Normal changes in spinal bone mineral density in a Chinese population: assessment by quantitative computed tomography and dual-energy X-ray absorptiometry

Developing Cut-off Values for Low and Very Low Bone Mineral Density at the Thoracic Spine Using Quantitative Computed Tomography

Osteoporosis is under-diagnosed while detectable by measuring bone mineral density (BMD) using quantitative computer tomography (QCT). Opportunistic screening for low BMD has previously been suggested using lumbar QCT. However, thoracic QCT also possesses this potential to develop upper and lower cut-off values for low thoracic BMD, corresponding to the current cut-offs for lumbar BMD. In participants referred with chest pain, lumbar and thoracic BMD were measured using non-contrast lumbar- and cardiac CT scans. Lumbar BMD cut-off values for very low (< 80 mg/cm3), low (80-120 mg/cm3), and normal BMD (> 120 mg/cm3) were used to assess the corresponding thoracic values. A linear regression enabled identification of new diagnostic thoracic BMD cut-off values. The 177 participants (mean age 61 [range 31-74] years, 51% women) had a lumbar BMD of 121.6 mg/cm3 (95% CI 115.9-127.3) and a thoracic BMD of 137.0 mg/cm3 (95% CI: 131.5-142.5), p < 0.001. Categorization of lumbar BMD revealed 14%, 35%, and 45% in each BMD category. When applied for the thoracic BMD measurements, 25% of participants were reclassified into a lower group. Linear regression predicted a relationship of Thoracic BMD = 0.85 * Lumbar BMD + 33.5, yielding adjusted thoracic cut-off values of < 102 and > 136 mg/cm3. Significant differences in BMD between lumbar and thoracic regions were found, but a linear relationship enabled the development of thoracic upper and lower cut-off values for low BMD in the thoracic spine. As Thoracic CT scans are frequent, these findings will strengthen the utilization of CT images for opportunistic detection of osteoporosis.

Quantitative CT lumbar spine BMD cutpoint value for classifying osteoporosis among older East Asian women should be lower than the value for Caucasians

For Caucasian women, the QCT (quantitative CT) lumbar spine (LS) bone mineral density (BMD) cutpoint value for classifying osteoporosis is 80 mg/ml. At the age of approximate 78 years, US Caucasian women QCT LS BMD population mean is 80 mg/ml, while that of Chinese women and Japanese women is around 50 mg/ml. Correlation analyses show, for Chinese women and Japanese women, QCT LS BMD of 45 mg/ml corresponds to the dual-energy X-ray absorptiometry cutpoint value for classifying osteoporosis. For Chinese and Japanese women, if QCT LS BMD 80 mg/ml is used as the threshold to classify osteoporosis, then the specificity of classifying subjects with vertebral fragility fracture into the osteoporotic group is low, whereas threshold of 45 mg/ml approximately achieve a similar separation for women with and without vertebral fragility fracture as the reports for Caucasian women. Moreover, by using 80mg/ml as the cutpoint value, LS QCT leads to excessively high prevalence of osteoporosis for Chinese women, with the discordance between hip dual-energy X-ray absorptiometry and LS QCT measures far exceeding expectation. Considering the different bone properties and the much lower prevalence of fragility fractures in the East Asian women compared with Caucasians, we argue that the QCT cutpoint value for classifying osteoporosis among older East Asian women will be close to and no more than 50 mg/ml LS BMD. We suggest that it is also imperative the QCT osteoporosis classification criterion for East Asian male LS, and male and female hips be re-examined.

Bone density of the cervical, thoracic and lumbar spine measured using Hounsfield units of computed tomography - results of 4350 vertebras

INTRODUCTION

The assessment of bone density has gained significance in recent years due to the aging population. Accurate assessment of bone density is crucial when deciding on the appropriate treatment plan for spinal stabilization surgery. The objective of this work was to determine the trabecular bone density values of the subaxial cervical, thoracic and lumbar spine using Hounsfield units.

MATERIAL AND METHODS

Data from 200 patients who underwent contrast-enhanced polytrauma computed tomography at a maximum care hospital over a two-year period were retrospectively analyzed. HUs were measured with an elliptical measurement field in three different locations within the vertebral body: below the upper plate, in the middle of the vertebral body, and above the base plate. The measured Hounsfield units were converted into bone density values using a validated formula.

RESULTS

The mean age of the patient collective was 47.05 years. Mean spinal bone density values decreased from cranial to caudal (C3: 231.79 mg/cm3; L5: 155.13 mg/cm3; p < 0.001), with the highest values in the upper cervical spine. Bone density values generally decreased with age in all spinal segments. There was a clear decrease in values after age 50 years (p < 0.001).

CONCLUSIONS

In our study, bone density decreased from cranial to caudal with higher values in the cervical spine. These data from the individual spinal segments may be helpful to comprehensively evaluate the status of the spine and to design a better preoperative plan before instrumentation.

Bone density of the axis (C2) measured using Hounsfield units of computed tomography

INTRODUCTION

The assessment of bone density is of great importance nowadays due to the increasing age of patients. Especially in regard to the surgical stabilization of the spine, the assessment of bone density is important for therapeutic decision making. The aim of this work was to record trabecular bone density values using Hounsfield units of the second cervical vertebra.

MATERIAL AND METHODS

The study is a monocentric retrospective data analysis of 198 patients who received contrast-enhanced polytrauma computed tomography in a period of two years at a maximum care hospital. Hounsfield units were measured in three different regions within the C2: dens, transition area between dens and vertebral body and vertebral body. The measured Hounsfield units were converted into bone density values using a validated formula.

