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Quantitative Computed Tomography (quantitative + computed_tomography)
Kinds of Quantitative Computed Tomography Selected AbstractsDoes orthodontic loading influence bone mineral density around titanium miniplates?ORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 1 2010An experimental study in dogs To cite this article: Cornelis MA, Mahy P, Devogelaer JP, De Clerck HJ, Nyssen-Behets C: Does orthodontic loading influence bone mineral density around titanium miniplates? An experimental study in dogs Orthod Craniofac Res 2010;13:21,27 Structured Abstract Authors,,, Cornelis MA, Mahy P, Devogelaer JP, De Clerck HJ, Nyssen-Behets C Objectives,,, To evaluate whether orthodontic loading has an effect on miniplate stability and bone mineral density (BMD) around the screws supporting those miniplates. Setting and Sample Population,,, Two miniplates were inserted in each jaw quadrant of 10 dogs. Material and Methods,,, Two weeks later, coil springs were placed between the miniplates of one upper quadrant and between those of the contralateral lower quadrant. The other miniplates remained non-loaded. The dogs were sacrificed 7 or 29 weeks after surgery, and the jaws were scanned with peripheral Quantitative Computed Tomography (pQCT) to assess BMD. Results,,, The success rate was not significantly different for the loaded and the non-loaded miniplates, but was significantly higher for the maxillary compared to the mandibular ones. Mobility, associated with local inflammation, most often occurred during the transition between primary and secondary stability. pQCT showed higher BMD around mandibular vs. maxillary screws, without significant difference between loaded and non-loaded ones. Furthermore, load direction did not lead to any significant difference in BMD. Conclusion,,, Miniplate stability and BMD of the adjacent bone did not appear to depend significantly on orthodontic loading, but rather on the receptor site anatomy. [source] Correlates of trabecular and cortical volumetric bone mineral density of the radius and tibia in older men: The osteoporotic fractures in men studyJOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2010Kamil E Barbour Abstract Quantitative computed tomography (QCT) can estimate volumetric bone mineral density (vBMD) and distinguish trabecular from cortical bone. Few comprehensive studies have examined correlates of vBMD in older men. This study evaluated the impact of demographic, anthropometric, lifestyle, and medical factors on vBMD in 1172 men aged 69 to 97 years and enrolled in the Osteoporotic Fractures in Men Study (MrOS). Peripheral quantitative computed tomography (pQCT) was used to measure vBMD of the radius and tibia. The multivariable linear regression models explained up to 10% of the variance in trabecular vBMD and up to 9% of the variance in cortical vBMD. Age was not correlated with radial trabecular vBMD. Correlates associated with both cortical and trabecular vBMD were age (,), caffeine intake (,), total calcium intake (+), nontrauma fracture (,), and hypertension (+). Higher body weight was related to greater trabecular vBMD and lower cortical vBMD. Height (,), education (+), diabetes with thiazolidinedione (TZD) use (+), rheumatoid arthritis (+), using arms to stand from a chair (,), and antiandrogen use (,) were associated only with trabecular vBMD. Factors associated only with cortical vBMD included clinic site (,), androgen use (+), grip strength (+), past smoker (,), and time to complete five chair stands (,). Certain correlates of trabecular and cortical vBMD differed among older men. An ascertainment of potential risk factors associated with trabecular and cortical vBMD may lead to better understanding and preventive efforts for osteoporosis in men. © 2010 American Society for Bone and Mineral Research [source] Changes in Bone Density During Childhood and Adolescence: An Approach Based on Bone's Biological OrganizationJOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2001Frank Rauch Abstract Bone densitometry has great potential to improve our understanding of bone development. However, densitometric data in children rarely are interpreted in light of the biological processes they reflect. To strengthen the link between bone densitometry and the physiology of bone development, we review the literature on physiological mechanisms and structural changes determining bone mineral density (BMD). BMD (defined as mass of mineral per unit volume) is analyzed in three levels: in bone material (BMDmaterial), in a bone's trabecular and cortical tissue compartments (BMDcompartment), and in the entire bone (BMDtotal). BMDmaterial of the femoral midshaft cortex decreases after birth to a nadir in the first year of life and thereafter increases. In iliac trabecular bone, BMDmaterial also increases from infancy to adulthood, reflecting the decrease in bone turnover. BMDmaterial cannot be determined with current noninvasive techniques because of insufficient spatial resolution. BMDcompartment of the femoral midshaft cortex decreases in the first months after birth followed by a rapid increase during the next 2 years and slower changes thereafter, reflecting changes in both relative bone volume and BMDmaterial. Trabecular BMDcompartment increases in vertebral bodies but not at the distal radius. Quantitative computed tomography (QCT) allows for the determination of both trabecular and cortical BMDcompartment, whereas