Decrease in the osteocyte lacunar density accompanied by hypermineralized lacunar occlusion reveals failure and delay of remodeling in aged human bone

Aging decreases the human femur's fatigue resistance, impact energy absorption, and the ability to withstand load. Changes in the osteocyte distribution and in their elemental composition might be involved in age-related bone impairment. To address this question, we carried out a histomorphometric assessment of the osteocyte lacunar distribution in the periosteal and endosteal human femoral cortexes of 16 female and 16 male donors with regard to age- and sex-related bone remodeling. Measurements of the bone mineral density distribution by quantitative backscattered electron imaging and energy dispersive X-ray analysis were taken to evaluate the osteocyte lacunar mineral composition and characteristics. Age-dependent decreases in the total osteocyte lacunar number were measured in all of the cases. This change signifies a risk for the bone's safety. Cortical subdivision into periosteal and endosteal regions of interest emphasized that, in both sexes, primarily the endosteal cortex is affected by age-dependent reduction in number of osteocyte lacunae, whereas the periosteal compartment showed a less pronounced osteocyte lacunar deficiency. In aged bone, osteocyte lacunae showed an increased amount of hypermineralized calcium phosphate occlusions in comparison with younger cases. With respect to Frost's early delineation of micropetrosis, our microanalyses revealed that the osteocyte lacunae are subject to hypermineralization. Intralacunar hypermineralization accompanied by a decrease in total osteocyte lacunar density may contribute to failure or delayed bone repair in aging bone. A decreased osteocyte lacunar density may cause deteriorations in the canalicular fluid flow and reduce the detection of microdamage, which counteracts the bone's structural integrity, while hypermineralized osteocyte lacunae may increase bone brittleness and render the bone fragile.

Osteocytic canalicular networks: morphological implications for altered mechanosensitivity

Osteocytes are ramified bone cells distributed throughout the bone matrix within a network of micrometer-scale cavities (lacunae) and numerous nanometer-thick tunnels (canaliculi). The integrity of the canalicular network might influence bone quality and reflect its mechanosensory potential. In this study, we applied an acid etching technique to embedded bone specimens that allows 3D observation of the canalicular network across a 2D plane to quantitatively assess the canalicular connections in cortical bone specimens from young and aged individuals. Our results showed a nearly 30% reduction in the number of canaliculi per osteocyte lacuna in aged individuals (N.Ot.Ca/Ot.Lc: 15.92 ± 1.5 in aged vs 22.10 ± 2.82 in young; p < 0.001); moreover, canalicular number was found to be inversely related to the osteonal tissue age represented by Ca/P ratio (p < 0.001). We frequently observed the phenomenon that canaliculi of osteocytes located near the osteon's periphery did not end at the osteon's cement line boundary but penetrated through the cement line and spread into the surrounding bone matrix, thus establishing an "external rooting" or "connection", which might have significant relevance to bone quality. Our findings showed that not only does the aging process diminish the canalicular network within osteons, but it also significantly reduces the probability of external osteonal rooting and connections with the surrounding bone tissue. Deterioration in the canalicular network with age reduces the connectivity between osteocytes and between osteons/interstitial tissue, which affects the supply of nutrients to osteocytes, degrades their mechanosensitivity, and contributes to increased bone fragility in the elderly.

Multi-level characterization of human femoral cortices and their underlying osteocyte network reveal trends in quality of young, aged, osteoporotic and antiresorptive-treated bone

Characterization of bone's hierarchical structure in aging, disease and treatment conditions is imperative to understand the architectural and compositional modifications to the material and its mechanical integrity. Here, cortical bone sections from 30 female proximal femurs - a frequent fracture site - were rigorously assessed to characterize the osteocyte lacunar network, osteon density and patterns of bone matrix mineralization by backscatter-electron imaging and Fourier-transform infrared spectroscopy in relation to mechanical properties obtained by reference-point indentation. We show that young, healthy bone revealed the highest resistance to mechanical loading (indentation) along with higher mineralization and preserved osteocyte-lacunar characteristics. In contrast, aging and osteoporosis significantly alter bone material properties, where impairment of the osteocyte-lacunar network was evident through accumulation of hypermineralized osteocyte lacunae with aging and even more in osteoporosis, highlighting increased osteocyte apoptosis and reduced mechanical competence. But antiresorptive treatment led to fewer mineralized lacunae and fewer but larger osteons signifying rejuvenated bone. In summary, multiple structural and compositional changes to the bone material were identified leading to decay or maintenance of bone quality in disease, health and treatment conditions. Clearly, antiresorptive treatment reflected favorable effects on the multifunctional osteocytic cells that are a prerequisite for bone's structural, metabolic and mechanosensory integrity.