RESULTS

A total of 198 patients were included. The median bone density varied in different regions of all measured C2 vertebrae: in the dens axis, C2 transition area between dens and vertebral body, and in the vertebral body bone densities were 302.79 mg/cm³, 160.08 mg/cm³, and 240.31 mg/cm³, respectively. The transition area from dens axis to corpus had statistically significant lower bone density values compared to the other regions (p < 0.001). There was a decrease in bone density values after age 50 years in both men and women (p < 0.001).

CONCLUSIONS

The transitional area from dens axis to corpus showed statistically significant lower bone density values compared to the adjacent regions (p < 0.001). This area seems to be a predilection site for fractures of the 2nd cervical vertebra, which is why special attention should be paid here in radiological diagnostics after a trauma.

Age-related changes in cationic compositions of human cranial base bone apatite measured by X-ray energy dispersive spectroscopy (EDS) coupled with scanning electron microscope (SEM)

One of the most common scientific methods to study the chemical composition of bone matter is energy-dispersive X-ray spectroscopy (EDS). However, interpretation of the data obtained can be quite complicated and require a thorough understanding of bone structure. This is especially important when evaluating subtle changes of chemical composition, including the age-related ones. The aim of current study is to create a method of processing the obtained data that can be utilized in clinical medicine and use it to evaluate the age evolution of bone chemical composition. To achieve this goal, an elemental composition of 62 samples of cadaver compact bone, taken from the skull base (age: Me = 57.5; 21/91(min/max); Q1 = 39.5, Q3 = 73.75), was studied with EDS. We used the original method to estimate the amount of Mg²⁺ cations. We detected and confirmed an increase of Mg²⁺ cation formula amount in the bone apatite, which characterizes age-related resorption rate. Analysis of cation estimated ratio in a normative bone hydroxylapatite showed an increase of Mg²⁺ amount (R = 0.43, p = 0.0005). Also, Ca weight fraction was shown to decrease with age (R = - 0.43, p = 0.0005), which in turn confirmed the age-dependent bone decalcification. In addition, electron probe microanalysis (EPMA) and X-ray diffraction analysis (XRD) were performed. EDS data confirmed the EPMA results (R = 0.76, p = 0.001). In conclusion, the proposed method can be used in forensic medicine and provide additional data to the known trends of decalcification and change of density and crystallinity of mineral bone matter.

Population-Stratified Analysis of Bone Mineral Density Distribution in Cervical and Lumbar Vertebrae of Chinese from Quantitative Computed Tomography

Objective

To investigate the bone mineral density (BMD) of cervical vertebrae in a population-stratified manner and correlate with that of the lumbar vertebrae.

Materials and Methods

Five hundred and ninety-eight healthy volunteers (254 males, 344 females), ranging from 20 to 64 years of age, were recruited for volumetric BMD (vBMD) measurements by quantitative computed tomography. Basic information (age, height, weight, waistline, and hipline), and vBMD of the cervical and lumbar vertebrae (C2–7 and L2–4) were recorded. Comparisons among sex, age groups and different levels of vertebrae were analyzed using analysis of variance. Linear regression was performed for relevance of different vertebral levels.

Results

The vBMD of cervical and lumbar vertebrae was higher in females than males in each age group. The vBMD of the cervical and lumbar vertebrae in males and the vBMD of lumbar vertebrae in females decreased with aging. In each age group, the vBMD of the cervical vertebrae was higher than that of the lumbar vertebrae with gradual decreases from C2 to C7 except for C3; moreover, the vBMD of C6 and C7 was significantly different from that of C2–5. Correlations of vBMD among different cervical vertebrae (females: r = 0.62–0.94; males: r = 0.63–0.94) and lumbar vertebrae (males: r = 0.93–0.98; females: r = 0.82–0.97) were statistically significant at each age group.

Conclusion

The present study provided normative data of cervical vertebrae in an age- and sex-stratified manner. Sex differences in vBMD prominently vary with age, which can be helpful to design a more comprehensive pre-operative surgical plan.

Racial Differences in Bone Microarchitecture and Estimated Strength at the Distal Radius and Distal Tibia in Older Adolescent Girls: a Cross-Sectional Study

BACKGROUND

Previous studies have demonstrated that an individual's race and ethnicity are important determinants of their areal bone mineral density (aBMD), assessed by dual-energy X-ray absorptiometry. However, there are few data assessing the impact of race on bone microarchitecture and strength estimates, particularly in older adolescent girls and young adults. We hypothesized that bone microarchitecture and strength estimates would be superior in Blacks compared to White and Asian American adolescent girls and young adults of similar age based on reports of higher aBMD in Blacks.

METHODS

We assessed BMD using dual-energy X-ray absoptiometry (DXA), bone microarchitecture at the distal radius and distal tibia using high-resolution peripheral quantitative computed tomography (HRpQCT) and estimated measures of bone strength using micro-finite element analysis (FEA) in 35 White, 15 Asian American, and 10 Black girls 14-21 years.

RESULTS

After controlling for height, most DXA measures of aBMD and aBMD Z scores were higher in Black girls compared with Whites and Asian Americans. HRpQCT and FEA showed that at the distal radius, Blacks had greater cortical perimeter, cortical area, trabecular thickness, trabecular BMD, estimated failure load, and stiffness than the other two groups. For the distal tibia, trabecular number and BMD were higher in Blacks than Asian Americans.

