Internal Bone Structure Research Articles

How compactness affects long bone resistance to compression-An investigation into the rhinoceros humerus.

The functional signal of bone internal structure has been widely studied. Isolated form-function relationships have often been assumed from the observation of presumed morphofunctional relationships, but have never been truly tested. Indeed, distinct bone microanatomical feature co-evolve in response to various constraints that are difficult to detangle. This study tested for the first time the impact of various microanatomical parameters taken one by one, plus some in pairs, on bone strength under compression using biomechanical modelling. We carried out finite element analyses on humerus models, obtained from a white rhinoceros, with different heterogeneous internal structures, and analysed the magnitude and distribution of von Mises stresses. These tests validated earlier hypotheses of form-function relationships about the greater resistance to compression provided by the thickening of the cortex and the filling of the medullary area by trabecular bone and highlighted the stronger impact of increasing trabecular bone compactness than of avoiding an open medullary cavity. By making it possible to estimate the relative impact of each parameter and ofcombinations of microanatomical features, they also showed the more limited impact of the trabecular bone compactness in the epiphyses to resist compression, and the fact that microanatomical changes of opposite but of similar amplitude impact can compensate each other, but that the impact of the sum of two negative microanatomical changes far exceeds the sum of the impacts of each of the two changes taken separately. These results contribute to a better understanding of bone adaptation and form-function relationships so that they later can be used with confidence for palaeobiological inferences on fossil specimens, contributing to a better understanding of skeletal evolution during the evolutionary history of vertebrates. They also highlight the potential of taking internal structure into account in the bone biomechanical analyses. In addition, they can be used in bioinspiration to design resistant structures subjected to compression.

Male-female spatio-temporal differences of age-related bone changes show faster bone deterioration in older women at femoral regions associated with incident hip fracture.

A better understanding of how age-related bone loss affects the fracture-prone regions of the proximal femur could lead to more informed fracture-prevention strategies. Therefore, the aim of this work was to assess the spatio-temporal distribution of bone deterioration in older men and women with aging. A subset of 305 men (74.87 ± 4.76years; mean ± SD) and 371 age-matched women (74.84 ± 4.71years) with no history of fracture was randomly selected from the Age, Gene/Environment Susceptibility-Reykjavik study. Quantitative computed tomography (QCT) scans of the left proximal femur obtained at baseline and at 5.2 ± 0.4years follow-up were processed to assess local changes in volumetric bone mineral density (vBMD), cortical bone thickness (Ct.Th), and internal bone structure using voxel-based morphometry (VBM), surface-based statistical parametric mapping (surf-SPM), and tensor-based morphometry (TBM). Local parametric changes within each sex and sex differences in these changes were statistically assessed using linear mixed effects models allowing for baseline and time-varying covariates, yielding Student's t-test and p-value statistical maps of the proximal femur. The statistical maps indicated regions with significant parametric changes in each sex and with significant different parametric changes between older men and older women with aging. Older women manifested significantly larger losses in vBMD, (Ct.Th), and structure than older men, and they did so in regions where deficiency in these parameters has been associated with incident hip fracture. Using longitudinal QCT scans of the proximal femur and Computational Anatomy, we provided new insights into the higher fracture rates of the proximal femur in older women compared with men of similar age providing new information on the pathophysiology of osteoporosis.

Ultra-short time-echo based ray tracing for transcranial focused ultrasound aberration correction in human calvaria.

