Evaluation of cortical bone density using clinical computed tomography images: Detection of cortical porosity areas or transitional zones in human femoral diaphyses.

Age-related changes in human trabecular bone and cortical bone are known to vary. Although the porosity of cortical bone has been suggested to increase the risk of bone fracture, most of the currently available instruments for osteoporosis testing target trabecular bone. In this study, we evaluated cortical bone density using clinical computed tomography (CT) and compared the reliability of the cortical bone density index (CDI) with that of a polished male femoral bone from the same region. CDI images revealed that the porous area of cortical bone was extended in low CDI values. Moreover, this method was used to semi-quantitatively evaluate the cortical bones of the diaphysis of male femur specimens (n = 46). We found that there was a significant relationship (r = 0.70, p < 0.01) between the value of the cortical index (the ratio of cortical bone area to the cross-sectional area of the femoral diaphysis) and the average of CDI in the low signal area. Our findings suggest that the smaller the cortical bone occupancy, the more areas of consequential bone density loss were present. This may be the first step toward using clinical CT to assess cortical bone density.

Morphological divergence in the curvature of human femoral diaphyses: Tracing the central mass distributions of cross-sections.

The diaphysis of the human femoral bone has a physiological anterior curvature; additionally, there is a curvature to the medial side or lateral side. In addition to compression stress from gravity during standing, walking, and running, these bones are continuously exposed to complex stresses from the traction forces of the various strong muscles attached to them. The femoral diaphysis is subjected to these mechanical stresses, and the direction and size of its curvature are defined according to Wolff's law and the mechanostat theory of Frost. The purpose of this study was to quantitatively evaluate the curvature of the femoral diaphysis in Japanese skeletons by determining the curve connecting the central mass distributions (CMD) of cross-sectional images. A total of 90 right femora (46 males and 44 females) were randomly selected from modern Japanese skeletal specimens. Full-length images of these bones were acquired using a clinical computed tomography scanner. The range between the lower end of the lesser trochanter and the adductor tubercle of each femur was divided at regular intervals to obtain ten planes, and nine levels were analyzed. The CMD curve was determined by connecting the CMDs of each of the nine cross-sections. First, the CMD of a cross-section in each of the nine slices was calculated, and the nine trajectories were superimposed from above. Then, by converting the shape of the entire CMD curve to superimpose the coordinates of the endpoint on the starting point, a closed arc representing the curvature of the femur was determined. For both males and females, the patterns varied from mostly medial to largely lateral curvature. The size of the curvature also varied for individuals. By analyzing only the coordinates of the vertex of the CMD curve of each femoral bone, the outlines of the diaphyseal curvatures could be recognized. The femora were thereby divided into two groups: medial bending and lateral bending. Considering males and females together, the number in the lateral-curvature group (n = 51) was larger than that in the medial-curvature group (n = 39). Moreover, the average age of the lateral-curvature group was significantly higher than that of the medial-curvature group (p < 0.05). In males, with an increase in the cortical bone proportion of the cross-sectional area, the anterior vertex of diaphyseal bending tended to be more prominent. This cortical proportion was significantly higher in the medial-curvature groups than in the lateral-curvature group (p < 0.01). The phenomena observed in this study may be related to pathophysiologies such as atypical fractures of the femur and osteoarthritis of the knee joints.

Course of the thoracic nerves around the umbilicus within the posterior layer of the rectus sheath: a cadaver study.

Rectus sheath block is used to anesthetize thoracic nerves around the umbilicus. However, the appropriate point for anesthetic injection during rectus sheath block has not been determined anatomically. Here, we examined the course of thoracic nerve T10 at the posterior layer of the rectus sheath and the anatomical relationship between the nerve and the rectus abdominis and transversus abdominis muscles in formalin-fixed adult cadavers. The cranio-caudal distance from a horizontal line running through the umbilicus to where the thoracic nerve T10 passes through the posterior layer of the rectus sheath was 33.8 ± 14.4 (mean ± standard deviation) mm, while that from the horizontal line running through the umbilicus to the position where the lateral edge of the rectus abdominis muscle and the medial border of the transversus abdominis muscle cross was 33.1 ± 17.1 mm. The position where the lateral edge of the rectus abdominis muscle and the medial border of the transversus abdominis muscle cross approximates the position where thoracic nerves T10 passes through the posterior layer of the rectus sheath. Our results identify effective landmarks to guide the performance of rectus sheath block.

