Clinical use of bone densitometry

Metabolic bone assessment in patients with inflammatory bowel disease

BACKGROUND/AIMS

Patients with inflammatory bowel disease are at risk for osteopenia. To study the metabolic bone status of these patients, a cross-sectional study was conducted.

METHODS

Eighty-four patients (49 women, 35 men) with inflammatory bowel disease, 34 of whom had Crohn's disease and 50 ulcerative colitis (including 18 with prior coloproctectomy and ileoanal anastomosis), underwent clinical, dietary, and spine radiological assessments. Bone metabolism was assessed by measuring serum levels of calcium, phosphate, parathyroid hormone (1-84), 25-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, and osteocalcin. Lumbar and femoral neck bone mineral densities were measured by dual energy X-ray absorptiometry.

RESULTS

Serum osteocalcin level was decreased in 29 patients (34%), 12 of whom had never undergone steroid therapy. The other biochemical markers of bone metabolism were in the normal range. Thirty-six patients (43%) had osteopenia, and 6 patients (7%) had vertebral crush fractures. Osteopenia was observed in 27 patients (52%) and 9 patients (28%) with and without corticosteroid therapy, respectively. No patient had clinical or biological signs of osteomalacia. Analysis of bone density (lumbar Z score) by a multiple regression analysis showed a statistically significant correlation with age, cumulative corticosteroid doses, sedimentation rate, and osteocalcin level (R2 = 0.76; P = 0.05).

CONCLUSIONS

The results suggest that bone turnover in inflammatory bowel disease is characterized by low bone formation in the presence of normal levels of calcium-regulating hormones.

Influence of steroid medication on bone mineral density in children with nephrotic syndrome

Bone mineral density (BMD) was studied in 26 children with idiopathic nephrotic syndrome and in age- and sex-matched healthy controls. BMD was selectively measured in trabecular (TBD), cortical (CBD) and total bone (BD) using peripheral quantitative computed tomography. Patients showed a decrease in BD, CBD and TBD. BD and CBD were inversely correlated with the cumulative dose of steroid treatment. Of the 26 patients with high cumulative doses of steroid, 16 were also treated with cyclophosphamide. In this group BD and CBD were decreased significantly compared with the children with a low cumulative steroid dose only. Compared with controls for each subgroup, significant decreases in BD, CBD and TBD were found in the group with high cumulative doses of steroids only. The higher cumulative steroid dose and the initial steroid toxicity which made cytotoxic therapy necessary, rather than cyclophosphamide itself, may be responsible for these findings.

Comparison of radiographic absorptiometry with dual-energy x-ray absorptiometry and quantitative computed tomography in normal older white and black women

Bone mineral density (BMD) of the phalanges of the hand was measured by the technique of radiographic absorptiometry (RA) in 199 older postmenopausal women previously determined to have normal BMD by dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT). The average age of the women was 66.8 +/- 4.9 years, and they were 19.9 +/- 6.7 years postmenopause. In the 54 black women, phalangeal BMD was 11.7% greater than in the 145 white women, a difference comparable to that found using DXA at the radial midshaft, the lumbar spine, and femoral neck. A correlation matrix comparing BMD measured by RA to BMD measured by DXA and QCT indicates that, in general, RA was related to the various DXA and QCT measurement sites as well as these sites were related to each other. When results for RA, DXA, and QCT obtained in our cohort of older women were compared to available reference data for peak adult bone mass, the average difference (SD units) from peak value was greatest for RA (-1.77 radius, -1.24 spine, -2.13 femoral neck, -2.34 QCT spine, and -2.71 phalanges). We conclude that RA is an acceptable measure of phalangeal BMD and that the data in our cohort can serve as reference data for older white and black women aged 55-75 years. Once the ability of RA to predict future fracture occurrence has been demonstrated, it could be rapidly deployed as a low-cost, widely available bone mass measurement technique.

Reduced bone mineral density in men with a previous femur fracture

This study determined the areal bone mineral density (BMD) from the lumbar spine (L2-4), right distal radius and ulna, and the femoral neck, trochanter area of the femur, distal femur, patella, proximal tibia, and calcaneus of both extremities in 29 men who had a femur shaft fracture 10 years earlier. For evaluation of the patients' BMDs in the spine and distal forearm, 29 age-, weight-, and height-matched normal men were also measured. Compared with normal men (mean +/- SD = 1.123 +/- 0.153), the spinal BMDs of the patients were significantly (p = 0.0054) lower (1.018 +/- 0.119, -9.3%). Distal radius and distal ulna showed no significant group differences. In patients, the mean BMD of the injured extremity (compared with the uninjured side) was significantly lower in the distal femur (-6.8%; p = 0.0000), patella (-5.4%; p = 0.0000), proximal tibia (-4.7%; p = 0.0000), and calcaneus (-2.2%; p = 0.0259). In the proximal femur, this value was at the same level (femoral neck 1.3%, NS) or higher (trochanter area 6.3%, p = 0.0002) than that in the uninjured extremity. The relative BMDs of the injured extremity did not associate with the fracture type, fracture location, age, muscle strength, follow-up time, or non-weight-bearing time but showed significant (r = 0.33-0.64) positive correlation with low pain assessment and high functional scores of the injured extremity.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of glucocorticoids on skeletal growth in rabbits evaluated by dual-photon absorptiometry, microscopic connectivity and vertebral compressive strength

The effects of corticosteroid on bone were examined in female growing rabbits treated with 0.7 mg/kg per day prednisolone for 5 months. The evolution of whole-body total bone mineral measured by dual-photon absorptiometry showed a significant difference between the prednisolone-treated group and the control group from the first to the fifth month. The histomorphometric profile of corticosteroid-induced osteoporosis was observed, in particular the lower bone volume and thinner and fewer trabecular plates. Mechanical tests are possible on rabbit vertebrae and showed a very significant difference in bone strength between the prednisolone-treated and control groups, and a good correlation between mechanical tests and histomorphometric or densitometric results. This bone corticosteroid model shows that vertebral compression tests are possible on rabbit lumbar vertebrae. It may contribute to a better evaluation of corticosteroid treatments.