Magnetic resonance guided transcranial focused ultrasound holds great promises for treating neurological disorders. This technique relies on skull aberration correction which requires computed tomography (CT) scans of the skull of the patients. Recently, ultra-short time-echo (UTE) magnetic resonance (MR) sequences have unleashed the MRI potential to reveal internal bone structures. In this study, we measure the efficacy of transcranial aberration correction using UTE images.
Approach. We compare the efficacy of transcranial aberration correction using UTE scans to CT based correction on four skulls and two targets using a clinical device (Exablate Neuro, Insightec, Israel). We also evaluate the performance of a custom ray tracing algorithm using both UTE and CT estimates of acoustic properties and compare these against the performance of the manufacturer's proprietary aberration correction software. 
Main results. UTE estimated skull maps in Hounsfield units (HU) had a mean absolute error of 242 ± 20 HU (n=4). The UTE skull maps were sufficiently accurate to improve pressure at the target (no correction: 0.44 ± 0.10, UTE correction: 0.79 ± 0.05, manufacturer CT: 0.80 ± 0.05), pressure confinement ratios (no correction: 0.45 ± 0.10, UTE correction: 0.80 ± 0.05, manufacturer CT: 0.81 ± 0.05), and targeting error (no correction: 1.06 ± 0.42 mm, UTE correction 0.30 ± 0.23 mm, manufacturer CT: 0.32 ± 0.22) (n=8 for all values). When using CT, our ray tracing algorithm performed slightly better than UTE based correction with pressure at the target (UTE: 0.79 ± 0.05, CT: 0.84 ± 0.04), pressure confinement ratios (UTE: 0.80 ± 0.05, CT: 0.84 ± 0.04), and targeting error (UTE: 0.30 ± 0.23 mm, CT: 0.17 ± 0.15). 
Significance. These 3D transcranial measurements suggest that UTE sequences could replace CT scans in the case of MR guided focused ultrasound with minimal reduction in performance which will avoid ionizing radiation exposure to the patients and reduce procedure time and cost.&#xD.

A hybrid statistical morphometry free-form deformation approach to 3D personalized foot-ankle models

Foot and ankle joint models are widely used in the biomechanics community for musculoskeletal and finite element analysis. However, personalizing a foot and ankle joint model is highly time-consuming in terms of medical image collection and data processing. This study aims to develop and evaluate a framework for constructing a comprehensive 3D foot model that integrates statistical shape modeling (SSM) with free-form deformation (FFD) of internal bones. The SSM component is derived from external foot surface scans (skin measurements) of 50 participants, utilizing principal component analysis (PCA) to capture the variance in foot shapes. The derived surface shapes from SSM then guide the FFD process to accurately reconstruct the internal bone structures. The workflow accuracy was established by comparing three model-generated foot models against corresponding skin and bone geometries manually segmented and not part of the original training set. We used the top ten principal components representing 85 % of the population variation to create the model. For prediction validation, the average Dice similarity coefficient, Hausdorff distance error, and root mean square error were 0.92 ± 0.01, 2.2 ± 0.19 mm, and 2.95 ± 0.23 mm for soft tissues, and 0.84 ± 0.03, 1.83 ± 0.1 mm, and 2.36 ± 0.12 mm for bones, respectively. This study presents an efficient approach for 3D personalized foot model reconstruction via SSM generation of the foot surface that informs bone reconstruction based on FFD. The proposed workflow is part of the open-source Musculoskeletal Atlas Project linked to OpenSim and makes it feasible to accurately generate foot models informed by population anatomy, and suitable for rigid body analysis and finite element simulation.

Evolution of the temporal skull openings in land vertebrates: A hypothetical framework on the basis of biomechanics.

The complex constructions of land vertebrate skulls have inspired a number of functional analyses. In the present study, we provide a basic view on skull biomechanics and offer a framework for more general observations using advanced modeling approaches in the future. We concentrate our discussion on the cranial openings in the temporal skull region and work out two major, feeding-related factors that largely influence the shape of the skull. We argue that (1) the place where the most forceful biting is conducted and (2) the handling of resisting food (sideward movements) constitute the formation and shaping of either one or two temporal arcades surrounding these openings. Diversity in temporal skull anatomy among amniotes can be explained by specific modulations of these factors with different amounts of acting forces which inevitably lead to deposition or reduction of bone material. For example, forceful anterior bite favors an infratemporal bar, whereas forceful posterior bite favors formation of an upper temporal arcade. Transverse forces (inertia and resistance of seized objects) as well as neck posture also influence the shaping of the temporal region. Considering their individual skull morphotypes, we finally provide hypotheses on the feeding adaptation in a variety of major tetrapod groups. We did not consider ligaments, internal bone structure, or cranial kinesis in our considerations. Involving those in quantitative tests of our hypotheses, such as finite element system synthesis, will provide a comprehensive picture on cranial mechanics and evolution in the future.