Morphological profile of atypical femoral fractures: age-related changes to the cross-sectional geometry of the diaphysis.

The use of bisphosphonates for osteoporosis patients has markedly decreased the incidence of femoral neck or trochanteric fractures. However, anti-osteoporosis drugs have been reported to increase the incidence of atypical femoral fractures, which involve stress fractures in the subtrochanteric region or the proximal diaphysis. In this study, the morphological characteristics of the cortical bone in human femoral diaphysis samples were analyzed from individuals who lived before bisphosphonate drugs were available in Japan. A total of 90 right femoral bones were arbitrarily selected (46 males and 44 females) from modern Japanese skeletal specimens. Full-length images of these femurs were acquired using a computed tomography scanner. An image processing method for binarization was used to calculate the threshold values of individual bones for determining their contours. The range between the lower end of the lesser trochanter and the adductor tubercle of each femur was divided at regular intervals to obtain 10 planes. The mean value of cortical bone thickness, periosteal border length, and the cortical cross-sectional area was evaluated for all planes. Moreover, the ratio of the area of the cortical bone to the total area of cross-section at the mid-diaphysis was calculated. A comparison between males and females demonstrated that most females had lower cortical bone area ratios at the mid-diaphysis. The femoral outer shape did not differ markedly according to age or sex; however, substantial individual differences were observed in the shape of the inner surface of the cortical bone. The cortical bone thickness and the cross-sectional area decreased with age in the femoral diaphysis; furthermore, in females, the decrease was higher for the former than for the latter. This may be due to a compensatory increase in the circumference of the femoral diaphysis. In addition, in about half of the subjects there was a discrepancy between the region with maximal value of the cortical bone thickness and that of the total cross-sectional area. Biological responses to mechanical stresses to the femoral diaphysis are thought not to be uniform. Bisphosphonates inhibit bone resorption and may promote non-physiological bone remodeling. Thus, a nonhomogeneous decrease in cortical thickness may be related to the fracture occurrence in the femoral diaphysis in some cases. Thus, long-term administration of bisphosphonates in patients with morphological vulnerability in the femoral cortical bones may increase the occurrence of atypical femoral fractures.

Three-dimensional morphological analysis of the human sacroiliac joint: influences on the degenerative changes of the auricular surfaces.

The sacroiliac joint (SIJ) is responsible for weight transmission between the spine and lower extremity. However, details of the structure and function of the SIJ remain unclear. In a previous study, we devised a method of quantitatively evaluating the level of degeneration of the SIJ using an age estimation procedure for the auricular surface of the ilium. Our results in that study suggested that the degree of degeneration of the joint surface may be associated with the morphology of the auricular surface of the ilium. In that study, however, the morphology of the auricular surface of the ilium was simplified for analysis, meaning that more detailed investigations were required in future. In the present study, we focused on individual differences in the shape of SIJ and carried out three-dimensional quantitative evaluation of the morphology of the auricular surface of the ilium to ascertain its association with joint degeneration. We produced three-dimensional images of the right auricular surfaces of the ilium of 100 modern Japanese men (age 19-83), and obtained the three-dimensional rectangular coordinates of 11 defined measurement points. We then calculated 16 parameters indicating the morphological characteristics of the auricular surfaces of the ilium from the three-dimensional rectangular coordinates of these measurement points, and used these to perform principal component analysis to investigate trends in the morphology of the auricular surface of the ilium. We found that the morphology of the auricular surface of the ilium could be characterized in terms of (i) size, (ii) concavity of the posterior border and (iii) amount of undulation. An investigation of the correlation between these parameters and age suggested that the amount of undulation of the auricular surface of the ilium tends to diminish with advancing age. In an investigation of the association between morphology of the auricular surface of the ilium and degeneration of the articular surface when the subjects were divided into a high-degeneration group (n = 55) and a low-degeneration group (n = 45) and the 16 parameters were compared, there was a significant difference in the amount of undulation of the auricular surface of the ilium. In an investigation limited to older subjects aged ≥ 60 (n = 47) at the time of death, there were significant differences between the high-degeneration group (n = 27) and low-degeneration group (n = 20) in terms not only of the parameters indicating the amount of undulation of the auricular surface of the ilium but also of those indicating the amount of the concavity of the posterior border. These results suggested that the amount of undulation of the auricular surface of the ilium may affect the degree of degeneration of the articular surface. In addition, in older subjects, the degree of concavity of the posterior border of the SIJ may also affect the degree of degeneration of the articular surface. It is thus likely that differences in the morphology of the auricular surface of the ilium may affect degenerative changes in the SIJ.

