Cortical Bone Measurements Research Articles

Distribution of hydroxyapatite crystallite orientation and ultrasonic wave velocity in ring-shaped cortical bone of bovine femur

At the nanoscopic level, bone consists of calcium phosphate, which forms incomplete hydroxyapatite (HAp) crystals. The preferred orientation of the c-axis of HAp crystallites induces anisotropy and inhomogeneity of elastic properties in bone. In this study, the effect of the preferred orientation of HAp crystallites on the spatial distribution of ultrasonic wave velocity was experimentally investigated, considering bone mineral density (BMD) and microstructure. Three ring-shaped cortical bone samples were made from a 36-month-old bovine femur. Longitudinal wave velocity was measured by a conventional ultrasonic pulse system, using self-made polyvinylidene fluoride transducers. The integrated intensity of the (0002) peak obtained using X-ray diffraction was estimated to evaluate the amount of preferred orientation. The velocity distribution pattern was similar to the distribution of integrated intensity of (0002). The effect of the preferred orientation of HAp crystallites on velocity was clearly observed in the plexiform structure, despite the fact that the BMD value was almost independent of the preferred orientation of HAp crystallites. Velocity measurement of cortical bone can reveal information about HAp crystallite orientation.

Quantifying Leisure Physical Activity and Its Relation to Bone Density and Strength

Compare three published methods of quantifying physical activity (total activity, peak strain, and bone-loading exposure (BLE) scores) and identify their associations with areal bone mineral density (aBMD), volumetric BMD (vBMD), and bone strength. Postmenopausal women (N = 239; mean age: 53.8 yr) from Iowa (ISU) and California (UCD) completed the Paffenbarger Physical Activity Questionnaire, which was scored with each method. Dual energy x-ray absorptiometry assessed aBMD at the spine, hip, and femoral neck, and peripheral quantitative computed tomography (pQCT) measured vBMD and bone strength properties at the distal tibia and midshaft femur. UCD women had higher total activity scores and hours per week of leisure activity. All scoring methods were correlated with each other. No method was associated with aBMD. Peak strain score was negatively associated with polar moment of inertia and strength-strain index at the tibia, and total activity score was positively associated with cortical area and thickness at the femur. Separating by geographic site, the peak strain and hip BLE scores were negatively associated with pQCT measures at the tibia and femur among ISU subjects. Among UCD women, no method was significantly associated with any tibia measure, but total activity score was positively associated with measures at the femur (P < 0.05 for all associations). Given the significantly greater hours per week of leisure activity done by UCD subjects, duration may be an important determinant of the effect physical activity has on bone. The positive association between leisure physical activity (assessed by the total activity score) and cortical bone measures in postmenopausal women may indicate a lifestyle factor that can help offset age-related bone loss.

Serum levels of osteoprotegerin and receptor activator of nuclear factor kB ligand (RANKL) in children with various stages of chronic renal disease

We recruited 93 cases (children with a current fracture, including some with previous fracture) and 32 controls (no current or previous fracture) by approaching families attending our A&E department with a history of trauma and suspected bony injury. The children underwent bone densitometry of the hip, spine and total body and spiral CT of the lower legs with an in-line Mindways calibration phantom. The latter technique provided complete 3-D images of both tibias with associated volumetric densitometry of the different compartments of bone. The vQCT measures of cortical bone were performed in the mid shaft of the left tibia (50% tibia). Measures of trabecular bone were acquired at sites where the distance to the distal tibial inferior articular cartilage corresponded to 6% and 8% of the length of the left tibia. The inferior articular cartilage was selected as a reference point as it is consistent at all ages in children. We obtained data from single tomographic slices of 2.5 mm transectional thickness at a voxel size of 0.5 mm. A threshold algorithm was used to separate cortical and trabecular bone. As previously, we found significant differences in the relationship between the bone parameters-bone mass, areal bone density and bone area-and body size for children who had had a fracture compared with non-fracture subjects (pb0.01). There was a significant difference between the groups in hip cross-sectional area (pb0.05). However, we found no significant difference between the groups in cortical bone volumetric bone density or cross-sectional area at the mid tibia either before or after adjustment for potential confounders. Neither was there any clear difference between the groups in metaphyseal crosssectional area or volumetric density at either the 6% or 8% site. This study confirms previous observations of lower bone mass for body size in children who fracture, and reduced bone size at the hip, but has not as yet indicated that there are significant accompanying changes in bone microarchitecture in the lower legs.