projectional techniques such as dual-energy X-ray absorptiometry (DXA) can be used only to assess cortical BMDcompartment of long bone diaphyses. BMDtotal of long bones decreases by about 30% in the first months after birth, reflecting a redistribution of bone tissue from the endocortical to the periosteal surface. In children of school age and in adolescents, changes in BMDtotal are site-specific. There is a marked rise in BMDtotal at locations where relative cortical area increases (metacarpal bones, phalanges, and forearm), but little change at the femoral neck and midshaft. BMDtotal can be measured by QCT at any site of the skeleton, regardless of bone shape. DXA allows the estimation of BMDtotal at skeletal sites, which have an approximately circular cross-section. The system presented here may help to interpret densitometric results in growing subjects on a physiological basis. [source] Quantitative computed tomography of the lumbar spine, not dual x-ray absorptiometry, is an independent predictor of prevalent vertebral fractures in postmenopausal women with osteopenia receiving long-term glucocorticoid and hormone-replacement therapyARTHRITIS & RHEUMATISM, Issue 5 2002Q. Rehman Objective To determine which measurement of bone mineral density (BMD) predicts vertebral fractures in a cohort of postmenopausal women with glucocorticoid-induced osteoporosis. Methods We recruited 114 subjects into the study. All had osteopenia of the lumbar spine or hip, as demonstrated by dual x-ray absorptiometry (DXA), and were receiving long-term glucocorticoids and hormone replacement therapy (HRT). Measurements of BMD by DXA of the lumbar spine, hip (and subregions), and forearm (and subregions), quantitative computed tomography (QCT) of the spine and hip (n = 59), and radiographs of the thoracolumbar spine were performed on all subjects to assess prevalent vertebral fractures. Vertebral fracture prevalence, as determined by morphometry, required a ,20% (or ,4-mm) loss of vertebral body height. Demographic information was obtained by questionnaire. Multiple regression and classification and regression trees (CART) analyses were used to assess predictors of vertebral fracture. Results Twenty-six percent of the study subjects had prevalent fractures. BMD of the lumbar spine, total hip and hip subregions, as measured by QCT, but only the lumbar spine and total hip, as measured by DXA, were significantly associated with prevalent vertebral fractures. However, only lumbar spine BMD as measured by QCT was a significant predictor of vertebral fractures. CART analysis showed that a BMD value <0.065 gm/cm3 was associated with a 7-fold higher risk of fracture than a BMD value ,0.065 gm/cm3. Conclusion In postmenopausal women with osteoporosis induced by long-term glucocorticoid treatment who are also receiving HRT, BMD of the lumbar spine as measured by QCT, but not DXA, is an independent predictor of vertebral fractures. [source] Fractal analysis of lumbar vertebral cancellous bone architectureCLINICAL ANATOMY, Issue 6 2001G.P. Feltrin Abstract Osteoporosis is characterized by bone mineral density (BMD) decreasing and spongy bone rearrangement with consequent loss of elasticity and increased bone fragility. Quantitative computed tomography (QCT) quantifies bone mineral content but does not describe spongy architecture. Analysis of trabecular pattern may provide additional information to evaluate osteoporosis. The aim of this study was to determine whether the fractal analysis of the microradiography of lumbar vertebrae provides a reliable assessment of bone texture, which correlates with the BMD. The lumbar segment of the spine was removed from 22 cadavers with no history of back pain and examined with standard x-ray, traditional tomography, and quantitative computed tomography to measure BMD. The fractal dimension, which quantifies the image fractal complexity, was calculated on microradiographs of axial sections of the fourth lumbar vertebra to determine its characteristic spongy network. The relationship between the values of the BMD and those of the fractal dimension was evaluated by linear regression and a statistically significant correlation (R = 0.96) was found. These findings suggest that the application of fractal analysis to radiological analyses can provide valuable information on the trabecular pattern of vertebrae. Thus, fractal dimensions of trabecular bone structure should be considered as a supplement to BMD evaluation in the assessment of osteoporosis. Clin. Anat. 6:414,417, 2001. © 2001 Wiley-Liss, Inc. [source] Compensatory bone remodelling in moose: a study of age, sex, and cross-sectional cortical bone dimensions in moose at Isle Royale National ParkINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 5 2002Mary Hindelang Abstract We studied interrelationships among age, sex, and cross-sectional cortical bone dimensions using quantitative computed tomography (QCT) scans of metatarsal bones of 180 moose (Alces alces) that died in Isle Royale National Park, Michigan. As a large-bodied quadruped with demanding ecological constraints on movement and behaviour, a moose experiences different weight-bearing and mechanical stressors than humans, to whom most existing studies of mechanical adaptations of bone pertain. In moose, both sexes showed significant subperiosteal expansion and an increase in medullary area, with an overall increase in cortical bone area over time. Female moose did not exhibit cortical