The Quantitative Method for Following Radiologic Healing in Endodontic Retreatment; 1-Year Follow-up Study

Objectives: This study aimed to quantitatively evaluate the changes in the internal bone structure at the periapical bone regions after retreatment in endodontics using fractal analysis method on periapical radiographs.
 Materials and Methods: 29 single-rooted, asymptomatic, single-visit retreatment teeth with apical lesion were included in the study. All teeth included in the study were selected from the maxilla anterior region. Periapical radiograph (T0) was taken for baseline diagnosis at the start of retreatment. Second periapical follow-up radiograph (T1) of the patients was taken at the end of 1 year. The first evaluation phase of the 1-year results of endodontic retreatment is based on the periapical index (PAI). Fractal dimension (FD) was calculated by box-counting method. The paired-sample t-test was used to compare T0 and T1 FDs. The independent samples t-test was employed to compare FD changes between the sexes. The significance level was set to 0.05.
 Results: PAI scores were found to be statistically significantly decreased in T1 radiographs compared to T0 (p

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.

Evaluation of the mandibular condyles trabecular structure in patients with severe class III pattern: a computed tomography (CT) fractal analysis study

Class III malocclusion is a combination of dental and skeletal disorders that causes discrepancies in occlusion. Malocclusion can affect the structure of the Temporomandibular joint (TMJ) resulting in many problems, one of which is affecting the internal structure of the bone. This study aimed to examine the morphological features of class III patients’ trabecular structure of the mandibular condyle in comparison with normal class I individuals using fractal analysis (FA). To study the internal structure of the mandibular condyle bone, Computed Tomography (CT) scans of 45 severe class III patients (age: 16–46) who were the candidates for orthognathic surgery were selected and matched by age and sex with 45 normal class I individuals. The trabecular bone structure of the left and right mandibular condyles in three CT planes of the study group and control group were evaluated employing the FA. The result of the present study indicated that the fractal dimensions (FD) values of class III patients were lower than those of the normal class I individuals in axial (class I: 1.31 ± 0.02, class III: 1.28 ± 0.02), sagittal (class I: 1.25 ± 0.03, class III: 1.19 ± 0.08), and coronal (class I: 1.5 ± 0.06, class III: 1.45 ± 0.07) planes (P < 0.001). There were no significant differences between the FD values of the males and females. The intra-group evaluation revealed that there was no correlation between age and FD values. No evidence of laterality was found regarding the FD values of the right and left condyles. Given the noticeable differences between the FD values, it can be implied that severe class III malocclusion may affect the trabecular pattern of the cancellous bone of the mandibular condyle compared to class I individuals. Therefore, due to the altered trabecular structure, clinicians should be cautious when planning treatments for these patients.

The influence of bone model geometries on the determination of skull acoustic properties.