Quantitative genetics of cortical bone mass in healthy 10-year-old children from the Fels Longitudinal Study

The genetic influences on bone mass likely change throughout the life span, but most genetic studies of bone mass regulation have focused on adults. There is, however, a growing awareness of the importance of genes influencing the acquisition of bone mass during childhood on lifelong bone health. The present investigation examines genetic influences on childhood bone mass by estimating the residual heritabilities of different measures of second metacarpal bone mass in a sample of 600 10-year-old participants from 144 families in the Fels Longitudinal Study. Bivariate quantitative genetic analyses were conducted to estimate genetic correlations between cortical bone mass measures, and measures of bone growth and development. Using a maximum likelihood-based variance components method for pedigree data, we found a residual heritability estimate of 0.71 for second metacarpal cortical index. Residual heritability estimates for individual measures of cortical bone (e.g., lateral cortical thickness, medial cortical thickness) ranged from 0.47 to 0.58, at this pre-pubertal childhood age. Low genetic correlations were found between cortical bone measures and both bone length and skeletal age. However, after Bonferonni adjustment for multiple testing, ρ G was not significantly different from 0 for any of these pairs of traits. Results of this investigation provide evidence of significant genetic control over bone mass largely independent of maturation while bones are actively growing and before rapid accrual of bone that typically occurs during puberty.

THE CLASSIC: Quantitative Computed Tomography of Vertebral Spongiosa: A Sensitive Method for Detecting Early Bone Loss after Oophorectomy

THE CLASSIC: Quantitative Computed Tomography of Vertebral Spongiosa: A Sensitive Method for Detecting Early Bone Loss after Oophorectomy

Ankylosing spondylitis and bone mineral density—what is the ideal tool for measurement?

Ankylosing spondylitis (AS) is characterised by chronic inflammation and partial ossification, yet vertebral fractures due to osteoporosis, although common, are frequently unrecognised. The aim of this study was to (1) show the frequency of changes in the progress of osteopenia/osteoporosis in AS depending on duration and stage of the disease and (2) assess the ranking of two different methods of bone density measurement in this clinical pattern. We measured bone density in 84 male and female patients with both dual X-ray absorptiometry (DXA) and single energy quantitative computed tomography (SE-QCT). In the initial and advanced stages of the disease, a high decrease in axial bone density could be verified (DXA: osteopenia in 5% and osteoporosis in 9.2%; SE-QCT: osteopenia in 11.8% and osteoporosis in 30.3%). Peripheral bone density decrease as in osteopenia could be proven in 17.6% by DXA measurement. With SE-QCT, a decrease in vertebral trabecular bone density could already be observed in the initial stage and continued steadily during the course of the disease; cortical bone displayed the same trend up to stages of ankylosis. With DXA, valid conclusions are more likely to be expected in less marked ankylosing stages of AS. In stages of advanced ankyloses in the vertebral region (substantial syndesmophytes), priority should be given to SE-QCT, due to the selective measurement of trabecular and cortical bone. The DXA method often yields values that are too high, and the replacement of vertebral trabecular bone by fatty bone marrow is not usually recorded as standard. There may already be an increased risk of bone fracture in AS in osteopenia on DXA along with an osteoporosis already established on SE-QCT.

Bone strength in multiple sclerosis: cortical midtibial speed-of-sound assessment.

It has been previously suggested that multiple sclerosis (MS) patients are at increased risk for osteoporosis due to reduced mobility, decreased exposure to sunlight and recurrent steroid treatment. In order to systematically evaluate bone strength we assessed 256 MS patients (171 females, 75 males) through quantitative ultrasound measurement of cortical bone. Tibial speed of sound (SOS, m/sec) was measured at midpoint of the tibial shaft using a Soundscan 2000 (Myriad Ultrasound Systems, Rehovot, Israel) and results were compared to age- and gender-matched population norms. T-score distribution in male MS patients was similar to normal population. In contrast, for female MS patients T-score distribution was significantly different from population norms, reflected by increased SOS in 30.4% (T-score intervals 1-2 and >2 above normal values; P=0.001), compared with 7.4% in controls. These findings held true for both female patients younger and older than 45 years of age. Increased neurological disability and specifically motor involvement were more frequent in female patients with increased SOS (P<0.05). Bone strength was preserved in MS patients. In a subgroup of female patients increased SOS was conceivably related to spasticity.