Micro-structural basis for particular vulnerability of the superolateral neck trabecular bone in the postmenopausal women with hip fractures

In this study we analyzed the trabecular bone micro-architecture in the inferomedial and superolateral subregions of the femoral neck in a group with hip fractures and a control group of elderly women, with aim to clarify the micro-structural basis of bone fragility. Proximal femora from 29 Caucasian female cadavers were collected at Institute of Forensic Medicine in Belgrade (15 women with hip fracture: age 79.5±8.5 yrs.; and 14 women without hip fractures: age 74.1±9.3 yrs.). The femoral neck section was scanned in dry conditions using a micro-computed tomography (Scanco μCT 40), at 70 kV, 114 μA, 300 ms integration time, 36 μm resolution, isotropic, 1024×1024 pixels per slice, automatically evaluating trabecular micro-architecture using the built-in program of the micro-CT with direct 3D morphometry. The samples were foam padded to avoid any movement artifacts during scanning. Analysis of the neck section in the fracture group compared to the control cases demonstrated significantly lower bone volume fraction (mean: 6.3% vs. 11.2%, p=0.002), lower connectivity density (0.33/mm(3) vs. 0.74/mm(3), p=0.019) and higher trabecular separation (0.87 mm vs. 0.83 mm, p=0.030). Division into the superolateral and inferomedial regions of interest revealed that the superolateral neck displayed even more differences in micro-architectural properties between the fracture and non-fracture groups. Namely, while in the inferomedial neck only bone volume fraction and degree of anisotropy displayed significant inter-group variability (lower BV/TV with higher degree of anisotropy in the fracture group), in the superolateral neck almost all parameters were different between the fracture cases and the controls, where the fracture group showed a lower trabecular bone volume fraction (3.6% vs. 8.2%, p=0.001), lower connectivity (0.21 vs. 0.63/mm(3), p=0.008), more rod like trabecular structure (SMI: 2.94 vs. 2.62, p=0.049), higher separation and the thinned trabeculae (Tb.Sp: 0.89 vs. 0.85 mm, p=0.013; Tb.Th: 0.17 vs. 0.20 mm, p=0.05). In addition, after adjusting for the effects of BV/TV, the majority of differences disappeared, demonstrating that the bone loss manifests itself via the changes in micro-architectural parameters: trabecular thinning, rising the spacing between individual trabeculae, reducing trabecular connectivity and accentuating trabecular perforations leading to predominance of rod-like trabecular elements. Preferential impairment of the superolateral neck trabecular structure and organization in women with hip fracture reveals the region-dependent micro-structural basis of bone fragility in elderly women.

Micro-morphological properties of osteons reveal changes in cortical bone stability during aging, osteoporosis, and bisphosphonate treatment in women

SUMMARY

We analyzed morphological characteristics of osteons along with the geometrical indices of individual osteonal mechanical stability in young, healthy aged, untreated osteoporotic, and bisphosphonate-treated osteoporotic women. Our study revealed significant intergroup differences in osteonal morphology and osteocyte lacunae indicating different remodeling patterns with implications for fracture susceptibility.

INTRODUCTION

Bone remodeling is the key process in bone structural reorganization, and its alterations lead to changes in bone mechanical strength. Since osteons reflect different bone remodeling patterns, we hypothesize that the femoral cortices of females under miscellaneous age, disease and treatment conditions will display distinct osteonal morphology and osteocyte lacunar numbers along with different mechanical properties.

METHODS

The specimens used in this study were collected at autopsy from 35 female donors (young group, n = 6, age 32 ± 8 years; aged group, n = 10, age 79 ± 9 years; osteoporosis group, n = 10, age 81 ± 9 years; and bisphosphonate group, n = 9, age 81 ± 7 years). Von Kossa-modified stained femoral proximal diaphyseal sections were evaluated for osteonal morphometric parameters and osteocyte lacunar data. Geometrical indices of osteonal cross-sections were calculated to assess the mechanical stability of individual osteons, in terms of their resistance to compression, bending, and buckling.

RESULTS

The morphological assessment of osteons and quantification of their osteocyte lacunae revealed significant differences between the young, aged, osteoporosis and bisphosphonate-treated groups. Calculated osteonal geometric indices provided estimates of the individual osteons' resistance to compression, bending and buckling based on their size. In particular, the osteons in the bisphosphonate-treated group presented improved osteonal geometry along with increased numbers of osteocyte lacunae that had been formerly impaired due to aging and osteoporosis.

CONCLUSIONS

The data derived from osteons (as the basic structural units of the cortical bone) in different skeletal conditions can be employed to highlight structural factors contributing to the fracture susceptibility of various groups of individuals.