Diversity in intracortical remodeling in the human femoral bone: A novel view point with the morphological analysis of secondary osteons.

INTRODUCTION: In humans, intracortical bone remodeling is performed by a basic multicellular unit (BMU) composed of osteoclasts and osteoblasts penetrating through cortical bones. As a result, secondary osteons and their boundaries, cement lines, can be observed on the transverse section. There have been few reports mention whether there is diversity within a single individual and on the relevance to bone remodeling. The purpose of this study is to investigate the morphological diversity of secondary osteons in human femoral bone and to examine the relationship with bone remodeling. MATERIAL AND METHODS: First of all, we developed an original method to get the cross-sectional images of the cortical bones around the whole circumference for the purpose of evaluating the morphology of the secondary osteon exhaustively. Then, a total of ten cross-sectional slices from one right human femoral bone of male were prepared and stained with this method. The osteon population density and complexity of cement lines in osteons were evaluated in detail. RESULTS: Within this femoral bone, the osteon population density was significantly higher in the periosteal side and in the posterior area. Conversely, the cement line density and the osteon complexity were higher in the endosteal side; the proportion of complexed osteon significantly increased from the periosteal side toward the endosteal side. DISCUSSION: The results suggested that there were diversities in osteon population densities and osteon morphological pattern within one human femoral bone. It seemed that the BMUs ran to avoid the existing regions of osteon in the periosteal sides and to overlap the existing osteon in the endosteal sides. This seemed to be one of the novel viewpoints in the morphological analysis of secondary osteons. It might be better for the orthopedic surgeons to be aware that the osteon distribution in the cortical bone is not uniform.

Anatomical study of the articular branches innervated the hip and knee joint with reference to mechanism of referral pain in hip joint disease patients.

INTRODUCTION: Referred pain in the anterior knee joint is the most common symptom in hip disease patients. The development of referred pain is considered to be related to dichotomizing peripheral sensory fibers. However, no gross anatomical findings identify any dichotomizing fibers innervating both the hip and knee joints. We dissected the femoral and obturator nerves in human cadavers to investigate the distribution of the articular branches in the hip and knee joints. Fourteen embalmed left lower limbs from 14 Japanese adult cadavers (five from females, nine from males, average age 73.8 ± 14.1 years) were observed macroscopically. The articular branches of the femoral and obturator nerves were dissected at the anterior margin of the groin toward the thigh region. After dissections of the articular nerves of the hip joints, the femoral and obturator nerves were exposed from proximally to distally to identify the articular nerves of the knee joints. The branching pattern of the articular branches in the hip and knee joints was recorded. In six of 14 limbs (42.9%), the femoral nerve supplied articular branches to the anteromedial aspect of both the hip and knee joints. These articular branches were derived from the same bundle of femoral nerve. These gross anatomical findings suggested that dichotomizing peripheral sensory fibers innervate the hip and knee joints and these could relate to the referred pain confirmed in the anterior knee joints of patients with hip disease. Clin. Anat. 31:705-709, 2018. © 2018 Wiley Periodicals, Inc.

