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PubMed1997

Bone density variation and its effects on risk of vertebral deformity in men and women studied in thirteen European centers: the EVOS Study.

In Europe there is a 3-fold variation, according to geographical center, in risk of vertebral deformity in men and women over the age of 50. We investigated the relationship between bone density, as assessed by dual-energy X-ray absorptiometry (DEXA) of the spine and hip and prevalent vertebral deformities in 13 of the 36 centers participating in the European Vertebral Osteoporosis Study (EVOS). Each center recruited an age-stratified sample of men and women aged 50 years and over, and of those who agreed to densitometry, 288/2088 women and 233/1908 men were found to have one or more deformities of the vertebrae between T4 and L4 as assessed by the McCloskey algorithm. DEXA was in each case performed on L2-L4, the proximal femur, or both. Bone densitometry results were cross-calibrated between centers using the European Spine Phantom prototype and results expressed as bone mineral density (BMD, g/cm2). In both genders, subjects with deformities involving loss of anterior vertebral body height alone comprised over 20% of the total with deformities and these related poorly to BMD. Other classes of deformity were found by logistic regression to relate significantly to BMD in one or both genders, with odds ratios for the risk of any of these ranging from 1.67 to 2.11 for a 1 SD reduction in bone density at spine, femoral neck, or trochanter (p < 0.001). Adjusting for anthropometric variables and BMD did not remove the effect of age on risk which rose 1.67- to 1.78-fold per decade according to gender. The greater unadjusted rate of increase in deformity risk with age in women was attributable to their faster rate of bone loss with age; after adjusting for age, body mass index (BMI), and BMD at the trochanter in grams per square centimeter, men had a 2-fold higher risk of deformity than women. Analysis of the relationship between mean bone density and the prevalence of deformity in each center demonstrated no significant differences between centers in either gender, after adjusting for BMD, age, and BMI together with an a posteriori statistical adjustment for imperfect cross-calibration of densitometers. It is concluded that BMD is an important determinant of deformity risk in both genders. Together with age, BMD explains much of the differences in risk both between the sexes and between individual geographical centers in Europe.

Aged↗

PubMed2000

Exercise-induced bone gain is due to enlargement in bone size without a change in volumetric bone density: a peripheral quantitative computed tomography study of the upper arms of male tennis players.

Bilateral bone characteristics of the humerus (proximal, shaft, and distal sites) and radius (shaft and distal sites) in 12 former Finnish national-level male tennis players (mean age 30 years) and their 12 age-, height-, and weight-matched controls were measured with peripheral quantitative computed tomography (pQCT). The pQCT variables analyzed were bone mineral content (BMC), total cross-sectional area of bone (Tot.Ar), cross-sectional area of the marrow cavity (M.Cav.Ar), cortical bone (Co.Ar) and trabecular bone (Tr.Ar), volumetric density of cortical (Co.Dn) and trabecular (Tr. Dn) bone, cortical wall thickness (Co.Wi.Th), bone strength index (BSI), and principal moments of inertia (I(min) and I(max)). In the players, significant side-to-side differences, in favor of the dominant (playing) arm, were found in BMC (ranging 14%-27%), Tot.Ar (16%-21%), Co.Ar (12%-32%), BSI (23%-37%), I(min) (33%-61%), and I(max) (27%-67%) at all measured bone sites, and in Co.Wi.Th. (5%-25%) at the humeral and radial shafts, and distal humerus. The side-to-side M.Cav.Ar difference was significant at the proximal humerus (19%) and radial shaft (29%). Concerning the players' Co.Dn and Tr.Dn, the only significant side-to-side difference was found in the Co.Dn of the distal humerus, with the playing arm showing a slightly smaller Co.Dn than the nonplaying arm (-2%). In controls, significant dominant-to-nondominant side differences were also found, but with the majority of the differences being rather small, and significantly lower than those of the players. In conclusion, despite the large side-to-side differences in BMC, the volumetric bone density (Co.Dn, Tr.Dn) was almost identical in the dominant and nondominant arms of the players and controls. Thus, the players' high playing-arm BMC was due to increases in the Tot.Ar, M.Cav.Ar, Co.Ar, and CW.Th. In other words, the playing arm's extra bone mineral, and thus increased bone strength, was mainly due to increased bone size and not due to a change in volumetric bone density. These upper arm results may not be generalized to the entire skeleton, but the finding may give new insight into conventional dual-energy X-ray absorptiometry (DXA)-based bone density measurements when interpreting the effects of exercise on bone.

