Direct quantification of skeletal pneumaticity illuminates ecological drivers of a key avian trait.

Skeletal pneumaticity is a key feature of extant avian structure and biology, which first evolved among the non-flying archosaurian ancestors of birds. The widespread presence of air-filled bones across the postcranial skeleton is unique to birds among living vertebrates, but the true extent of skeletal pneumaticity has never been quantitatively investigated-hindering fundamental insights into the evolution of this key avian feature. Here, we use microCT scans of fresh, frozen birds to directly quantify the fraction of humerus volume occupied by air across a phylogenetically diverse taxon sample to test longstanding hypotheses regarding the evolution and function of avian skeletal pneumatization. Among other insights, we document weak positive allometry of internal air volume with humeral size among pneumatized humeri and provide strong support that humeral size, body mass, aquatic diving, and the presence or absence of pneumaticity all have independent effects on cortical bone thickness. Our quantitative evaluation of humeral pneumaticity across extant avian phylogeny sheds new light on the evolution and ontogenetic progression of an important aspect of avian skeletal architecture, and suggests that the last common ancestor of crown birds possessed a highly pneumatized humerus.

Micro-CT Imaging and Mechanical Properties of Ovine Ribs.

The use of ovine animal models in the study of injury biomechanics and modeling is increasing, due to their favorable size and other physiological characteristics. Along with this increase, there has also been increased interest in the development of in silico ovine models for computational studies to compliment physical experiments. However, there remains a gap in the literature characterizing the morphological and mechanical characteristics of ovine ribs. The objective of this study therefore is to report anatomical and mechanical properties of the ovine ribs using microtomography (micro-CT) and two types of mechanical testing (quasi-static bending and dynamic tension). Using microtomography, young ovine rib samples obtained from a local abattoir were cut into approximately fourteen 38 mm sections and scanned. From these scans, the cortical bone thickness and cross-sectional area were measured, and the moment of inertia was calculated to enhance the mechanical testing data. Based on a standard least squares statistical model, the cortical bone thickness varied depending on the region of the cross-section and the position along the length of the rib (p < 0.05), whereas the cross-sectional area remained consistent (p > 0.05). Quasi-static three-point bend testing was completed on ovine rib samples, and the resulting force-displacement data was analyzed to obtain the stiffness (44.67 ± 17.65 N/mm), maximum load (170.54 ± 48.28 N) and displacement at maximum load (7.19 ± 2.75 mm), yield load (167.81 ± 48.12 N) and displacement at yield (6.10 ± 2.25 mm), and the failure load (110.90 ± 39.30 N) and displacement at failure (18.43 ± 2.10 mm). The resulting properties were not significantly affected by the rib (p > 0.05), but by the animal they originated from (p < 0.05). For the dynamic testing, samples were cut into coupons and tested in tension with an average strain rate of 18.9 strain/sec. The resulting dynamic testing properties of elastic modulus (5.16 ± 2.03 GPa), failure stress (63.29 ± 14.02 MPa), and failure strain (0.0201 ± 0.0052) did not vary based on loading rate (p > 0.05).

Correlation between mandibular anatomy and bad split occurrence during bilateral sagittal split osteotomy: a three-dimensional study.

OBJECTIVES: This study aimed to find out the correlation between different anatomical parameters of the mandible and the occurrence of a bad split in patients who had undergone bilateral split sagittal ramus osteotomy (BSSRO). MATERIALS AND METHOD: At both the distal roots of the first molar (1) and the retromolar area (2), we measured the distance from the buccal margin of the inferior dental canal (IDC) to the buccal margin of the cortical bone (MCBC), the thickness of both buccal cortical (WBCB) and cancellous bone (WBCA), distance from the superior border of IDC to the alveolar crest (MCAC), buccolingual thickness (BLT), and thickness of cancellous bone (WCA). At the ramus, the distances between the sigmoid notch to the upper part of the lingula (SL) and the inferior border of the mandible (SIBM), the thickness of the ramus at the level of the lingula (BLTR), and the anteroposterior width of the ramus (APWR) were measured. The paired and independent t-tests were used when applicable, and a P-value < 0.05 was considered significant. RESULTS: MCBC1 showed a significant difference between bad and non-bad split sides (P = 0.037). Both WBCA1 and WBCA2 show the same significant difference (P = 0.023, 0.024). Similarly, WCA1 and WCA2 showed a statistical difference between the bad and non-bad split sides (P = 0.027, 0.036). There were no statistically significant differences between the compared sides of WBCB1, WBCB2, MCAC1, MCAC2, SIBM, APWR, SL, and BLTR. CONCLUSION: Narrow space between IDC and the buccal cortical margin, along with the decrease in the thickness of both buccal cancellous bone and total cancellous bone at the inferior border of the mandible along the course of SSRO, has been implicated in the occurrence of bad split intraoperatively.