CONCLUSIONS

Particularly at the distal radius, adolescent and young adult White and Asian American girls have less favorable bone microarchitecture and lower bone strength than Blacks, possibly explaining the lower risk of fracture seen in Blacks.

LEVEL OF EVIDENCE

Level II.

Age-related differences in volumetric bone mineral density, microarchitecture, and bone strength of distal radius and tibia in Chinese women: a high-resolution pQCT reference database study

In a cohort of 393 Chinese women, by using high-resolution peripheral quantitative computed tomography (HR-pQCT), we found that significant cortical bone loss occurred after midlife. Prominent increase in cortical porosity began at the fifth decade but reached a plateau before the sixth decade. Trabecular bone loss was already evident in young adulthood and continued throughout life.

INTRODUCTION

This study aimed to investigate age-related differences in volumetric bone mineral density (vBMD), microarchitecture, and estimated bone strength at peripheral skeleton in Chinese female population.

METHODS

In a cross-sectional cohort of 393 Chinese women aged 20-90 years, we obtained vBMD, microarchtecture, and micro-finite element-derived bone strength at distal radius and tibia using HR-pQCT.

RESULTS

The largest predictive age-related difference was found for cortical porosity (Ct.Po) which showed over four-fold and two-fold differences at distal radius and tibia, respectively, over the adulthood. At both sites, cortical bone area, vBMD, and thickness showed significant quadratic association with age with significant decrease beginning after midlife. Change of Ct.Po became more prominent between age of 50 and 57 (0.26 %/year at distal radius, 0.54 %/year at distal tibia, both p ≤ 0.001) but thereafter, reached a plateau (0.015 and 0.028 %/year, both p > 0.05). In contrast, trabecular vBMD and microarchitecture showed linear association with age with significant deterioration observed throughout adulthood. Estimated age of peak was around age of 20 for trabecular vBMD and microarchitecture and Ct.Po and age of 40 for cortical vBMD and microarchitecture. Estimated stiffness and failure load peaked at mid-30s at the distal radius and at age 20 at distal tibia.

CONCLUSIONS

Age-related differences in vBMD and microarchitecture in Chinese women differed by bone compartments. Significant cortical bone loss occurred after midlife. Prominent increase in Ct.Po began at the fifth decade but appeared to be arrested before the sixth decade. Loss of trabecular bone was already evident in young adulthood and continued throughout life.

Age-related changes in osteometry, bone mineral density and osteophytosis of the lumbar vertebrae in Japanese macaques

The age-related changes in lumbar vertebrae were studied in 77 young/full adult Japanese macaques (Macaca fuscata) (40 females, 37 males), in terms of their morphometry, density and osteophytosis, and the interrelationship between these three aspects. The most common age-related pattern of morphometric changes was an initial increase during young adulthood until reaching the peak and then a subsequent decrease with age. Most of the peaks were in the age group 15-20 and 10-15 years in females and males, respectively. In both sexes, the age-related decrease in the vertebral body depth (ventro-dorsal) was greater than in the height and width. The ventral height of the vertebral body relative to the dorsal height continuously decreased with age. The trabecular bone mineral density (BMD) continuously decreased after young adulthood. However, the magnitude of the decreased trabecular BMD with age was greater in females than in males, especially in the older age groups. Osteophytosis clearly increased with age in both sexes, but males showed an earlier appearance of osteophytes and females tended to have more severe osteophytes from 15 years old upwards. A correlation between the osteometry, density, and osteophytosis severity appeared in all vertebrae, but not all of these reached statistical significance after controlling for the influence of age. Although Japanese macaques showed the higher prevalence and rapid increase of osteophytosis, a similar age change profile was observed in the lumbar vertebrae of Japanese macaques and humans.

Prevalence of osteoporosis in the Korean population based on Korea National Health and Nutrition Examination Survey (KNHANES), 2008-2011

PURPOSE

We analyzed age-related changes of bone mineral density (BMD) and compared with those of U.S and Japanese participants to investigate the prevalence of osteoporosis in Korea.

MATERIALS AND METHODS

The data were collected in the 2008-2011 in Korea National Health and Nutrition Examination Survey (KNHANES) IV and V to select a representative sample of civilian, noninstitutionalized South Korean population. Bone mineral measurements were obtained from 8332 men and 9766 women aged 10 years and older.

RESULTS

BMD in men continued to decline from 3rd decade, however, in women, BMD remained nearly constant until the 4th decade and declined at rapid rate from the 5th decade. The prevalence of osteoporosis in Korea is 7.3% in males and 38.0% in females aged 50 years and older. The prevalence of osteopenia in Korea is 46.5% in males and 48.7% in females, aged 50 years and older. The lumbar spine and femur BMD in Korean females 20 to 49 years of ages was lower than in U.S. and Japan participants.

CONCLUSION

There was obvious gender, and age differences in the BMD based on the 2008-2011 KNHANES IV and V, a nationwide, cross-sectional survey conducted in a South Korean population. We expect to be able to estimate reference data through ongoing KNHANES efforts in near future.

Establishment of age-specified bone mineral density reference range for Indian females using dual-energy X-ray absorptiometry

We undertook this study to establish age-specified bone mineral density (BMD) reference range for Indian females using dual-energy X-ray absorptiometry. BMD at multiple skeletal sites was measured in 2034 healthy women aged 18--85yr. The effect of anthropometry and biochemical parameters on BMD was determined. Peak BMD was observed between 30 and 35yr at the hip, lumbar spine, and radius. Significant positive correlation of height and weight with BMD was observed at 33% radius, femur neck, and lumbar spine, whereas significant negative correlation was seen between serum alkaline phosphatase (ALP) and serum parathyroid hormone levels with BMD at aforementioned sites. On multivariate regression analysis, age, weight, and serum ALP were the most consistent contributors to variance in the BMD. Compared with age-matched US females, BMD of lumbar spine was significantly lower for our subjects in all age groups. Prevalence of osteoporosis among women aged older than 50yr was significantly higher based on Caucasian T-scores as opposed to using peak BMD/standard deviation values from the population under review at lumbar spine but not at femoral neck.

