial divergence on cortical thickness in posterior areas of the mandible (p < 0.01).

CONCLUSIONS

Within the limitations of this review, specific loading regimes and their consequent variables (diet, culture, facial divergence) were linked to cortical thickness distribution. Sex was found to be unrelated to cortical thickness pattern.

Human femur morphology and histology variation with ancestry and behaviour in an ancient sample from Vietnam

BACKGROUND

There is a genetic component to the minimum effective strain (MES)-a threshold which determines when bone will adapt to function-which suggests ancestry should play a role in bone (re)modelling. Further elucidating this is difficult in living human populations because of the high global genetic admixture. We examined femora from an anthropological skeletal assemblage (Mán Bạc, Vietnam) representing distinct ancestral groups. We tested whether femur morphological and histological markers of modelling and remodelling differed between ancestries despite their similar lifestyles.

METHODS

Static histomorphometry data collected from subperiosteal cortical bone of the femoral midshaft, and gross morphometric measures of femur robusticity, were studied in 17 individuals from the Mán Bạc collection dated to 1906-1523 cal. BC. This assemblage represents agricultural migrants with affinity to East Asian groups, who integrated with the local hunter-gatherers with affinity to Australo-Papuan groups during the mid-Holocene. Femur robusticity and histology data were compared between groups of 'Migrant' (n = 8), 'Admixed' (n = 4), and 'Local' (n = 5).

RESULTS

Local individuals had more robust femoral diaphyses with greater secondary osteon densities, and relatively large secondary osteon and Haversian canal parameters than the migrants. The Migrant group showed gracile femoral shafts with the least dense bone made up of small secondary osteons and Haversian canals. The Admixed individuals fell between the Migrant and Local categories in terms of their femoral data. However, we also found that measures of how densely bone is remodelled per unit area were in a tight range across all three ancestries.

CONCLUSIONS

Bone modelling and remodelling markers varied with ancestral histories in our sample. This suggests that there is an ancestry related predisposition to bone optimising its metabolic expenditure likely in relation to the MES. Our results stress the need to incorporate population genetic history into hierarchical bone analyses. Understanding ancestry effects on bone morphology has implications for interpreting biomechanical loading history in past and modern human populations.

Biomechanical properties and clinical significance of cancellous bone in proximal femur: A review

Trabecular bone plays an important role in the load-bearing capacity of the femur. Understanding the structural characteristics, biomechanics, and mechanical conduction of the trabecular bone is of great value in studying the mechanism of fractures and formulating surgical plans. The past decade has witnessed unprecedented progress in imaging, biomechanics and finite element analysis techniques, translating into a better understanding of trabecular bone. This article reviews the research progress achieved over the years regarding femoral trabecular bone, especially on factors influencing the strength of the proximal femoral cancellous bone and cancellous bone microfractures and provides a comprehensive overview of the latest findings on proximal femoral trabecular bone and their clinical significance.

Periosteal chondrosarcoma: an unusual juxtacortical sarcoma

Periosteal chondrosarcoma is a rare tumor. It can be difficult to diagnose radiographically and pathologically and can be confused with periosteal osteosarcoma; however, the treatment of these two lesions is quite different. Increased awareness of imaging features of this lesion, particularly those that can help differentiate it from other surface-based tumors, can help one recognize this entity. We report the case of a periosteal chondrosarcoma in a young woman, highlighting the diagnostic imaging features of this disease, and her treatment with a joint-sparing geometric resection of the distal femur, using patient-specific 3D-printed cutting guides and matched allograft reconstruction.