The ultrasonic assessment of osteopenia as defined by dual X-ray absorptiometry

Dual X-ray absorptiometry (DXA) studies of bone mineral density (BMD) of the lumbar spine and femoral neck were compared with measurements of broadband ultrasonic attenuation (BUA) and velocity of ultrasound (VOS) in the calcaneus in 300 pre- and postmenopausal women (mean age 53 years). The women were referred for evaluation of possible osteopenia as defined by DXA. The ability of ultrasound measurements to predict osteopenia in women was compared with the ability of lumbar spine and femoral neck DXA scans to predict osteopenia in the hip and spine. A new ultrasound parameter obtained by combining BUA and VOS (combined attenuation and velocity (CAV)) was also evaluated. Linear regression analysis of the three ultrasound parameters and lumbar spine and femoral neck BMD gave weak but statistically significant correlations (r = 0.45-0.54). The correlation between spine and femoral neck BMD was statistically significantly better (r = 0.72). Receiver-operating characteristic (ROC) analysis was used to investigate the sensitivity and specificity of ultrasound measurements in predicting patients with osteopenia. The areas under the ROC curves ranged from 0.64 to 0.75 and ultrasound parameters were shown to be poor at predicting osteopenia as defined by DXA. The ability of lumbar spine and femoral neck DXA measurement to predict osteopenia in the hip and spine, respectively, was statistically significantly better than any of the ultrasound parameters. Ultrasound measurements in the calcaneus did not appear to identify accurately patients with osteopenia defined by DXA measurements of bone density in the axial and appendicular skeleton.

Bone mass measurements around menopause and prevention of osteoporotic fractures

The objective of this work is to try to answer the question: is it useful to recommend bone densitometry at the time of the menopause as a screening test for women at high risk of osteoporotic fractures? This analysis is based on a review of the literature for the period 1981-1993, considering published articles in English or French. Prospective studies demonstrate that low bone mass (BM) in women who have been menopausal for more than 10 years is actually a risk factor for fracture, with a fracture risk multiplied by about two for a decrease in BM of one standard deviation. At present no studies have shown this association when BM determinations have been realised at the age of 50 years. The use of BM measurements remains difficult in practice because there is no international consensus concerning the definition and the value of a threshold for a high fracture risk. Concerning the efficacy of preventive interventions applied following the identification of a low BM, i.e. hormonal replacement therapy (HRT), data are lacking concerning the magnitude of its efficacy on fracture prevention and in the presence of an already decreased BM. Moreover osteoporosis is not the only indication for HRT, which may be prescribed for other consequences of the menopause. There is not enough evidence for the screening, by BM measurements, of high risk fracture at the time of the menopause. These measurements may help women who hesitate to take HRT, but they do not seem to improve compliance with the treatment to a large extent. Knowledge concerning osteoporosis and its prevention remains a major determinant in the use of preventive measures.

Improved assessment of lumbar vertebral body strength using supine lateral dual-energy x-ray absorptiometry

Clinical and biomechanical investigations indicate that assessment of vertebral body bone mineral density (BMD) by anteroposterior dual-energy x-ray absorptiometry (DXA) is a useful index of vertebral body strength and fracture risk in osteoporosis. However, inclusion of non-force-bearing and small-force-bearing mineralized structures, such as the posterior elements and aortic calcifications, in the measurement of anterior BMD obscures the assessment of vertebral body mass by this technique. Indeed, such interference is particularly severe in the presence of posterior element degeneration or previous spinal surgery. Recent anatomic studies illustrate that the lateral view provides unobstructed visualization of the L3, L4, and possibly L2 vertebral bodies, suggesting that supine lateral BMD may more accurately assess vertebral body fracture risk. We evaluated this hypothesis in a blinded using human cadaver spines to compare the value of supine lateral and anteroposterior BMD in assessing vertebral body fracture force, average compressive stress, maximum stored strain energy, and strain at failure. Both measures of BMD significantly correlate with these biomechanical measures. However, statistical comparison of the methods using multiple and stepwise regression reveals that supine lateral BMD provides a better assessment of the vertebral body fracture properties than anteroposterior BMD. The enhanced predictive value of supine lateral BMD occurs because of the variable contribution of posterior element mineral to the anteroposterior BMD measurement. Evaluation to test the utility of supine lateral BMD for the assessment of fracture risk and a fracture threshold in patients with osteoporosis is therefore recommended.