Cortical bone in the human femoral neck: three-dimensional appearance and porosity using synchrotron radiation.

A high-resolution CT system using synchrotron radiation allowed visualization of the 3D cortical bone microarchitecture and measurement of intracortical porosity of femoral neck cortical bone specimens from 19 female cadavers imaged at 10.13-microm resolution. 3D reconstruction of specimens showed osteonal system arrangement. Mean porosity was 15.88%. This technique will provide insights into the mechanisms involved in osteoporotic hip fractures. The purpose of this study was to show that a high-resolution CT system using synchrotron radiation (SR) allows visualization of the 3D cortical bone microarchitecture of the human femoral neck and quantification of intracortical porosity. Bone specimens from the inferior femoral neck were obtained from 19 female cadavers with no hip fracture (mean, 86.9 +/- 8.3 years). The specimens, consisting of embedded approximately 7 x 7 x 12-mm cortical bone parallelepipeds, were imaged using SR at 10.13-microm resolution. Commercial software was used to visualize both the 660 x 660 x 660-voxel volumes and the 2D axial slices through each volume. Qualitative examination of 2D axial slices focused on the appearance of the vessel canal system, presence of small bright zones (fully mineralized tissue) in the osseous matrix, and presence of cracks. A method was developed to automatically measure 3D intracortical porosity after separating pure bone from pores and cortical bone from trabecular bone. 3D reconstruction of the specimens showed the entire structure and arrangement of the osteonal systems, parallel to the axis of the femoral neck. Bright zones were seen in the outer cortex. No cracks were observed. Porosity values varied widely from 4.96% to 38.87% (mean, 15.88 +/- 9.87%). This study establishes that SR microtomography can be used to display the 3D bone microstructure of the human femoral neck cortex and to quantify intracortical porosity. This technique will provide insights into the mechanisms involved in cortical bone loss and osteoporotic hip fractures.

Effects of viscoelasticity and time-dependent plasticity on nanoindentation measurements of human cortical bone.

The viscoelastic and time-dependent plastic effects on the nanoindentation measurement of osteonal lamella in a human cortical bone were investigated. The elastic modulus of osteonal lamella obtained from the quasi-static technique was strongly affected by the indentation rate and time-dependent plasticity. The effects of time-dependent plasticity can be diminished by multiple loading-unloading cycles and a long holding period at maximal load. After minimizing the contribution of time-dependent plasticity to unloading data, it was surprisingly found that the elastic modulus was proportional to indentation strain rate raised to the 0.06 power, which is similar to conventional test results.

The effects of chronic alcohol consumption and exercise on the skeleton of adult male rats

Background Lifestyle factors are known to affect skeletal development and integrity. Specifically, running has been reported to increase risk of fatigue fractures, whereas chronic alcohol consumption has been shown to reduce bone formation and bone mass. The combined effect of exercise and alcohol on the skeleton has yet to be explored, although alcohol consumption is common among certain physically active populations (e.g., military recruits, college athletes). It was hypothesized that chronic alcohol consumption would accentuate the inherent risk associated with endurance running exercise. Methods Six-month-old male Sprague Dawley® rats were assigned to one of five groups: baseline, exercise-alcohol diet, exercise-normal diet, sham-alcohol diet, and sham-normal diet. Alcohol-fed rats (35% caloric intake) received a liquid diet ad libitum. Normal animals were pair-fed the identical diet with a maltose dextrin caloric substitute. Exercise was conducted on a motorized treadmill 5 days/wk for 16 weeks. Sham rats were placed on a stationary treadmill for matching time periods. Fluorochrome labels were administered 3 days before baseline and at 10 and 2 days before animals were killed. Heart, soleus, and rectus femoris muscles were wet weighed to assess the effects of training. Tibiae were collected for static and dynamic histomorphometric measurements on cancellous and cortical bone. Results Muscle weights were larger in the exercised rats versus the sham rats. Alcohol had no significant effect on skeletal muscle weight but did result in larger heart weights in both alcohol-treated groups. Cancellous and periosteal bone formation rates were significantly decreased in the alcohol-fed rats versus rats on the normal diet and were associated with a significant reduction in trabecular thickness in the tibial metaphysis. Cortical and cross-sectional areas were also significantly lower in the alcohol-fed groups compared with the non-alcohol-fed groups. Exercise had no significant effect on cancellous or cortical bone measurements. Conclusions Chronic alcohol consumption significantly reduced bone formation. Exercise had no effect on the bone and did not attenuate any of the negative effects of alcohol. The results suggest that alcohol consumption weakens the skeleton and increases the incidence of endurance-exercise-related bone injuries. Thus, individuals who are participating in endurance exercise and consuming alcohol may be at greater risk for exercise-related skeletal injuries. Further investigation of the potential for alcohol to induce detrimental effects on the hearts of individuals participating in endurance exercise is indicated.