thinning or reduction in cross-sectional area with age, rather they showed an increase in cortical bone area with periosteal apposition exceeding endosteal resorption, similar to the males. We also found that moose undergo changes in bone geometry through remodelling of bone similar to humans, suggesting a compensatory mechanism for increasing bone strength under conditions of decline in bone mineral density with age. Copyright © 2002 John Wiley & Sons, Ltd. [source] Bone microstructure at the distal tibia provides a strength advantage to males in late puberty: An HR-pQCT studyJOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2010Melonie Burrows Abstract Bone is a complex structure with many levels of organization. Advanced imaging tools such as high-resolution (HR) peripheral quantitative computed tomography (pQCT) provide the opportunity to investigate how components of bone microstructure differ between the sexes and across developmental periods. The aim of this study was to quantify the age- and sex-related differences in bone microstructure and bone strength in adolescent males and females. We used HR-pQCT (XtremeCT, Scanco Medical, Geneva, Switzerland) to assess total bone area (ToA), total bone density (ToD), trabecular bone density (TrD), cortical bone density (CoD), cortical thickness (Cort.Th), trabecular bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular spacing standard deviation (Tb.Sp SD), and bone strength index (BSI, mg2/mm4) at the distal tibia in 133 females and 146 males (15 to 20 years of age). We used a general linear model to determine differences by age- and sex-group and age,×,sex interactions (p,<,0.05). Across age categories, ToD, CoD, Cort.Th, and BSI were significantly lower at 15 and 16 years compared with 17 to 18 and 19 to 20 years in males and females. There were no differences in ToA, TrD, and BV/TV across age for either sex. Between sexes, males had significantly greater ToA, TrD, Cort.Th, BV/TV, Tb.N, and BSI compared with females; CoD and Tb.Sp SD were significantly greater for females in every age category. Males' larger and denser bones confer a bone-strength advantage from a young age compared with females. These structural differences could represent bones that are less able to withstand loads in compression in females. © 2010 American Society for Bone and Mineral Research [source] Correlates of trabecular and cortical volumetric bone mineral density of the radius and tibia in older men: The osteoporotic fractures in men studyJOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2010Kamil E Barbour Abstract Quantitative computed tomography (QCT) can estimate volumetric bone mineral density (vBMD) and distinguish trabecular from cortical bone. Few comprehensive studies have examined correlates of vBMD in older men. This study evaluated the impact of demographic, anthropometric, lifestyle, and medical factors on vBMD in 1172 men aged 69 to 97 years and enrolled in the Osteoporotic Fractures in Men Study (MrOS). Peripheral quantitative computed tomography (pQCT) was used to measure vBMD of the radius and tibia. The multivariable linear regression models explained up to 10% of the variance in trabecular vBMD and up to 9% of the variance in cortical vBMD. Age was not correlated with radial trabecular vBMD. Correlates associated with both cortical and trabecular vBMD were age (,), caffeine intake (,), total calcium intake (+), nontrauma fracture (,), and hypertension (+). Higher body weight was related to greater trabecular vBMD and lower cortical vBMD. Height (,), education (+), diabetes with thiazolidinedione (TZD) use (+), rheumatoid arthritis (+), using arms to stand from a chair (,), and antiandrogen use (,) were associated only with trabecular vBMD. Factors associated only with cortical vBMD included clinic site (,), androgen use (+), grip strength (+), past smoker (,), and time to complete five chair stands (,). Certain correlates of trabecular and cortical vBMD differed among older men. An ascertainment of potential risk factors associated with trabecular and cortical vBMD may lead to better understanding and preventive efforts for osteoporosis in men. © 2010 American Society for Bone and Mineral Research [source] Osteoblast-Specific Targeting of Soluble Colony-Stimulating Factor-1 Increases Cortical Bone Thickness in Mice,,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2003SL Abboud Abstract The soluble and membrane-bound forms of CSF-1 are synthesized by osteoblasts and stromal cells in the bone microenvironment. Transgenic mice, generated to selectively express sCSF-1 in bone, showed increased cortical thickness in the femoral diaphysis caused by new bone formation along the endosteal surface. The ability of sCSF-1 to enhance bone cell activity in vivo is potentially relevant for increasing cortical bone in a variety of disorders. Introduction: The soluble form of colony-stimulating factor-1 (sCSF-1) and the membrane-bound form of CSF-1 (mCSF-1) have been shown to support osteoclastogenesis in vitro; however, the effect of each peptide on bone remodeling in vivo is unclear. To determine the effect of sCSF-1, selectively expressed in bone, the skeletal phenotype of transgenic mice harboring the human sCSF-1 cDNA under the control of the osteocalcin promoter was assessed. Methods: At 5 and 14 weeks, mice were analyzed for CSF-1 protein levels, weighed, and X-rayed, and femurs were removed for peripheral quantitative computed tomography, histology, and