Adult↗

PubMed1997

Osteoprotegerin: a novel secreted protein involved in the regulation of bone density.

A novel secreted glycoprotein that regulates bone resorption has been identified. The protein, termed Osteoprotegerin (OPG), is a novel member of the TNF receptor superfamily. In vivo, hepatic expression of OPG in transgenic mice results in a profound yet nonlethal osteopetrosis, coincident with a decrease in later stages of osteoclast differentiation. These same effects are observed upon administration of recombinant OPG into normal mice. In vitro, osteoclast differentiation from precursor cells is blocked in a dose-dependent manner by recombinant OPG. Furthermore, OPG blocks ovariectomy-associated bone loss in rats. These data show that OPG can act as a soluble factor in the regulation of bone mass and imply a utility for OPG in the treatment of osteoporosis associated with increased osteoclast activity.

Amino Acid Sequence↗

PubMed2001

Bone density, ultrasound measurements and body composition in early ankylosing spondylitis.

OBJECTIVES: In this cross-sectional study, we evaluated bone density using both dual-energy X-ray absorptiometry (DEXA) and quantitative ultrasound (QUS) techniques and examined the changes in body composition in patients with ankylosing spondylitis (AS). METHODS: Seventy-one patients were compared with seventy-one sex- and age-matched controls. Bone mineral density (BMD) was evaluated at the lumbar spine and femoral neck with a Lunar device. Total body measurements were also performed, giving BMD and bone mineral content (BMC) of the whole body, and fat and lean masses. Broadband ultrasound attenuation (BUA), speed of sound and stiffness were measured at the calcaneus using an Achilles ultrasound device. RESULTS: The patients had significantly lower lumbar spine, femoral neck and total body BMD as compared with controls (all P < 0.05). Total body BMC was also decreased in AS (P = 0.002). On the contrary, fat and lean masses did not differ between patients and controls as observed for QUS values. Mild to good correlations were found between BMD and QUS parameters (r ranging from 0.22 to 0.53; all P < or = 0.01). When applying the World Health Organization (WHO) definition for osteoporosis, we found that 46.5% of patients had lumbar spine osteopenia and/or osteoporosis, while 26.8% had femoral neck osteopenia and/or osteoporosis (controls: 23.9 and 10%; P = 0.001 and 0.08, respectively). No relationships between disease activity (as evaluated by erythrocyte sedimentation rate, serum C-reactive protein levels and BASDAI, a clinical index of disease activity) and BMD measurements were found and only femoral neck BMD correlated with disease duration (r = -0.25; P = 0.04). Finally, the presence of talalgia in AS did not influence the QUS values. CONCLUSION: These results confirm that AS patients have decreased BMD values at both the spine and femur, and also in total body measurements, reflecting a generalized bone loss. On the contrary, soft tissue composition does not seem to be influenced by the disease. QUS parameters were found to be similar between patients and controls, suggesting that the QUS method did not provide additive information to DEXA. As it is thought that QUS provides information about qualitative properties of bone, the normal results of QUS values in our patient series argue against modifications in AS bone micro-architecture.

Absorptiometry, Photon↗

PubMed2000

The Canadian SCORE questionnaire: optimizing the use of technology for low bone density assessment. Simple Calculated Osteoporosis Risk Estimate.