Region-specific sex-dependent pattern of age-related changes of proximal femoral cancellous bone and its implications on differential bone fragility

Despite evident interest in age-related bone changes, data on regional differences within the proximal femur are scarce. To date, there has been no comprehensive study on site-specific age-related changes in the trabecular architecture of three biomechanically important femoral subregions (medial neck, lateral neck, and intertrochanteric region) for both genders. In this study we investigated age-related deterioration in the trabecular architecture of those three subregions of the femoral neck for both genders. The research sample included 52 proximal femora (26 males, 26 females; age range, 26-96 years) from Forensic Department at University of Belgrade. Bone sections from the three regions of interest were scanned by micro-CT at University of Hamburg. The study revealed that proximal femoral microarchitecture cannot be perceived as homogeneous and, more importantly, that the aging process is not uniform. Besides the initial intersite differences, microarchitecture changed differently with increasing age, maintaining significant differences between the regions. In addition, we observed a different aging pattern between genders: deterioration was most significant in the intertrochanteric region in women, while the lateral neck was most affected in men. This finding supports epidemiological data about the differential occurrence of cervical vs. trochanteric fractures in aging males and females. In conclusion, the aging process in the proximal femur cannot be regarded as a simple function of quantitative bone loss but, rather, as an alteration of specific architecture that may degrade bone strength.

Fractures in late medieval skeletal populations from Serbia

Bone fractures were analyzed from skeletal remains of 861 adult individuals from six cemeteries dating to the Late Medieval period in Serbia. Results of the study were compared to other cemetery populations (635 individual skeletons) of the same date and region in an attempt to understand fracture patterns. The association of types of fractures and their prevalence with sex, age at death, cemetery site, and information deriving from historical sources are discussed. Results showed that the long bone fracture frequency was 0.7%, and the majority of the fractures were the result of direct force. This rate is similar to some studies of contemporary British skeletal samples. However, it is much lower than for some other Old World sites. Cranial vault fractures had a rate of 6.7%, and of the facial skeleton, 1.3%; the frontal bone was the most affected of bones of the cranial vault. Injuries were more common on the upper extremities (0.8%) compared to the lower (0.6%). However, the fibula was the most fractured bone (2.8%), followed by the ulna (2.4%). This pattern is similar to three of six Late Medieval urban sites in Britain. These findings suggest that this rural community was exposed to a low risk of trauma, probably related mostly to accidents sustained during farming, and rarely to interpersonal violence.

Analysis of neck injuries in hanging

Retrospective study of suicidal hangings was made on 175 cases (133 male victims, 42 female victims) for a 5-year period. The mean age was 47.33 +/- 17.51 years. The sample was divided in 4 groups according to the position of the ligature knot (anterior, right, left, and posterior hanging). The authors analyzed all visible injuries of soft tissues and bones and cartilage of the neck, and in 150 cases (85.7%), we established that there was at least one injury of these structures (hematoma or fracture for example). The most frequent injury was to sternocleidomastoid muscles. Fracture of throat skeleton was detected in 119 cases (68%). The proportion of fractures increases with age of the deceased. There was no clear correlation between frequency of neck injuries and type of hanging.

Evaluation of the Suchey-Brooks method for aging skeletons in the Balkans

This study has been carried out to examine whether the Suchey-Brooks (S&B) methods could be successfully applied in age assessment of populations from the Balkans. The known-age sample consists of 33 females and 52 males pairs of pubic bones collected from the autopsy cases. Age estimation by S&B method showed an accuracy of 89.74% in males and 72.0% in females. Statistical analysis showed a positive correlation between the actual age of the investigated individuals and age phases obtained by the S&B method, although the mean values of the sixth age category differed significantly compared with the original model. The most reliable indicators in both sexes were the relief of the symphyseal surface, lipping, symphyseal rim, and dorsal margin. The discriminating power of these indicators was the least reliable in distinguishing S&B phases 2 and 3. Based on these results, the appropriate recommendations for aging Serbian populations are made. There was a good agreement between two observers (kappa=0.726).