Asymmetry in Metacarpal Cortical Bone in a Collection of British Post-Mediaeval Human Skeletons

Bilateral asymmetry in measures of metacarpal cortical bone, particularly second moments of area, in a group of 18th–19th century ad skeletons was investigated. The aim was to study variation in bilateral asymmetry with respect to sex and occupation. The skeletal material came from the crypt at Christ Church Spitalfields, London. The study sample comprised individuals with personal identifications from coffin plates. For a subset of the males, occupation was known from documentary sources. Results showed that bilateral asymmetry in second moment of area varied, to a limited extent, with occupation. Sex differences in bilateral asymmetry were also found.

Diagnostic discrepancies between two closely related forearm bone density measurement sites.

At the present time the diagnosis of osteoporosis is based on the use of T-scores. Measurements at different skeletal sites or of different regions of interest may result in diagnostic discrepancies. In this study, we tried to demonstrate that bone mineral density (BMD)values at the closely related forearm sites may lead to diagnostic uncertainty, and to assess the degree of site heterogeneity across different age groups. The study consisted of 2348 women (age 20-83) referred for bone densitometry. Forearm BMD was measured at the distal and ultradistal sites by single X-ray absorptiometry (DTX-100 device). T-scores were calculated from Bulgarian reference data. Diagnostic disagreement between sites was found in 19.3% of all women. In 7.7% of all cases, the difference between T-scores at the two sites exceeded 1. The discrepancies were more pronounced after age 60. This corresponds well to the different onset and rates of trabecular and cortical bone losses as well as to their different distribution along the forearm. We encourage the separate assessment of cortical and trabecular bone densities or measurements at axial sites in case forearm sites yield conflicting results or low-normal BMD values.

Effects of titanium prosthesis, offset and size of field of view on bone mineral density measurements using quantitative computed tomography.

To estimate the accuracy of quantitative computed tomography (QCT) as a method to measure bone mineral density (BMD) in the vicinity of a titanium prosthesis, we investigated the effects of (1) titanium prosthesis, (2) offset of the longitudinal axis of the bone to be examined from that of the gantry of the CT scanner, (3) size of the field of view (FOV) and (4) the combination of these effects on CT based measurements of mineral density of cortical and cancellous bone specimens. 14 bovine cortical bone parallelepipeds and 14 bovine cancellous bone parallelepipeds were used in this investigation. The bone specimens were scanned with and without a titanium prosthesis, when centered in the gantry of the CT scanner and offset from the axis of the gantry of the CT scanner at a distance of 14 cm. Image data were then reconstructed separately with a FOV of 10 cm and 30 cm. All BMD values taken from CT images obtained under different scanning condition were compared with the BMD values of the corresponding bone parallelepiped obtained under standard condition (centered in the gantry of the CT scanner, 10 cm FOV, without titanium prosthesis). When centered in the gantry of the CT scanner, the mean relative difference of BMD measurements caused by the presence of the titanium prosthesis was less than 1% for both cortical bone and cancellous bone. Size of the FOV had a negligible effect on BMD measurements. Offset at 14 cm, however, caused a significant difference in BMD measurements (p < 0.001). It was concluded that titanium prosthesis did not interfere with BMD measurements of cortical and cancellous bone when both the specimen and prosthesis were centered in the gantry of the CT scanner. However, the effect on BMD measurements of offset at 14 cm combined with the presence of a titanium prosthesis in bone was significant.