histomorphometry. Results: High levels of human sCSF-1 were detected in bone extracts and, to a lesser extent, in plasma. Adult transgenic mice showed normal body weight and increased circulating monocytic cells. At 5 weeks, the femoral diaphysis was similar in CSF-1T and wt/wt littermates. However, by 14 weeks, the femoral diaphysis in CSF-1T mice showed increased cortical thickness and bone mineral density. In contrast to the diaphysis, the femoral metaphysis of CSF-1T mice showed normal cancellous bone comparable with wt/wt littermates at each time point. Histological sections demonstrated increased woven bone along the endosteal surface of the diaphysis and intracortical remodeling. Fluorochrome-labeling analysis confirmed endocortical bone formation in CSF-1T, with a 3.1-fold increase in the percentage of double-labeled surfaces and a 3.6-fold increase in the bone formation rate compared with wt/wt mice. Although remodeling resulted in a slightly porous cortex, sCSF-1 preferentially stimulated endocortical bone formation, leading to increased cortical thickness. Conclusions: These findings indicate that sCSF-1 is a key determinant of bone cell activity in the corticoendosteal envelope. [source] Adrenarche and Bone Modeling and Remodeling at the Proximal Radius: Weak Androgens Make Stronger Cortical Bone in Healthy Children,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2003Thomas Remer Abstract Adrenarche, the physiological increase in adrenal androgen secretion, may contribute to better bone status. Proximal radial bone and 24-h urinary steroid hormones were analyzed cross-sectionally in 205 healthy children and adolescents. Positive adrenarchal effects on radial diaphyseal bone were observed. Obviously, adrenarche is one determinant of bone mineral status in children. Introduction: Increased bone mass has been reported in several conditions with supraphysiological adrenal androgen secretion during growth. However, no data are available for normal children. Therefore, our aim was to examine whether adrenal androgens within their physiological ranges may be involved in the strengthening of diaphyseal bone during growth. Methods: Periosteal circumference (PC), cortical density, cortical area, bone mineral content, bone strength strain index (SSI), and forearm cross-sectional muscle area were determined with peripheral quantitative computed tomography (pQCT) at the proximal radial diaphysis in healthy children and adolescents. All subjects, aged 6,18 years, who collected a 24-h urine sample around the time of their pQCT analysis (100 boys, 105 girls), were included in the present study, and major urinary glucocorticoid (C21) and androgen (C19) metabolites were quantified using gas chromatography-mass spectrometry. Results and Conclusions: We found a significant influence of muscularity, but not of hormones, on periosteal modeling (PC) before the appearance of pubic hair (prepubarche). Similarly, no influence of total cortisol secretion (C21) was seen on the other bone variables. However, positive effects of C19 on cortical density (p < 0.01), cortical area (p < 0.001), bone mineral content (p < 0.001), and SSI (p < 0.001),reflecting, at least in part, reduction in intracortical remodeling,were observed in prepubarchal children after muscularity or age had been adjusted for. This early adrenarchal contribution to proximal radial diaphyseal bone strength was further confirmed for all cortical variables (except PC) when, instead of C19 and C21, specific dehydroepiandrosterone metabolites were included as independent variables in the multiple regression model. During development of pubic hair (pubarche), muscularity and pubertal stage rather than adrenarchal hormones seemed to influence bone variables. Our study shows that especially the prepubarchal increase in adrenal androgen secretion plays an independent role in the accretion of proximal radial diaphyseal bone strength in healthy children. [source] Effect of 8-Month Vertical Whole Body Vibration on Bone, Muscle Performance, and Body Balance: A Randomized Controlled Study,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 5 2003Saila Torvinen MD Abstract Recent animal studies have given evidence that vibration loading may be an efficient and safe way to improve mass and mechanical competence of bone, thus providing great potential for preventing and treating osteoporosis. Randomized controlled trials on the safety and efficacy of the vibration on human skeleton are, however, lacking. This randomized controlled intervention trial was designed to assess the effects of an 8-month whole body vibration intervention on bone, muscular performance, and body balance in young and healthy adults. Fifty-six volunteers (21 men and 35 women; age, 19-38 years) were randomly assigned to the vibration group or control group. The vibration intervention consisted of an 8-month whole body vibration (4 min/day, 3-5 times per week). During the 4-minute vibration program, the platform oscillated in an ascending order from 25 to 45 Hz, corresponding to estimated maximum vertical accelerations from 2g to 8g. Mass, structure, and estimated strength of bone at the distal tibia and tibial shaft were assessed by peripheral quantitative computed tomography (pQCT) at baseline and at 8 months. Bone mineral content was measured at the lumbar spine, femoral neck, trochanter, calcaneus, and distal radius using DXA at baseline and after the 8-month intervention. Serum markers