The Simple Calculated Osteoporosis Risk Estimation (SCORE) questionnaire is a tool to assist physicians to identify women who might require bone densitometry. The purpose of this study was to develop a Canadian SCORE and to assess validity and reliability. Twenty sites enrolled 307 postmenopausal women ages 50-70 yr. SCORE results were compared to hip and lumbar spine bone density assessed by dual X-ray absorptiometry. Sensitivity and specificity of a range of SCORE cut-points were assessed in a receiver operating characteristics analysis to determine the optimal cut-point for SCORE. With low bone density defined as a T-score < or = -2.0, a SCORE cut-point of 6 in women ages 50-59 yr displayed a sensitivity of 0. 96, 95% confidence interval (CI) (0.89, 1.00), a specificity of 0.51, 95% CI (0.43, 0.58). In women ages 60-70 yr, a SCORE cut-point of 8 displayed a sensitivity of 0.90, 95% CI (0.80, 0.97) and a specificity of 0.20, 95% CI (0.11, 0.29). The test-retest reliability (intraclass correlation coefficient) was 0.95. SCORE performed better in women in their fifties than women in ther sixties. Older women require higher SCORE cut-points. The use of SCORE as an initial measure for identifying those at risk for osteoporosis may reduce costs by limiting unnecessary tests.

Absorptiometry, Photon↗

PubMed1998

Vitamin D and bone mineral density.

Bone mineral density (BMD) at the lumbar spine and the neck of femur and serum concentrations of 25-hydroxyvitamin D (25OHD), intact parathyroid hormone (PTH), alkaline phosphatase, calcium, albumin, creatinine and phosphate were measured in a group of 166 postmenopausal women (30-79 years) attending a bone clinic for bone density measurements. Four subjects with suspected primary hyperparathyroidism were excluded from analysis. BMD at the lumbar spine was correlated with body mass index (BMI) (r = 0.278, p = 0.0003), age (r = -0.194, p = 0.0134) and serum 25OHD (r = 0.188, p = 0.0167). BMD at the neck of femur correlated with BMI (r = 0.391, p < 0.0001), age (r = -0.356, p < 0.0001), PTH (r = -0.156, p = 0.047) and serum 25OHD (r = 0.231, p = 0.0031). Stepwise multiple regression analysis showed that age, BMI and serum 25OHD contributed to the variation in BMD at lumbar spine. At the neck of femur, PTH was an additional contributor. We conclude that serum 25OHD makes a contribution to BMD a lumbar spine and neck of femur.

Adult↗

PubMed1995

The effect of three hormone replacement regimens on bone density in the aged ovariectomized rat.

OBJECTIVE: To investigate the effects of estrogen (E) alone or with cyclic, continuous, or interrupted P regimens on bone density in an aged rat model. DESIGN: Randomized controlled trial. ANIMALS: Twenty 12-month-old female Sprague-Dawley rats were sham operated (intact control) and 100 were ovariectomized (OVX). INTERVENTION: Four groups of 20 OVX rats were implanted with silastic capsules containing 5% E2 (wt/wt) in cholesterol. All rats in the intact control (group 1), OVX (group 2), and the first of the OVX plus E groups (group 3) were injected subcutaneously daily for 6 months with corn oil (vehicle). Three other groups of rats with E capsules received daily injections of norethindrone in corn oil, according to the following dosage schedules: 6 micrograms norethindrone/rat per day for 2 of every 4 weeks (cyclic; group 4); 3 micrograms norethindrone/rat per day every day (continuous; group 5); or 3 micrograms norethindrone/rat per day for 3 of every 6 days (interrupted; group 6). MAIN OUTCOME MEASURES: Bone mineral content (BMC) and bone mineral density (BMD) in the femur and vertebrae were measured by dual-energy roentgenogram absorptiometry. RESULTS: The OVX rats (group 2) receiving corn oil alone had the lowest BMD. Intact controls (group 1), E plus cyclic P (group 4), and E and interrupted P (group 6) were all similar and had significantly greater bone density in the vertebrae than the OVX controls. In contrast, vertebral BMD with E alone (group 3) and continuous E and P (group 5) was not significantly different from the OVX group. Femur BMD was significantly lower in the OVX group compared with the other five groups, which did not differ significantly from each other. CONCLUSION: In this experimental model, compared with OVX controls, combined hormone replacement therapy with E and cyclic or interrupted P resulted in the best vertebral BMD whereas continuous E and P resulted in the worst BMD. In the femurs, E alone and E plus P had equal effects on BMD.

Adrenal Glands↗

PubMed1985

A gamma-ray computed tomography scanner for the quantitative measurement of bone density.