Prevalence and magnitude of osteopenia associated with insulin-dependent diabetes mellitus

The authors evaluated the prevalence, magnitude, and contributing factors for osteopenia in insulin-dependent diabetes mellitus (IDDM). We measured bone mineral density (BMD) in the lumbar spine and femoral region in 90 patients aged 18-54 years with IDDM using dual-energy x-ray absorptiometry. The blood-glucose control, insulin dosage, duration of disease, and presence of chronic complications of diabetes were evaluated. Serum ionized calcium, magnesium, phosphorus, alkaline phosphatase (ALP), 25-hydroxycholecalciferol, immunoreactive parathyroid hormone (iPTH), and urinary calcium, phosphorus, and hydroxyproline were also analyzed. Thirty-one patients (34%) were classified as having a reduced BMD (less than 2 SD below the mean). The comparison between normal and low BMD patients showed that the osteopenics had a tendency to be younger (median, 28 years versus 32 years), showed a higher mean plasma glucose (15.5 +/- 5.0 mmol/L versus 12.9 +/- 3.8 mmol/L; p = 0.018), longer duration of disease (11.2 +/- 2.1 years versus 5.0 +/- 1.3 years; p = 0.004), and needed a higher insulin dosage (56 +/- 17 U/day versus 43 +/- 16 U/day; p < 0.001). There was a positive correlation between mean glucose levels, duration of disease, insulin dosage, and bone-mass decrease. A higher incidence of chronic complications, mainly retinopathy (58% versus 25%) and neuropathy (52% versus 22%) was found in the low BMD group. There was no alteration of serum calcium, phosphorus, iPTH, 25-hydroxycholecalciferol, and urinary calcium and phosphorus. The ALP levels were significantly higher in the osteopenic group, and magnesium and hydroxyproline levels were lower in the whole diabetic group, but these measurements did not correlate with BMD reduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Osteoporosis in men with a history of tibial fracture

The long-term effects of bone fractures on bone mineral density (BMD) at various skeletal sites are poorly established, although a serious fracture, such as a tibia fracture, followed by long immobility and disuse may lead to permanently decreased BMD and, through this mechanism, may be a risk factor for osteoporotic fractures in later life. To determine whether such an injury leads to osteoporosis, we measured the areal BMD (g/cm2) from the lumbar spine (L2-4), right distal radius and ulna, and the femoral neck, distal femur, patella, proximal tibia, distal tibia, and calcaneus of both extremities in 14 men with a history of primarily nonunited (finally bone-grafted) shaft fracture of the tibia and 20 men with a history of primary union. For evaluation of the patients' BMD in the spine and distal forearm, 22 age-, weight-, and height-matched normal men were also measured. The average time of immobilization in a long plaster cast was 27 weeks in the former group of patients and 16 weeks in the latter. The measurements were performed an average of 9 years after the fracture using a dual-energy x-ray absorptiometric scanner. Compared with normal men (mean +/- SD = 1.116 +/- 0.160), the spinal BMDs were significantly lower in men with a history of a primary nonunion (0.979 +/- 0.100, -12.3%) and union (1.010 +/- 0.124, -9.5%). In distal radius and distal ulna, there were no significant differences between the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Body composition: research and clinical advances--1993 A.S.P.E.N. research workshop

The 1993 ASPEN Research Workshop examined research and clinical advances in the study of human body composition. The workshop had two themes: (1) compartments of the body and their measurement, and (2) clinical applications of body composition measurements. There were 12 speakers of varied backgrounds who gave short lectures followed by panel discussions. Speakers explored the validity and potential uses of new body composition methodologies, including dual-energy x-ray absorptiometry, multiple frequency bioimpedance analysis, computerized axial tomography, magnetic resonance imaging, nuclear magnetic resonance spectroscopy, neutron inelastic scattering, and gamma-ray resonance. The application of these methods to chronically and acutely ill hospitalized patients was described. The study of body composition is an emerging distinct research area within the broad study of human biology. This conference provided an overview of important new advances in the study of human body composition.

Can radiologists detect osteopenia on plain radiographs?

The main purpose of this study was to compare subjective estimates of vertebral ostepenia with bone mineral density (BMD) measurements of the same region in 200 (107 male, 93 female) subjects, aged 52-90 years, invited randomly from the community. Standardized plain thoracolumbar radiographs were examined by three senior radiologists, and given a semiquantitative osteopenia score using the method of Saville. The BMD of the anteroposterior (AP) lumbar spine and femoral neck was measured by dual energy X-ray absorptiometry. In addition BMD measurements were compared in subjects without significant vertebral deformity, and those with mild (20-25%) or definite (> 25%) reductions of vertebral height. For the Saville score, intraobserver agreement was moderate to good (kappa 0.46-0.57), and interobserver agreement was fair to moderate (kappa 0.25-0.41). Although the overlap between gradings was considerable, BMD was significantly related to visually estimated osteopenia. Subjects without apparent radiographic osteopenia (Saville grade 0) had a low risk (9-15%), compared to those with definite osteopenia (64-86%), of falling below the lowest quartile of BMD at either the femoral neck or the AP spine. In women (but not men), BMD measured at the hip and spine was related to vertebral deformity.

Dual energy X-ray absorptiometry is also an accurate and precise method to measure the dimensions of human long bones

The accuracy, as well as the in vitro and in vivo precision of width and length measurements of human humerus and femur from dual energy X-ray absorptiometry (DXA) images, was investigated. The measurement was based on the bone area inside a specified region determined by the bone edge detection software of the scanner. The accuracy and in vitro precision studies were performed using a bone-simulating aluminum phantom embedded in different amounts of water. The in vivo precision was determined by measuring both limbs twice in 10 subjects (for humerus) and in 9 subjects (for femur). The accuracy was not significantly affected by the amount of water, and varied from 0.6 to 1.2%. Similarly, the in vitro precision varied from 0.4 to 0.6%. The average in vivo precision of the width measurement ranged from 0.4% (humeral and femoral midshaft) to 0.9% (proximal humerus), not depending on the size of the measured bone. The precision of the length measurement was 0.3% for the humerus and 3.7% for the femoral neck. In conclusion, the standard DXA technique provides a reliable measurement of the width and length in human humerus and femur in vivo, and thus may be useful in evaluating the properties of these bones in conjunction with the standard bone mineral measurements. Specifically, studies evaluating the effects of various types of mechanical loading (exercise) on bone may greatly benefit from this possibility because not only the bone mineral content and density but also the bone geometry change due to loading.