The Effect of Omega-9 on Bone Viscoelasticity and Strength in an Ovariectomized Diet-Fed Murine Model

Few studies have investigated the effect of a monosaturated diet high in ω-9 on osteoporosis. We hypothesized that omega-9 (ω-9) protects ovariectomized (OVX) mice from a decline in bone microarchitecture, tissue loss, and mechanical strength, thereby serving as a modifiable dietary intervention against osteoporotic deterioration. Female C57BL/6J mice were assigned to sham-ovariectomy, ovariectomy, or ovariectomy + estradiol treatment prior to switching their feed to a diet high in ω-9 for 12 weeks. Tibiae were evaluated using DMA, 3-point-bending, histomorphometry, and microCT. A significant decrease in lean mass (p = 0.05), tibial area (p = 0.009), and cross-sectional moment of inertia (p = 0.028) was measured in OVX mice compared to the control. A trend was seen where OVX bone displayed increased elastic modulus, ductility, storage modulus, and loss modulus, suggesting the ω-9 diet paradoxically increased both stiffness and viscosity. This implies beneficial alterations on the macro-structural, and micro-tissue level in OVX bone, potentially decreasing the fracture risk. Supporting this, no significant differences in ultimate, fracture, and yield stresses were measured. A diet high in ω-9 did not prevent microarchitectural deterioration, nevertheless, healthy tibial strength and resistance to fracture was maintained via mechanisms independent of bone structure/shape. Further investigation of ω-9 as a therapeutic in osteoporosis is warranted.

Pathology or expected morphology? Investigating patterns of cortical porosity and trabecularization during infancy and early childhood

Increased cortical porosity is associated with a heightened risk of skeletal fragility due to bone loss and structural decay in adults. However, few studies have examined the etiology of cortical porosity in infants and children. This study examines whether age-related changes in femoral growth and locomotor development influence femoral midshaft cortical porosity in a sample of 48 individuals (fetal to 3.99 years) from the 10th-13th century cemetery of St. Étienne de Toulouse, France. Histological sections were prepared and imaged using light microscopy. Midshaft geometric variables such as total area, cortical area, and pore area were calculated using BoneJ. Increased porosity and cortical trabecularization were found to be significantly associated with age, being almost exclusively present in individuals aged 0.5-1.99 years. At approximately 6 months of age infants typically begin engaging in regular femoral loading and experience an acceleration in growth. The observed increase in midshaft porosity and trabecularization, therefore, likely results from the reorganization and redistribution of cortical bone, stimulated by increased growth velocity and the onset of weight-bearing activities. The reduction in cortical porosity and trabecularization in individuals aged 2.0-3.99 years indicates that children are approaching some sort of homeostasis as growth velocity slows and their femora adapt to consistent loading. Understanding what expected skeletal development looks like is necessary when conducting bioarcheological studies and this study provides evidence for a pattern of transient midshaft porosity during infancy and early childhood.

Quantitative Load Dependency Analysis of Local Trabecular Bone Microstructure to Understand the Spatial Characteristics in the Synthetic Proximal Femur

Analysis of the dependency of the trabecular structure on loading conditions is essential for understanding and predicting bone structure formation. Although previous studies have investigated the relationship between loads and structural adaptations, there is a need for an in-depth analysis of this relationship based on the bone region and load specifics. In this study, the load dependency of the trabecular bone microstructure for twelve regions of interest (ROIs) in the synthetic proximal femur was quantitatively analyzed to understand the spatial characteristics under seven different loading conditions. To investigate the load dependency, a quantitative measure, called the load dependency score (LDS), was established based on the statistics of the strain energy density (SED) distribution. The results showed that for the global model and epiphysis ROIs, bone microstructures relied on the multiple-loading condition, whereas the structures in the metaphysis depended on single or double loads. These results demonstrate that a given ROI is predominantly dependent on a particular loading condition. The results confirm that the dependency analysis of the load effects for ROIs should be performed both qualitatively and quantitatively.