Ontogenetic changes in cortical bone vascular microstructure in the domestic duck (Anas platyrhynchos) and ring-necked pheasant (Phasianus colchicus).

Age-related changes in bone microstructure can inform our understanding the biology of both extant and fossil birds, but to date, histological work in birds, and particularly work using high-resolution 3D imaging, has largely been restricted to limited growth stages. We used minimally destructive synchrotron radiation-based X-ray computed tomography to visualise and measure key morphological and histological traits in 3D across development in the domestic duck and ring-necked pheasant. We use these measurements to build on the database of key reference material for interpreting bone histology. We found that growth patterns differed between the two species, with the ducks showing rapid growth in their lower limbs and early lower limb maturation, while pheasants grew more slowly, reflecting their later age at maturity. In the pheasant, both walking and flight occur early and their upper and lower limbs grew at similar rates. In the duck, flight and wing development are delayed until the bird is almost at full body mass. Through juvenile development, the second moment of area for the duck wing was low but increased rapidly towards the age of flight, at which point it became significantly greater than that of the lower limb, or the pheasant. On a microstructural level, both cortical porosity and canal diameter were related to cortical bone deposition rate. In terms of orientation, vascular canals in the bone cortex were more laminar in the humerus and femur compared with the tibiotarsus, and laminarity increased through juvenile development in the humerus, but not the tibiotarsus, possibly reflecting torsional vs compressive loading. These age-related changes in cortical bone vascular microstructure of the domestic duck and pheasant will help understanding the biology of both extant and fossil birds, including age estimation, growth rate and growth patterns, and limb function.

Automated cortical thickness measurement of the mandibular condyle head on CBCT images using a deep learning method.

This study proposes a deep learning model for cortical bone segmentation in the mandibular condyle head using cone-beam computed tomography (CBCT) and an automated method for measuring cortical thickness with a color display based on the segmentation results. In total, 12,800 CBCT images from 25 normal subjects, manually labeled by an oral radiologist, served as the gold-standard. The segmentation model combined a modified U-Net and a convolutional neural network for target region classification. Model performance was evaluated using intersection over union (IoU) and the Hausdorff distance in comparison with the gold standard. The second automated model measured the cortical thickness based on a three-dimensional (3D) model rendered from the segmentation results and presented a color visualization of the measurements. The IoU and Hausdorff distance showed high accuracy (0.870 and 0.928 for marrow bone and 0.734 and 1.247 for cortical bone, respectively). A visual comparison of the 3D color maps showed a similar trend to the gold standard. This algorithm for automatic segmentation of the mandibular condyle head and visualization of the measured cortical thickness as a 3D-rendered model with a color map may contribute to the automated quantification of bone thickness changes of the temporomandibular joint complex on CBCT.