Deep and superficial circumflex iliac arteries and their relationship to the ultrasound-guided femoral nerve block procedure: A cadaver study.

The in-plane lateral to medial approach is a standard technique for ultrasound-guided femoral nerve block (USG-FNB). The first bifurcation of the femoral artery, which consists of the deep artery of the thigh (DAT) or occasionally the lateral circumflex femoral artery (LCFA), is regarded as the distal border for this procedure. We sometimes detect arteries along the estimated needle trajectory for USG-FNB. The superficial (SCIA) and deep (DCIA) circumflex iliac arteries run laterally parallel to the inguinal ligament from the femoral or external iliac artery. The relationship between the SCIA and DCIA and other anatomical structures related to USG-FNB around the femoral triangle region was studied by gross anatomical examination of 100 formalin-fixed adult cadavers. At least one SCIA and one DCIA were identified around each femoral triangle; 81.8% of SCIA and 58% of DCIA originated from the femoral artery. All DCIA coursed between the fascia lata and fascia iliaca and 80% of SCIA penetrated the fascia lata. In 94% of femoral triangles, at least one arterial branch heading towards the lateral part of the thigh originated from the femoral artery from the level of the inguinal ligament to the first bifurcation of the femoral artery. The presence of SCIA and DCIA should be considered during USG-FNB using the in-plane lateral to medial approach to avoid inadvertently injuring them, as they are occasionally located along the presumed needle trajectory superficial to the fascia iliaca. Clin. Anat. 30:413-420, 2017. © 2017 Wiley Periodicals, Inc.

The cross-sectional morphology of the proximal femoral diaphysis is defined by the anteversion angle.

Osteoporosis in postmenopausal women is one of the causes of femoral fractures and is prevented by the administration of bisphosphonates. Individual morphologies are considered to increase the risk of atypical fractures associated with long-term administration. To evaluate cortical bone morphology quantitatively, we established a method to measure the distance from the center point of a cross-section to the external and internal borders based on CT images. Using this method, 44 sides of a female femoral skeleton specimen were examined and areas of protrusion and thickening in the medial anterior and lateral posterior regions just below the lesser trochanter were identified. These positions strongly correlated with the anteversion angle, suggesting the involvement of the distribution of the load received from body weight defined by the angle. The finite element method was used to examine the relationships between the positions of these areas with compressive and tensile stress distribution areas in the one-legged standing condition. The medial anterior region and lateral posterior region protruded and thickened in response to compressive and tensile stress, respectively. In addition, a hierarchical relationship was observed between the anteversion angle, tensile stress distribution, protrusion, and thickening in femurs with thinning of cortical bone, indicating that morphogenesis occurs adaptively to loading. The present results demonstrate the usefulness of this method in considering the formation mechanism and function of the femoral diaphysis and suggest that bone remodeling is necessary to maintain adaptability.

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.

Geographic variation in body form of prehistoric Jomon males in the Japanese archipelago: its ecogeographic implications.

Diversity of human body size and shape is often biogeographically interpreted in association with climatic conditions. According to Bergmann's and Allen's rules, populations in regions with a cold climate are expected to display an overall larger body and smaller/shorter extremities than those in warm/hot environments. In the present study, the skeletal limb size and proportions of prehistoric Jomon hunter-gatherers, who extensively inhabited subarctic to subtropical areas in the ancient Japanese archipelago, were examined to evaluate whether or not the inter-regional differences follow such ecogeographic patterns. Results showed that the Jomon intralimb proportions including relative distal limb lengths did not differ significantly among five regions from northern Hokkaido to the southern Okinawa Islands. This suggests a limited co-variability of the intralimb proportions with climate, particularly within genealogically close populations. In contrast, femoral head breadth (associated with body mass) and skeletal limb lengths were found to be significantly and positively correlated with latitude, suggesting a north-south geographical cline in the body size. This gradient therefore comprehensively conforms to Bergmann's rule, and may stem from multiple potential factors such as phylogenetic constraints, microevolutionary adaptation to climatic/geographic conditions during the Jomon period, and nutritional and physiological response during ontogeny. Specifically, the remarkably small-bodied Jomon in the Okinawa Islands can also be explained as an adjustment to subtropical and insular environments. Thus, the findings obtained in this study indicate that Jomon people, while maintaining fundamental intralimb proportions, displayed body size variation in concert with ambient surroundings.