Mechanochemistry of collagen

The collagen molecular family is the result of nearly one billion years of evolution. It is a unique family of proteins, the majority of which provide general mechanical support to biological tissues. Fibril forming collagens are the most abundant collagens in vertebrate animals and are generally found in positions that resist tensile loading. In animals, cells produce fibril-forming collagen molecules that self-assemble into larger structures known as collagen fibrils. Collagen fibrils are the fundamental, continuous, load-bearing elements in connective tissues, but are often further aggregated into larger load-bearing structures, fascicles in tendon, lamellae in cornea and in intervertebral disk. We know that failure to form fibrillar collagen is embryonic lethal, and excessive collagen formation/growth (fibrosis) or uncontrolled enzymatic remodeling (type II collagen: osteoarthritis) is pathological. Collagen is thus critical to vertebrate viability and instrumental in maintaining efficient mechanical structures. However, despite decades of research, our understanding of collagen matrix formation is not complete, and we know still less about the detailed mechanisms that drive collagen remodeling, growth, and pathology. In this perspective, we examine the known role of mechanical force on the formation and development of collagenous structure. We then discuss a mechanochemical mechanism that has the potential to unify our understanding of collagenous tissue assembly dynamics, which preferentially deposits and grows collagen fibrils directly in the path of mechanical force, where the energetics should be dissuasive and where collagen fibrils are most required. We term this mechanism: Mechanochemical force-structure causality. STATEMENT OF SIGNIFICANCE: Our mechanochemical-force structure causality postulate suggests that collagen molecules are components of mechanochemically-sensitive and dynamically-responsive fibrils. Collagen molecules assemble preferentially in the path of applied strain, can be grown in place by mechanical extension, and are retained in the path of force through strain-stabilization. The mechanisms that drive this behavior operate at the level of the molecules themselves and are encoded into the structure of the biomaterial. The concept might change our understanding of structure formation, enhance our ability to treat injuries, and accelerate the development of therapeutics to prevent pathologies such as fibrosis. We suggest that collagen is a mechanochemically responsive dynamic element designed to provide a substantial "material assist" in the construction of adaptive carriers of mechanical signals.

Factors associated with bone thickness: Comparison of the cranium and humerus

Cortical bone thickness is important for the mechanical function of bone. Ontogeny, aging, sex, body size, hormone levels, diet, behavior, and genetics potentially cause variations in postcranial cortical robusticity. However, the factors associated with cranial cortical robusticity remain poorly understood. Few studies have examined cortical robusticity in both cranial and postcranial bones jointly. In the present study, we used computed tomography (CT) images to measure cortical bone thicknesses in the cranial vault and humeral diaphysis. This study clearly showed that females have a greater cranial vault thickness and greater age-related increase in cranial vault thickness than males. We found an age-related increase in the full thickness of the temporal cranial vault and the width of the humeral diaphysis, as well as an age-related decrease in the cortical thickness of the frontal cranial vault and the cortical thickness of the humeral diaphysis, suggesting that the mechanisms of bone modeling in cranial and long bones are similar. A positive correlation between cortical indices in the cranial vault and humeral diaphysis also suggested that common factors affect cortical robusticity. We also examined the association of polymorphisms in the WNT16 and TNFSF11 genes with bone thickness. However, no significant associations were observed. The present study provides fundamental knowledge about similarities and differences in the mechanisms of bone modeling between cranial and postcranial bones.

Cross-sectional geometry of the femoral diaphyseal cortical bones: analysis of central mass distribution

A detailed analysis of differences in skeletal shape among many individuals is expected to reveal the mechanical significance behind various morphological features. To confirm the distribution of the cortical bone region in cross sections, the relative position of the central mass distribution (CMD) of the cortical bone region to the CMD of the entire cross section was examined. A total of 90 right human femoral skeletons were examined using clinical multi-slice computed tomography. For nine cross sections of each femur, we determined the CMD of the whole area, including both cortical bone and medullary areas, as CMD-W, and that of the cortical bone region in the same cross section as CMD-C, and they were compared. The medial and anterior portion of the cortex was relatively thick just below the lesser trochanter. The posterior cortical bone tended to be relatively thick in the region from the center to the distal part of the diaphysis. Females had a significantly more medially deviated CMD than males throughout the entire diaphysis. These results suggest that femurs with advanced cortical bone thinning tend to have a concentration of cortical bone in their medial portion. CMD-C was located farther from the diaphysis axis as the degree of medial bending increased. Conversely, the greater the lateral bending of the diaphysis, the closer CMD-C was to the diaphysis axis. As the amount of bone decreases with age, self-adjustment could occur so that the cortical bone's critical area remains to prevent a decrease in mechanical strength.