Optimal microimplant sites in the mandibular retromolar area: mesh analysis of cortical bone thickness and density in CBCT images / Sitios de microimplantes óptimos en el área retromolar mandibular: análisis de malla del grosor y densidad del hueso cortical en imágenes CBCT

SUMMARY: This study was performed to identify optimal microimplant sites in the mandibular retromolar area by measurement and analysis of cortical bone thickness and density. Forty-nine records of cone-beam computed tomography were selected from 173 patients. Invivo 5.2 software was used to measure the thickness and density of 25 sites on a mesh in the mandibular retromolar area. Pearson correlation, Spearman correlation, and binary logistic regression analyses were performed to explore correlations between retromolar measurements and patient characteristics. The LSD test was used to identify optimal microimplant sites in this area. One-way ANOVA, with post hoc SNK test, was used to compare optimal microimplant sites among the retromolar area, the distobuccal bone of the second molar, and a location between the first and second molars. The mean thickness and density of mandibular retromolar cortical bone were 2.35 ± 0.76 mm and 530.49 ± 188.83 HU, respectively. In the mandibular retromolar area, the thickness and density of cortical bone increased from the lingual to buccal sides, and from the distal to mesial. Among 25 sites, S5C1 had the greatest thickness and density; it exhibited greater thickness and density, compared with the distobuccal bone of the second molar and the site between the first and second molars. For distal uprighting of mesially tipped molars, we recommend placement of microimplants into the retromolar distobuccal site; for distalization of mandibular dentition, we recommend placement of microimplants into the retromolar mesiobuccal site (S5C1) or 2 mm from the mesial direction of the second molar distobuccal site (B).

RESUMEN: Este estudio se realizó para identificar los sitios óptimos de microimplantes en el área retromolar mandibular mediante la medición y el análisis del grosor y la densidad del hueso cortical. Se seleccionaron 49 registros de tomografía computarizada de haz cónico de 173 pacientes. Se utilizó el software Invivo 5.2 para medir el grosor y la densidad de 25 sitios en una malla en el área retromolar mandibular. Se realizaron análisis de correlación de Pearson, correlación de Spearman y regresión logística binaria para explorar las correlaciones entre las mediciones retromolares y las características del paciente. La prueba de LSD se utilizó para identificar los sitios óptimos de microimplantes en esta área. Se utilizó ANOVA unidireccional, con prueba SNK post hoc, para comparar los sitios óptimos de microimplante entre el área retromolar, el hueso distobucal del segundo molar y una ubicación entre el primer y el segundo molar. El grosor y la densidad medios del hueso cortical retromolar mandibular fueron 2,35 ± 0,76 mm y 530,49 ± 188,83 HU, respectivamente. En el área retromolar mandibular, el grosor y la densidad del hueso cortical aumentaron desde el lado lingual al bucal y desde el distal al mesial. Entre los 25 sitios, S5C1 se determinó el mayor espesor y densidad; presentó mayor grosor y densidad, en comparación con el hueso distobucal del segundo molar y el sitio entre el primero y el segundo molar. Para rectificación distal de molares con punta mesial, recomendamos la colocación de microimplantes en el sitio retromolar bucal; para la distalización de la dentición mandibular, recomendamos la colocación de microimplantes en el sitio retromolar mesiobucal (S5C1) o 2 mm desde la dirección mesial del sitio distobucal del segundo molar (B).

Cortical and trabecular bone structure of the hominoid capitate.

Morphological variation in the hominoid capitate has been linked to differences in habitual locomotor activity due to its importance in movement and load transfer at the midcarpal joint proximally and carpometacarpal joints distally. Although the shape of bones and their articulations are linked to joint mobility, the internal structure of bones has been shown experimentally to reflect, at least in part, the loading direction and magnitude experienced by the bone. To date, it is uncertain whether locomotor differences among hominoids are reflected in the bone microarchitecture of the capitate. Here, we apply a whole-bone methodology to quantify the cortical and trabecular architecture (separately and combined) of the capitate across bipedal (modern Homo sapiens), knuckle-walking (Pan paniscus, Pan troglodytes, Gorilla sp.), and suspensory (Pongo sp.) hominoids (n = 69). It is hypothesized that variation in bone microarchitecture will differentiate these locomotor groups, reflecting differences in habitual postures and presumed loading force and direction. Additionally, it is hypothesized that trabecular and cortical architecture in the proximal and distal regions, as a result of being part of mechanically divergent joints proximally and distally, will differ across these portions of the capitate. Results indicate that the capitate of knuckle-walking and suspensory hominoids is differentiated from bipedal Homo primarily by significantly thicker distal cortical bone. Knuckle-walking taxa are further differentiated from suspensory and bipedal taxa by more isotropic trabeculae in the proximal capitate. An allometric analysis indicates that size is not a significant determinate of bone variation across hominoids, although sexual dimorphism may influence some parameters within Gorilla. Results suggest that internal trabecular and cortical bone is subjected to different forces and functional adaptation responses across the capitate (and possibly other short bones). Additionally, while separating trabecular and cortical bone is normal protocol of current whole-bone methodologies, this study shows that when applied to carpals, removing or studying the cortical bone separately potentially obfuscates functionally relevant signals in bone structure.