Quantitative computed tomography of vertebral spongiosa: a sensitive method for detecting early bone loss after oophorectomy. 1982.

We assessed serially the bone mineral loss in 37 premenopausal women for 24 months after oophorectomy and determined the dose-response for conjugated estrogen therapy in preventing this loss. Spinal cancellous bone was measured by quantitative computed tomography and measurement of appendicular cortical bone by radial photon absorptiometry and metacarpal radiogrammetry. For the placebo and low-dose treatment groups, the mean annual bone mineral losses were 7% to 9% from the vertebral spongiosum and 1% to 3% from the peripheral cortex. The correlation between axial and appendicular loss was weak (r = 0.581), precluding a reliable estimate of spinal loss from peripheral measurements. For the maximal-dose group (0.6 mg/d), the mean annual bone mineral losses were less than 0.5% from the axial and appendicular sites, and were not significant. The results indicate that spinal quantitative computed tomography provides a highly sensitive measurement of bone mineral loss after oophorectomy, that bone mineral loss is five- to sevenfold greater from the spinal spongiosum than from the appendicular cortex, and that conjugated estrogen in doses of less than 0.6 mg/d are inadequate to prevent the vertebral mineral loss.

Guidelines for osteoporosis in coeliac disease and inflammatory bowel disease

Osteoporotic fractures are a major public health problem. It has been estimated that in the USA the remaining lifetime fracture risk at the age of 50 years is 40% for...

Measurement of forearm bone in children by peripheral computed tomography.

By means of peripheral computed tomography (pQCT), adult cortical bone density and volume was shown to be under a fixed rectilinear relationship regardless of age, sex, and presence or absence of osteoporosis. In children, however, the density-volume regression line followed a clearly different slope from that for adults (P < 0. 001), indicating a difference in property and composition of the cortical bone between growing bone of children and grown-up bone of adults. Although both relative cortical volume and density increased with age in both boys and girls, no significant increase of trabecular bone was noted in either during the growth period. When the same technique was applied to the bone of rats known to continue growing with indefinite modeling without remodeling, the regression line between cortical bone density and volume was different from that of adult humans and similar to that of growing human children. Growing bone in a constant process of modeling and mineralization thus seems to have cortical bone possibly with less complete mineralization somewhat different from those of grown-up bone only undergoing remodeling. Selective cortical bone measurement by pQCT appears to be useful in characterizing the unique properties of the cortex of the growing bone.

Accuracy of cortical and trabecular bone measurements with peripheral quantitative computed tomography (pQCT)

In order to assess the accuracy of peripheral QCT (Stratec XCT 960) we analysed scans of the European Forearm Phantom and another phantom consisting of HPO encased in aluminium tubes to simulate cortical walls. Additionally 14 cadaveric forearm specimen scans were compared to CT scans acquired on a GE9800Q. The accuracy for density assessment of the European Forearm Phantom was better than 3%. A small increase in density was observed with increasing thickness of the aluminium wall (10% for each mm). Density measurements within the wall were confounded by limited spatial resolution. For a thickness of less than 4 mm, the density within the wall was underestimated by up to 40%. The measurement of mineral content was not influenced by this effect and showed an accuracy error of less than 6%. The agreement of density measurements on the different CT systems was very strong (; RMSE<6.2%). Our findings suggest that the Stratec pQCT scanner very accurately measures volumetric trabecular and total bone mineral densities at the distal radius while the assessment of cortical density is associated with considerable inaccuracies due to limited spatial resolution.

Evidence that ibuprofen antagonizes selective actions of estrogen and tamoxifen on rat bone.