A special purpose gamma-ray computed tomography scanner has been developed for the precise measurement of bone density in the distal forearm. Details of the scanner hardware and computer analysis technique are given. Suitable phantoms have been used to test the operation of the scanner, which has been used to measure trabecular and cortical bone density with a precision better than 1%.

Biomedical Engineering↗

PubMed2005

Large variations occur in bone density measurements of children when using different software.

BACKGROUND: Paediatric dual X-ray absorptiometry (DXA) studies present a number of technical problems. One of these is that the edge detection algorithms designed for the adult skeleton may fail for paediatric studies. Hologic provide alternative algorithms for low bone density studies. AIM: To assess low-density software for the analysis of paediatric DXA studies and to compare with the adult protocol. METHODS: Our centre has scanned 450 normal children as part of a normal range study. A subgroup of 103 children was selected using a random number generator. The group was distributed evenly between males and females and across the age range 5-17 years. Each individual underwent both a lumbar spine and a whole-body scan on a Hologic QDR-4500W DXA scanner. Both scans were analysed using the standard adult protocol and then re-analysed using the Hologic experimental paediatric protocol for whole body and the Hologic low-density protocol for lumbar spine. RESULTS: Both lumbar spine protocols showed an increase in bone mineral density with age; however, the low-density protocol always produced a lower bone mineral density result than the adult protocol. Bland-Altman analysis showed limits of agreement of 0.031-0.093 g x cm(-2) (male, 0.032-0.089 g x cm(-2); female, 0.031-0.096 g x cm(-2)). This represents a mean difference of 9%. Five results showed differences greater than the upper limit of agreement. All these cases were children under 11 years of age who had large areas of spine not identified as bone by the adult protocol. These children were all below the 30th percentile for the body mass index. The whole-body protocols showed similar increases in bone mineral density with age; however, the experimental paediatric protocol always produced a lower bone mineral density result than the adult protocol. Paired results showed limits of agreement of 0.0668-0.130 g x cm(-2) (male, 0.063-0.124 g x cm(-2); female, 0.073-0.134 g x cm(-2)). This represents a mean difference of 11%. Five results showed differences greater than the upper limit of agreement. CONCLUSIONS: For anteroposterior (AP) lumbar spine scans, the use of the paediatric algorithm in children under 11 years of age would prevent the largest failures in analysis. For whole-body scanning, the adult algorithm showed no major failures in children of 11 years or older. It is hoped that forthcoming improvements in whole-body density analysis will improve the results for those under 11 years of age. Normal range data should be generated for any new algorithm to allow proper interpretation of clinical studies.

Absorptiometry, Photon↗

PubMed2001

Genetic loci determining bone density in mice with diet-induced atherosclerosis.

This study investigates the phenotypic and genetic relationships among bone-density-related traits and those of adipose tissue and plasma lipids in mice with diet-induced atherosclerosis. Sixteen-month-old female F2 progeny of a C57BL/6J and DBA/2J intercross, which had received an atherogenic diet for 4 mo, were examined for multiple measures of femoral bone mass, density, and biomechanical properties using both computerized tomographic and radiographic methods. In addition, body weight and length, adipose tissue mass, plasma lipids and insulin, and aortic fatty lesions were assessed. Bone mass was inversely correlated with extent of atherosclerosis and with a prooxidant lipid profile and directly correlated with body weight, length, and, most strongly, adipose tissue mass. Quantitative trait locus (QTL) analysis, using composite interval mapping (CIM) and multi-trait analysis, identified six loci with multi-trait CIM LOD scores > 5. Three of these coincided with loci linked with adipose tissue and plasma high-density lipoprotein. Application of statistical tests for distinguishing close linkage vs. pleiotropy supported the presence of a potential pleiotropic effect of two of the loci on these traits. This study shows that bone mass in older female mice with atherosclerosis has multiple genetic determinants and provides phenotypic and genetic evidence linking the regulation of bone density with adipose tissue and plasma lipids.

Adipose Tissue↗

PubMed2001

Posttransplant bone disease: a case illustrating dramatic improvements in bone density with vitamin D replacement therapy.