Comparative microcomputed tomographic structural analysis of the trabecular and cortical bone architecture of radius and ulna in toy dog breeds.

Radius and ulna fractures can be detected in dogs with an incidence of 18.0% and occur more frequently in toy breeds with increased complication rates. The reasons for the predisposition and the increased complication rate of antebrachial fractures in toy breeds are not yet fully understood. The aim of this study was to research the associated mechanisms by investigating the trabecular structure parameters (BV/TV (%), Tb.N (mm-1), Tb.Th (mm), Tb.Sp (mm), Conn. D (mm-3), DA) and the cortical bone density (Mean Density (mg HA/ccm)) for toy breeds and small dogs of other breeds using microcomputed tomography and to identify the differences between both groups. A total of 70 forearms, originating from toy breeds (n = 36) and small dogs of other breeds (n = 34) were evaluated by microcomputed tomography. The results of this study showed a lower bone volume fraction (BV/TV), more (Tb.N) but thinner trabeculae (Tb.Th) with greater separation (Tb.Sp) and decreased diaphyseal cortical density (Mean Density) in toy breed dogs. This could thus contribute to the increased risk of antebrachial fractures in toy breeds. Within the group of toy breeds inhomogeneous results were observed, whereby the values of the Chihuahuas deviated. This breed had significantly thinner trabeculae (Tb.Th) with a greater trabecular separation (Tb.Sp), lower bone volume fraction (BV/TV) and significantly lower diaphyseal cortical density (Mean Density). These parameters could therefore indicate an increased antebrachial fracture and complication risk, especially in Chihuahuas.

Age related changes of rib cortical bone matrix and the application to forensic age-at-death estimation.

Forensic anthropology includes, amongst other applications, the positive identification of unknown human skeletal remains. The first step in this process is an assessment of the biological profile, that is: sex, age, stature and ancestry. In forensic contexts, age estimation is one of the main challenges in the process of identification. Recently established admissibility criteria are driving researchers towards standardisation of methodological procedures. Despite these changes, experience still plays a central role in anthropological examinations. In order to avoid this issue, age estimation procedures (i) must be presented to the scientific community and published in peer reviewed journals, (ii) accurately explained in terms of procedure and (iii) present clear information about the accuracy of the estimation and possible error rates. In order to fulfil all these requirements, a number of methods based on physiological processes which result in biochemical changes in various tissue structures at the molecular level, such as modifications in DNA-methylation and telomere shortening, racemization of proteins and stable isotopes analysis, have been developed. The current work proposes a new systematic approach in age estimation based on tracing physicochemical and mechanical degeneration of the rib cortical bone matrix. This study used autopsy material from 113 rib specimens. A set of 33 parameters were measured by standard bio-mechanical (nanoindentation and microindentation), physical (TGA/DSC, XRD and FTIR) and histomorphometry (porosity-ImageJ) methods. Stepwise regressions were used to create equations that would produce the best 'estimates of age at death' vs real age of the cadavers. Five equations were produced; in the best of cases an equation counting 7 parameters had an R2 = 0.863 and mean absolute error of 4.64 years. The present method meets all the admissibility criteria previously described. Furthermore, the method is experience-independent and as such can be performed without previous expert knowledge of forensic anthropology and human anatomy.

Bone Microarchitecture and Strength Adaptation to Physical Activity: A Within-Subject Controlled HRpQCT Study.