The risk of Creutzfeldt-Jakob disease infection in cadaveric surgical training.

The usefulness of cadaver surgical training in the clinical field is already well known. In Japan, the number of universities introducing cadaver surgical training is increasing. In addition to formalin fixation, various fixation methods are used, such as the Thiel method, saturated salt solution method, N-vinyl-2-pyrrolidone method, and fresh-frozen cadavers. Although protection against infections during fixation and cadaver surgical training has been implemented in most universities, it is currently inadequate. Furthermore, the possibility of undiagnosed infectious diseases in donors cannot be excluded. Prion diseases, such as Creutzfeldt-Jakob disease, are relatively rare, but they are fatal, with no effective treatment. The abnormal prion protein that causes prion diseases is resistant to formaldehyde and cannot be inactivated by all methods of cadaver fixation presently in use. Recently developed real-time quaking-induced conversion has been reported to be a useful screening method for prion infection. In addition, this article aims to raise awareness of prion diseases in cadaver surgical training by reviewing the current understanding of prion diseases in cadavers and their screening methods.

Application of Methods for a Morphological Analysis of the Femoral Diaphysis Based on Clinical CT Images to Prehistoric Human Bone: Comparison of Modern Japanese and Jomon Populations from Hegi Cave, Oita, Japan.

A morphological analysis of ancient human bones is essential for understanding life history, medical history, and genetic characteristics. In addition to external measurements, a three-dimensional structural analysis using CT will provide more detailed information. The present study examined adult male human skeletons excavated from Hegi cave, Nakatsu city, Oita Prefecture. CT images were taken from the femurs of adult males (Initial/Early Jomon Period (n = 10) and Late Jomon Period (n = 5)). Cross-sectional images of the diaphysis from below the lesser trochanter to above the adductor tubercle were obtained using the method established by Imamura et al. (2019) and Imamura et al. (2021). Using Excel formulas and macros, the area of cortical bone, thickness, and degree of curvature were quantitatively analyzed. The results were compared with data on modern Japanese. The maximum thickness of cortical bone in the diaphysis and the degree of the anterior curvature were significantly greater in Late Jomon humans than in the other groups. In contrast to modern humans, the majority of Jomon femurs showed the S-shaped curvature with the medial side at the top position and the lateral side at the lower position. The present results demonstrate that Late Jomon humans had a wider range of activity than the other groups and also provide insights into diseases in the hip and knee joints of Jomon humans.

Similarities and Differences in Bone Mineral Density between Multiple Sites in the Same Individual: An Elderly Cadaveric Study.

Bone mineral density (BMD) is known to vary based on various factors, and the degree of variation is site-specific. However, few studies have investigated the relationship between bone density at trabecular bone-rich and cortical bone-rich sites in the same individual. In this study, we attempted to measure BMD at multiple sites using whole-body computed tomography images taken immediately after death and to clarify the similarities and differences between skeletal sites. Additionally, we aimed to examine the factors that influence changes in BMD, such as the loading environment, bone microstructure, and the ossification process of each skeletal region. A 3D model containing BMD data of the skull, clavicle, lumbar vertebrae, and femur (neck and diaphysis) was created using computed tomography images taken immediately after the death of 60 individuals (28 men and 32 women, average age: 84.0 years) who consented to participate in the study before death. Arbitrary measurement sites were defined, and bone density was measured at each site. We found that the BMDs of all regions were negatively correlated with age, but this correlation was weaker in the skull than in other regions. The negative correlation was especially pronounced in areas with more trabecular bones in men and in areas with more cortical bones in women. Furthermore, these findings suggest that factors, such as the loading environment, bone microstructure, and the ossification process of the skeletal sites, affect the BMD. Furthermore, our results suggest that it is important to assess the BMD of cortical bone in older women.