Trabecular bone remodeling in the aging mouse: A micro-multiphysics agent-based in silico model using single-cell mechanomics

Bone remodeling is regulated by the interaction between different cells and tissues across many spatial and temporal scales. Notably, in silico models are regarded as powerful tools to further understand the signaling pathways that regulate this intricate spatial cellular interplay. To this end, we have established a 3D multiscale micro-multiphysics agent-based (micro-MPA) in silico model of trabecular bone remodeling using longitudinal in vivo data from the sixth caudal vertebra (CV6) of PolgA^{(D257A/D257A)} mice, a mouse model of premature aging. Our in silico model includes a variety of cells as single agents and receptor-ligand kinetics, mechanomics, diffusion and decay of cytokines which regulate the cells' behavior. We highlighted its capabilities by simulating trabecular bone remodeling in the CV6 of five mice over 4 weeks and we evaluated the static and dynamic morphometry of the trabecular bone microarchitecture. Based on the progression of the average trabecular bone volume fraction (BV/TV), we identified a configuration of the model parameters to simulate homeostatic trabecular bone remodeling, here named basal. Crucially, we also produced anabolic, anti-anabolic, catabolic and anti-catabolic responses with an increase or decrease by one standard deviation in the levels of osteoprotegerin (OPG), receptor activator of nuclear factor kB ligand (RANKL), and sclerostin (Scl) produced by the osteocytes. Our results showed that changes in the levels of OPG and RANKL were positively and negatively correlated with the BV/TV values after 4 weeks in comparison to basal levels, respectively. Conversely, changes in Scl levels produced small fluctuations in BV/TV in comparison to the basal state. From these results, Scl was deemed to be the main driver of equilibrium while RANKL and OPG were shown to be involved in changes in bone volume fraction with potential relevance for age-related bone features. Ultimately, this micro-MPA model provides valuable insights into how cells respond to their local mechanical environment and can help to identify critical pathways affected by degenerative conditions and ageing.

Contextualizing bilateral asymmetry and gender: A multivariate approach to femoral cross-sectional geometry at rural Medieval Pieve di Pava, Italy

OBJECTIVES

Our objective was to identify the relationship between biocultural factors of sex-gender and age and patterns of femoral cross-sectional geometry with historical evidence about labor and activity from an archeological skeletal sample excavated from the rural Medieval site Pieve di Pava.

MATERIALS AND METHODS

The study site, Pieve di Pava, was a rural parish cemetery in Tuscany with osteoarcheological remains from the 7th to 12th centuries. Cross-sectional geometric analysis of femora from 110 individuals dated to the 10th-12th centuries were used to examine trends in bone quantity, shape, and bending strength between age and sex groups, as well as in clusters identified through Hierarchical Cluster Analysis (HCA).

RESULTS

Overall, our study sample showed remarkable heterogeneity and our cluster analysis revealed a complex underlying structure, indicating that divisions of labor did not follow a strict gender binary in our sample. We found high levels of bilateral asymmetry in our sample in multiple cross-sectional areas for a significant proportion of the population. We found minimal differences between age groups or sex.

DISCUSSION

Our results suggest that males and females had varied experiences of labor and work during their lives that did not reflect the strict binary gender roles sometimes documented for medieval Europe. One important axis of difference is the direction and magnitude of bilateral asymmetry observed in our femur sample, which is associated with divergent trends in section moduli and bone area measures.

Anatomical Imaging Study on Uneven Settlement of the Proximal Tibia

OBJECTIVE

Uneven settlement of the proximal tibia significantly contributes to the onset and progression of medial compartment knee OA; however, the specific location and variations of proximal tibial deformity remain unclear. Therefore, this study aimed to explore the effects of the anatomic morphology of different tibial regions on proximal tibial vara and proximal tibial microstructural changes with age in both sexes to reveal the pattern of uneven settlement of the proximal tibia.

METHODS

In this retrospective study, we reviewed the radiographs of 414 patients (789 legs) between May and September 2021. The medial proximal tibial angle (MPTA) and four anatomic angles of the tibia (i.e., the tibial plateau-epiphyseal line [PT-EL] angle, epiphyseal line-tibial platform [EL-PF] angle, epiphyseal axis inclination angle [EAIA], and subepiphyseal axis inclination angle [SAIA]) were measured. The effect of each angle on MPTA and their changes with age in both sexes were investigated using Pearson's correlation coefficient and multiple linear regression.