PURPOSE: Physical activity benefits bone mass and cortical bone size. The current study assessed the impact of chronic (≥10 yr) physical activity on trabecular microarchitectural properties and microfinite element analyses of estimated bone strength. METHODS: Female collegiate-level tennis players (n = 15; age = 20.3 ± 0.9 yr) were used as a within-subject controlled model of chronic unilateral upper-extremity physical activity. Racquet-to-nonracquet arm differences at the distal radius and radial diaphysis were assessed using high-resolution peripheral quantitative computed tomography. The distal tibia and the tibial diaphysis in both legs were also assessed, and cross-country runners (n = 15; age = 20.8 ± 1.2 yr) included as controls. RESULTS: The distal radius of the racquet arm had 11.8% (95% confidence interval [CI] = 7.9% to 15.7%) greater trabecular bone volume/tissue volume, with trabeculae that were greater in number, thickness, connectivity, and proximity to each other than that in the nonracquet arm (all P < 0.01). Combined with enhanced cortical bone properties, the microarchitectural advantages at the distal radius contributed a 18.7% (95% CI = 13.0% to 24.4%) racquet-to-nonracquet arm difference in predicted load before failure. At the radial diaphysis, predicted load to failure was 9.6% (95% CI = 6.7% to 12.6%) greater in the racquet versus nonracquet arm. There were fewer and smaller side-to-side differences at the distal tibia; however, the tibial diaphysis in the leg opposite the racquet arm was larger with a thicker cortex and had 4.4% (95% CI = 1.7% to 7.1%) greater strength than the contralateral leg. CONCLUSION: Chronically elevated physical activity enhances trabecular microarchitecture and microfinite element estimated strength, furthering observations from short-term longitudinal studies. The data also demonstrate that tennis players exhibit crossed symmetry wherein the leg opposite the racquet arm possesses enhanced tibial properties compared with in the contralateral leg.

Cortical and medullary morphology of the tibia.

Bone resorption caused by stress shielding and insufficient bone-implant contact continues to be problematic for orthopedic endoprostheses that utilize osseointegration (OI) for skeletal fixation. Morphologic analyses have helped combat this issue by defining anatomic parameters to optimize endoprosthesis loading by maximizing bone-implant contact. These studies have not typically included diaphyseal medullary morphology, as this region is not pertinent to total joint replacement. To the contrary, percutaneous OI endoprostheses for prosthetic limb attachment are placed in the diaphysis of the long bone. This study examined the cortical and medullary morphology of 116 fresh-frozen human cadaveric tibia using computed tomography. Anatomic landmarks were selected and custom MATLAB scripts were used to analyze the cross-sectional cortical and medullary morphology normalized to biomechanical length (BML). BML measured the distance between the tibial plateau and the tibial plafond. Properties such as cortical thickness, medullary diameter, and circularity of the medullary canal were quantified. We tested the influence of sex and laterality on morphology, and examined variations along the length of the bone. Results showed that while both sex and laterality impacted the location of anatomic landmarks, only sex influenced cross-sectional morphology. Overall, morphology significantly affected shape along the length of the bone for all examined properties except medullary circularity. This analysis found that distal to 35% BML, the canal is conducive to a circular implant, with medullary diameter ranging from 13 to 32 mm between 20 and 80% BML. A large size range is necessary for sufficient implant contact in order to accommodate residual limb length after amputation.

Investigating the impact of captivity and domestication on limb bone cortical morphology: an experimental approach using a wild boar model.

The lack of bone morphological markers associated with the human control of wild animals has prevented the documentation of incipient animal domestication in archaeology. Here, we assess whether direct environmental changes (i.e. mobility reduction) could immediately affect ontogenetic changes in long bone structure, providing a skeletal marker of early domestication. We relied on a wild boar experimental model, analysing 24 wild-born specimens raised in captivity from 6 months to 2 years old. The shaft cortical thickness of their humerus was measured using a 3D morphometric mapping approach and compared with 23 free-ranging wild boars and 22 pigs from different breeds, taking into account sex, mass and muscle force differences. In wild boars we found that captivity induced an increase in cortical bone volume and muscle force, and a topographic change of cortical thickness associated with muscular expression along a phenotypic trajectory that differed from the divergence induced by selective breeding. These results provide an experimental proof of concept that changes in locomotor behaviour and selective breeding might be inferred from long bones morphology in the fossil and archaeological record. These trends need to be explored in the archaeological record and further studies are required to explore the developmental changes behind these plastic responses.