of bone turnover were determined at baseline and 3, 6, and 8 months. Five performance tests (vertical jump, isometric extension strength of the lower extremities, grip strength, shuttle run, and postural sway) were performed at baseline and after the 8-month intervention. The 8-month vibration intervention succeeded well and was safe to perform but had no effect on mass, structure, or estimated strength of bone at any skeletal site. Serum markers of bone turnover did not change during the vibration intervention. However, at 8 months, a 7.8% net benefit in the vertical jump height was observed in the vibration group (95% CI, 2.8-13.1%; p = 0.003). On the other performance and balance tests, the vibration intervention had no effect. In conclusion, the studied whole body vibration program had no effect on bones of young, healthy adults, but instead, increased vertical jump height. Future human studies are needed before clinical recommendations for vibration exercise. [source] Bone Mineral Content per Muscle Cross-Sectional Area as an Index of the Functional Muscle-Bone Unit,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2002Eckhard Schoenau M.D. Abstract Bone densitometric data often are difficult to interpret in children and adolescents because of large inter- and intraindividual variations in bone size. Here, we propose a functional approach to bone densitometry that addresses two questions: Is bone strength normally adapted to the largest physiological loads, that is, muscle force? Is muscle force adequate for body size? To implement this approach, forearm muscle cross-sectional area (CSA) and bone mineral content (BMC) of the radial diaphysis were measured in 349 healthy subjects from 6 to 19 years of age (183 girls), using peripheral quantitative computed tomography (pQCT). Reference data were established for height-dependent muscle CSA and for the variation with age in the BMC/muscle CSA ratio. These reference data were used to evaluate results from three pediatric patient groups: children who had sustained multiple fractures without adequate trauma (n = 11), children with preterminal chronic renal failure (n = 11), and renal transplant recipients (n = 15). In all three groups mean height, muscle CSA, and BMC were low for age, but muscle CSA was normal for height. In the multiple fracture group and in renal transplant recipients the BMC/muscle CSA ratio was decreased (p < 0.05), suggesting that bone strength was not adapted adequately to muscle force. In contrast, chronic renal failure patients had a normal BMC/muscle CSA ratio, suggesting that their musculoskeletal system was adapted normally to their (decreased) body size. This functional approach to pediatric bone densitometric data should be adaptable to a variety of densitometric techniques. [source] Glucocorticoid Excess During Adolescence Leads to a Major Persistent Deficit in Bone Mass and an Increase in Central Body FatJOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2001Veronica Abad Abstract Endogenous Cushing's syndrome (CS) in children causes growth retardation, decreased bone mass, and increased total body fat. No prospective controlled studies have been performed in children to determine the long-term sequelae of CS on peak bone mass and body composition. A 15-year-old girl with Cushing disease (CD), and her healthy identical co-twin, were followed for 6 years after the CD was cured. At the 6-year follow-up both twins had areal bone mineral density (BMD) and body composition determined by dual-energy X-ray absorptiometry (DXA) and three-dimensional quantitative computed tomography (3DQCT). Z scores for height, weight, and body mass index (BMI) were ,2.3, ,0.8 and 0.2, and 1.2, 0.2, and ,0.6, in the twin with CD and her co-twin, respectively. In the twin with CD, areal BMD and bone mineral apparent density (BMAD) at different sites varied from 0.7 to 3 SD below her co-twin. Volumetric lumbar spine bone density Z score was ,0.75 and 1.0, and total body, abdominal visceral, and subcutaneous fat (%) was 42, 10, and 41 versus 26, 4, and 17 in the twin with CD and her co-twin, respectively. The relationship between total body fat and L2-L4 BMAD was inverse in the twin with CD (p < 0.05), which by contrast in her co-twin was opposite and direct (p < 0.001). In the twin with CD, despite cure, there was a persistent deficit in bone mass and increase in total and visceral body fat. These observations suggest that hypercortisolism (exogenous or endogenous) during adolescence may have persistent adverse effects on bone and fat mass. [source] Mice Lacking the Plasminogen Activator Inhibitor 1 Are Protected from Trabecular Bone Loss Induced by Estrogen DeficiencyJOURNAL OF BONE AND MINERAL RESEARCH, Issue 8 2000E. Daci Abstract Bone turnover requires the interaction of several proteases during the resorption phase. Indirect evidence suggests that the plasminogen activator/plasmin pathway is involved in bone resorption and turnover, and recently we have shown that this cascade plays a role in the degradation of nonmineralized bone matrix in vitro. To elucidate the role of the plasminogen activator inhibitor 1 (PAI-1) in bone turnover in vivo, bone metabolism was analyzed in mice deficient in the expression of PAI-1 gene (PAI-1,/,) at baseline (8-week-old mice) and 4 weeks after ovariectomy (OVX) or sham operation (Sham) and compared with wild-type (WT) mice. PAI-1 inactivation was without any effect on bone metabolism at baseline or in Sham