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PubMed2002

Measurement of bone adjacent to tibial shaft fracture.

Delayed union and non-union are common complications after fracture of the tibial shaft. Response of the surrounding bone as a fracture heals could be monitored using techniques currently used in the study of osteoporosis. The aims of our study were to: (1) evaluate the decrement in bone measurements made close to the fracture using dual-energy X-ray absorptiometry (DXA), quantitative ultrasound (QUS) and peripheral quantitative computed tomography (pQCT); (2) compare values for fractured versus non-fractured leg to determine the duration of decrement in bone measurements; and (3) calculate short-term precision in DXA, QUS and pQCT in order to calculate the ratio of decrement to precision (response ratio, RR) to determine the optimal test for monitoring changes after tibial fracture. The biggest decrement in bone measurements at the ipsilateral limb of 28 patients with tibial shaft fracture was observed at the pQCT tibial trabecular sites (distal = 19%, p<0.0001; proximal 5% = 21%, p<0.001; proximal 10% = 28%, p<0.001) and the ultradistal tibia/fibula measured by DXA (19%, p<0.0001). When comparing Z-scores, the magnitude of decrements at the ipsilateral limb was bigger for variables measured directly at the tibia, both proximal and distal to the fracture. The magnitude of the decrement in ultradistal tibia/fibula BMD decreased as the time since fracture increased ( r = 0.55). When response ratios are considered, pQCT measurements at the distal tibia (RR 6-8) and proximal 5% and 10% trabecular sites (RR 5 and 9 respectively) were found to be the most sensitive to change. Therefore, pQCT of the trabecular regions of either the proximal or distal tibia should prove the most sensitive measurement for monitoring changes in bone adjacent to a tibial shaft fracture.

Absorptiometry, Photon↗
PubMed1998

Functional magnetic resonance imaging of motor, sensory, and posterior parietal cortical areas during performance of sequential typing movements.

We investigated the activation of sensory and motor areas involved in the production of typing movements using functional magnetic resonance imaging (fMRI). Eleven experienced typists performed tasks, in which the spatial and temporal requirements as well as the number of digits involved were varied. These included a simple uni-digit repetitive task, a uni-digit sequential task, a dual-digit sequential task, a multi-digit sequential task, and typing text from memory. We found that the production of simple repetitive keypresses with the index finger primarily involved the activation of contralateral primary motor cortex (M1), although a small activation of the supplementary motor area (SMA) and other regions was sometimes observed as well. The sequencing of keypresses involved bilateral M1 and a stronger activation of the SMA and to a lesser extent the premotor area, cingulate gyrus, caudate, and lentiform nuclei. However, the activation of these areas did not exclusively depend on the complexity of the movements, since they were often activated during more simple movements, such as alternating two keypresses repeatedly. Somatosensory and parietal regions were also found to be activated during typing sequences. The activation of parietal areas did not exclusively depend on the spatial requirements of the task, since similar activation was observed during movements within intra-personal space (finger-thumb opposition) and may instead be related to the temporal requirements of the task. Our findings suggest that the assembly of well-learned, goal-directed finger movement sequences involves the SMA and other secondary motor areas as well as somatosensory and parietal areas.

Adult↗
PubMed2001

Quantitative assessment of forearm muscle size, forelimb grip strength, forearm bone mineral density, and forearm bone size in determining humerus breaking strength in 10 inbred strains of mice.

Bone strength is an important clinical endpoint of osteoporosis research. The evaluation of the relative importance of bone and muscle components to bone strength has widespread implications for the understanding and preventing of osteoporosis. The objectives of this study were to understand the interrelationship between the different components of the muscular skeletal system and to determine the effect of forearm muscle size, forelimb grip strength, forearm bone mineral density (BMD), and forearm bone size on the humerus breaking strength among 10 inbred strains of mice. The forearm muscle size was measured using a peripheral quantitative computed tomography (pQCT). The forearm BMD and forearm bone size were measured using a PIXIMUS Densitometer. The forelimb grip strength and humerus breaking strength were measured using an Instron Mechanical Tester. Significant correlations were found among the five regional phenotypes. All variables have a moderately high genetic component with heritability estimates of 0.83 for forelimb grip strength, 0.76 for forearm muscle size, 0.6 for forearm BMD, 0.63 for forearm bone size, and 0.68 for humerus breaking strength. Forward stepwise multiregression analysis showed that the forearm BMD, forelimb grip strength, and forearm bone size were three major determinants of bone strength and explained 61% of the variation in bone breaking strength. These data suggest that evaluation of these three parameters together, rather than BMD alone, is a more effective, noninvasive approach for predicting fracture risk.