Rib Variation at Multiple Locations and Implications for Histological Age Estimation.

Existing histological age estimation methods using the rib were developed mainly from the midshaft; however, in forensic practice, uncertainty of sampling location often arises due to fragmented or previously sampled ribs. The potential for error increases when sampling location is uncertain and utilizing a section beyond the midshaft (either anterior or posterior) may result in erroneous age estimates. Additionally, there is debate within the field regarding the minimum number of sections needed for accurate age estimation. The aim of this research is to determine the importance of the midshaft distinction for age-at-death assessment and the necessity of analyzing serial sections by evaluating histological variables at sampling locations along the length of the rib. Three seriated histological sections at three sampling locations (anterior, midshaft, and posterior) were obtained from sixth ribs of ten postmortem human subjects. Cortical area (Ct.Ar) and osteon population density (OPD) were collected from each section (n = 90). Significant differences were determined in Ct.Ar between sampling locations, demonstrating the variation present along the length of the rib. A comparison of OPD at sampling locations revealed significant differences, suggesting that sampling site is critical to accurate age estimates. When sampling location is uncertain, a more anterior section should be taken. Analysis of serial sections within locations revealed no significant differences in OPD or Ct.Ar, supporting the practice of collecting data from one section for age estimation. While an age estimate can be achieved through the analysis of one section, best practice suggests reading two sections to capture intraindividual variation.

Association between Age of Menopause and Thickness of Crestal Cortical Bone at Dental Implant Site: A Cross-Sectional Observational Study.

Satisfactory host bone quality and quantity promote greater primary stability and better osseointegration, leading to a high success rate in the use of dental implants. However, the increase in life expectancy as a result of medical advancements has led to an aging population, suggesting that osteoporosis may become a problem in clinical dental implant surgery. Notably, relative to the general population, bone insufficiency is more common in women with post-menopausal osteoporosis. The objective of this study was to compare the thickness of the crestal cortical bone at prospective dental implant sites between menopausal and non-menopausal women. Prospective dental implant sites in the jawbone were evaluated in two groups of women: a younger group (<50 years old), with 149 sites in 48 women, and an older group (>50 years old) with 191 sites, in 37 women. The thickness of the crestal cortical bone at the dental implant site was measured based on each patient's dental cone-beam computed tomography images. For both groups, one-way analysis of variance and Tukey's post-test were used to assess the correlation between cortical bone thickness and the presence of implants in the four jawbone regions. Student's t-test was further used to compare differences between the older and younger groups. From the retrospective study results, for both groups, thickness of the crestal cortical bone was the highest in the posterior mandible, followed by anterior mandible, anterior maxilla, and posterior maxilla. Compared with the younger group, the older group had a lower mean thickness of the crestal cortical bone. Among the four regions, however, only in the posterior maxilla was the crestal cortical bone significantly thinner in the older group than in the younger group.

Ontogenetic changes in femoral cross-sectional geometry during childhood locomotor development.

OBJECTIVES: The femur is a major weight-bearing bone that is variably loaded throughout growth as children transition through locomotory states prior to the attainment of a mature bipedal gait. Here, we document ontogenetic trends in femoral cross-sectional geometry (CSG) and explore how changes in loading regime may impact the structural arrangement of cortical bone along the length of the developing diaphysis. MATERIALS AND METHODS: Micro-CT scans of 110 immature femora were generated from a documented archaeological sample ranging in age from birth to 8.5 years old. CSG properties indicative of relative bone strength and bending rigidity were analyzed from cross-sections extracted at 35%, 50% and 65% of total intermetaphyseal length. RESULTS: Infants experience a marked redistribution of cortical bone between birth and 7 months facilitating a more advantageous mechanical structure for early load bearing behaviors as bone is displaced further from the section centroid. Early walkers are characterized by a mediolaterally reinforced cross-section that becomes more circular as gait continues to develop. DISCUSSION: During ontogeny the femur undergoes distinct morphological phases, which correspond with changes in loading regime. This study illustrates the importance of loading conditions in shaping immature bone morphology. Nonmechanical factors such as changes in hormonal environmental can also impact on this dynamic.