mice. However, significant differences were observed in the response of WT and PAI-1,/, mice to ovariectomy. The OVX WT mice showed, as expected, decreased trabecular bone volume (BV/TV) and increased osteoid surface (OS/BS) and bone formation rate (BFR), as assessed by histomorphometric analysis of the proximal tibial metaphysis. In contrast, no significant change in any of the histomorphometric variables studied was detected in PAI-1,/, mice after ovariectomy. As a result, the OVX PAI-1,/, had a significantly higher BV/TV, lower OS/BS, lower mineral apposition rate (MAR) and BFR when compared with the OVX WT mice. However, a comparable decrease in the cortical thickness was observed in OVX PAI-1,/, and WT mice. In addition, the cortical mineral content and density assessed in the distal femoral metaphysis by peripheral quantitative computed tomography (pQCT), decreased significantly after ovariectomy, without difference between PAI-1,/, mice and WT mice. In conclusion, basal bone turnover and bone mass are only minimally affected by PAI-1 inactivation. In conditions of estrogen deficiency, PAI-1 inactivation protects against trabecular bone loss but does not affect cortical bone loss, suggesting a site-specific role for PAI-1 in bone turnover. [source] In vivo ultra-high-field magnetic resonance imaging of trabecular bone microarchitecture at 7 TJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2008Roland Krug PhD Abstract Purpose To investigate the feasibility of 7T magnetic resonance imaging (MRI) to visualize and quantify trabecular bone structure in vivo by comparison with 3T MRI and in vivo three-dimensional (3D) high-resolution peripheral quantitative computed tomography (HR-pQCT). Materials and Methods The distal tibiae of 10 healthy volunteers were imaged. Therefore, fully balanced steady state free precession (bSSFP) and spin-echo (bSSSE) pulse sequences were implemented and optimized for 7T. Structural bone parameters, such as apparent bone-volume over total-volume fraction (app.BV/TV), apparent trabecular plate separation (app.TbSp), apparent trabecular plate thickness (app.TbTh), and apparent trabecular plate number (app.TbN), were derived. Results All structural trabecular bone parameters correlated well (r > 0.6) between 7T and 3T, and between 7T and HR-pQCT (r > 0.69), with the exception of app.TbTh, which correlated modestly (r = 0.41) between field strengths and very low with HR-pQCT (r < 0.16). Regarding absolute values, app.TbN varied only 4% between field strengths, and only 0.6% between 7T and HR-pQCT. App.TbSp correlated best between 7T and HR-pQCT (r = 0.89). Using bSSSE, significant smaller trabecular thickness and significant higher trabecular number were found compared to bSSFP. Conclusion We concluded that imaging and quantification of the trabecular bone architecture at 7T is feasible and preferably done using bSSSE. There exists great potential for ultra-high-field (UHF) MRI applied to trabecular bone measurements. J. Magn. Reson. Imaging 2008;27:854,859. © 2008 Wiley-Liss, Inc. [source] Biomechanical evaluation of healing in a non-critical defect in a large animal model of osteoporosisJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2003C. A. Lill Abstract Current methods for fracture treatment in osteoporosis are not always sufficient. To develop new fixation strategies (both mechanical and biological) requires pre-clinical testing utilizing appropriate models. The aim of this study was to apply a recently developed sheep model of osteoporosis to the study of healing in a non-critical long bone defect. A standardized transverse mid-shaft tibial osteotomy (with a fracture gap of 3 mm) was performed in seven osteoporotic and seven normal sheep and stabilized with a special external fixator for 8 weeks. The fixator was used for weekly in vivo bending stiffness measurements. Ex vivo bending stiffness and torsional stiffness of the callus zone were also determined. Callus area, callus density, and osteoporosis status were determined at 0, 4, and 8 weeks using peripheral quantitative computed tomography. The increase of in vivo bending stiffness of the callus was delayed approximately 2 weeks in osteoporotic animals. A significant difference (33%) in torsional stiffness was found between the osteotomized and contralateral intact tibia in osteoporotic animals, but no significant difference occurred in normal sheep (2%). In osteoporotic animals, ex vivo bending stiffness was reduced 21% (p = 0.05). Bending stiffness was correlated with callus density (r = 0.76, r = 0.53); torsional stiffness was correlated with callus area (r = 0.60) and to a lesser extent with callus density (r = 0.53). This study demonstrated a delay of fracture healing in osteoporotic sheep tibiae with respect to callus formation, mineralization, and mechanical properties. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Habitual throwing and swimming correspond with upper limb diaphyseal strength and shape in modern human athletesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Colin N. Shaw Abstract Variation in upper limb long bone cross-sectional properties may reflect a phenotypically plastic response to habitual loading patterns. Structural differences between limb bones have often been used to infer past behavior from hominin remains; however, few studies have examined direct relationships between behavioral differences and bone structure in humans. To help address this, cross-sectional images (50% length) of the humeri and ulnae of university varsity-level swimmers, cricketers, and controls were captured using peripheral quantitative computed tomography. High levels of humeral robusticity were found in the dominant arms of cricketers, and bilaterally among swimmers, whereas the most gracile humeri were found in both arms of controls, and the nondominant arms of cricketers. In addition, the dominant humeri of cricketers were more circular than controls. The highest levels of ulnar robusticity were also found in the dominant arm of cricketers, and bilaterally amongst swimmers. Bilateral asymmetry in humeral rigidity among cricketers was greater than swimmers and controls, while asymmetry for ulnar rigidity was greater in cricketers than controls. The results suggest that more mechanically loaded upper limb elements,,unilaterally or bilaterally,,are strengthened relative to less mechanically loaded elements, and that differences in mechanical loading may have a more significant effect on proximal compared to distal limb segments. The more circular humerus in the dominant arm in cricketers may be an adaptation to torsional strain associated with throwing activities. The reported correspondence between habitual activity patterns and upper limb diaphyseal properties may inform future behavioral interpretations involving hominin skeletal remains. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] Local ex vivo gene therapy with bone marrow stromal cells expressing human BMP4 promotes endosteal bone formation in miceTHE JOURNAL OF GENE MEDICINE, Issue 1 2004Xiao S. Zhang Abstract Background Bone loss in osteoporosis is caused by an imbalance between resorption and formation on endosteal surfaces of trabecular and cortical bone. We investigated the feasibility of increasing endosteal bone formation in mice by ex vivo gene therapy with bone marrow stromal cells (MSCs) transduced with a MLV-based retroviral vector to express human bone morphogenetic protein 4 (BMP4). Methods We assessed two approaches for administering transduced MSCs. ,-Galactosidase (,-Gal) transduced C57BL/6J mouse MSCs were injected intravenously via tail vein or directly injected into the femoral bone marrow cavity of non-marrow-ablated syngenic recipient mice and bone marrow cavity engraftment was assessed. BMP4- or ,-Gal-transduced cells were injected into the femoral bone marrow cavity and effects on bone were evaluated by X-ray, peripheral quantitative computed tomography (pQCT), and histology. Results After tail-vein injection less than 20% of recipient mice contained ,-Gal-positive donor cells in femur, humerus or vertebra marrow cavities combined, and in these mice only 0.02,0.29% of injected cells were present in the bone marrow. In contrast, direct intramedullary injection was always successful and an average of 2% of injected cells were present in the injected femur marrow cavity 24 hours after injection. Numbers of donor cells decreased over the next 14 days. Intramedullary injection of BMP4-transduced MSCs induced bone formation. Trabecular bone mineral density (BMD) determined by pQCT increased 20.5% at 14 days and total BMD increased 6.5% at 14 days and 10.4% at 56 days. Conclusions The present findings support the feasibility of using ex vivo MSC-based retroviral gene therapy to induce relatively sustained new bone formation, with normal histological appearance, at endosteal bone sites. Copyright © 2004 John Wiley & Sons, Ltd. [source] Tibial subchondral trabecular volumetric bone density in medial knee joint osteoarthritis using peripheral quantitative computed tomography technologyARTHRITIS & RHEUMATISM, Issue 9 2008Kim L. Bennell Objective Knee osteoarthritis (OA) is an organ-level failure of the joint involving pathologic changes in articular cartilage and bone. This cross-sectional study compared apparent volumetric bone mineral density (vBMD) of proximal tibial subchondral trabecular bone in people with and without knee OA, using peripheral quantitative computed tomography (pQCT). Methods Seventy-five individuals with mild or moderate medial compartment knee OA and 41 asymptomatic controls were recruited. Peripheral QCT was used to measure vBMD of trabecular bone beneath medial and lateral tibiofemoral compartments at levels of 2% and 4% of tibial length, distal to the tibial plateau. Results There was no significant difference in vBMD beneath the overall medial and lateral compartments between the 3 groups. However, in the affected medial compartment of those with moderate OA, lower vBMD was seen in the 2 posterior subregions compared with controls and those with mild knee OA, while higher vBMD was seen in the anteromedial subregion. Beneath the unaffected or lesser affected lateral compartment, significantly lower vBMD was seen at the 2% level in the anterior and lateral subregions of those with moderate disease. Volumetric BMD ratios showed relatively higher vBMD in the medial compartment compared with the lateral compartment, but these ratios were not influenced by disease status. Conclusion Subregional vBMD changes were evident beneath the medial and lateral compartments of those with moderate medial knee OA. Of import, the posterior subchondral trabecular regions of the medial tibial plateau have markedly lower vBMD. [source] Musculoskeletal abnormalities of the tibia in juvenile rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 3 2007Elena M. O. Felin Objective To characterize local bone