Epidemiology and structural basis of racial differences in fragility fractures in Chinese and Caucasians

Chinese have similar vertebral fracture prevalence but lower incidence of hip and distal forearm fractures than in Caucasians. The underlying structural and biomechanical basis of racial differences in bone fragility is still largely undefined but Chinese assemble their smaller appendicular skeleton with thicker cortices and trabeculae compared with Caucasians. Vertebral fracture prevalence is similar by race, but the incidence of hip and distal forearm fractures is lower in Chinese than in Caucasians. This racial dimorphism cannot be explained by differences in areal bone mineral density (aBMD) as aBMD is lower in Chinese mainly due to their smaller size. The underlying structural and biomechanical basis of racial differences in bone fragility is still largely undefined but Chinese assemble their smaller appendicular skeleton with more mineralised bone matrix within it; the cortices are thicker and perhaps less porous while trabeculae are fewer but thicker and more connected. This configuration produces a bone with a lower surface/volume ratio, which in turn reduces the surface available for remodelling to occur upon so that the lower surface/volume ratio may make the bone less exposed to remodelling and the thicker cortices and trabeculae less vulnerable to remodelling when it does occur during advancing age. However, prospective studies are needed to define racial differences at the age of onset, rate of bone loss from the intracortical, endocortical and trabecular components of the endosteal envelope and bone formation upon the periosteal envelope; notions of bone 'loss' are derived mainly from cross-sectional studies. Studies of the site- and surface-specific changes in bone modelling and remodelling are needed to better define racial differences in bone fragility in old age.

Integrated imaging approach to osteoporosis: state-of-the-art review and update

Osteoporosis is the most common of all metabolic bone disorders. It is characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fractures. Because of the increasing aging of the world population, the number of persons affected by osteoporosis is also increasing. Complications related to osteoporosis can create social and economic burdens. For these reasons, the early diagnosis of osteoporosis is crucial. Conventional radiography allows qualitative and semiquantitative evaluation of osteoporosis, whereas other imaging techniques allow quantification of bone loss (eg, dual-energy x-ray absorptiometry and quantitative computed tomography [CT]), assessment for the presence of fractures (morphometry), and the study of bone properties (ultrasonography). In recent years, new imaging modalities such as micro-CT and high-resolution magnetic resonance imaging have been developed in an attempt to help diagnose osteoporosis in its early stages, thereby reducing social and economic costs and preventing patient suffering. The correct diagnosis of osteoporosis results in better management in terms of prevention and adequate pharmacologic or surgical treatment.

Trabecular bone deficits among Vietnamese immigrants

SUMMARY

Compared to white women, lower areal bone mineral density (aBMD) in middle-aged Vietnamese immigrants is due to reduced trabecular volumetric bone mineral density (vBMD), which in turn is associated with greater trabecular separation along with lower estrogen levels.

INTRODUCTION

The epidemiology of osteoporosis in Asian populations is still poorly known, but we previously found a deficit in lumbar spine aBMD among postmenopausal Southeast Asian women, compared to white women, that persisted after correction for bone size. This issue was revisited using more sophisticated imaging techniques.

METHODS

Twenty Vietnamese immigrants (age, 44-79 years) were compared to 162 same-aged white women with respect to aBMD at the hip, spine and wrist, vBMD at the hip and spine by quantitative computed tomography and vBMD and bone microstructure at the ultradistal radius by high-resolution pQCT. Bone turnover and sex steroid levels were assessed in a subset (20 Vietnamese and 40 white women).

RESULTS

The aBMD was lower at all sites among the Vietnamese women, but femoral neck vBMD did not differ from middle-aged white women. Significant differences in lumbar spine and ultradistal radius vBMD in the Vietnamese immigrants were due to lower trabecular vBMD, which was associated with increased trabecular separation. Bone resorption was elevated and bone formation depressed among the Vietnamese immigrants, although trends were not statistically significant. Serum estradiol was positively associated with trabecular vBMD in the Vietnamese women, but their estrogen levels were dramatically lower compared to white women.

CONCLUSIONS

Although reported discrepancies in aBMD among Asian women are mainly an artifact of smaller bone size, we identified a specific deficit in the trabecular bone among a sample of Vietnamese immigrants that may be related to low estrogen levels and which needs further study.

The differences of femoral neck geometric parameters: effects of age, gender and race

This study aims at investigating the effects of age, sex, and ethnicity on five femoral neck geometric parameters (FNGPs): femoral neck periosteal diameter, cross-sectional area, cortical thickness, sectional modulus, and buckling ratio and found that the three factors would influence the FNGPs.

INTRODUCTION

Bone geometry is one of the most important predictors of bone strength and osteoporotic fractures. This study aims at investigating the effects of age, sex, and ethnicity on five femoral neck geometric parameters (FNGPs): femoral neck periosteal diameter (W), cross-sectional area (CSA), cortical thickness (CT), sectional modulus (Z), and buckling ratio (BR).