Significant Asymmetry of the Bilateral Upper Extremities of a Skeleton Excavated from the Mashiki-Azamabaru Site, Okinawa Island, Japan.

The human skeleton of a young adult male with marked asymmetry of the bilateral upper extremities was excavated from the Mashiki-Azamabaru site (3000-2000 BCE) on the main island of Okinawa in the southwestern archipelago of Japan. The skeleton was buried alone in a corner of the cemetery. In this study, morphological and radiographic observations were made on this skeleton, and the pathogenesis of the bone growth disorder observed in the left upper limb was discussed. The maximum diameter of the midshaft of the humerus was 13.8 mm on the left and 21.2 mm on the right. The long bones comprising the left upper extremity lost the structure of the muscle attachments except for the deltoid tubercle of the humerus. The bone morphology of the right upper extremity and the bilateral lower extremities was maintained and was close to the mean value of females from the Ohtomo site in northwestern Kyushu, Japan, during the Yayoi period. It is assumed that the anomalous bone morphology confined to the left upper extremity was secondary to the prolonged loss of function of the muscles attached to left extremity bones. In this case, birth palsy, brachial plexus injury in childhood, and acute grey matter myelitis were diagnosed. It was suggested that this person had survived into young adulthood with severe paralysis of the left upper extremity due to injury or disease at an early age.

Gross anatomical investigation of the muscular head between the vastus lateralis and intermedius in the Japanese population: a cadaver study.

Unlike the general understanding of the quadriceps femoris, the existence of a new muscular head between the vastus lateralis and the vastus intermedius was reported, and named the tensor of the vastus intermedius in the Swedish population. The purpose of this study was to investigate the presence and form of the muscular head in the Japanese population and to clarify its structure by gross anatomical approaches. A total of 35 thighs of 20 Japanese cadavers were investigated. We searched for the muscular head and classified it into four types. In addition, nerve fiber analysis was performed for each classification type. Regarding classification, 11% were the independent type, 29% were the common type, 37% were the vastus lateralis type, and 23% were the vastus intermedius type. Based on nerve fiber analysis, in the common type, the muscular head was under dual nerve supply from the vastus lateralis and intermedius. The other three types were innervated only by nerves from the vastus lateralis. The target muscular head may always be present in Japanese. The nerves from the vastus lateralis were always distributed in the target muscular head based on nerve fiber analysis; therefore, this muscular head may be most closely related to the vastus lateralis. The name of this muscular head should be "the accessory head of the vastus lateralis" rather than "the tensor of the vastus intermedius."

Reduced cortical bone thickness increases stress and strain in the female femoral diaphysis analyzed by a CT-based finite element method: Implications for the anatomical background of fatigue fracture of the femur.