Although bisphosponates are proposed as first-line treatment for posttransplant bone disease they are not optimal in all situations. A kidney transplant recipient developed hypercalcemia from mobilization of extraskeletal calcium. He had low serum parathyroid hormone and vitamin D; high calcium excretion; and normal calcium intake. Bone biopsy revealed severe osteomalacia. Bisphosphonates, used in the early treatment of acute hypercalcemia, were not indicated to treat osteomalacia. However, over several months serum calcium declined sufficiently to allow treatment of the bone disease with oral calcitriol. Dual-energy radiographic absorptiometry over the next 2 years documented dramatic improvements in bone density (percent of young-normal controls) : from 63 to 85%, at the lumbar spine; from 38 to 67%, at the femoral neck. This response to treatment could not have been achieved with an antiresorptive strategy. Optimal management of posttransplant bone disease requires a diagnostic approach, which considers all plausible contributing factors.

Absorptiometry, Photon↗

PubMed2005

Misinterpretation of osteodensitometry with high bone density: BMD Z > or = + 2.5 is not "normal".

Osteodensitometry is increasingly used to identify low bone density resulting from osteoporosis. The universally accepted World Health Organization (WHO) criteria for assessing bone mineral density (BMD) contrasts individual T-scores to peak BMD in healthy adult control populations. In this scheme, "osteoporosis" refers arbitrarily to T-values below -2.5, "osteopenia" to values between -1.0 and -2.5, and "normal" to values above -1.0. Although individually rare, numerous conditions cause supranormal BMD in children and adults. Increasingly, elevated BMD is detected by osteodensitometry, especially dual-energy X-ray absorptiometry. Illustrated here, the absence of upper limits for BMD in the WHO criteria jeopardizes recognition of high-BMD disease for all age groups. This oversight requires correction using Z-scores.

Absorptiometry, Photon↗

PubMed2003

The effect of teriparatide [human parathyroid hormone (1-34)] therapy on bone density in men with osteoporosis.

Teriparatide [rhPTH(1-34)] increases bone mineral density and reduces the risk of vertebral fracture in women. We randomized 437 men with spine or hip bone mineral density more than 2 SD below the young adult male mean to daily injections of placebo, teriparatide 20 microg, or teriparatide 40 microg. All subjects also received supplemental calcium and vitamin D. The study was stopped after a median duration of 11 months because of a finding of osteosarcomas in rats in routine toxicology studies. Biochemical markers of bone formation increased early in the course of therapy and were followed by increases in indices of osteoclastic activity. Spine bone mineral density was greater than in placebo subjects after 3 months of teriparatide therapy, and by the end of therapy it was increased by 5.9% (20 microg) and 9.0% (40 microg) above baseline (p < 0.001 vs. placebo for both comparisons). Femoral neck bone mineral density increased 1.5% (20 microg; p = 0.029) and 2.9% (40 microg; p < 0.001), and whole body bone mineral content increased 0.6% (20 microg; p = 0.021) and 0.9% (40 microg;p = 0.005) above baseline in the teriparatide subjects. There was no change in radial bone mineral density in the teriparatide groups. Bone mineral density responses to teriparatide were similar regardless of gonadal status, age, baseline bone mineral density, body mass index, smoking, or alcohol intake. Subjects experienced expected changes in mineral metabolism. Adverse events were similar in the placebo and 20-microg groups, but more frequent in the 40-microg group. This study shows that teriparatide treatment results in an increase in bone mineral density and is a potentially useful therapy for osteoporosis in men.

Adult↗

PubMed2000

Osteocalcin gene polymorphism is related to bone density in healthy adolescent females.