Absorptiometry, Photon↗
PubMed2002

Site-specific skeletal response to long-term weight training seems to be attributable to principal loading modality: a pQCT study of female weightlifters.

Physical training may be able to improve bone strength through site-specific changes in the composition, size and structure of the bone without notable increases in volumetric density. To address this possibility specifically, we compared 14 competitive female weightlifters with 14 female physical therapy students. Peripheral quantitative computed tomographic scans (pQCT) were taken from the distal radius, radial shaft, distal femur, and tibial midshaft of the dominant limb. Analysis of covariance (ANCOVA) was used to estimate the intergroup differences, using body weight and age as covariates. Cortical density did not differ between the weightlifters and controls at any site, whereas trabecular density was greater in the weightlifters, the benefit being 10% (P = 0.186) at the distal radius and 11% (P = 0.040) at the distal femur compared with the controls. Weightlifters' cortical cross-sectional area was 38% (P = 0.029) larger at the distal radius, 26% larger (P = 0.001) at the radial shaft, and 9% larger at the tibial midshaft (P = 0.034). Consequently, the weightlifters' forearm bone strength indices were also significantly higher, the intergroup difference being 41% (P = 0.001) at the distal radius and 43% (P = 0.004) at the radial shaft. Thus, the observed intergroup difference at the distal radius was mainly due to enlarged bone, particularly its cortex, rather than higher volumetric bone density. Findings at the radial shaft were similar. In contrast, weightlifters' trabecular tissue at the distal femur was denser but the bone per se was not clearly bigger than that of the controls' (intergroup difference 5%, P = 0.117). We suggest that bones subjected to exceptionally high bending-loading (distal radius and radial shaft) are larger than their normal counterparts while at sites experiencing axial, compressive-loading (e.g., distal femur), a denser trabecular structure (more load-carrying area) may be sufficient and any substantial enlargement in bone size may not be necessary.

Adult↗
PubMed2002

Bone mineral content and density in the humerus of adult myostatin-deficient mice.

Myostatin (GDF-8), a member of the transforming growth factor-b superfamily of secreted growth and differentiation factors, is a negative regulator of skeletal muscle growth. We investigated the effects of increased muscle mass on bone morphology by examining bone mineral content and density in the humeri of myostatin-deficient mice. We compared the humeri of 11 mixed-gender, adult mice homozygous for the disrupted myostatin sequence with those from 11 mixed-gender, adult wild-type mice. Body mass, deltoid mass, and triceps mass were recorded from each animal and densitometric and geometric parameters were collected from the humerus using peripheral quantitative computed tomography (pQCT). Cross-sectional slices were scanned at four different positions along the humerus corresponding to 15%, 40%, 60%, and 85% of total humerus length. Results show that the myostatin- deficient mice weigh more than controls and have significantly larger triceps and deltoid muscles. The myostatin-deficient animals also have significantly (P < 0.05) higher trabecular area and trabecular bone mineral content (BMC) in the proximal humerus (15% length) and significantly (P < 0.01) higher cortical BMC, cortical area, and periosteal circumference in the region of the deltoid crest (40% length). The myostatin knockouts otherwise do not differ from controls in cortical BMC. Moreover, experimental and control mice do not differ significantly from one another in cortical bone mineral density (BMD) at any of the sites examined. These results suggest that the effects of increased muscle mass on the mouse humerus are localized to regions where muscles attach; furthermore, these effects include increased mineral content of both trabecular and cortical bone.

Animals↗
PubMed2002

Rodent model for investigating the effects of estrogen on bone and muscle relationship during growth.