geometry, density, and strength, using peripheral quantitative computed tomography (pQCT), compared with general bone characteristics as measured using dual x-ray absorptiometry (DXA), and to assess their relationship to disease-related factors in children with juvenile rheumatoid arthritis (JRA). Methods Forty-eight children ages 4,18 years with JRA (17 pauciarticular, 23 polyarticular, 8 systemic) were compared with age-matched healthy controls (n = 266). Measurements included cortical and trabecular bone geometry, density, and strength at the distal and midshaft tibia determined by pQCT, and whole-body, lumbar spine, and femoral neck measurements by DXA. Results Methotrexate (MTX) was prescribed to 23 of 48 patients (47.9%) and glucocorticoids and MTX were prescribed to 15 of 48 patients (31.3%), with the greatest use in children with systemic JRA. All JRA patients had decreased tibia trabecular bone density, cortical bone size and strength, and muscle mass. Children with systemic JRA had lower femoral neck densities. Systemic JRA was associated with a shorter, less mineralized skeleton, while a narrower, less mineralized skeleton was observed in polyarticular JRA. The tibia diaphysis was narrower with decreased muscle mass, but normal, size-adjusted bone mineral in all subtypes indicated a localized effect of JRA on bone. Patients exposed to glucocorticoids and MTX or to glucocorticoids or MTX alone had greatly reduced trabecular density, cortical bone geometry properties, and bone mineral content, muscle mass, and bone strength. Conclusion Children with JRA have decreased skeletal size, muscle mass, trabecular bone density, cortical bone geometry, and strength. Not surprisingly, these bone abnormalities are more pronounced in children with greater disease severity. [source] Quantitative computed tomography of the lumbar spine, not dual x-ray absorptiometry, is an independent predictor of prevalent vertebral fractures in postmenopausal women with osteopenia receiving long-term glucocorticoid and hormone-replacement therapyARTHRITIS & RHEUMATISM, Issue 5 2002Q. Rehman Objective To determine which measurement of bone mineral density (BMD) predicts vertebral fractures in a cohort of postmenopausal women with glucocorticoid-induced osteoporosis. Methods We recruited 114 subjects into the study. All had osteopenia of the lumbar spine or hip, as demonstrated by dual x-ray absorptiometry (DXA), and were receiving long-term glucocorticoids and hormone replacement therapy (HRT). Measurements of BMD by DXA of the lumbar spine, hip (and subregions), and forearm (and subregions), quantitative computed tomography (QCT) of the spine and hip (n = 59), and radiographs of the thoracolumbar spine were performed on all subjects to assess prevalent vertebral fractures. Vertebral fracture prevalence, as determined by morphometry, required a ,20% (or ,4-mm) loss of vertebral body height. Demographic information was obtained by questionnaire. Multiple regression and classification and regression trees (CART) analyses were used to assess predictors of vertebral fracture. Results Twenty-six percent of the study subjects had prevalent fractures. BMD of the lumbar spine, total hip and hip subregions, as measured by QCT, but only the lumbar spine and total hip, as measured by DXA, were significantly associated with prevalent vertebral fractures. However, only lumbar spine BMD as measured by QCT was a significant predictor of vertebral fractures. CART analysis showed that a BMD value <0.065 gm/cm3 was associated with a 7-fold higher risk of fracture than a BMD value ,0.065 gm/cm3. Conclusion In postmenopausal women with osteoporosis induced by long-term glucocorticoid treatment who are also receiving HRT, BMD of the lumbar spine as measured by QCT, but not DXA, is an independent predictor of vertebral fractures. [source] Fractal analysis of lumbar vertebral cancellous bone architectureCLINICAL ANATOMY, Issue 6 2001G.P. Feltrin Abstract Osteoporosis is characterized by bone mineral density (BMD) decreasing and spongy bone rearrangement with consequent loss of elasticity and increased bone fragility. Quantitative computed tomography (QCT) quantifies bone mineral content but does not describe spongy architecture. Analysis of trabecular pattern may provide additional information to evaluate osteoporosis. The aim of this study was to determine whether the fractal analysis of the microradiography of lumbar vertebrae provides a reliable assessment of bone texture, which correlates with the BMD. The lumbar segment of the spine was removed from 22 cadavers with no history of back pain and examined with standard x-ray, traditional tomography, and quantitative computed tomography to measure BMD. The fractal dimension, which quantifies the image fractal complexity, was calculated on microradiographs of axial sections of the fourth lumbar vertebra to determine its characteristic spongy network. The relationship between the values of the BMD and those of the fractal dimension was evaluated by linear regression and a statistically significant correlation (R = 0.96) was found. These findings suggest that the application of fractal analysis to radiological analyses can provide valuable information on the trabecular pattern of vertebrae. Thus, fractal dimensions of trabecular bone structure should be considered as a supplement to BMD evaluation in the assessment of osteoporosis. Clin. Anat. 6:414,417, 2001. © 2001 Wiley-Liss, Inc. [source] | |||||||||||||