A Sectioning, Coring, and Image Processing Guide for High-Throughput Cortical Bone Sample Procurement and Analysis for Synchrotron Micro-CT.

Bone is a dynamic and mechanically active tissue that changes in structure over the human lifespan. The products of the bone remodeling process have been studied substantially using traditional two-dimensional techniques. Recent advancements in X-ray imaging technology via desktop micro-computed tomography (µCT) and synchrotron radiation micro-computed tomography (SRµCT) have allowed for the acquisition of high-resolution three-dimensional (3D) scans of a larger field of view (FOV) than other 3D imaging techniques (e.g., SEM) providing a more complete picture of microscopic structures within human cortical bone. The specimen should be accurately centered within the FOV, however, to limit the appearance of streak artifacts known to impact data analysis. Previous studies have reported procurement of irregularly shaped rectilinear bone blocks that result in imaging artifacts due to uneven edges or image truncation. We have applied a geological sampling protocol (coring) to procure consistently sized cortical bone core specimens for SRµCT experiments from the anterior aspect of human femora. This coring method is efficient and minimally destructive to tissue. It creates uniform cylindrical samples that decrease imaging artifacts by nature of being isometric during rotation and providing a uniform path length for X-ray beams throughout scanning. Image processing of X-ray tomographic data of cored and irregularly shaped samples confirms the potential of the technique to improve visualization and analysis of cortical bone microarchitecture. A goal of this protocol is to deliver a reliable and repeatable method for the extraction of cortical bone cores that is adaptable for various types of high-resolution bone imaging experiments. An overarching goal of the work is to create a standardized cortical bone procurement for SRµCT that is affordable, consistent, and straightforward. This procedure may further be adapted by researchers in related fields who commonly evaluate hard composite materials such as in biological anthropology, geosciences, or material sciences.

Integration of cortical thickness data in a statistical shape model of the scapula.

Knowledge about bone morphology and bone quality of the scapula throughout the population is fundamental in the design of shoulder implants. In particular, regions with the best bone stock (cortical bone) are taken into account when planning the supporting screws, aiming for an optimal fixation. As an alternative to manual measurements, statistical shape models (SSMs) have been commonly used to describe shape variability within a population. However, explicitly including cortical thickness information in an SSM of the scapula still remains a challenge. Therefore, the goal of this study is to combine scapular bone shape and cortex morphology in an SSM. First, a method to estimate cortical thickness, based on HU (Hounsfield Unit) profile analysis, was developed and validated. Then, based on the manual segmentations of 32 healthy scapulae, a statistical shape model including cortical information was created and evaluated. Generalization, specificity and compactness were calculated in order to assess the quality of the SSM. The average cortical thickness of the SSM was 2.0 ± 0.63 mm. Generalization, specificity and compactness performances confirmed that the combined SSM was able to capture the bone quality changes in the population. In this work we integrated information on the cortical thickness in an SSM for the scapula. From the results we conclude that this methodology is a valuable tool for automatically generating a large population of scapulae and deducing statistics on the cortex. Hence, this SSM can be useful to automate implant design and screw placement in shoulder arthroplasty.

Assessment of the cortical bone thickness by CT-scan and its association with orthodontic implant position in a young adult Eastern Mediterranean population: A cross sectional study.