It has been reported that in humans from about 11-12 years of age, bone mass begins to increase faster in girls than in boys with the same muscle mass, and by 14-15 years of age, bone mass per unit mass of muscle was found to be significantly higher in girls than in boys. Because around 15 years is the beginning of reproductive age in women, it was suggested that estrogen was involved in the higher bone mass in women during puberty. The present study was undertaken to determine if bone mass per unit muscle mass is higher in female than in male Sprague Dawley (SD) rats during growth, as has been reported in humans during growth and consequently, whether these SD rats are suitable for studying the musculoskeletal effects of estrogen, as may occur in humans during growth. L-4 vertebra of female and male SD rats aged 1-6 months were studied using peripheral quantitative computed tomography (pQCT). Muscle cross-sectional area was measured as a surrogate for muscle mass and bone mineral content (BMC) was measured as a surrogate for bone mass. From 1 to 6 months of age, total BMC, cortical BMC, and cancellous BMC increased faster in females than in males with similar muscle area, and at 3 and 6 months of age, the above vertebral indices of bone mass were significantly higher in female than in male rats. Since one of the main differences between female and male rats is the level of serum estrogen, the higher bone mass per unit muscle area seen at the L-4 vertebra in these female SD rats is similar to what has been reported in humans during puberty when serum estrogen level is high in females. The findings from this study indicate that female and male SD rats aged 1-6 months can be used as appropriate model for studying the effects of serum estrogen on the skeletal response of voluntary muscle forces, as has been reported in humans during growth.

Animals↗
PubMed2002

The estrogen receptor ligand ICI 182,780 does not impair the bone-sparing effects of testosterone in the young orchidectomized rat model.

Testosterone (T) can affect bone metabolism not only directly, but also via its metabolites, estrogen or dihydrotestosterone, produced by enzymes present in bone. Therefore, the aim of this study was to investigate whether the high-affinity estrogen receptor ligand ICI 182,780 (ICI) impaired the bone-protective action of T in 3-month-old orchidectomized (Orch) rats, studied during an experimental period of 3 months. As expected, Orch significantly decreased trabecular bone volume in the proximal tibial metaphysis (-52%), as measured by histomorphometry, and had a similar negative effect on volumetric bone mineral density (BMD) in the distal femoral metaphysis (-53%), as assessed by peripheral quantitative computed tomography (pQCT). The loss of bone induced by Orch was completely prevented by T administration. Moreover, the Orch-associated increases of biochemical markers of bone turnover (serum osteocalcin, urinary deoxypyridinoline, and calcium excretion) did not occur when Orch rats received T. Administration of ICI in combination with T did not impair this bone-sparing effect. Cortical bone parameters (as determined by pQCT), body weight gain, and body composition (as measured by dual-energy X-ray absorptiometry) were not affected by T or ICI in combination with T. Furthermore, no differences were observed in serum concentrations of insulin-like growth factor-I or glucose homeostasis. In conclusion, ICI does not impair the long-term bone-protective effects of T in orchidectomized male rats, suggesting that testosterone can mediate its effect on the male skeleton directly via the androgen receptor. The absence of effects on body growth via the growth hormone--insulin-like growth factor-I axis may be a possible explanation for the lack of skeletal effects of this selective estrogen receptor antagonist.

Animals↗
PubMed2002

Regional bone loss after orthotopic liver transplantation in inbred rats: the role of hepatic denervation.

Bone loss and long-term persistence of osteoporosis with increased fracture risk are common after liver transplantation. It is unknown whether transplantation-induced disruption of hepatic nerves, serving numerous regulatory metabolic and sensory functions, is herein involved. To test this possibility, we measured bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT) and studied dynamic histomorphometry, radiocalcium kinetics, and biochemical parameters in 7 liver-transplanted and 7 sham-operated inbred rats. Although liver function was normal in TX rats, trabecular BMD of the first lumbar vertebra and total BMD of the femoral diaphysis were decreased by 13% and 6%, respectively, 9 months postsurgery. The breaking force of the femur was significantly lower by 21%. However, bone mass in the femoral and tibial metaphysis was preserved as evidenced by pQCT measurements and histomorphometry. Trabecular width and wall thickness were significantly decreased in vertebral cancellous bone, whereas indices of bone formation and resorption were normal or slightly reduced. Serum minerals, mineral balance, fractional and net absorption of Ca and Mg, serum calciotropic hormones, IGF-I, leptin, specific activity of 45Ca in bone, 45Ca excretion, and biochemical indices of bone formation and bone resorption remained unchanged. We conclude that liver transplantation-related denervation causes cancellous and cortical bone loss in well-innervated bone sites such as the lumbar spine and the long bone diaphysis. Cancellous bone loss in TX rats is due to an impairment of osteoblast team performance and subsequent trabecular thinning. The mechanism uncovered by our study may contribute to long-term bone loss after liver transplantation.