In this study, we investigated the impact of various simulated skull bone geometries on the determination of skull speed of sound and acoustic attenuation values via optimization using transmitted pressure amplitudes beyond the bone. Using the hybrid angular spectrum method (HAS), we simulated ultrasound transmission through four model sets of different geometries involving sandwiched layers of diploë and cortical bone in addition to three models generated from CT images of ex-vivo human skull-bones. We characterized cost-function solution spaces for each model and, using optimization, found that when a model possessed appreciable variations in resolvable layer thickness, the predefined attenuation coefficients could be found with low error (RMSE < 0.01 Np/cm). However, we identified a spatial frequency cutoff in the models' geometry beyond which the accuracy of the property determination begins to fail, depending on the frequency of the ultrasound source. There was a large increase in error of the attenuation coefficients determined by the optimization when the variations in layer thickness were above the identified spatial frequency cutoffs, or when the lateral variations across the model were relatively low in amplitude. For our limited sample of three CT-image derived bone models, the attenuation coefficients were determined successfully. The speed of sound values were determined with low error for all models (including the CT-image derived models) that were tested (RMSE < 0.4 m/s). These results illustrate that it is possible to determine the acoustic properties of two-component models when the internal bone structure is taken into account and the structure satisfies the spatial frequency constraints discussed.

Hominin locomotion and evolution in the Late Miocene to Late Pliocene

In this review, we present on the evolution of the locomotor adaptation of hominins in the Late Miocene to Late Pliocene, with emphasis on some of the prominent advances and debates that have occurred over the past fifty years. We start with the challenging issue of defining hominin locomotor grades that are currently used liberally and offer our own working definitions of facultative, habitual, and obligate bipedalism. We then discuss the nature of the Pan-Homo last common ancestor and characterize the locomotor adaptation of Sahelanthropus, Orrorin, and Ardipithecus—often referred to as facultative bipeds—and examine the debates on the extent of bipedality and arboreality in these taxa. Moreover, the question of Middle Pliocene hominin locomotor diversity is addressed based on information derived from the ‘Little Foot’ specimen from Sterkfontein, footprints from Laetoli, and the Burtele Foot in Ethiopia. Our review suggests that the most convincing evidence for locomotor diversity comes from Burtele, whereas the evidence from Sterkfontein and Laetoli is unconvincing and equivocal, respectively. Finally, we address the decades old issue of the significance of arboreality in the otherwise habitual biped, Australopithecus, with emphasis on Australopithecus afarensis and its implications for the paleobiology of these creatures. We conclude that many of the apelike features encountered, mostly in the upper part of the Australopithecus skeleton, were retained for their significance in climbing. Approaches that have investigated character plasticity and those exploring internal bone structure have shown that the shoulder and limbs in Au. afarensis and Australopithecus africanus were involved in arboreal activities that are thought to be key for feeding, nesting, and predator avoidance. We conclude that many of the so-called retained ape-like features persisted due to stabilizing selection, that early hominins engaged in a considerable amount of arboreality even after Australopithecus had become a habitual biped, and arboreality only ceased to be an important component of hominin locomotor behavior after the emergence of Homo erectus.

Earliest Triassic ichthyosaur fossils push back oceanic reptile origins

Reptiles first radiated into oceanic environments after the cataclysmic end-Permian mass extinction (EPME)1, 251.9 million years (Ma) ago. The geologically oldest fossils evincing this adaptive transition have been recovered from upper-Lower Triassic (lower Spathian) strata, ∼248.8 Ma2, and postdate a landmark turnover of amphibian-dominated to reptile-dominated marine ecosystems spanning the late Smithian crisis (LSC)3, ∼249.6 Ma4 -less than ∼2.3 Ma after the EPME. Here, we report ichthyopterygian (the group including 'fish-shaped' ichthyosaurians1) remains from the Arctic island of Spitsbergen that predate the LSC in later-middle to early-late Smithian5 deposits up to ∼250 Ma. Unexpectedly, however, their large size and spongy internal bone structure indicate a fully pelagic ichthyopterygian1,6. Given this unambiguous occurrence ∼2 Ma after the EPME, these pioneering seagoing tetrapods can now be feasibly recast as mass extinction survivors instead of ecological successors2,3 within the earliest Mesozoic marine predator communities.