METHODS

In the studied 861 Caucasian subjects and 3,021 Chinese individuals, CSA, CT, and Z displayed trends of decrease with age, but W and BR showed increasing trends with age in both Chinese and Caucasian females and males (p < 0.05). W, CSA, CT, and Z were significantly higher (p <or= 0.001) in Caucasians than in Chinese and higher in males than in females except for BR between Chinese males and Chinese females.

CONCLUSION

In conclusion, the differences of FNGPs according to gender and ethnicity provide important implications in the different prevalence of osteoporotic fracture among different gender and ethnic groups.

Imaging of metabolic bone diseases

Osteoporosis is a serious public health problem. The incidence of osteoporotic fractures increases with age. As life expectancy increases, social costs associated with osteoporotic fractures will multiply exponentially. The early diagnosis of osteoporosis, thanks to evermore precise devices, becomes, therefore, fundamental to prevent complications of disease and unnecessary suffering.

Quantitative imaging of musculoskeletal tissue

Quantitative imaging of musculoskeletal tissue, including radiography, computed tomography (CT), and magnetic resonance imaging (MRI), has become the essential methodology in clinical practice for diagnosis and monitoring of various musculoskeletal conditions. Furthermore, quantitative imaging technologies have become indispensable for research and development in diseases of the human skeleton. Standardized methods of image analysis have been developed through the years to quantify measurements on bone and cartilage with high precision and accuracy. Key areas of musculoskeletal disease where quantitative imaging is currently employed are osteoporosis and arthritis.

Bone mineral density changes during the menopause transition in a multiethnic cohort of women

CONTEXT

Rates of bone loss across the menopause transition and factors associated with variation in menopausal bone loss are poorly understood.

OBJECTIVE

Our objective was to assess rates of bone loss at each stage of the transition and examine major factors that modify those rates.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a longitudinal cohort study of 1902 African-American, Caucasian, Chinese, or Japanese women participating in The Study of Women's Health Across the Nation. Women were pre- or early perimenopausal at baseline.

OUTCOME MEASURE

We assessed bone mineral density (BMD) of the lumbar spine and total hip across a maximum of six annual visits.

RESULTS

There was little change in BMD during the pre- or early perimenopause. BMD declined substantially in the late perimenopause, with an average loss of 0.018 and 0.010 g/cm2.yr from the spine and hip, respectively (P<0.001 for both). In the postmenopause, rates of loss from the spine and hip were 0.022 and 0.013 g/cm2.yr, respectively (P<0.001 for both). During the late peri- and postmenopause, bone loss was approximately 35-55% slower in women in the top vs. the bottom tertile of body weight. Apparent ethnic differences in rates of spine bone loss were largely explained by differences in body weight.

CONCLUSIONS

Bone loss accelerates substantially in the late perimenopause and continues at a similar pace in the first postmenopausal years. Body weight is a major determinant of the rate of menopausal BMD loss, whereas ethnicity, per se, is not. Healthcare providers should consider this information when deciding when to screen women for osteoporosis.

Age-related changes in trabecular architecture differ in female and male C57BL/6J mice

We used microCT and histomorphometry to assess age-related changes in bone architecture in male and female C57BL/6J mice. Deterioration in vertebral and femoral trabecular microarchitecture begins early, continues throughout life, is more pronounced at the femoral metaphysis than in the vertebrae, and is greater in females than males.

INTRODUCTION

Despite widespread use of mice in the study of musculoskeletal disease, the age-related changes in murine bone structure and the relationship to whole body BMD changes are not well characterized. Thus, we assessed age-related changes in body composition, whole body BMD, and trabecular and cortical microarchitecture at axial and appendicular sites in mice.

MATERIALS AND METHODS

Peripheral DXA was used to assess body composition and whole body BMD in vivo, and microCT and histomorphometry were used to measure trabecular and cortical architecture in excised femora, tibia, and vertebrae in male and female C57BL/6J mice at eight time-points between 1 and 20 mo of age (n = 6-9/group).

RESULTS

Body weight and total body BMD increased with age in male and female, with a marked increase in body fat between 6 and 12 mo of age. In contrast, trabecular bone volume (BV/TV) was greatest at 6-8 wk of age and declined steadily thereafter, particularly in the metaphyseal region of long bones. Age-related declines in BV/TV were greater in female than male. Trabecular bone loss was characterized by a rapid decrease in trabecular number between 2 and 6 mo of age, and a more gradual decline thereafter, whereas trabecular thickness increased slowly over life. Cortical thickness increased markedly from 1 to 3 mo of age and was maintained or slightly decreased thereafter.

CONCLUSIONS

In C57BL/6J mice, despite increasing body weight and total body BMD, age-related declines in vertebral and distal femoral trabecular bone volume occur early and continue throughout life and are more pronounced in females than males. Awareness of these age-related changed in bone morphology are critical for interpreting the skeletal response to pharmacologic interventions or genetic manipulation in mice.