Animals↗
PubMed2003

Three-dimensional distribution of bone density in the proximal humerus.

Bone quality of the proximal humerus is important for the surgical treatment of proximal humeral fractures and rotator cuff tears. However, very few studies have evaluated the areal bone mineral density (BMD) of the proximal humerus. The aim of this study was to analyze the volumetric BMD (vBMD) using peripheral-quantitative-computed-tomography. Total, trabecular and cortical vBMD were determined separately for the proximal and distal half of the humeral head, the surgical neck and seven specific regions of interest. The greater tuberosity (GT) was divided into three regions, and the lesser tuberosity (LT) and articular surface (AS) were each divided into two regions. The proximal head showed a significantly higher trabecular (+ 46%) and cortical vBMD (+ 15%) than the distal one. The mean trabecular vBMD of AS was significantly higher (+ 80%), and the cortical vBMD was significantly lower (- 11%) than that of the tuberosities. In the proximal half of GT, trabecular vBMD was higher in the posterior than in the middle and anterior regions. Cortical vBMD was higher in middle region than in the anterior and posterior ones. In the distal half of GT, trabecular vBMD was significantly higher in the posterior than in the middle region, and cortical vBMD was significantly higher in the anterior than in the middle region. In one. These results point to bone sites that may provide stronger fixation for implants, reduce the risk of implant loosening, and therefore improve patient outcome.

Absorptiometry, Photon↗
PubMed2003

Two inbred rat strains that differ substantially in hip fragility.

One approach to identifying the genetic influences on skeletal phenotypes involves the creation and genetic mapping of a population of the second filial (F2) offspring derived from a cross of two inbred strains of rodents. The two inbred strains should be chosen based upon a large difference in the phenotype of interest, e.g., bone fragility. We found previously that considerable variation exists in fragility phenotypes among inbred strains of rats, and the phenotypic variation was site specific. In particular, two inbred rat strains, Copenhagen 2331 (COP) and Dark Agouti (DA), were found to differ significantly in femoral neck geometry and strength. The aim of this study was to further characterize hip fragility in COP and DA rats at 6 months of age using peripheral quantitative computed tomography (pQCT), microcomputed tomography (mCT), and biomechanical tests. COP rats had a significantly wider femoral head (P = 0.04) and neck (P = 0.007), significantly larger bone area and cortical bone area in femoral neck (P = 0.03 and P = 0.02, respectively), significantly greater total bone mineral content (BMC) and cortical BMC in femoral neck (P = 0.01 and P = 0.001, respectively), and 65% greater femoral neck cross-sectional moment of inertia (P = 0.02), as compared with DA rats. As a result, COP rats had 22% higher ultimate force (Fu), 68% higher ultimate displacement (du), and 81% higher work to failure (U) than DA rats in the femoral neck biomechanical test (P = 0.04, P = 0.01, and P = 0.02, respectively). The biomechanical properties for the femoral midshaft and lumbar vertebrae were virtually the same in the two rat strains, suggesting a hip-specific genetic effect on bone strength. These data indicate that significant phenotypic variation at the femoral neck site exists between these two inbred strains, and COP rats appear to have genes that specifically enhance the femoral neck structural properties and strength. Therefore these two inbred strains, COP with DA, may facilitate effective genetic studies of hip fragility.

Animals↗
PubMed2003

Congenic mice reveal sex-specific genetic regulation of femoral structure and strength.