Nano-structural, compositional and micro-architectural signs of cortical bone fragility at the superolateral femoral neck in elderly hip fracture patients vs. healthy aged controls

To unravel the origins of decreased bone strength in the superolateral femoral neck, we assessed bone structural features across multiple length scales at this cortical fracture initiating region in postmenopausal women with hip fracture and in aged-matched controls. Our combined methodological approach encompassed atomic force microscopy (AFM) characterization of cortical bone nano-structure, assessment of mineral content/distribution via quantitative backscattered electron imaging (qBEI), measurement of bone material properties by reference point indentation, as well as evaluation of cortical micro-architecture and osteocyte lacunar density. Our findings revealed a wide range of differences between the fracture group and the controls, suggesting a number of detrimental changes at various levels of cortical bone hierarchical organization that may render bone fragile. Namely, mineral crystals at external cortical bone surfaces of the fracture group were larger (65.22nm±41.21nm vs. 36.75nm±18.49nm, p<0.001), and a shift to a higher mineral content and more homogenous mineralization profile as revealed via qBEI were found in the bone matrix of the fracture group. Fracture cases showed nearly 35% higher cortical porosity and showed significantly reduced osteocyte lacunar density compared to controls (226±27 vs. 247±32#/mm(2), p=0.05). Along with increased crystal size, a shift towards higher mineralization and a tendency to increased cortical porosity and reduced osteocyte lacunar number delineate that cortical bone of the superolateral femoral neck bears distinct signs of fragility at various levels of its structural organization. These results contribute to the understanding of hierarchical bone structure changes in age-related fragility.

Nanostructure and mineral composition of trabecular bone in the lateral femoral neck: implications for bone fragility in elderly women

Despite interest in investigating age-related hip fractures, the determinants of decreased bone strength in advanced age are not clear enough. Hitherto it has been obscure how the aging process affects the femoral neck nanostructure and composition, particularly in the lateral subregion of the femoral neck, which is considered as a fracture-initiating site. The femoral bone samples used in this study were obtained at autopsy in 10 women without skeletal disease (five younger: aged 20-40 years, and five elderly: aged 73-94 years). Atomic force microscopy (AFM) was applied to explore the mineral grain size in situ in young vs. old trabecular bone samples from the lateral femoral neck. The chemical compositions of the samples were determined using inductively coupled plasma optical emission spectroscopy and direct current argon arc plasma optical emission spectrometry. Our AFM study revealed differences in trabecular bone nanostructure between young and elderly women. The mineral grain size in the trabeculae of the old women was larger than that in the young (median: 95 vs. 59nm), with a particular bimodal distribution: 45% were small grains (similar to the young) and the rest were larger. Since chemical analyses showed that levels of calcium and phosphorus were unchanged with age, our study suggests that during aging the existing bone mineral is reorganized and forms larger aggregates. Given the mechanical disadvantage of large-grained structures (decreased material strength), the observed nanostructural differences contribute to our understanding of the increased fragility of the lateral femoral neck in aged females. Moreover, increasing data on mineral grains in natural bone is essential for advancing calcium-phosphate ceramics for bone tissue replacement.

Age-related deterioration in trabecular bone mechanical properties at material level: nanoindentation study of the femoral neck in women by using AFM

Despite general belief that the mechanical properties of bone material contribute to whole bone strength, it is still obscure what the age effects are on mechanical behavior of the bone material, particularly in the case of the femoral neck trabeculae. In this study, atomic force microscopy was used for imaging and measuring the size of mineral grains, as well as nano-scale mechanical characterization (nanoindentation) of the bone mineralized matrix of trabeculae, with the aim to explore the age effects on bone elasticity and give new insight into age-related bone fragility. The bone samples in this study comprised trabecular bone specimens of the femoral neck region, collected from eight skeletal healthy women (five young adults: 27-38yrs., three elderly: 83-94yrs.) at autopsy. Bone trabeculae in the elderly displayed a higher modulus and nanohardness, signifying a decreased amount of energy that can be accommodated by the bone tissue during loading. Regression analysis revealed that nearly 65% of variability in the bone matrix elastic modulus can be statistically explained by the changes in size of the matrix mineral grains. This study revealed that the bone trabeculae of elderly women express less elastic behavior at the material level, which makes them more vulnerable to unusual impact loads originating from a fall. The observed age-related structural and mechanical alteration at the bone material level adds new evidence for understanding why hip fractures are more frequent in elderly women.

Enhanced trabecular micro-architecture of the femoral neck in hip osteoarthritis vs. healthy controls: a micro-computer tomography study in postmenopausal women

PURPOSE

A controversial relationship between osteoarthritis (OA) and bone fragility has been attracting considerable attention. However, despite interest in the effects of OA on femoral neck fracture risk and numerous studies analysing the changes in the arthritic femoral head, there is insufficient data about femoral neck 3D bone micro-architecture in individuals with hip osteoarthritis. We compared trabecular micro-architecture of the femoral neck between postmenopausal women with coxarthrosis and controls to explore whether coxarthrosis may indicate reduced bone fragility from the trabecular micro-architectural perspective.

METHODS

The study sample included nine women with hip osteoarthritis and 13 age-matched controls. The femoral neck sections were scanned using micro-computed tomography, evaluating the cancellous bone from the superolateral and inferomedial neck subregions.