Establishment of peak bone mineral density in Southern Chinese males and its comparisons with other males from different regions of China

Peak bone mineral density (PBMD) is an important determinant of osteoporotic fracture and a precondition for correct diagnosis of osteoporosis. The objective of this study was to establish the reference data of PBMD at the lumber spine and hip in Southern Chinese males. Bone mineral density (BMD) was measured at the lumbar spine and hip (femoral neck, trochanter, intertrochanter, and total) in 1155 Chinese men aged 15-39 years, using dual-energy X-ray absorptiometry (DXA). We utilized a fit curve method to determine the best age range over which to calculate PBMD. Our results indicated that the PBMD was observed at the age range of 18-25 years at the various sites. The mean value and standard deviation of PBMD was 0.753 +/- 0.117, 1.156 +/- 0.148, 0.896 +/- 0.120, 0.989 +/- 0.122, and 0.980 +/- 0.116 g/cm2 at the trochanter, intertrochanter, femoral neck, total hip, and spine, respectively. When the present PBMD reference was compared with the documented PBMD reference of males from other regions of China, we found great difference in standardized PBMD between Changsha males and those from other regions of China. The PBMD for Chinese males in Changsha at the various sites were 3.19%-11.33% lower than that for American Caucasian males. In conclusion, the PBMD at the spine and hip may be used as normal reference data for Southern Chinese males in Changsha instead of documented PBMD from other regions of China and the manufacturer's reference data.

Office practice of osteoporosis evaluation

Osteoporosis is a metabolic disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk. Bone fragility depends on bone density, turnover and microarchitectural features, such as relative trabecular volume, spacing, number and connectivity. Previous fragility fractures increase the fracture risk irrespective of bone density. Other risk factors must also be considered as many fractures occur in patients with osteopenia on densitometry. On the other hand, the diagnosis of osteoporosis and increased fracture risk should not be based on densitometric data alone when young populations such as men below 65 years, premenopausal women, adolescents and children are considered.

Quantitative computed tomography BMD reference values in women of Izmir, Turkey

In quantitative computed tomography applications for the diagnosis of osteoporosis, the bone mineral density value obtained has to be compared with a reference data. This data is influenced by several factors including sex, age, and ethnicity. Therefore, reference data that accurately represent the population at large is essential. We established age-based quantitative computed tomography bone mineral density reference values for healthy women residing in Izmir, Turkey. We recruited 396 healthy women from 20 to 83 years old (mean age, 51.08 years). Quantitative computed tomography bone mineral density measurements were performed using the GE 9800 Highlight Advantage scanner at the L1, L2, and L3 lumbar vertebrae. The mean bone mineral density (mg/cm) +/- standard deviation of the normal reference group of women from 20 to 39 years old was 168.86 mmg/cm3 +/- 21.59. The threshold bone mineral density value for osteoporosis at a T score < -2.5 was 114.83 mg/cm3. The slope, intercept, and r values at bone mineral density versus age linear regression test were -2.44, 251.1, and 0.70, respectively. The percentage of annual bone mineral density loss was 1.6%. The bone mineral density values of Turkish women were not distinct from most countries' reference values.

LEVEL OF EVIDENCE

Diagnostic study, Level II (Development of diagnostic criteria on consecutive patients [with universally applied reference "gold" standard]). See the Guidelines for Authors for a complete description of the levels of evidence.

Effects of sex and age on bone microstructure at the ultradistal radius: a population-based noninvasive in vivo assessment

In a population-based cross-sectional study, we examined effects of sex and age on bone microstructure at the wrist using high-resolution 3-D pQCT. Compared with women, men had thicker trabeculae in young adulthood and had less microstructural damage with aging. These findings may contribute to the virtual immunity of men to age-related increases in wrist fractures.

INTRODUCTION

Although changes in bone microstructure contribute to fracture risk independently of BMD, it has not heretofore been possible to assess this noninvasively in population-based studies.

MATERIALS AND METHODS

We used high-resolution 3-D pQCT imaging (voxel size, 89 mum) to define, in a random sample of women (n = 324) and men (n = 278) 21-97 years of age, sex and age effects on bone microstructure at the wrist.

RESULTS

Relative to young women (age, 20-29 years), young men had greater trabecular bone volume/tissue volume (BV/TV; by 26%, p = 0.001) and trabecular thickness (TbTh; by 28%, p < 0.001) but similar values for trabecular number (TbN) and trabecular separation (TbSp). Between ages 20 and 90 years, cross-sectional decreases in BV/TV were similar in women (-27%) and in men (-26%), but whereas women had significant decreases in TbN (-13%) and increases in TbSp (+24%), these parameters had little net change over life in men (+7% and -2% for TbN and TbSp, respectively; p < 0.001 versus women). However, TbTh decreased to a greater extent in men (-24%) than in women (-18%; p = 0.010 versus men).

CONCLUSIONS

Whereas decreases with age in trabecular BV/TV are similar in men and women, the structural basis for the decrease in trabecular volume is quite different between the sexes. Thus, over life, women undergo loss of trabeculae with an increase in TbSp, whereas men begin young adult life with thicker trabeculae and primarily sustain trabecular thinning with no net change in TbN or TbSp. Because decreases in TbN have been shown to have a much greater impact on bone strength compared with decreases in TbTh, these findings may help explain the lower life-long risk of fractures in men, and specifically, their virtual immunity to age-related increases in distal forearm fractures.

Population-based study of age and sex differences in bone volumetric density, size, geometry, and structure at different skeletal sites

In a population-based, cross-sectional study, we assessed age- and sex-specific changes in bone structure by QCT. Over life, the cross-sectional area of the vertebrae and proximal femur increased by approximately 15% in both sexes, whereas vBMD at these sites decreased by 39-55% and 34-46%, respectively, with greater decreases in women than in men.

INTRODUCTION

The changes in bone structure and density with aging that lead to fragility fractures are still unclear.

MATERIALS AND METHODS

In an age- and sex-stratified population sample of 373 women and 323 men (age, 20-97 years), we assessed bone geometry and volumetric BMD (vBMD) by QCT at the lumbar spine, femoral neck, distal radius, and distal tibia.