Genetic linkage studies in C3H/HeJ (C3H) and C57BL/6J (B6) mice identified several chromosomal locations or quantitative trait loci (QTL) linked to femoral volumetric bone mineral density (vBMD). From QTL identified on chromosomes (chr) 1, 4, 6, 13, and 18, five congenic mouse strains were developed. In each of these mice, genomic DNA from the QTL region of the donor C3H strain was transferred into the recipient B6 strain. Here we report the effects of donated C3H QTL on femoral structure, cortical vBMD and bending strength. Femoral structure was quantified by the polar moment of inertia (Ip) at the mid-diaphysis, which reflects the bending or torsional rigidity of the femur. Although the C3H progenitor mice have a smaller Ip than B6 progenitor mice, the congenic mice carrying the C3H segment at Chr 4 had significantly increased Ip in both males and females, giving these mice stronger femora. In female mice from the congenic Chr 1 strain, Ip was increased whereas male mice from the Chr 1 strain had smaller femoral cross-sections and significantly reduced Ip. This sex-specific effect on femoral structure was seen to a lesser extent in Chr 18 congenic mice. In addition, cortical vBMD was measured using peripheral quantitative computed tomography. Cortical vBMD was similar among most congenic strains except in Chr 6 congenic mice, where cortical vBMD was significantly less in females, but not in males. We conclude that (1) chromosomal QTL from C3H mice, which are genetically linked to total femoral vBMD, also regulate femoral structure; (2) the QTL on Chr 4 improves femoral structure and strength; (3) QTL on Chr 1 and 18 impart sex-specific effects on femoral structure; and (4) the QTL on Chr 6 imparts a sex-specific effect on cortical vBMD and femoral strength.

Animals↗
PubMed2003

Biglycan-deficient mice have delayed osteogenesis after marrow ablation.

Biglycan (bgn) is a small proteoglycan in skeletal tissue that binds and regulates collagen and TGF-beta activities. Mice deficient in bgn (bgn-KO) develop age-dependent osteopenia and have multiple metabolic defects in their bone marrow stromal cells including increased apoptosis, reduced numbers of colony-forming units-fibroblastic (CFU-F) and decreased collagen production. In the present study we tested the hypothesis that bone formation capability in response to a physiological stress is compromised in bgn deficiency. We tested this theory using an in vivo bone marrow ablation assay. Ablation was performed on 6-week-old wild type (wt) and bgn-KO mice and bones were analyzed at days 7, 10, and 17 postsurgery. X-ray analysis showed that bone marrow ablation in femora induced vigorous new bone formation within 10 days in both genotypes but appeared greater in the wt compared to the bgn-KO. In order to quantitate the changes in bone formation in the ablated animals, bone densities of the proximal, midshaft, and distal femora were assessed using peripheral quantitative computed tomography (pQCT). The ratio of cancellous bone density at the midshaft (ablated limb/control limb) was significantly higher in wt compared to bgn-KO at day 10 postsurgery. Wt and bgn-KO femora had similar total and cancellous bone densities at days 7 and 17 postsurgery at all three locations indicating that the ablation effects were temporal and limited to the cancellous bone of the mid-shaft region. These data indicate that the absence of bgn directly impeded bone formation. Our results support the concept that bgn is important in controlling osteogenesis following marrow ablation.

Animals↗
PubMed2004

Growth of C57BL/6 mice and the material and mechanical properties of cortical bone from the tibia.

Murine models are becoming increasingly important for studying skeletal growth and regulation because of the relative ease with which their genomes can be manipulated. This study measured the changes in cortical bone of tibiae from one of the more common models, the C57Bl/6, as a function of aging. A total of 97 mice, male and female, were studied at the ages of 1, 2, 3, 6, 9, and 12 months. The body weight of the animals, the length of the tibiae, the composition (in terms of mineral and organic mass fractions), and the density and modulus of the bone were measured. Peripheral quantitative computed tomography was also used to measure bone mineral density (BMD), total and cortical areas, and the cross-sectional moment of inertia. Most parameters measured followed a growth-like curve, which leveled off some time before 6 months of age. Bone composition and modulus were the same at maturity in both sexes, but there were sex-related differences in the modulus with aging. Dimensional measurements and the density of the bone showed significant differences between male and female animals at all ages, with the male mice having larger values. Skeletal maturity for most factors in C57Bl/6 mice has been reached before the age of 6 months.

Aging↗
PubMed2005

Effects of pleiotrophin (PTN) over-expression on mouse long bone development, fracture healing and bone repair.