Effects of oral calcitriol on bone mineral density in patients with end-stage renal failure

Evolution of bone mineral density (BMD) at various skeletal sites and the influence of calcitriol on BMD are still poorly documented in patients with terminal renal failure. Using dual photon absorptiometry, we investigated the changes in BMD at the levels of lumbar spine, femoral neck and midfemoral shaft in 21 patients with end-stage renal failure (ESRF) treated with calcitriol (mean dosage +/- SEM: 0.21 +/- 0.02 microgram/day) and compared them to 25 patients with ESRF but not treated with calcitriol (control group) over a period of 20.3 +/- 1.5 and 17.2 +/- 1.2 months, respectively. Lumbar spine BMD increased by 7.7 +/- 3.2%/year in the treated group and decreased by 2.5 +/- 1.3%/year in the control group (P < 0.005). Femoral shaft BMD increased more in treated than in control group (+ 6.7 +/- 2.3 vs. + 1.4 +/- 2.0%/year; P < 0.05) and femoral neck BMD remained stable. PTH levels increased by 92 +/- 121 and 1033 +/- 254 pmol/year (P < 0.01) in the treated group and the controls, respectively. Osteocalcin changes were -2.7 +/- 3.7 and +20.1 +/- 11.7 micrograms/liter (P < 0.05) per year in the same groups. These results indicate that low doses of oral calcitriol in patients with end-stage renal failure were associated with an increase in BMD at the levels of lumbar spine and femoral shaft, and with a stabilization of serum PTH and osteocalcin concentrations.

Osteoporosis and bone morbidity in cardiac transplant recipients

PURPOSE

To evaluate the incidence and etiology of osteopenia and pathologic fractures in cardiac transplant recipients.

PATIENTS

Thirty-one adult male cardiac transplant recipients and 14 adult men with congestive heart failure (CHF) awaiting cardiac transplantation.

METHODS

Assessment of indices of bone and mineral metabolism and of bone mineral density (BMD) by dual-energy x-ray absorptiometry.

RESULTS

BMD in the proximal femur was below normal in both groups compared to that in age-matched control subjects, whereas BMD in the lumbar spine was normal. There was no significant difference in BMD at any site between the two groups. No clinical parameter predicted BMD. In all patients, laboratory indices of bone mineral metabolism, except parathyroid hormone (PTH) levels, were normal and not statistically different between the two groups. CHF patients had a trend toward elevations of PTH, 1,25-dihydroxyvitamin D, and urinary calcium excretion compared to transplant patients. Eight of 31 transplant patients and 2 of 14 CHF patients had vertebral compression fractures (c2 = 11.8, p < 0.0006). Transplant recipients with fractures had twice as many rejection episodes as did transplant patients without fractures, but did not differ in cumulative dose of steroids. Two patients developed avascular necrosis of the femoral head following transplantation.

CONCLUSIONS

Cardiac transplant recipients and patients with CHF awaiting transplantation had decreased hip BMD, but normal spine BMD. Although immunosuppressive therapy did not appear to influence bone mass, loop diuretics prior to transplantation may have stimulated a mild secondary increase in PTH that could have differentially caused loss of bone density at the hip in both groups. Pulse corticosteroids used in treating rejection may have contributed to the increased incidence of vertebral fractures in transplant patients. These data suggest that severe CHF with its associated diuretic use and decreased activity are primary contributors to osteopenia in these patients.

A comparison of reference bone mineral density measurements derived from two sources: referred and population based

The construction of reference ranges for bone mineral density (BMD) is of importance when defining risk of osteoporosis in an individual. This study examined lumbar spine BMD from two different populations of women aged 40-69 years, both measured by dual X-ray absorptiometry (DXA) using Hologic QDR-1000 machines. Results were compared with the manufacturer's reference range. At one site (Centre 1) women were referred by general practitioners for BMD measurement to aid decisions regarding long term hormone replacement therapy (HRT). At the other (Centre 2), women were drawn from the age/sex register of a London general practice (population 11,000) and invited to attend a screening examination at their local hospital. The BMD for both groups did not differ significantly from the manufacturer's reference range. The BMD at Centre 1 was lower than Centre 2 by 0.0175 g cm-2 but this did not reach significance and after calibration of both DXA machines with a spine phantom the difference in BMD of the two groups was reduced to only 0.0034 g cm-2. Population based sampling carries no advantage over a GP referral based method for the construction of spinal BMD reference ranges. Although local BMD reference ranges may be required for sites outside the spine the comparable results in this study of the two UK reference ranges and those of the USA manufacturer suggest that local reference ranges for lumbar spine BMD using DXA may be unnecessary in the UK.