RESULTS

Osteoarthritic subjects demonstrated a general trend of improved trabecular micro-architecture in both analysed subregions when compared with age-matched controls. In particular, several architectural properties that are important predictors of cancellous bone strength showed significantly better values in the OA group, even after adjusting for bone volume fraction. Namely, the OA group expressed higher trabecular connectivity (p = 0.008), lower SMI indicating more plate-like structure (p = 0.005), and reduced anisotropy (p = 0.006) particularly in the inferomedial neck. Osteoarthritic cases also trended towards higher BV/TV, particularly in the superolateral neck. All micro-architectural parameters displayed significant regional heterogeneity (p ≤ 0.01), with the inferomedial neck region showing more favourable values than the superolateral region.

CONCLUSIONS

Enhanced trabecular micro-architecture of the femoral neck in postmenopausal osteoarthritic subjects suggests reduced cancellous bone fragility in comparison with their age-matched healthy controls.

Inter-sex differences in structural properties of aging femora: implications on differential bone fragility: a cadaver study

In this paper we examined age-related and sex-specific deterioration in bone strength of the proximal femur reflected in mechanical properties from dual energy X-ray absorptiometry (DXA)-based hip structural analysis (HSA) on a cadaveric sample from the Balkans. Cadaveric studies permit more precise measurement of HSA parameters and allow further analyses by micromorphometric methods. DXA and HSA analysis was performed on a total of 138 cadaveric proximal femora (63 female, 75 male, age range 20-101 years) from Belgrade. HSA parameters are reported for three standard regions of the proximal femur (narrow neck, intertrochanteric, and shaft). Major age-related findings include an increase in the radius of gyration (first reported in this study), a decline in the cross-sectional area (CSA), a shift in the centroid towards the medial cortex, higher buckling ratios and lower section moduli. Whereas age appears to affect mostly the neck region in men, weakening is also evident in the intertrochanteric region in women, particularly after the age of 80. Aging femoral neck declines in bending strength and increases in buckling susceptibility. The reduced bone mass tends to be distributed farther from the centroidal axis (increase in radius of gyration with decline in CSA). Bone mass is preferentially lost from the lateral part of the cross-section shifting the centroid towards the medial cortex which may increase fragility of the lateral part during fall impact. Results of this study contribute to the epidemiologic data on gender differences and age trends in aging male and female femora.

Skeletal age estimation based on medial clavicle--a test of the method reliability

In order to establish a reliable age indicator in the period when all other epiphyseal age indicators have already been inactivated, medial clavicle as the bone with the longest period of growth became the object of various investigations. However, the lack of population-specific method often made it unreliable in some regions. The current study involved a Balkan population and it was designed in order to examine whether morphological, radiological, and histological analyses of medial clavicles could be applied with success in age assessment of individuals beyond their twenties in anthropological and forensic practice. The medial clavicular specimens were collected from contemporary Serbian population, autopsied in the period from 1998 to 2001, encompassing 67 individuals (42 males and 25 females) with the age range from 20 to 90 years. The conducted analyses of morphological features identified the epiphyseal union timing, signs of lipping in the region of the notch for the first rib as well as exostoses and bone overgrowths of the articular surface margin as age-dependent attributes. Trabecular bone volume fraction and minimum trabecular width were also highlighted as age-distinctive microscopic features. Sex difference was ascertainable in epiphyseal union timing, morphology of the notch for the first rib, margin of the articular surface, and basic morphology of articular surface as well as in two microscopic characteristics: trabecular bone volume fraction and minimum trabecular width. The study managed to identify several age- and sex-related features that could be applied as additional guidance for age estimation in Serbian population.

Region-dependent patterns of trabecular bone growth in the human proximal femur: A study of 3D bone microarchitecture from early postnatal to late childhood period

OBJECTIVES

Parallel with body growth and development, bone structure in non-adults is reorganized to achieve the particular design observed in mature individuals. We traced the changes in three-dimensional trabecular microarchitectural design during the phases of locomotor maturation to clarify how human bone adapts to mechanical demands.

MATERIALS AND METHODS

Micro-CT was performed on biomechanically-relevant subregions of the proximal femur (medial, intermediate and lateral neck regions, intertrochanteric region, metaphyseal region) from early postnatal period to late childhood.