Echo state network for features extraction and segmentation of tomography images

The paper proposes a novel approach for gray scale images segmentation. It is based on multiple features extraction from a single feature per image pixel, namely its intensity value, via a recurrent neural network from the reservoir computing family - Echo state network. The preliminary tests on the benchmark gray scale image Lena demonstrated that the newly extracted features - reservoir equilibrium states - reveal hidden image characteristics. In present work the developed approach was applied to a real life task for segmentation of a 3D tomography image of a of bone whose aim was to explore the object?s internal structure. The achieved results demonstrated the novel approach allows for clearer revealing the details of the bone internal structure thus supporting further tomography image analyses.

Challenges and perspectives on functional interpretations of australopith postcrania and the reconstruction of hominin locomotion

In 1994, Hunt published the ‘postural feeding hypothesis’—a seminal paper on the origins of hominin bipedalism—founded on the detailed study of chimpanzee positional behavior and the functional inferences derived from the upper and lower limb morphology of the Australopithecus afarensis A.L. 288-1 partial skeleton. Hunt proposed a model for understanding the potential selective pressures on hominins, made robust, testable predictions based on Au. afarensis functional morphology, and presented a hypothesis that aimed to explain the dual functional signals of the Au. afarensis and, more generally, early hominin postcranium. Here we synthesize what we have learned about Au. afarensis functional morphology and the dual functional signals of two new australopith discoveries with relatively complete skeletons (Australopithecus sediba and StW 573 ‘Australopithecus prometheus’). We follow this with a discussion of three research approaches that have been developed for the purpose of drawing behavioral inferences in early hominins: (1) developments in the study of extant apes as models for understanding hominin origins; (2) novel and continued developments to quantify bipedal gait and locomotor economy in extant primates to infer the locomotor costs from the anatomy of fossil taxa; and (3) novel developments in the study of internal bone structure to extract functional signals from fossil remains. In conclusion of this review, we discuss some of the inherent challenges of the approaches and methodologies adopted to reconstruct the locomotor modes and behavioral repertoires in extinct primate taxa, and notably the assessment of habitual terrestrial bipedalism in early hominins.

The internal trabecular bone structure of the odontoid process of the axis. A retrospective single-center comparative study in patients following cervical trauma.

Background Odontoid C2 fractures account for 9% to 15% of adult cervical spine fractures. The aim of this study is to report the incidence of a previous described Y-shaped trabecular bone structure (TBS) in the odontoid process in a larger sample of patients who performed a CT cervical scan following a cervical trauma to investigate if its absence can increase the risk of the odontoid process fracture of the axis. Methods A retrospective review of 245 patients who performed a CT cervical scan in our University Hospital, as results of cervical spine injury, was performed during a 12-month period between May 2020 and May 2021. Results The presence of a Y-shaped TBS at the odontocentral synchondrosis level was observed in 165 patients that is 67.3% of whole population included in this study. Eighteen patients (7.3%) reported an odontoid type II C2 fracture. Among patients with odontoid type II C2 fracture, the Y-shaped TBS at the odontocentral synchondrosis level was observed in 8 (44.4%) of them. The presence of the Y-shaped TBS at the odontocentral synchondrosis level was statistically more frequently observed in patients without odontoid process fracture (69.2% Vs 30.8%) compared to patients who developed odontoid process fracture (44.4 % Vs 55.6%) after a cervical trauma (p = 0.03). Conclusions This study showed the crucial role of this Y-shaped TBS in biomechanical structural dynamics of the C1-C2 joint and its significant clinical relevance in odontoid fractures of the axis.

Inner design of artificial test bones for biomechanical investigations using topology optimization

Artificial or human test bones are used for the biomechanical testing of implants. Human test bones are rare and not always available. These must, therefore, be substituted with artificial test bones. However, current artificial test bones are only available with specific characteristics (e.g., age groups or disease characteristics). Additionally, their mechanical properties are only comparable to a limited extent to those of a human bone. This paper presents a methodology for designing additively manufactured artificial test bones for biomechanical testing that replicate the mechanical behavior of a human bone. Topology optimization methods are used to generate the artificial test bone's internal structure. The geometric model is based on a computed tomography dataset of a human bone. The input data can be manipulated in advance to reproduce defects or disease patterns. The bone was fixed at the distal diaphysis and loaded with different biomechanical forces for topology optimization. Boundary conditions due to possible additive manufacturing processes were incorporated into the optimization to ensure manufacturability. The optimization result is compared with experimental data from a human bone. A bone-like internal structure and increased compliance of the topology-optimized test bone model compared to the commercial model were observed.