Recently a polymorphism was found in the human osteocalcin gene, and its association with bone mass was investigated in healthy postmenopausal Japanese women. The osteocalcin gene allelic variant HH was found to be overrepresented in women with osteopenia. The purpose of this study was to investigate whether the previously demonstrated polymorphism of the osteocalcin gene was related to bone mineral density (BMD; g/cm2) or osteopenia in a group of 97 healthy Caucasian adolescent females (aged 16.9 +/- 1.2 years, mean +/- SD). BMD of the left humerus, right femoral neck, lumbar spine and total body was measured using dual-energy X-ray absorptiometry. The relation between the allelic variants and bone density was analyzed as presence or absence of the H allele. Presence of the H allele was found to be related to a lower BMD of the humerus (0.97 vs 1.02, p = 0.03). There was also a strong tendency towards significance at the femoral neck (p = 0.06) and total body (p = 0.11). Using a multiple linear regression and including physical activity, weight, height and years since menarche, presence of the H allele was found to be an independent predictor of humerus BMD (beta = -0.21, p < 0.05) and femoral neck BMD (beta = -0.23, p < 0.01). Using logistic regression, presence of the H allele was also independently associated with a 4.5 times increased risk of osteopenia (p = 0.03) in the whole group. Osteopenia was defined as at least 1 SD lower bone density than the mean for the whole group of at least one of the BMD sites measured. We have demonstrated that the osteocalcin HindIII genotype is independently related to bone density in healthy adolescent females. The present study also suggests that presence of the H allele is predictive of osteopenia at an early age.

Adolescent↗

PubMedDate not supplied

Changes in bone density and turnover after alendronate or estrogen withdrawal.

OBJECTIVE: To compare bone mineral density (BMD) and bone turnover changes after therapy withdrawal in postmenopausal women treated with alendronate or estrogen-progestin. DESIGN: In this randomized, blinded, multinational, placebo-controlled trial, 1,609 healthy postmenopausal women ages 45 to 59 years were assigned to receive alendronate, placebo, or open-label estrogen-progestin (conjugated equine estrogens plus medroxyprogesterone acetate or a cyclic regimen of 17 beta-estradiol, norethisterone acetate and estradiol). Of the original women, one third after year 2 and one third after year 4 were switched from alendronate to placebo, while remaining blinded to treatment assignment. The women taking estrogen-progestin in years 1 to 4 were followed off therapy in years 5 and 6. BMD at the lumbar spine and hip and biochemical markers of bone turnover were measured. RESULTS: The treatment groups described in the current report represent 860 women at baseline; 481 women entered year 5, and 430 completed 6 years. BMD steadily decreased in the placebo group during all 6 years. In contrast, spine and hip BMD increased during the first 4 years in the groups receiving daily continuous alendronate 5 mg and estrogen-progestin. During years 5 and 6, BMD decreased at the lumbar spine -2.42% (95% CI = -4.10, -0.74) and total hip -1.09% (-2.60, 0.41) in the group previously treated with alendronate 5 mg for 4 years. In comparison, large BMD decreases were observed at the spine [-7.69% (-8.96, -6.41)] and total hip [-5.16% (-6.30, -4.01)] among women who had received estrogen-progestin for 4 years. CONCLUSION: Alendronate produces greater residual skeletal effects than estrogen-progestin after therapy discontinuation.

Aged↗

PubMed1994

Bone density at weight-bearing and nonweight-bearing sites in ballet dancers: the effects of exercise, hypogonadism, and body weight.