RESULTS

In young adulthood, men had 35-42% larger bone areas than women (p < 0.001), consistent with their larger body size. Bone area increased equally over life in both sexes by approximately 15% (p < 0.001) at central sites and by approximately 16% and slightly more in men at peripheral sites. Decreases in trabecular vBMD began before midlife and continued throughout life (p < 0.001), whereas cortical vBMD decreases began in midlife. Average decreases in trabecular vBMD were greater in women (-55%) than in men (-46%, p < 0.001) at central sites, but were similar (-24% and -26%, respectively) at peripheral sites. With aging, cortical area decreased slightly, and the cortex was displaced outwardly by periosteal and endocortical bone remodeling. Cortical vBMD decreased over life more in women ( approximately 25%) than in men (approximately 18%, p < 0.001), consistent with menopausal-induced increases in bone turnover and bone porosity.

CONCLUSIONS

Age-related changes in bone are complex. Some are beneficial to bone strength, such as periosteal apposition with outward cortical displacement. Others are deleterious, such as increased subendocortical resorption, increased cortical porosity, and, especially, large decreases in trabecular vBMD that may be the most important cause of increased skeletal fragility in the elderly. Our findings further suggest that the greater age-related decreases in trabecular and cortical vBMD and perhaps also their smaller bone size may explain, in large part, why fragility fractures are more common in elderly women than in elderly men.

Aged mice require full transcription factor, Runx2/Cbfa1, gene dosage for cancellous bone regeneration after bone marrow ablation

Runx2 is prerequisite for the osteoblastic differentiation in vivo. To elucidate Runx2 gene functions in adult bone metabolism, we conducted bone marrow ablation in Runx2 heterozygous knockout mice and found that aged (but not young) adult Runx2 heterozygous knockout mice have reduced new bone formation capacity after bone marrow ablation. We also found that bone marrow cells from aged Runx2 heterozygous knockout mice have reduced ALP(+) colony-forming potential in vitro. This indicates that full Runx2 dosage is needed for the maintenance of osteoblastic activity in adult mice.

INTRODUCTION

Null mutation of the Runx2 gene results in total loss of osteoblast differentiation, and heterozygous Runx2 deficiency causes cleidocranial dysplasia in humans and mice. However, Runx2 gene functions in adult bone metabolism are not known. We therefore examined the effects of Runx2 gene function in adult mice with heterozygous loss of the Runx2 gene.

MATERIALS AND METHODS

Bone marrow ablation was conducted in young adult (2.5 +/- 0.5 months old) or aged adult (7.5 +/- 0.5 months old) Runx2 heterozygous knockout mice and wildtype (WT) littermates. Cancellous bone regeneration was evaluated by 2D microCT.

RESULTS

Although new bone formation was observed after bone marrow ablation in the operated bone marrow cavity of WT mice, such bone formation was significantly reduced in Runx2 heterozygous knockout mice. Interestingly, this effect was observed specifically in aged but not young adult mice. Runx2 heterozygous deficiency in aged mice significantly reduced the number of alkaline phosphatase (ALP)(+) cell colonies in the bone marrow cell cultures, indicating a reduction in the numbers of osteoprogenitor cells. Such effects of heterozygous Runx2 deficiency on osteoblasts in vitro was specific to the cells from aged adult mice, and it was not observed in the cultures of marrow cells from young adult mice.

CONCLUSION

These results indicate that full gene dosage of Runx2 is required for cancellous bone formation after bone marrow ablation in adult mice.

Bone mineral density and total body bone mineral content in 18- to 22-year-old women

One hundred sixty-four (164) healthy, young Caucasian women enrolled as midshipmen at the United States Naval Academy with no known disease or bone injury were followed for 3.6 years. Change in bone mineral density (BMD) of the hip, lumbar spine and distal tibia, and total body bone mineral content (TBMC) was measured by dual energy X-ray absorptiometry (DXA). Bone mineral density and TBMC of these women were measured within 2 months (60 +/- 4 days) of entering the Academy and annually. Over the study period, hip BMD increased 2.26% (P < 0.001), lumbar spine BMD increased 3.27% (P < 0.001) and distal tibia BMD increased 5.2% (P < 0.001). Total body bone mineral content showed a 5.25% (P < 0.001) increase during the study period. In this group of young women, gain in BMD and TBMC continued until age 22. These results suggest that bone mass may accrue in certain groups of women beyond age 22. The significance of this increase in bone mass during early adulthood on risk for osteoporotic fractures in later life and its impact on exercise-related bone injuries are unknown and warrant further examination.

Standardized Data and Relationship between Bone Growth and Bone Metabolism in Female Goettingen Minipigs

Minipigs have been studied as a model of osteoporosis. However, little information is available regarding their bone physiology. We established standardized bone data and investigated the relationship between bone growth and bone metabolism in female minipigs. Blood and urine samples were obtained from 53 female Göttingen minipigs, 3-76 months of age, for measurement of bone biomarkers (i.e., BAP, OC, NTX, and DPD). The lumbar vertebra and femur were excised to determine the growth plate condition, bone length, bone mineral content (BMC), and bone mineral density (BMD). High levels of bone biomarkers were observed during the initial period after birth, decreasing thereafter with age. Bone biomarkers were confirmed to be highly correlated with age (R(2) > 0.7). The growth plates of the lumbar vertebra and the femur began to close at 21 and 25 months of age, respectively, and closed completely at 42 months of age. Bone length increased rapidly before growth plate closure, and reached a peak at 21 and 28 months of age in the lumbar vertebra and the femur, respectively. The levels of BMC and BMD increased rapidly before growth plate closure, and continued to increase slowly until 76 months of age. A high negative correlation (-0.855 < r < -0.711, p<0.001) was confirmed between the bone biomarkers and the bone measurement data. These results indicate that the bone turnover velocity is consistent with the bone growth velocity in female Göttingen minipigs.