Evaluation of Frequency Pattern of Risk Factors for Decreased Bone Mineral Density in Postmenopausal Women Referred to the Bone Mineral Density Assessment Center of Al-Zahra Hospital in Isfahan during Years 2018 and 2019

Introduction: Osteoporosis is a systemic skeletal disease in which the internal structure and ability of bone to repair its daily damage is impaired. Menopause is a vital period that affects bone health, causing rapid loss of bone mass, which in turn increases the risk of fractures in postmenopausal women. The present study was performed to evaluate the frequency pattern of risk factors for decreased bone mineral density in postmenopausal women referred to the bone mineral density assessment center of Al-Zahra Hospital in Isfahan in years 2018 and 2020.&#x0D; Methods: Among postmenopausal women referred to the Bone Density Assessment Center of Al-Zahra Hospital from March 2018 to March 2020, 384 people were included in the study using simple random sampling method. Patients’ information was extracted from their files. Data were analyzed using SPSS 16 software.&#x0D; Results: In this study, the prevalence of osteopenia and osteoporosis in postmenopausal women was 46.1% and 41.1%, respectively. The results showed that with increasing age, diabetes, use of corticosteroids, autoimmune disease and a previous history of femoral fracture, the chance of osteopenia and osteoporosis in postmenopausal women increased sharply. Among the known risk factors for decreased bone density, diabetes was the most common in postmenopausal women and followed by corticosteroids consumption.&#x0D; Conclusion: This study showed that 87.2% of postmenopausal women had decreased bone mineral density. Osteoporosis as one of the main problems of women's health requires proper planning and preventive measures.

Femoral neck phantom imaging using time-domain topological energy method.

Ultrasonic bone imaging is a complex task, primarily because of the low energy contained in the signals reflected from the internal bone structures. In this study, the reconstruction of a bone-mimicking phantom echographic image using time-domain topological energy (TDTE) is proposed. A TDTE image results from a combination of forward and adjoint fields. The first is a solution of a numerical model that reproduces the setup of the experimental data acquisition to the best extent possible. The second has similar characteristics, but the source term is the time-reversed residue between the forward field and signals obtained from the experiment. The acquisition-reconstruction system used a linear phased-array transducer with a 5 MHz center frequency to acquire the signals and was coupled with a k-wave toolbox to implement the numerical models and perform the image reconstruction. The results showed good agreement between the geometry of the real phantom and the ultrasonic images. However, thickness evaluation errors were observed, which may be due to incorrect assumptions about the velocity models throughout the medium, a priori assumed to be known. Thus, this method has shown promising results and should be applied to the real femoral neck as a long-term objective.

The Role of Structural Deterioration and Biomechanical Changes of the Necrotic Lesion in Collapse Mechanism of Osteonecrosis of the Femoral Head.

Osteonecrosis of the femoral head (ONFH) is a crippling disease which is due to a lack of effective therapeutic measures. Its natural progression is rapid, the internal bone structure of the femoral head changes dramatically, and the subsequent fractures and collapse cause severe hip pain and loss of hip function. Femoral head collapse is a critical turning point in the development of ONFH and is related to the prognosis of patients. Early prevention and intervention help to preserve the hip joint and delay femoral head collapse. However, the mechanism of collapse still needs to be further studied because it is affected by different complex factors. This review discusses the underlying causes of femoral head collapse from two aspects: structural degradation and regional changes of biomechanical properties in the necrotic femoral head.