RESULTS

In females, PT-EL angle, EL-PF angle, and SAIA negatively correlated with MPTA (r = -0.325, -0.246, and -0.502; p < 0.05), and EAIA positively correlated with MPTA (r = 0.099, p < 0.05). Regression analysis showed that the correlations between MPTA and PT-EL angle, EL-PF angle, and SAIA were significant (β = -1.003, -0.013, and -0.971; adjusted R²  = 0.979). Furthermore, MPTA negatively correlated with age (r = -0.202, p < 0.05); PT-EL angle and EAIA positively correlated with age (r = 0.237 and 0.142, p < 0.05). Regression analysis showed that only the correlation between PT-EL angle and age was significant (β = 5.635, p < 0.05). In males, PT-EL angle, EL-PF angle, and SAIA negatively correlated with MPTA (r = -0.270, -0.267, and -0.533; p < 0.05), and EAIA positively correlated with MPTA (r = 0.135, p < 0.05). Regression analysis showed that the correlations between MPTA and PT-EL angle, EL-PF angle, and SAIA were significant (β = -0.992, -0.017, and -0.958; adjusted R²  = 0.970). However, there was no significant correlation between age and any of the measured angles (p > 0.05).

CONCLUSIONS

Proximal tibial vara is affected by the anatomic morphology of the epiphyseal and subepiphyseal regions. In females, the uneven settlement of the epiphysis progresses with age and may be responsible for dynamic varus deformity of the proximal tibia.

Polg mtDNA mutator mice reveal limited involvement of vertebral bone loss in premature aging-related thoracolumbar hyperkyphosis

Background

Age-related hyperkyphosis is multifactorial and involves alterations of vertebral bone, intervertebral discs (IVD) and paraspinal muscles. The relative contribution of these tissues remains unclear. Here, we compared differences in vertebral bone microarchitecture and IVD thickness between prematurely aging mice with spinal hyperkyphosis and wild type littermates.

Methods

Thoracolumbar vertebral columns were dissected from homozygous Polg ^D257A and age-matched wild type littermates. Micro-computed tomography was performed to quantify cortical and trabecular bone parameters at anterior and posterior portions of T8-L4 vertebrae. In addition, vertebral shape, transaxial facet joint orientation and IVD thickness were quantified. Differences in anterior/posterior ratios between genotypes were compared by Student's t-test and association between vertebral bone and IVD parameters was investigated using Pearson correlation analysis.

Results

Hyperkyphotic homozygous mice displayed generalized osteopenia that was more pronounced at the posterior compared with anterior portion of thoracolumbar vertebrae. An increase in the anterior/posterior ratio of trabecular bone parameters was revealed at the thoracolumbar junction (T13-L1). Polg ^D257A displayed diffuse loss of cortical bone thickness, yet anterior/posterior ratios were unchanged. Despite generalized and regional bone loss, vertebral shape was unaffected. PolG ^D257A mice showed a 10-20 % reduction of IVD thickness at both thoracic and lumbar levels, with only minimal histopathological changes. IVD thickness was negatively correlated with anterior/posterior ratios of trabecular bone parameters, as well as with more coronally oriented facet joints, but negatively correlated with the anterior/posterior ratio of cortical bone thickness.

Conclusions

Aging-induced regional changes of vertebral trabecular and cortical bone did not lead to altered vertebral shape in Polg ^D257A mice but may indirectly cause hyperkyphosis through reduction of IVD thickness. These findings suggest a limited role for aging-induced bone loss in spinal hyperkyphosis and warrants further research on the involvement of paraspinal muscle degeneration.

Ape femoral-humeral rigidities and arboreal locomotion

OBJECTIVES

This study investigates patterns of bone functional adaptations in extant apes through comparing hindlimb to forelimb bone rigidity ratios in groups with varying levels of arboreality.