Femoral neck bone density. Direct measurement and histomorphometric validation

The purpose of this study was to develop a method for directly measuring bone density of femoral neck sections. Three types of density were measured. Real density equals wet weight divided by the actual volume of bone tissue (real volume). Apparent density equals wet weight divided by the total volume occupied by the bone plus the pore spaces (total sample volume). Ash density equals the ash weight divided by the real volume. Corticocancellous cross-sections of the femoral neck were analyzed for density at two levels: level 1, proximal neck and level 3, distal neck. Density measurements were compared with histomorphometric measurements performed on cross-sections at the midportion of the femoral neck (level 2) and with a clinical radiographic measure of bone density (cortical index 3 cm below the lesser trochanter). No correlation was found between apparent density and either real (r = .12, P = .62) or ash density (r = -.09, P = .72) within a given femoral neck section. There was, however, a strong correlation between real and ash density (r = .93, P = .0001). This was expected because real and ash densities are both reflections of bone mineralization. Apparent density showed better correlation, when comparing level 1 with level 3 sections (r = .76, P = .0001), than did ash (r = .57, P = .01) or real density (r = .55, P = .01). There was no correlation between either real or ash density with any histomorphometric parameter. Apparent density was moderately correlated with total bone area expressed as a percentage of cross-sectional area (r = .66, P = .008). This finding tends to validate the direct measurement of apparent density in that both apparent density and total bone area are measurements of the concentration of bone in space. No significant correlation was found between any of the density measurements and the cortical index at 3 cm. This underscores the necessity for precisely qualifying any definition or discussion of bone quality. The success or failure of hip implants may be at least partially determined by the ability of the bone to withstand the insult of implantation of the prosthesis and to adapt successfully to the new mechanical environment. This study represents an early phase of defining parameters that may have prognostic value in long-term implant fixation.

One-year psoas training can prevent lumbar bone loss in postmenopausal women: a randomized controlled trial

On the premise that bone response to exercise is locally controlled, we conducted a randomized trial to evaluate the effects of a 1-year training of psoas muscles (treatment group: TG) versus a 1-year training of deltoid muscles (control group: CG) on the lumbar trabecular bone mineral density (TBMD). TBMD was measured with computed tomography scan. Seventy-eight subjects were included and 67 completed the study. Intention to treat analysis revealed no significant change in TBMD from 0 to 12 months. Data analysis in the 67 remaining women, including both assiduous and nonassiduous subjects, revealed greater bone loss in CG than in TG although the difference was not significant. Similar analysis in a subgroup of subjects who performed the exercises assiduously (TG: n = 23, CG: n = 26) showed that the mean bone loss of all four vertebrae from 0 to 12 months was significantly greater in the CG (-8.87 +/- 12.75 mg/cm3, mean +/- SD) than in the TG (0.14 +/- 11.21 mg/cm3, mean +/- SD, P = 0.01). These results suggest that continuous 1-year psoas training can prevent lumbar bone loss in postmenopausal women and support the hypothesis of local action of physical activity.

Long-term fracture prediction by bone mineral assessed at different skeletal sites

Bone mineral density (BMD) was measured at the lumbar spine and cervical and intertrochanteric regions of the proximal femur by dual-photon absorptiometry and bone mineral content was assessed at the distal and midradius by single-photon absorptiometry in an age-stratified random sample of 304 Rochester, Minnesota women aged 30-94 years. Over follow-up extending to 10 years (median 8.3 years), 93 women experienced 163 new fractures. After adjusting for age, these bone mineral measurements predicted the likelihood of any incident fracture due to moderate trauma, with relative hazards varying from 1.4 to 1.6 per SD decrease in baseline bone mineral. A 1 SD decrease in lumbar spine BMD increased the risk of a new vertebral fracture comparably to a 17 year increase in age; a 1 SD decrease in femoral BMD was comparable to a 13-14 year increase in age on the risk of a hip fracture. We conclude that bone mineral measurements made at a variety of skeletal sites can predict the occurrence for at least 8-10 years of moderate trauma fractures of the sort that might be related to osteoporosis.

Osteoporosis: The Role of the Orthopaedist

Osteoporosis is one of the most prevalent musculoskeletal disorders encountered in orthopaedic practice today. This review provides an update on the pathophysiology of bone metabolism leading to osteoporosis, describes the latest methodology in the diagnostic workup of patients with low bone mass, and summarizes the current status of osteoporosis treatment regimens. The special needs of the osteoporotic fracture patient are also addressed. In general, load-sharing devices and sliding nail-plate constructs are preferred over rigid internal-fixation systems. Prolonged immobilization should be avoided.

Reduced bone mineral density in long-term survivors of medulloblastoma

Bone mineral density (BMD) reaches a peak at approximately 30 years of age, and may be influenced by radiotherapy before completion of skeletal maturation. Regional BMD has been measured using dual energy X-Ray absorptiometry (DEXA) in adults following craniospinal irradiation for medulloblastoma between ages 4 and 19 years, receiving doses of 3500-4000 cGy to the brain and spinal cord. Lumbar spine (LS) and was failure to achieve normal adult BMD at both LS and FN, with a mean reduction at LS of 12.1% +/- 2.4% (p < 0.01) and a mean reduction at FN of 14.3% +/- 3.4% (p < 0.01). The mean body mass index (BMI) was also less than that of a standard population (21.8 +/- 1.5), as were mean standing and sitting heights. No relationship was found between reduction in BMD at either site and age at irradiation, time elapsed since irradiation or BMI at time of scanning. Biochemical and endocrine markers including corrected calcium, alkaline phosphatase, sex hormones and IGF-1 were normal in all seven patients. The reduction in BMD outside the irradiated area suggests that indirect factors may be important in this effect.