Exercise is recommended as a means of preventing osteoporosis. When intensive, weight-bearing exercise is often associated with hypogonadism. As weight-bearing exercise is likely to be more beneficial at weight-bearing than nonweight-bearing sites, and hypogonadism is likely to be more detrimental to trabecular than cortical bone, we tested the hypothesis that exercise and hypogonadism result in differing regional effects: net benefits at weight-bearing, predominantly cortical sites, and net deficits at nonweight-bearing trabecular-rich sites. Bone density (grams per cm2), body fat, and fat-free mass (kilograms) were measured using dual x-ray absorptiometry in 44 ballet dancers, aged 17.0 +/- 0.2 yr (mean +/- SEM), 18 sedentary amenorrheic girls with anorexia nervosa, and 23 girls of comparable age with regular menstrual cycles. Bone density, expressed as a percentage above or below the mean in the girls with regular menstrual cycles, was normal or elevated at weight-bearing sites in dancers [femoral neck, 3.1 +/- 1.7% (P = NS); Wards triangle, 4.1 +/- 2.3% (P = NS); trochanter, 5.9 +/- 1.9% (P < 0.05)] and normal or reduced at these sites in girls with anorexia nervosa [-10.5 +/- 3.8% (P < 0.05), -7.8 +/- 4.3% (P = NS), and -8.7 +/- 4.0% (P < 0.05), respectively]. By contrast, deficits similar to those in girls with anorexia nervosa were found in dancers at nonweight-bearing sites [ribs, -5.7 +/- 0.8% (P < 0.01); arms, -4.6 +/- 1.1% (P < 0.01); skull, -5.9 +/- 1.3% (P < 0.01)] before, but not after, correcting for fat mass. Fat mass was 7.8 +/- 0.4 kg in dancers, similar to that in girls with anorexia nervosa (6.3 +/- 0.7 kg) and lower than that in girls with regular menstrual cycles (16.8 +/- 1.6 kg; P < 0.01). The net result of vigorous exercise, hypogonadism, and leanness in athletic amenorrhea may not be generalized osteoporosis. Weight-bearing exercise may offset the effects of hypogonadism at predominantly cortical weight-bearing sites, such as the proximal femur. Non-weight-bearing sites and weight-bearing sites containing substantial amounts of trabecular bone, such as the lumbar spine, may be adversely affected by hypogonadism while benefiting little from weight-bearing exercise. Deficits at nonweight-bearing sites may be attenuated by maintenance of body weight.

Absorptiometry, Photon↗

PubMed1997

Implant diameter and bone density: effect on initial stability and pull-out resistance.

It is well known that the standard diameter dental implant so often utilized is often inadequate in patients with poor bone quality or quantity, and larger diameter implants have been utilized to overcome this deficiency. The objective of this study was to compare the pull-out resistance of small and large diameter (3.25- and 4.5-mm) dental implants and the relationship of these implants to bone density. Two groups of implants, consisting of 18 implants of each diameter, were placed in the mandibles of five embalmed humans. The bone mineral density of the area surrounding the implant site in the coronal cross section was measured by quantitative computed tomography (QCT). Initial implant stability was tested with a periodontium diagnostic device and pull-out resistance was tested with a mechanical testing system. Results showed the same initial stability for the two implants. The maximum pull-out force required for the large diameter implants was 15% greater than that required for the small diameter implants, although given the small number of samples, this difference was not statistically significant. There were significant positive correlations between the pull-out resistance and the bone density for both the large and small diameter implants (p < 0.05, p < 0.01). We conclude that larger diameter implants appear to have advantages over smaller ones; however, more extensive testing is needed to determine quantitatively the increased load-carrying capacity.

Aged↗

PubMed2001

Bone density loss after allogeneic hematopoietic stem cell transplantation: a prospective study.

The incidence and course of bone density abnormalities following hematopoietic stem cell transplantation are poorly understood and complicated by the impact of multiple factors. Hip, spine, and wrist bone mineral densities (BMDs) were measured in 104 adults (54 women, 54 men; mean age, 40 years [range, 18-64 years]) at 3 and 12 months after allogeneic transplantation. Clinical and laboratory variables were evaluated using univariate and multivariate analyses to determine risk factors for osteoporosis, fracture, and avascular necrosis. At 3 months posttransplantation, combined (male and female) hip, spine, and wrist z scores were -0.35, -0.42, and +0.04 standard deviations, respectively. At 12 months both men and women experienced significant loss of hip BMD (4.2%, P < .0001); changes in the spine and wrist were minimal. The cumulative dose and number of days of glucocorticoid therapy and the number of days of cyclosporine or tacrolimus therapy showed significant associations with loss of BMD; age, total body irradiation, diagnosis, and donor type did not. Nontraumatic fractures occurred in 10.6% of patients and avascular necrosis in 9.6% within 3 years posttransplantation. The decrease in height between pretransplantation and 12 months posttransplantation was significant (P = .0001). Results indicate that loss of BMD after allogeneic stem cell transplantation is common and accelerated by the length of immunosuppressive therapy and cumulative dose of glucocorticoid. An increased incidence of fracture and avascular necrosis may adversely impact long-term quality of life. Prevention of bone demineralization appears warranted after stem cell transplantation.

Adolescent↗