MATERIALS AND METHODS

Using CT scans, bone rigidity (J) was calculated at three regions of interest (ROI) along femoral and humeral diaphyses in Homo, Pongo, Pan, and Gorilla with further comparisons made between species and subspecies divisions within Pan and Gorilla.

RESULTS

Consistent with previous work on extant hominoids, species exhibited differences in midshaft femoral to humeral (F/H) rigidity ratios. Results of the present study confirm that these midshaft differences extend to 35% and 65% diaphyseal ROIs. Modern humans, exhibiting larger ratios, and orangutans, exhibiting smaller ratios, bracketed the intermediate African apes in comparisons. Within some African apes, limb rigidity ratios varied significantly between taxonomic groups. Eastern gorillas exhibited the highest mean ratios and chimpanzees the lowest at all three ROIs. In posthoc comparisons, chimpanzees and bonobos did not differ in relative limb rigidity ratios at any of the three ROIs. However, western gorillas were more similar to bonobos than eastern gorillas at 50% and 35% ROIs, but not at the 65% ROI.

CONCLUSION

Species, and to a lesser extent subspecies, can be distinguished by F/H limb rigidity ratios according to broad positional behavior patterns at multiple regions of interest along the diaphyses. Similarity of bonobos and western gorillas is in line with behavioral data of bonobos being the most terrestrial of Pan species, and western gorillas the most arboreal of the Gorilla groups.

Preserved soft anatomy confirms shoulder-powered upstroke of early theropod flyers, reveals enhanced early pygostylian upstroke, and explains early sternum loss

Anatomy of the first flying feathered dinosaurs, modern birds and crocodylians, proposes an ancestral flight system divided between shoulder and chest muscles, before the upstroke muscles migrated beneath the body. This ancestral flight system featured the dorsally positioned deltoids and supracoracoideus controlling the upstroke and the chest-bound pectoralis controlling the downstroke. Preserved soft anatomy is needed to contextualize the origin of the modern flight system, but this has remained elusive. Here we reveal the soft anatomy of the earliest theropod flyers preserved as residual skin chemistry covering the body and delimiting its margins. These data provide preserved soft anatomy that independently validate the ancestral theropod flight system. The heavily constructed shoulder and more weakly constructed chest in the early pygostylian Confuciusornis indicated by a preserved body profile, proposes the first upstroke-enhanced flight stroke. Slender ventral body profiles in the early-diverging birds Archaeopteryx and Anchiornis suggest habitual use of the pectoralis could not maintain the sternum through bone functional adaptations. Increased wing-assisted terrestrial locomotion potentially accelerated sternum loss through higher breathing requirements. Lower expected downstroke requirements in the early thermal soarer Sapeornis could have driven sternum loss through bone functional adaption, possibly encouraged by the higher breathing demands of a Confuciusornis-like upstroke. Both factors are supported by a slender ventral body profile. These data validate the ancestral shoulder/chest flight system and provide insights into novel upstroke-enhanced flight strokes and early sternum loss, filling important gaps in our understanding of the appearance of modern flight.

Female bone physiology resilience in a past Polynesian Outlier community

Remodelling is a fundamental biological process involved in the maintenance of bone physiology and function. We know that a range of health and lifestyle factors can impact this process in living and past societies, but there is a notable gap in bone remodelling data for populations from the Pacific Islands. We conducted the first examination of femoral cortical histology in 69 individuals from ca. 440-150 BP Taumako in Solomon Islands, a remote 'Polynesian Outlier' island in Melanesia. We tested whether bone remodelling indicators differed between age groups, and biological sex validated using ancient DNA. Bone vascular canal and osteon size, vascular porosity, and localised osteon densities, corrected by femoral robusticity indices were examined. Females had statistically significantly higher vascular porosities when compared to males, but osteon densities and ratios of canal-osteon (~ 8%) did not differ between the sexes. Our results indicate that, compared to males, localised femoral bone tissue of the Taumako females did not drastically decline with age, contrary to what is often observed in modern populations. However, our results match findings in other archaeological samples-a testament to past female bone physiology resilience, also now observed in the Pacific region.