Pleiotrophin (PTN) was found to have potent effects on regulation of osteoblast recruitment, proliferation and differentiation. The present study examined the long-term effects of targeted PTN over-expression on bone development and repair in a transgenic mouse model. Femurs and tibiae from the PTN transgenic mice and the wild type mice at age 1, 2, 4, 6, 12 and 24 months were collected, and examined by radiography, peripheral quantitative computed tomography (pQCT), histology and mechanical testing. Age-matched PTN and the control mice received a standardized femoral fracture, followed by regular x-rays and sacrificed at day 16 post-fracture for histology examination. A cortical hole was drilled on the tibiae of age-matched PTN and wild type mice, collagen sponge with either saline, 100 ng of rhBMP-2 or rhPTN was implanted in the holes, and animals were sacrificed 10 days later, subject to pQCT and histology examinations. During early stages of bone development, the PTN mice had advanced bone growth in length and maturation, but the difference diminished in later life. The fracture healing was impaired in the PTN mice, and there was delayed callus formation and remodelling. The cortical holes treated with BMP-2 in the PTN mice had significantly less trabecular bone formation. The current study confirmed that the targeted PTN over-expression in mouse bone has moderate enhancing effects on early bone development; but the bones become brittle in later life. Fracture healing was impaired in the adult PTN mice and this may be due to inhibitory effects of PTN over-expression on BMP-2 mediated bone induction.

Animals↗
PubMed2000

Comparison of radiographic and pQCT analyses of healing rat tibial fractures.

Fracture healing and callus formation have traditionally been evaluated by using X-ray radiography. Here we compared X-ray radiography and peripheral quantitative computed tomography (pQCT) in evaluating the healing callus of standardized tibial fractures in 141 female rats after a 4- or 8-week follow-up. The results were compared with the tensile (4-week) and compressive (8-week) failure load of the callus. The projectional size of callus, as defined from lateral ex vivo radiographs, correlated significantly with the pQCT-defined cross-sectional area (CSA) of midcallus. This relationship was dependent on the pQCT attenuation threshold, being higher for the CSA of compact bone (r = 0.85, P < 0.0001) than for the total bone CSA (r = 0.68, P < 0.0001). Radiographically defined callus projectional area also correlated strongly with bone mineral content (BMC) (r = 0.84-0.86, P < 0.0001). The mean optical density of the callus analyzed from the radiographs had only a weak correlation with the pQCT-defined bone mineral density (BMD) of callus. A weak negative relationship was found between CSA and BMD. The optical density analyzed from lateral radiographs did not correlate with the tensile or compressive failure load of callus. Callus size, BMC, and BMD were associated with the compressive failure load, whereas both radiographs and pQCT were poor in explaining the failure load in tension.

Animals↗
PubMed1997

Can the fast bone loss in osteoporotic and osteopenic patients be stopped with active vitamin D metabolites?

The aim of this study was to evaluate whether fast trabecular bone loss in osteoporotic and osteopenic patients can effectively be treated with active vitamin D metabolites. Thirty-one osteoporotic and osteopenic patients were monitored between 4 and 22 months before and between 8 and 18 months during the treatment. Fast bone losers were designated as osteoporotic or osteopenic patients with a loss of trabecular bone density in the radius of 3% or more calculated for 1 year. For this differentiation, the high precise peripheral quantitative computed tomography system (DENSISCAN 1000) was used (reproducibility 0.3% in mixed collectives). The pretreatment loss and the "gain" under treatment with active vitamin D metabolites was calculated for 1 year. The treatment consisted of either 0.5 micro;g calcitriol daily or 1 micro;g of alfacalcidol daily. Before treatment, the trabecular bone loss in the radius/year was -6.6 +/- 0.5% (mean +/- SEM). After treatment with vitamin D metabolites, the trabecular bone gain in the radius/year was 0.01 +/- 0.6% (mean +/- SEM). The difference was highly significant (P < 0.001). In contrast to this, the loss of cortical bone density before treatment was -1.8 +/- 0.3% (mean +/- SEM) and the reduced loss after treatment -0.2 +/- 0.4% (mean +/- SEM), both values calculated for 1 year. This difference was less significant (P < 0. 05). This study shows that the treatment with active vitamin D metabolites is very effective in slowing fast trabecular bone loss in osteoporotic and osteopenic patients.