RESULTS

Developmental patterns of trabecular microarchitecture showed that gestationally overproduced bone present at birth underwent the most dramatic reduction during the first year, followed by a reversing trend in some of the quantitative parameters (e.g., bone volume fraction, trabecular anisotropy). Certain regional anisotropy already present at birth is further accentuated into the childhood suggesting an adaptation to differential loading environments. Trabecular eccentricity in the femoral neck was particularly accentuated during childhood, giving the medial neck-the site mostly loaded in walking-superior microarchitectural design (high bone volume fraction and anisotropy, the earliest appearance and predominance of plate- and honeycomb-shaped trabeculae).

DISCUSSION

While providing quantitative data on how bone microarchitecture adapts to increasing mechanical demands occurring during the phases of locomotor maturation, the study reveals how regional anisotropy develops in the proximal femur to ensure a functional and competent bone structure. Decomposing the region-specific patterns of bone mass accrual is important in understanding skeletal adaptations to bipedalism, as well for understanding why fractures often occur location-dependent, both in pediatric and elderly individuals.

Evidence of degraded BMD and geometry at the proximal femora in male patients with alcoholic liver cirrhosis

We examined the association of alcoholic cirrhosis in 33 patients with areal bone mineral density (BMD) and the assessed bone geometric strength of their proximal femora. Lower areal BMD, cross-sectional area and section modulus, thinner cortex, and higher buckling ratio suggest that the alcoholic liver cirrhosis is associated with lower measures of bone strength.

INTRODUCTION

Hepatic bone disease is an important complication of chronic liver disease and is associated with significant morbidity through fractures resulting in pain, deformity, and immobility. In this study, we examined the association of alcoholic cirrhosis and liver insufficiency stage with areal bone mineral density (aBMD) and additionally employed hip structure analysis (HSA) as an advanced method to assess bone geometric strength of the proximal femur in men with alcoholic liver cirrhosis.

METHODS

The study included 33 male patients with alcoholic liver cirrhosis and a control group of 36 healthy patients. Laboratory testing included the following biochemical markers of bone turnover: serum levels of osteocalcin and C-telopeptide of type 1 collagen. Areal BMD was measured by dual x-ray absorptiometry on the proximal femora. Structural parameters were then derived from these scans using hip structure analysis software.

RESULTS

After adjusting for age, body height, and weight, we found lower cross-sectional area (p = 0.005) and section modulus (p = 0.005), thinner cortex (p = 0.012), and higher buckling ratio (p = 0.043) in the neck region among patients with cirrhosis. The findings suggest that alcoholic liver cirrhosis is associated with lower measures of bone strength. These findings were consistent with decreased osteocalcin values and increased C-telopeptide of type 1 collagen in patients with cirrhosis, indicating reduction in bone formation and increased bone resorption.

CONCLUSION

Our results emphasize that HSA-derived structural indices of proximal femoral structure may be an important index of greater fragility in patients with alcoholic cirrhosis.

Rate of occurrence, gross appearance, and age relation of hyperostosis frontalis interna in females: a prospective autopsy study

The aim of our study was to determine rate of occurrence and appearance of hyperostosis frontalis interna (HFI) in females and correlation of this phenomenon with ageing. The sample included 248 deceased females: 45 of them with different types of HFI, and 203 without HFI, average age 68.3 +/- 15.4 years (range, 19-93), and 58.2 +/- 20.2 years (range, 10-101), respectively. According to our results, the rate of HFI was 18.14%. The older the woman was, the higher the possibility of HFI occurring (Pearson correlation 0.211, N=248, P=0.001), but the type of HFI did not correlate with age (Pearson correlation 0.229, N=45, P=0.131). Frontal and temporal bone were significantly thicker in women with than in women without HFI (t= -10.490, DF=246, P=0.000, and t= -5.658, DF=246, P=0.000, respectively). These bones became thicker with ageing (Pearson correlation 0.178, N=248, P=0.005, and 0.303, N=248, P=0.000, respectively). The best predictors of HFI occurrence were respectively, frontal bone thickness, temporal bone thickness, and age(Wald. coeff.=35.487, P=0.000; Wald. coeff.=3.288, P=0.070, and Wald.coeff. =2.727, P =0.099). Diagnosis of HFI depends not only on frontal bone thickness, but also on waviness of internal plate of the frontal bone, as well as-the involvement of the inner bone surface.