Maintenance of bone mass in patients receiving dialytic therapy

To determine what factors contribute to and change bone mineral density (BMD) in dialysis patients, serial lumbar spine dual x-ray absorptiometry studies were analyzed by stepwise regression analysis in 67 black dialysis patients. The patients were 50.5 +/- 2.0 years of age (mean +/- SE) and 49% were men; the patients had received dialytic therapy for 3.7 +/- 0.5 years. The mean initial BMD z-score was 0.147 +/- 0.182. By cross-sectional analysis, the BMD increased in the male and premenopausal female patients but decreased in the postmenopausal female patients by 2.5% g/cm2/decade of life, less than that observed in black patients with normal renal function. Univariate analysis and stepwise regression analysis demonstrated radiographic evidence of osteopenia (beta-coefficient = -0.180 +/- 0.050; P = 0.001) and prior parathyroidectomy (beta-coefficient = 0.133 +/- 0.070; P = 0.054) as the only variables significantly correlated to the BMD. The effects of biochemical variables and different treatments on the delta BMD, calculated as the difference between each patient's first and second BMDs divided by the interval in years, were evaluated by stepwise regression analysis in 41 patients. The mean interval between the two BMDs was 18.4 +/- 1.02 months (range, 5 to 34 months) and the delta BMD was 0.025 +/- 0.018 g/cm2/yr, increasing in 65% of the patients. By univariate and stepwise regression analysis, the mean monthly serum total alkaline phosphatase concentration was the only variable that correlated with the delta BMD (beta-coefficient = 0.0001; P = 0.030).(ABSTRACT TRUNCATED AT 250 WORDS)

Precision of dual-energy x-ray absorptiometry: development of quality control rules and their application in longitudinal studies

In research settings, longitudinal measurements of bone mineral density have become an integral part of the assessment of patients with metabolic skeletal disorders. To adequately utilize longitudinal measures, confidence in the long-term precision of the measurement technique must be very high. Dual-energy x-ray absorptiometry (DXA) has become commonly utilized in this context, and to better understand its long-term precision and to develop quality assurance protocols for its use, we examined the performance of eight DXA machines over a 3 year period. Anthropomorphic spine phantoms were measured frequently on each machine during the period of observation, and precision was estimated from the consistency of these determinations. Overall precision was excellent (mean longitudinal coefficient of variation, 0.4%). Nevertheless, by using a series of objective quality control criteria, small alterations in the performance of each machine were identified (mean number of changes, 4.6 in 3 years; mean magnitude, 0.0039 g/cm2, or 0.4%). The cumulative effects of those changes were sufficient to cause a significant (albeit minor) change in the regression slopes (phantom mineral density versus time) of most machines. The same quality control rules were also used to quantitate the magnitude of change and to adjust retrospectively machine performance during the period of observation, such that alterations were minimal and regression slopes were not significantly different from zero. Although the precision of DXA is excellent, alterations in machine function must be anticipated during longitudinal use. The development of quality control protocols provides the means to detect change objectively and to adjust for alterations in performance during the course of longitudinal evaluations.

Relationships between metacarpal morphometry, forearm and vertebral bone density and fractures in post-menopausal women

The relationships between metacarpal morphometric, vertebral and forearm density measurements and the prevalence of vertebral and peripheral fractures were examined in 239 postmenopausal women (median age 63, range 32-84 years). Metacarpal cortical area/total area ratio (CA/TA) was measured with needle calipers, forearm mineral density (FMD) by single photon absorptiometry and vertebral mineral density (VMD) by single energy quantitative computed tomography. Of the 239 subjects 97 had not suffered any fractures, 44 had at least one previous vertebral fracture but no peripheral fractures, 41 had a history of peripheral fracture but no vertebral fracture and 57 had suffered both peripheral and vertebral fractures. There were significant correlations between a single measurement of CA/TA and both FMD (r = 0.65, p < 0.001) and VMD (r = 0.41, p < 0.001). Similar correlations existed between the mean of multiple measurements of CA/TA and both FMD and VMD. CA/TA (p < 0.001), FMD (p < 0.001) and VMD (p < 0.001) were reduced in subjects who had suffered fractures, when compared with the no fracture group. The percentage of cases in each of the four fracture groups (vertebral fracture only, peripheral fracture only, peripheral and vertebral fracture, peripheral or vertebral fracture) misclassified with reference to the no fracture group were similar with CA/TA, FMD or VMD measurements. We suggest that metacarpal morphometry, which is widely available at relatively low cost, yields cross-sectional information about bone density and fracture risk, comparable with that obtained by forearm and vertebral densitometry.