Aged↗
PubMed1997

Comparison of three bone densitometry methods in osteoporotic women.

Three techniques of bone mass measurement were evaluated in the diagnosis of postmenopausal osteoporosis; the overlap in the measurements and the capacity for discriminating was determined among 51 postmenopausal normal (mean age 66.6 +/- 8.4 years) and 42 postmenopausal osteoporotic women (mean age 68.5 +/- 7.5 years). All bone mass was evaluated by total body bone mineral content (BMCTB), density (BMDTB), ultrasound bone velocity (UBV) in proximal phalanxes 2-5 of the nondominant hand (UBV = mean value of all ultrasound measurements), and peripheral quantitative computed tomography of the nondominant forearm (pQCT). BMCTB was found to be significantly better (P < 0.0001) for diagnosing postmenopausal osteoporosis than the other methods; both cortical and trabecular pQCT measurements were more discriminating than the corresponding UBV measurements (P < 0.001). T-score values in normals, subjects versus osteoporotic ones were BMCTB -1.15 +/- 0.79 versus -3.17 +/- 0.74; BMDTB -1.01 +/- 0.97 versus -3.28 +/- 0.81; UBV -1.51 +/- 1.02 versus -2.34 +/- 1.21; trabecular-pQCT -0.40 +/- 0.72 versus -1.57 +/- 0.37; cortical-pQCT -1.00 +/- 0.87 versus -2.67 +/- 0.53; and total-pQCT -0.65 +/- 1.01 versus -2.34 +/- 0.27, respectively. The overlap in values between the postmenopausal normal and postmenopausal osteoporotic groups was 50% with UBV, 6% with BMCTB, 9% with BMDTB, 25% with cortical pQCT, and 42% with trabecular pQCT. BMCTB, BMDTB, UBV, and pQCT correlated well with each other as measurements of bone mass, but BMCTB was more discriminating than the other measurements in the diagnosis of osteoporosis.

Absorptiometry, Photon↗
PubMed1998

Measurement of forearm bone mineral density: comparison of precision of five different instruments.

Measurement of bone mineral density (BMD) is used for clinical estimation of fracture risk in osteoporosis. The precision of the method is important for the evaluation of true and clinical relevant changes in BMD in patients with osteoporosis. We measured BMD of the forearm in 14 young, healthy probands (10 males, 4 females), aged 24. 6 +/- 1.5 years with five different instruments using dual-energy X-ray absorptiometry (DXA), single-photon absorptiometry (SPA), and peripheral quantitative computed tomography (pQCT). Precision was expressed as the percentage coefficient of variation (CV%). In addition, the standardized CV% (sCV%) and the root mean square standard deviation (rmsSD%) was calculated for long-term precision. CV% ranged from 1.04 (SPA, distal BMD) to 2.75% (pQCT, trabecular BMD) for short-term precision and from 1.49 (DXA, QDR 1000, 1/3-distal BMD) to 4.33% (SPA, ultradistal) for long-term precision, respectively. The results for the rmsSD% were higher but correlated well with the CV%. A change that exceeds 2 radical2 CV% has been considered as being significant. On this basis, 24.0 +/- 5.1% (mean +/- SEM) of the participants in our study would be expected to have a significant change in BMD without any correlation to the time-delay between the two measurements. Measurements of BMD were done at two locations with all five instruments: ultradistal and middistal BMD using DXA and SPA and total and trabecular BMD using pQCT, respectively. Coefficients of correlation for "between-instrumental" correlation were greater than 0.5 for almost all instruments. Distal and ultradistal BMD measured by SPA and trabecular and total BMD measured by pQCT correlated better with ultradistal BMD measured by DXA. Correspondingly, "within-instrumental" correlation was better for pQCT and SPA than for DXA. The coefficients of correlation between the different DXA methods were greater than 0.95 when corresponding locations were compared. We conclude that the clinical value of monitoring bone loss by measurement of forearm BMD is compromised by the low precision which was seen for DXA methods as well as for SPA and even pQCT in young healthy controls.

Absorptiometry, Photon↗