OBJECTIVE: This study was conducted to assess cortical bone thickness in the alveolar process of maxilla and mandible and to investigate its association with different orthodontic implant positions in Eastern Mediterranean young adults. MATERIALS AND METHODS: Computed tomography images of 50 patients aged between 18-35 years were included. Buccal, palatal and lingual cortical bone thicknesses were measured at 2, 4, 6, and 8mm from cemento-enamel junction starting from the mesial side of the second molar to the contralateral side. Pearson correlation was used to assess the association between cortical bone thickness and proposed orthodontic implant positions at all inter-radicular sites (p<0.05). RESULTS: The highest value of buccal cortical bone thickness was found mesial to the second molar in the maxilla and mandible for both genders. The value of palatal cortical bone thickness was found to be at the highest rate mesial to canine and first premolar in males and females respectively. On the other hand, the highest value of lingual cortical bone thickness was recorded to be mesial to the first molar in both genders. In addition to that, the buccal cortical bone thickness was significantly higher than palatal at the area mesial to the second molar at all four levels from the cemento-enamel junction. A significant correlation was found between cortical bone thickness and 2, 4, 6, and 8mm orthodontic implant levels in all inter-radicular sites. The values of correlation coefficients ranged from 0.280 to 0.674 in the maxillary arch and from 0.266 to 0.605 in the mandibular arch. CONCLUSIONS: From this study, we can conclude that as the position of the orthodontic implant moved more posteriorly and apically more cortical bone thickness was expected to be found in both jaws. A significant correlation was found between cortical bone thickness and the site of the orthodontic implant. Cortical bone thickness and its relationship with implant position should be taken into consideration when attempts are made to insert the orthodontic implant.

Biomechanical analysis and optimization of screw fixation technique for the cortical bone channel of lower thorax: Study protocol clinical trial (SPIRIT Compliant).

INTRODUCTION: It is well known that the main segments of spinal fracture is thoracolumbar (T11-L11). Therefore, in addition to the lumbar, the lower thoracic vertebra (T9-T12) often has the clinical needs of implantation of cortical bone trajectory (CBT) screws. However, the anatomic parameters of the lower thoracic vertebrae are quite different from those of the lumbar vertebrae, which means that if CBT screws are to be implanted in the lower thoracic vertebrae, the selection of the screw entry point, the length, diameter, angle and path of the screws in each segment need to be redefined. Methods In this part, 3-dimensional finite element model was established to analyze the stress and fixation efficiency of CBT screws in thoracic vertebrae after 5000 times of fatigue loading of normal model and osteoporosis model. Discussion If the outcomes indicate the trial is feasible and there is evidence to provide some basic anatomical parameters for CBT screw implantation in the lower thoracic spine, so that the ideal insertion point, length, diameter, and angle of CBT screw in different segments of the lower thoracic spine were determined.Trial Registration Chinese Clinical Trial Registry, ChiCTR1900026915.Registered on September 26, 2019.

Age- and sex-related characteristics in cortical thickness of femoral diaphysis for young and elderly subjects.

INTRODUCTION: Cortical thickness of the femoral diaphysis is assumed to be a preferred parameter in the assessment of the structural adaptation by mechanical use and biological factors. This study aimed to investigate the age- and sex-specific characteristics in cortical thickness of the femoral diaphysis between young and elderly non-obese people. MATERIALS AND METHODS: This study investigated 34 young subjects (21 men and 13 women; mean age: 27 ± 8 years) and 52 elderly subjects (29 men and 23 women; mean age: 70 ± 6 years). Three-dimensional (3D) cortical thickness of the femoral diaphysis was automatically calculated for 5000-8000 measurement points using the high-resolution cortical thickness measurement from clinical CT data. In 12 assessment regions created by combining three heights (proximal, central, and distal diaphysis) and four areas of the axial plane at 90° (medial, anterior, lateral, and posterior areas) in the femoral coordinate system, the standardized thickness was assessed using the femoral length. RESULTS: As per the trends, (1) there were no differences in medial and lateral thicknesses, while the posterior thickness was greater than the anterior thickness, (2) the thickness in men was higher than that in women, and (3) the thickness in young subjects was higher than that in elderly subjects. CONCLUSIONS: The results of this study are of clinical relevance as reference points to clarify the causes of various pathological conditions for diseases of the lower extremities.