Spine and femur BMD by DXA in patients with varying severity spinal osteoporosis

Bone mineral density (BMD) at the lumbar spine, femoral neck, trochanteric region, and Ward's triangle was measured using dual-energy X-ray absorptiometry (DXA) in 118 women with osteoporotic vertebral collapse (average age 65 years), divided into four groups according to numbers and SD of vertebral deformation below norms: group 1: -3SD deformations only; group 2: one -4SD deformation; group 3: two-four -4SD deformations; and group 4: 5 or more -4SD deformations. There were no significant differences between the groups. Results were compared with those from 80 premenopausal (average age 32 years, range 20-40 years) and 109 postmenopausal normal women (average age 64, range 60-70 years). Mean BMD in osteoporotic group 1 was lower than premenopausal normal women by 32% at the lumbar spine, 31% femoral neck, 30% trochanteric region, and 44% at Ward's triangle, and postmenopausal controls by 17% lumbar spine, 16% femoral neck, 17% trochanter, and 14% Ward's triangle. There was a clear trend to reduction in mean BMD between osteoporotic groups 1 and 4 at all four measured sites with significant differences at the spine of 0.102 g/cm2 (P < 0.01) and Ward's triangle 0.059 g/cm2 (P < 0.01). When compared with premenopausal controls, there was a reduction in mean BMD between osteoporotic groups 1 and 4 of 10% at the lumbar spine, 7% femoral neck, 8% trochanteric region, and 13% Ward's triangle. Receiver operating characteristic analysis showed no significant differences in diagnostic sensitivities among the four measured sites for vertebral fractures. We conclude from this cross-sectional data that the majority of bone loss in spinal osteoporosis occurs before the onset of fractures.

Osteoporosis: assessment of bone loss and remodeling

Osteoporosis, the most common metabolic bone disorder, is a major health problem in older individuals, and especially in postmenopausal women throughout the world. It is characterized by low bone mass, structural deterioration, and an increased risk of fracture. The expected growth in the percentage of the world population over 65 years of age suggests that control of the chronic diseases of the elderly must be a major international priority. In order to design and implement appropriate prevention and treatment strategies for osteoporosis, it is necessary to assess the extent of the disease or condition in populations, and in individuals in a clinical setting. This review focuses on available and emerging techniques to measure bone mass or density, and on the role of biochemical markers of bone remodeling in the prediction of future bone loss. In order to prevent a disease that progresses without any obvious symptoms, it is important to determine not only the current status of bone mass and remodeling but also to develop methods to predict future bone loss. Different information is derived from each of the assessment approaches, and a combination of measures may be necessary to develop accurate predictive models.

Efficacy and safety of low-dose troleandomycin therapy in children with severe, steroid-requiring asthma

BACKGROUND

Troleandomycin (TAO), a macrolide antibiotic, was studied as an alternative treatment in 18 children with severe, steroid-requiring asthma.

METHODS

In this investigation three treatment arms were used in randomized, double-blind, parallel fashion: combination TAO and methylprednisolone (MPn), combination TAO and prednisone, and MPn alone.

RESULTS

All groups tolerated a considerable reduction in glucocorticoid dose over the 12 weeks of the study: 80% +/- 6% for TAO-MPn, 55% +/- 8% for TAO-prednisone, and 44% +/- 14% for MPn alone. These reductions are all statistically significant (p < 0.05) within groups, and the differences between groups were statistically significant between the TAO-MPn and MPn alone groups. The concentration of methacholine required to induce a 20% decrease in forced expiratory volume in 1 second and pulmonary function were not significantly improved in any treatment group. Safety parameters including blood chemistry and hematology, adrenal function assessment; bone densitometry, and muscle strength testing, were not altered significantly. Two patients who received TAO had elevated liver enzyme levels; one required discontinuation of TAO and one experienced spontaneous resolution without intervention. Lack of statistically significant changes in the efficacy parameters were likely a result of small sample size and effects of the glucocorticoid dose taper.

CONCLUSIONS

TAO is safe and may be a reasonable treatment alternative in a limited trial for patients who are unable to tolerate tapering of their glucocorticoid dosage. Therapy should be guided by the goal of treatment, that is, glucocorticoid dose reduction or improvement of pulmonary function with appropriate monitoring of pulmonary function and adverse effects.

Estrogen-replacement therapy after breast cancer. Risks versus benefits

In the current aging society, more than 30 million women have an average postmenopausal life expectancy of 28 years. Coronary heart disease is the leading cause of death in older women, and osteoporosis results in an estimated 1.5 million fractures per year. Various studies have suggested that postmenopausal estrogen-replacement therapy could reduce the morbidity and mortality associated with these conditions. Based on the results of several "natural experiments," it was proposed that estrogen-replacement therapy should be considered for menopausal women who have been treated successfully for breast cancer. The benefits and risks of estrogen-replacement therapy are reviewed, and recommendations for management and future research are suggested.

Measurement of mandibular bone density ex vivo and in vivo by dual-energy X-ray absorptiometry

Severe bone resorption is a vexing clinical problem, especially in patients without teeth. To study resorption in vivo, measurements of bone mineral density (BMD) of the mandible of both patients with and without teeth are needed. Using a Hologic QDR-1000 bone densitometer designed to measure lumbar spine and hips, ex vivo and in vivo measurements were made in selected areas of the mandible. The mandible was positioned such that the X-ray beam was perpendicular to its sagittal plane. In this way the beam hits first one half of the mandible and then the other. The reproducibility--expressed as coefficient of variation--of the ex vivo measurements was 0.5%. For in vivo measurements this coefficient was 3%. The method used for mandibular BMD would make it possible to define an average BMD in several categories of the normal population and of patients, and to compare bone density in the mandible with that in the axial and perpendicular skeleton. Improvement may be obtained by repeating the measurement. The entrance dose per scan is low, equalling that of one bitewing/radiograph.

The epidemiology of fragility fractures: is there a role for bone quality?