Studies were performed to determine if the nonsteroidal anti-inflammatory drug ibuprofen alters bone and mineral metabolism in female rats. In experiment 1, four groups of growing rats underwent either sham operation or ovariectomy (OVX). One week later, controlled-release pellets with ibuprofen or placebo were implanted subcutaneously at the back of the neck. Following 3 weeks of treatment, rats were sacrificed and blood and bone samples were removed for serum assays and histomorphometric analysis. Body growth rate and the static cortical bone measurements made at the tibial diaphysis did not change in response to OVX. OVX, however, did increase radial bone growth, lowered serum 17beta-estradiol, reduced uterine weight, and decreased the cancellous bone area of the tibial metaphysis in the rats. Ibuprofen did not alter serum 17beta-estradiol or uterine weight but reduced radial bone growth as well as cancellous bone area of the tibial metaphysis in both sham-operated and OVX animals. In experiments 2 and 3, we tested the influence of ibuprofen on the effects of the tissue-selective estrogen agonist tamoxifen and of exogenous 17beta-estradiol in the OVX rat. Ibuprofen completely blocked the effects of tamoxifen and partially blocked the effects of 17beta-estradiol to prevent cancellous osteopenia. In contrast, ibuprofen did not influence the effects of tamoxifen and 17beta-estradiol to reduce radial bone growth. Besides the skeletal effects, ibuprofen suppressed estrogen-induced uterine growth. Our data suggest that ibuprofen blocks selective estrogen receptor-mediated activities in the rat.

Bone lead as a biological marker in epidemiologic studies of chronic toxicity: conceptual paradigms.

The skeleton contains the majority of the body's lead burden in both children and adults. The half-life of lead in bone is in the range of years to decades, depending on bone type, metabolic state, and subject age, among other things. Measurement of skeletal lead has benefited greatly from the recent development of X-ray fluorescence (XRF) instruments that can make rapid, safe, accurate, and relatively precise measurements of lead in bone. Two types of XRF technologies exist, LXRF and KXRF; this paper focuses on KXRF, which has been the most widely validated and used. KXRF is proving to be a powerful analytical methodology for evaluating bone lead levels as a measure of time-integrated (i.e., cumulative) lead dose in epidemiologic studies of the effects of chronic lead exposure. However, insufficient attention has been given to conceptualizing the paradigms by which bone lead levels reflect lead exposure and by which the skeleton serves as an endogenous source of lead. Consideration of these paradigms, which rely on bone lead kinetics, is necessary for the proper development of a priori hypotheses involving bone lead accumulation and release, the selection of bone sites for measurement by KXRF, and the design of epidemiologic studies involving bone lead dynamics. We discuss and present supporting evidence for a conceptual model that distinguishes two major paradigms of skeletal lead, including 1) bone lead as an indicator of cumulative lead exposure (bone lead as repository), and 2) bone lead as a source of body lead burden that is mobilizable into the circulation (bone lead as source). These two roles are not mutually exclusive. Instead, they are components of the processes controlling lead accumulation into and release from bone over time. Developing successful strategies for distinguishing these two processes in epidemiologic studies will require separate measurements of lead in cortical and trabecular bone and additional measurement of specific markers of bone mineral turnover and resorption. It may also involve developing accurate methods for evaluating lead in labile compartments of the circulation, such as plasma, as a potentially useful and responsive measure of bone lead release, of the partitioning of circulatory lead, and of the toxicological significance of lead released from bone to other target organs.

Bone density in children and adolescents with rheumatic diseases. Preliminary results of selective measurement of trabecular and cortical bone using peripheral computerized tomography

Selective measurements of bone mineral density (BMD) of trabecular and cortical bone at the ultradistal radius were made in 27 children with rheumatic diseases and in age- and sex-matched healthy controls using peripheral quantitative computed tomography (pQCT). Mineral density of trabecular bone (-34,5%) and total bone mineral density (-18,9%) differed significantly between patients and controls (p < 0.01). BMD of the cortical bone (-13,6%) did not differ significantly between the groups. There was no difference in BMD in patients with systemic or non-systemic diseases. BMD did not correlate with duration of disease or steroid medication. Total bone mineral density and trabecular bone density are decreased in children and adolescents with sytemic and non-systemic rheumatic diseases. Age of onset of disease and steroid medication did not correlate with bone mineral density. PQCT has the advantages of low local and no total body radiation, high sensitivity, high reproducibility and selective measurement of different bone compartements. Because selective measurement can be made in metabolically active trabecular bone changes of BMD can be detected at an early stage before the whole bone is affected. With this method therapy for chronic diseases affecting bone density can be initiated and the course of the disease can be followed.