Systemic fat embolism and the patent foramen ovale--a prospective autopsy study

A fat embolism is a known and common complication of blunt force injuries, especially pelvic and long bones fractures. The aim of this study was to determine the importance of a patent foramen ovale (PFO) in developing systemic fat embolism (SFE) and eventually fat embolism syndrome (FES) in patients suffering from orthopaedic blunt injuries and consequent lung fat embolism. The sample was divided: 32 subjects with a sealed foramen ovale (SFO), and 20 subjects with a PFO. In our sample, there was no difference in either the incidence of renal fat embolism in subjects with PFO compared to those with SFO (Fisher's exact test 0.228, p=0.154) or in the grade of renal fat embolism (Pearson Chi-square 2.728, p=0.435). However, there was a statistically significant correlation between the grade of lung fat embolism and the number of fractured bones for the whole sample (Spearman's rho 0.271, p=0.052), but no correlation between the grade of lung fat embolism and the ISS or NISS (Pearson correlation 0.048, p=0.736, and 0.108, p=0.445, respectively). In our study, the presence of fat emboli in the kidney, i.e. SFE, could effectively be predicted by the grade of lung fat embolism (the moderate and slight grades of lung fat embolism were better predictors than the massive one: logistic regression - Wald. Coeff.=11.446, p=0.003, Wald. Coeff.=10.553, p=0.001, and Wald. Coeff.=4.128, p=0.042), and less effectively by presence of PFO (Wald. Coeff.=2.850, p=0.091). This study pointed out that lung and SFE are not pure biomechanical events, so the role of a PFO is not crucial in developing a lung fat embolism into a systemic embolism: the fat embolism is more of a biochemical and pathophsyiological event, than a biomechanical one. The appearance of a patent foramen ovale associated with a systemic fat embolism should be less emphasised: maybe arteriovenous shunts and anastomosis between the functional and nutritive, i.e. systemic circulation of lungs play a more important role in developing a SFE than a PFO.

Mechano-structural alteration in proximal femora of individuals with alcoholic liver disease: Implications for increased bone fragility

Although increased hip fracture risk is noted in patients with alcoholic liver disease (ALD), their femoral microstructural and mechanical properties were not investigated previously. The present study aimed to analyze the associations between subregional deteriorations in femoral mechano-structural properties and clinical imaging findings to explain increased femoral fracture risk among ALD patients. This study analyzed proximal femora of 33 male cadaveric donors, divided into ALD (n = 13, 57 ± 13 years) and age-matched control group (n = 20, 54 ± 13 years). After pathohistological verification of ALD stage, DXA and HSA measurements of the proximal femora were performed, followed by micro-CT and Vickers microindentation of the superolateral neck, inferomedial neck, and intertrochanteric region. Bone mineral density and cross sectional area of the femoral neck were deteriorated in ALD donors, compared with healthy controls (p < 0.05). Significant ALD-induced degradation of trabecular and cortical microstructure and Vickers microhardness reduction were noted in the analyzed femoral regions (p < 0.05). Still, the most prominent ALD-induced mechano-structural deterioration was noted in intertrochanteric region. Additionally, more severe bone alterations were observed in individuals with an irreversible stage of ALD, alcoholic liver cirrhosis (ALC), than in those with an initial ALD stage, fatty liver disease. Observed osteodensitometric and mechano-structural changes illuminate the basis for increased femoral fracture risk in ALD patients. Additionally, our data suggest bone strength reduction that may result in increased susceptibility to intertrochanteric femoral fracture in men with ALD. Thus, femoral fracture risk assessment should be advised for all ALD patients, especially in those with ALC.

Skeletal manifestations of hydatid disease in Serbia: demographic distribution, site involvement, radiological findings, and complications

Although Serbia is recognized as an endemic country for echinococcosis, no information about precise incidence in humans has been available. The aim of this study was to investigate the skeletal manifestations of hydatid disease in Serbia. This retrospective study was conducted by reviewing the medical database of Institute for Pathology (Faculty of Medicine in Belgrade), a reference institution for bone pathology in Serbia. We reported a total of 41 patients with bone cystic echinococcosis (CE) during the study period. The mean age of 41 patients was 40.9±18.8 years. In 39% of patients, the fracture line was the only visible radiological sign, followed by cyst and tumefaction. The spine was the most commonly involved skeletal site (55.8%), followed by the femur (18.6%), pelvis (13.9%), humerus (7.0%), rib (2.3%), and tibia (2.3%). Pain was the symptom in 41.5% of patients, while some patients demonstrated complications such as paraplegia (22.0%), pathologic fracture (48.8%), and scoliosis (9.8%). The pathological fracture most frequently affected the spine (75.0%) followed by the femur (20.0%) and tibia (5.0%). However, 19.5% of patients didn't develop any complication or symptom. In this study, we showed that bone CE is not uncommon in Serbian population. As reported in the literature, therapy of bone CE is controversial and its results are poor. In order to improve the therapy outcome, early diagnosis, before symptoms and complications occur, can be contributive.

Bone loss in chronic liver diseases: Could healthy liver be a requirement for good bone health?