The incidence of hip fractures is increasing in Japan and is high among women older than 70 years. While osteoporosis has been identified as one of the causative factors of fracture, atypical femoral fracture has emerged as a potential complication of bisphosphonate therapy. Atypical femoral fracture is prevalent among Asian women and has been attributed to morphological parameters. Age-related decreases in the morphological parameters of the femoral diaphysis, such as cortical bone thickness, cortical cross-sectional area, and the cortical index, were reported in Japanese women prior to bisphosphonate drugs being approved for treatment. Thus, in the present study, the relationships between biomechanical and morphological parameters were analyzed using a CT-based finite element method. Finite element models were constructed from 44 femurs of Japanese women aged 31-87 years using CT data. Loading conditions were set as the single-leg configuration and biomechanical parameters, maximum and minimum principal stresses, Drucker-Prager equivalent stress, maximum and minimum strains, and strain energy density were calculated in 7 zones from the subtrochanteric region to distal diaphysis. Pearson's correlation coefficient test was performed to investigate relationships with morphological parameters. While absolute stresses gradually decreased from the subtrochanteric region to distal diaphysis, absolute strains markedly declined in the proximal diaphysis and were maintained at the same levels as those in the distal regions. All types of stresses and minimum principal strain in the femoral diaphysis scored higher absolute values in the high-risk group (≥70 years, n = 28) than in the low-risk group (<70 years, n = 16) (p < 0.05). The distribution patterns of equivalent stress and strain energy density were similar to that of Young's modulus, except for the region of the linea aspera. All biomechanical parameters correlated with morphological parameters and correlation efficiencies, with the reciprocal of cortical bone thickness showing the strongest correlation. The present results demonstrated that biomechanical parameters may be predicted by calculating the cortical bone thickness of femurs not treated with bisphosphonates. Furthermore, strain appeared to be repressed at a low level despite differences in stress intensities among the regions by bone remodeling. This remodeling is considered to be regulated by Wolff's law driven by equivalent stress and strain energy densities from the proximal to distal femur. The present results will promote further investigations on the contribution of morphological parameters in the femoral diaphysis to the onset of atypical femoral fracture.

Sex-based differences in human sacroiliac joint shape: a three-dimensional morphological analysis of the iliac auricular surface of modern Japanese macerated bones.

The human pelvis is one of the skeletons where sex differences are expressed, but few detailed studies have been conducted on sex-related differences in the sacroiliac joint morphology. Therefore, we conducted a three-dimensional morphological analysis evaluation of the sacroiliac joints to clarify the sex-related difference of the joint's morphology. Right-side macerated innominate bones of Japanese males (n = 100) and females (n = 70) whose ages at death were recorded were included in the study. Three-dimensional images were created from the subjects' iliac auricular surface images, and 16 measurement parameters were acquired on the basis of 11 defined measurement points. All measurement parameters were compared between the male and female groups. The values of the measurement parameters indicating the size of the iliac auricular surface were significantly larger in the male group than in the female group. In addition, the angle between the short and long arms of the auricular surface was larger in the male group. Furthermore, on the basis of the corrected values of the physical disparity, the long arm dimension of the iliac auricular surface was larger in the male group, while the short arm dimension was larger in the female group. The sex-based differences in the iliac auricular surface morphology that were confirmed in this study may reflect the sex-based differences in the sacroiliac joint function. The findings of this study may contribute to the elucidation of the pathophysiology of the sacroiliac joint dysfunction that frequently occurs in women.

A health crisis during the Japanese Medieval Period: A new paleodemographic perspective.

OBJECTIVE: To test the hypothesis that the "Little Ice Age" (LIA) (in Japan, ˜1440 - 1730 CE) co-occurred with unique age-at-death patterns. MATERIALS: 810 adult human skeletons from the early Medieval Period (EMP) of Japan, which are contemporaneous with the Medieval Warm Period (10th - mid 13th century AD), and the late Medieval Period (LMP) and Edo Period, which are contemporary with the LIA. METHODS: Age at death and sex was determined for each skeleton and demographic profiles of the Yayoi Period (5th century BC - 3rd century AD), EMP, LMP, and Edo site samples were compared. Paleopathological data from previously published reports were evaluated. RESULTS: The EMP had the highest mortality among young adults. Longevity increased in the samples (LMP and Edo) contemporaneous with the LIA. CONCLUSIONS: EMP early age-at-death was the result of poor community health, violent death, and frequent large-scale natural catastrophes. The LMP and Edo Period samples have an older age-at-death pattern and higher frequency of stress markers, argued to be a consequence of a colder climate. SIGNIFICANCE: This study is the first to synthesize paleodemographic and paleopathological data on a large scale to assess the possible effects of the Little Ice Age in Japan. LIMITATIONS: Varying skeletal preservation and focus on adult skeletons reduces the ability to evaluate health throughout the life span. SUGGESTIONS FOR FURTHER RESEARCH: Analysis of nonadult remains and multiple health indicators will likely shed more light on the effects of the Little Ice Age in Japan.