Paleoradiological tests in Hungary and abroad

Although anthropology and archaeology have often taken separate paths, publications in recent years have demonstrated the importance of working together in these two areas to draw the right conclusions. At the same time, such projects also involve archaeozoologists, physicists, geneticists, and even radiologists. Imaging methods have been used in the study of the past since the nineteenth century. With them, we can examine not only human or animal remains but also archaeological finds. During our work, we have already studied ceramic vessels, metal objects, mummified human remains, human and animal bones. Radiological methods can be used to obtain additional information about the internal structure of bones, to reveal hitherto unseen defects in the case of a sword, or to examine in situ fragile grave goods lying in the middle of a lump of soil. In this paper, we present the theoretical background of radiological methods and their applicability in the fields of anthropology and archaeology, highlighting their advantages and limitations, to encourage as many members of the Hungarian professional community as possible to employ such methods.

Patterns of internal bone structure and functional adaptation in the hominoid scaphoid, lunate, and triquetrum

AbstractThe morphology of the proximal carpals (scaphoid, lunate, triquetrum) are linked to the range of motion (ROM) at the radiocarpal and midcarpal joints. While the relationship between ROM and habitual locomotor mode is well established, it has yet to be investigated whether relative patterns of internal bone architecture reflect the kinematics and kinetics at the proximal row. As internal bone is known to model its structure to habitually incurred forces, internal architecture has the potential to provide insight into how joints have been loaded during the lifetime of an individual. Using a broad sample of extant great apes and humans (n = 177 total bones), this study investigates whether relative differences in the bone volume to total volume (BV/TV) and degree of anisotropy (DA) across the scaphoid, lunate and triquetrum correlate with the presumed force transfer and biomechanics of the hominoid wrist. Results reveal that broad patterns in BV/TV and DA differentiate hominoids by their predominant locomotor mode. The human pattern suggests the lunate may be the most highly strained bone within the proximal row. Both knuckle‐walking taxa (Gorilla, Pan) exhibited similar architectural patterns suggesting they are adapted to resist similar forces in this region of the wrist. The relatively high DA across all Pongo carpals suggests it may have more stereotypical wrist loading than commonly assumed. Finally, the distinctly low DA in the triquetrum across all taxa suggests force transfer via the synapomorphic triangular fibrocartilage complex may leave a distinctive signature in the internal bone architecture that requires further investigation.ObjectivesFunctional adaptation in the trabecular and cortical bone of individual wrist bones has been investigated across hominoid species but functional conclusions remain limited. This study examines whether relative patterns in internal bone architecture across multiple carpal bones can be correlated to the known or assumed kinetics and kinematics of the wrist joint in extant hominoids.Materials and MethodsThis study applied a whole‐bone methodology to quantify the internal architecture (cortical and trabecular bone) of the scaphoid, lunate, and triquetrum of suspensory (Pongo sp.), knuckle‐walking (Pan paniscus, Pan troglodytes, Gorilla sp.) and bipedal (Homo sapiens) hominoids (n = 177 total bones).ResultsH. sapiens showed unique patterns in both measured parameters: a decrease in degree of anisotropy (DA) from the scaphoid to the triquetrum with higher bone volume to total volume (BV/TV) in the lunate relative to the other bones. Knuckle‐walking taxa had similar patterns in both parameters: highest mean DA in the lunate and lowest in the triquetrum while significantly higher BV/TV was recorded the triquetrum. Pongo exhibited the same DA pattern as knuckle‐walking taxa but a distinct pattern of continual decrease in BV/TV from scaphoid to triquetrum.DiscussionRelative differences in the internal bone structure across multiple carpals differentiated locomotor modes in extant hominoids. The triquetrum and lunate are particularly understudied but their importance to differentiating locomotor mode indicates further research is warranted. Establishing patterns across more carpal joints in primates should be a research priority as they will provide critical context to interpreting fossil species represented by single or few carpal elements.