Given that the liver is involved in many metabolic mechanisms, it is not surprising that chronic liver disease (CLD) could have numerous complications. Secondary osteoporosis and increased bone fragility are frequently overlooked complications in CLD patients. Previous studies implied that up to one-third of these individuals meet diagnostic criteria for osteopenia or osteoporosis. Recent publications indicated that CLD-induced bone fragility depends on the etiology, duration, and stage of liver disease. Therefore, the increased fracture risk in CLD patients puts a severe socioeconomic burden on the health system and urgently requires more effective prevention, diagnosis, and treatment measures. The pathogenesis of CLD-induced bone loss is multifactorial and still insufficiently understood, especially considering the relative impact of increased bone resorption and reduced bone formation in these individuals. It is essential to note that inconsistent findings regarding bone mineral density measurement were previously reported in these individuals. Bone mineral density is widely used as the "golden standard" in the clinical assessment of bone fragility although it is not adequate to predict individual fracture risk. Therefore, microscale bone alterations (bone microstructure, mechanical properties, and cellular indices) were analyzed in CLD individuals. These studies further support the thesis that bone strength could be compromised in CLD individuals, implying that an individualized approach to fracture risk assessment and subsequent therapy is necessary for CLD patients. However, more well-designed studies are required to solve the bone fragility puzzle in CLD patients.

Inter-site variability of the osteocyte lacunar network in the cortical bone underpins fracture susceptibility of the superolateral femoral neck

BACKGROUND

The osteocytic lacunar network is considered to be an integral player in the regulation of bone homeostasis, and reduction in osteocytes is associated with reduced bone strength. Here, we analyzed site-specific patterns in osteocyte characteristics and matrix composition in the cortical compartment of the femoral neck to reveal the structural basis of its fragility.

METHODS

Cross-sections of the human femoral neck - one of the most common fracture sites - were acquired from 12 female cadavers (age 34-86 years) and analyzed with backscattered scanning electron microscopy and high-resolution micro-computed tomography (μ-CT). The 2D/3D density and size of the osteocyte lacunae as well as bone mineral density distribution (BMDD) were measured in two regions subject to different biomechanical loads in vivo: the inferomedial (medial) region (habitually highly loaded in compression) and the superolateral (lateral) region (lower habitual loading intensity). Using quantitative polarized light microscopy, collagen fiber orientation was quantified in these two regions, accordingly.

RESULTS

In 2D measurements, the inferomedial region displayed lower mineralization heterogeneity, 19% higher osteocyte lacunar density (p = 0.005), but equal lacunar size compared to the superolateral region. 3D measurements confirmed a significantly higher osteocyte lacunar density in the inferomedial region (p = 0.015). Osteocyte lacunar density decreased in aged individuals, and inter-site differences were reduced. Site-specific osteocyte characteristics were not accompanied by changes in collagen fiber orientation.

CONCLUSIONS

Since osteocyte characteristics may provide valuable insights into bone mechanical competence, the variations in osteocyte properties might reflect the increased fracture susceptibility of the superolateral neck.

Moderate hyperhomocysteinemia induced by short-term dietary methionine overload alters bone microarchitecture and collagen features during growth

AIMS

In general, hyperhomocysteinemia is increasingly appreciated as a risk factor for various diseases, including osteoporosis. However, its effects in non-adults remain largely unknown. Our aim was to determine whether dietary-caused increased homocysteine levels have deleterious effects on bone structure during growth.

MAIN METHODS

We developed a model of moderate hyperhomocysteinemia caused by short-term methionine nutritional overload in growing rats. 30-days-old male Wistar albino rats were randomly assigned to either experimental group subject to a 30-days hypermethionine diet or control group. High-resolution 3D assessment of bone geometry and microarchitecture, as well as fluorescence spectroscopic analysis of bone matrix were performed.

KEY FINDINGS

Short-term moderate hyperhomocysteinemia (~30μmol/L) achieved in the study notably affected bone and cartilage characteristics. Parameters of the cortical bone geometry in the experimental group indicated peculiar reorganization of the bone cross-section. Trabecular bone microarchitecture was especially sensitive to hyperhomocysteinemia showing clearly negative bone balance in the experimental group (almost 30% reduced bone volume, mainly due to ~25% decrease in trabecular number as well as markedly reduced trabecular connections). Fluorescent spectroscopy of bone matrix revealed multiple alterations to collagen spectra due to homocysteine accumulation in bone, indicative of broken collagenous cross-links.

SIGNIFICANCE

Given that appropriate accrual of bone mass during growth has important effects on the risk of osteoporosis in adulthood, understanding the skeletal effects of dietary-induced hyperhomocysteinemia in non-adults is essential for interpreting its importance as a modifiable risk factor for osteoporosis and improving programs to preserve/re-establish bone health.