Fragility fractures, particularly those of the hip, vertebrae, and distal forearm, constitute a major public health problem. The two ultimate determinants of fracture are bone strength and propensity to trauma. Bone strength depends not only upon bone mass but also upon a variety of qualitative aspects of bone structure. These include its architecture, the amount of fatigue damage it has sustained, and changes in its bulk material properties, indices that are collectively subsumed into the term "bone quality." Fragility fractures show differences in their patterns of incidence by age, sex, ethnic group, geographic area, and season. Many of these differences are currently unexplained, and disorders of bone quality might contribute to them. There are two fracture sites at which evidence implicates bone quality more directly--the spine and proximal femur. Many vertebral compression fractures follow minimal trauma, and controlled studies suggest that vertebral microarchitecture contributes to fracture risk independently of vertebral bone mass. At the hip, observational studies have pointed to a role for disordered trabecular architecture, accumulation of microfractures (fatigue damage), and the accumulation of osteoid. The extent to which these phenomena act independently of bone mass, however, remains uncertain.

Bone densitometry in patients with multiple myeloma

PURPOSE, PATIENTS, AND METHODS

We performed dual-energy x-ray absorptiometry in 10 selected patients with aggressive multiple myeloma in whom substantial tumor mass reduction was achieved after high-dose chemoradiotherapy followed by autologous blood stem cell transplantation.

RESULTS

In most cases, bone mineral density (BMD) of the spine was initially low (Mean Z score: -2.69, SEM 0.76) and dramatically increased after treatment (mean increase 16.4%; 7.7% with 95% confidence interval 2.2 to 12.2, excluding one patient whose spine BMD increased by 94.8%). In contrast, skeletal roentgenograms, computed tomographic scans, and magnetic resonance imaging did not reveal any significant improvement of patients' bone lesions.

CONCLUSIONS

In patients with multiple myeloma, bone densitometry could be a useful way to assess the efficacy of treatment on bone status.

Bone mineral density during puberty in western Canadian children

To assess the influence of puberty and its associated changes in body weight and height on bone mineral density (BMD), lumbar spine (L2-L4) and femoral neck BMD were measured in 74 healthy, active children (9-16 years) using dual-photon absorptiometry. Competitive swimmers were recruited to minimize the potential effect variability in mechanical loading regime may have on bone density of the lumbar spine. Tanner staging was used to assess stage of puberty. Current dietary calcium intake was assessed by analysis of 6-day dietary records. Significant differences in spinal and femoral neck BMD occurred between early (Tanner 1 and 2) and late stages of puberty (Tanner 4 and 5), P < 0.05. A significant correlation was found between bone density and dietary calcium intake. However stepwise regression analyses demonstrated stage of puberty or body weight were the only factors which significantly affected spinal BMD, accounting for 77% and 68% of the variability respectively; while at the femoral neck, body weight accounted for 52% of the variability. These results demonstrate that when potential interacting factors are controlled for through regression analyses, differences in BMD occur mainly as a function of puberty and the associated gains in body weight.

Lateral spine densitometry is a more sensitive indicator of glucocorticoid-induced bone loss

Osteoporosis is a common complication of glucocorticoid therapy. Bone density measurement is now commonly used in assessing which steroid-treated patients require specific interventions to reduce fracture risk. The recently developed techniques for the measurement of bone mineral density (BMD) of the vertebral body alone, by dual-energy x-ray absorptiometry (DXA) in the lateral projection, may be particularly useful in this context since steroid-induced bone loss is most marked in trabecular-rich regions like the vertebral body. This possibility has been assessed in the present study by the measurement of BMD in the lateral and anterioposterior (AP) projections in 28 women receiving chronic glucocorticoid treatment. The two BMD measurements were significantly related (r = 0.62, p < 0.001). When expressed in relation to age-appropriate normal values, lateral BMDs were lower than AP BMDs both in percentage terms (70.8 +/- 4.4 versus 90.3 +/- 2.6%, p < 0.001) and in terms of Z scores (-1.42 +/- 0.22 versus -0.91 +/- 0.24, p = 0.027). AP BMD Z scores classified 12 patients as osteopenic, whereas a further 7 were so categorized by lateral BMD Z score. It is concluded that lateral DXA scanning is a more sensitive indicator of glucocorticoid-induced osteopenia than conventional BMD measurement in the AP projection.

Long-term gonadal dysfunction and its impact on bone mineralization in patients following COPP/ABVD chemotherapy for Hodgkin's disease

Only limited data is currently available on long-term gonadal toxicity and its impact on bone mineralization in men and women treated for Hodgkin's disease. The present study was therefore conducted to evaluate gonadal toxicity and bone loss in 49 patients with Hodgkin's disease 2-10 (median 5.37) years after chemotherapy. Most patients were treated with the COPP/ABVD regimen +/- irradiation according to the protocols of the German Hodgkin Study Group. Blood samples were tested for gonadotropins (FSH, LH), gonadal steroids, parathyroid hormone, osteocalcin, and calcitonin. Bone mineral density was measured using single- and dual-energy quantitative computed tomography as well as single-photon absorptiometry. FSH serum levels were significantly increased in 21/27 (80%) men demonstrating germ-cell aplasia. 13/15 (86%) men showed azoospermia after the COPP/ABVD regimen. In contrast, testosterone levels were within normal limits in all men tested, suggesting normal Leydig-cell function. 17/22 (77%) women exhibited increased FSH and LH levels, indicating premature ovarian failure. Women with therapy-induced ovarian failure had a significantly lower trabecular (98 +/- 34) and cortical (292 +/- 48 mg/cm3) spinal bone density than those with normal ovarian function. Men showed no evidence of bone loss after therapy. These data suggest severe gonadal toxicity in both men and women treated with the COPP/ABVD regimen. In female patients, drug-induced ovarian failure has a significant impact on bone mineralization.