Changes in bone structure and mass with advancing age in the male C57BL/6J mouse

To determine whether the mouse loses bone with aging and whether the changes mimic those observed in human aging, we examined the changes in the tibial metaphysis and diaphysis in the male C57BL/6J mouse over its life span using microcomputed tomography (microCT). Cancellous bone volume fraction (BV/TV) decreased 60% between 6 weeks and 24 months of age. Loss was characterized by decreased trabecular number (Tb.N), increased trabecular spacing (Tb.Sp), and decreased connectivity. Anisotropy decreased while the structure model index increased with age. Cortical bone thickness increased between 6 weeks and 6 months of age and then decreased continuously to 24 months (-12%). Cortical bone area (Ct.Ar) remained constant between 6 and 24 months. Fat-free weight reached a peak at 12 months and gradually declined to 24 months. Total mass lost between 12 and 24 months reached 10%. Overall, the age-related changes in skeletal mass and architecture in the mouse were remarkably similar to those seen in human aging. Furthermore, the rapid early loss of cancellous bone suggests that bone loss is not just associated with old age in the mouse but rather occurs as a continuum from early growth. We conclude that the C57BL/6J male mouse maybe a useful model to study at least some aspects of age-related bone loss in humans.

Dual energy X-ray absorptiometry reference data for Greek population. The impact on diagnosis of using various normal ranges for comparison

INTRODUCTION

The interpretation of bone mineral density (BMD) measurements and the individual classification of a patient is based on a normal reference range. Unfortunately, not all the manufacturers include in their analysis-software reference values specific for each population.

METHODS AND PATIENTS

In our study, using Lunar's DPX-L densitometer, we measured BMD of the lumbar spine and the femur of 4400 healthy women aged (25-80) years and we calculated the corresponding T- and Z-scores. Multiple regression analysis was applied to examine the dependence of BMD on age and weight. Greek data was compared with American and Italian.

RESULTS

There was a statistically significant difference between Greek and American mean values of all age groups. The Italian normal range is closer to our data and can be reliably used at least as T-scores are concerned. Still, there is a small discrepancy in Z-scores, which might influence patient management.

CONCLUSION

We conclude that Greek reference range should be used for the assessment of osteoporosis of Greek population for better evaluation of bone status and appropriate treatment.

Effects of aging on bone mineral content and bone biomarkers in female cynomolgus monkeys

Age-related changes in bone mineral content and bone biomarkers were assessed over the complete lifespan of female cynomolgus monkeys. The bone mass of the lumbar spine increased linearly from birth to about 2.5 years of age, and this increase gradually slowed thereafter until a peak bone mass was achieved at 9 years of age. The bone mass stabilized after 9 years of age, showing no sign of further reduction with age. In contrast with the significant increase in bone mass before 2.5 years of age, significant decreases occurred in the serum concentrations of the following bone formation markers: intact osteocalcin, bone-specific alkaline phosphatase and amino-terminal propeptide of type I procollagen, but the serum concentration of carboxy-terminal propeptide of type I procollagen did not change significantly throughout the entire lifespan. Concerning the bone resorption markers, the levels of tartrate-resistant acid phosphatase fluctuated throughout the entire lifespan. The skeleton of an aging female monkey undergoes changes similar to those observed in senescent humans, but did not undergo the menopausal changes seen in women. The use of female cynomolgus monkeys to model human skeletal interventions should therefore be undertaken with consideration of the similarities and differences between cynomolgus monkeys and humans.

Cross-sectional assessment of age-related bone loss in men: the MINOS study

There are few data on osteoporosis in men, but cross-sectional studies have shown that age-related bone loss in men is of lower magnitude than in women. To elucidate some controversies related partially to methodological aspects, we measured bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA) at various skeletal sites (spine, hip, and whole body using a Hologic QDR-1500 device; forearm using an Osteometer DTX 100 device) in a large cohort of 1040 men, aged 19-85 years. The final investigation was performed on 934 men, aged 19-85 years, after exclusion of 106 men with disease or treatment known to affect bone metabolism. Peak BMD was achieved at 25 and 29 years at the lumbar spine and hip, respectively, but only at 40 and 37 years at the distal forearm and whole body, respectively. The magnitude of bone loss between peak bone mass and 80 years of age was linear at most sites and averaged 13%-18%; that is, SD of 1.1-1.8 from peak BMD, except for Ward's triangle, which showed a marked bone loss of 43% (i.e., 2.5 SD), and for the lumbar spine. In the entire cohort, increase of the average lumbar spine BMD after the age of 55 years was related to the development of osteoarthritis, because, in men without severe arthritis, lumbar spine BMD continued to decrease. Height-adjusted partial correlations indicate that both the mineral content and the area of long bones of the limbs increased with age up to 50 years, followed by a significant decrease of BMD without change of bone surface. SD of mean BMD increased significantly with age at most skeletal sites. In summary, age-related change of BMD varied according to skeletal site in men with peak bone mass achieved earlier at sites rich in trabecular bone than at those rich in cortical bone. Bone loss varied according to skeletal site from 14% to 43%. The variability of BMD increased with age, which may reflect interindividual variability of age-related bone loss.