Dual Photon Absorptiometry Research Articles

Mechanical loading regime and its relationship to bone mineral density in children

This study tested the hypothesis that differences in mechanical loading regime was important when evaluating the potential role of physical activity on bone density in children. Seventeen children competing regularly in weight-bearing sports producing loads of at least 3 times body weight (Impact Load) were matched for race, gender, stage of puberty, body weight, and average daily training time with children involved in competitive swimming (Active Load). Bone mineral density (BMD) was measured using dual photon absorptiometry at the lumbar spine (L2-L4) and femoral neck (FN), Tanner staging was used to assess puberty, diet was evaluated based on 3-d dietary records from two occasions, and a questionnaire assessed average daily nonweight-bearing hours. There were no significant differences in age (13.2 +/- 0.4 and 12.6 +/- 0.4), height (154.9 +/- 2.9 and 157.6 +/- 3.0), or weight (43.6 +/- 2.7 and 44.5 +/- 2.2) between Impact and Active Load groups. Impact Load children had significantly greater FN BMD (0.78 +/- 0.02) than Active Load children (0.72 +/- 0.02) and a tendency for greater BMD L2-L4; 0.70 +/- 0.03 and 0.66 +/- 0.03, respectively. These data indicate that children involved in sports producing significant impact loading on the skeleton had greater femoral neck bone density and a trend for greater spinal bone density, than children in sports producing loads to bone primarily through muscular contraction.

Hormonal status and clinical relevance of hirsutism in elderly women

Hirsutism is a common condition of elderly women, but its aethiopathogeny and its clinical implications remain unclear. We therefore studied circulating androgen concentrations in elderly women. In addition, this study aims to define a possible relationship between hirsutism and anthropometric determinations, bone mass and serum lipids. Androgen levels were determined at basal state, after adrenocorticotrophin (ACTH) stimulation and after dexamethasone administration in 10 hirsute elderly women and compared to 10 age-matched non-hirsute women. Anthropometric determinations included measurements of skinfold thickness and body mass index. Spinal bone mass density was assessed using dual photon absorptiometry. Hirsute women presented significantly higher levels of testosterone than controls (1.49 +/- 0.38 vs 0.59 +/- 0.05 nmol/l, mean +/- SEM; p < 0.05) and dihydrotestosterone (0.54 +/- 0.07 vs 0.32 +/- 0.03; p < 0.02). 17-hydroxyprogesterone levels after ACTH stimulation tended to be higher in hirsute women than in controls. No differences were observed between the two groups in serum oestrogen concentrations, plasma lipid pattern or bone mineral density. Hirsute women had a lower body mass index and lower calculated percentage body fat than the control group. We conclude that: (i) hirsutism of elderly women is associated with increased androgen levels, probably from adrenal origin; (ii) in some cases, enhanced response in 17-hydroxyprogesterone after ACTH stimulation suggests a partial adrenal 21-hydroxylase deficiency; (iii) hirsute women present anthropometric characteristics compatible with the known anabolic effect of androgens on fat-free mass.

Effect of rectal salmon calcitonin treatment on bone mass and bone turnover in patients with established postmenopausal osteoporosis: A 1-year crossover study

A new suppository formulation of salmon calcitonin (sCT) is now available to increase the choices for the clinician in the treatment of osteoporotic patients. To test this new formulation, we studied the efficacy and tolerability of rectal sCT in 40 patients with postmenopausal osteoporosis. According to a double-blind, placebo-controlled design, the patients were divided into two groups and treated with a daily dose of 100 IU of sCT administered by suppository or matching placebo for 6 months. After 6 months, patients were crossed over so that the sCT-treated group received placebo for the subsequent 6 months and vice versa. Bone mineral density (BMD), measured at the distal radius by dual photon absorptiometry and at the lumbar spine by dual energy X-ray absorptiometry, increased by 3.3% and 3.0%, respectively, after 6 months in the sCt-treated group. The placebo group showed a significant ( P < 0.05) decrease only at the lumbar spine. The differences between the two groups were significant, as determined by one-way analysis of variance. After the crossover period, only the group receiving the active treatment showed an increase in BMD. No significant changes were observed in the biochemical indexes of bone turnover (serum osteocalcin and hydroxyproline/creatinine ratio) in both groups, although during the sCT treatment periods a reduction of bone turnover rate was observed, as demonstrated by the reduction of these markers. This new formulation was well tolerated. Our results indicate that a 6-month treatment with sCT, at a daily dose of 100 IU administered by suppositories, is able to increase bone mass and to exert an inhibitory effect on bone turnover.

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.

Variation of cortical hypertrophy depending on the medullary filling material: An experimental study of canine tibial diaphysis

In order to evaluate the mineralization of bone after polymethyl methacrylate cementation, measurements of the periosteal apposition were made histologically and measurements of the bone—mineral content were made by dual-photon absorptiometry of the tibial diaphysis in 15 adult mongrel dogs in paired studies. Six dogs were investigated 4 weeks after intramedullary reaming of both sides and obturation of the medullary cavity with bone—wax on one side. Nine dogs were reamed on both sides. The medullary cavities were filled with polymethyl methacrylate bone—cement and bone—wax, respectively. The authors found (1) an increased bone—mineral content and an increased periosteal apposition after filling with bone—wax in comparison with the reamed side and (2) a decreased bone—mineral content and a decreased periosteal apposition on the cemented side in comparison with bone—wax. These findings are interpreted as consequential upon repair processes with a high remodeling and mineralization rate after reaming or filling with bone—wax, whereas remodeling is inhibited after filling with acrylic bone—cement.

Variation of cortical hypertrophy depending on the medullary filling materialAn experimental study of canine tibial diaphysis

In order to evaluate the mineralization of bone after polymethyl methacrylate cementation, measurements of the periosteal apposition were made histologically and measurements of the bone—mineral content were made by dual-photon absorptiometry of the tibial diaphysis in 15 adult mongrel dogs in paired studies. Six dogs were investigated 4 weeks after intramedullary reaming of both sides and obturation of the medullary cavity with bone—wax on one side. Nine dogs were reamed on both sides. The medullary cavities were filled with polymethyl methacrylate bone—cement and bone—wax, respectively. The authors found (1) an increased bone—mineral content and an increased periosteal apposition after filling with bone—wax in comparison with the reamed side and (2) a decreased bone—mineral content and a decreased periosteal apposition on the cemented side in comparison with bone—wax. These findings are interpreted as consequential upon repair processes with a high remodeling and mineralization rate after reaming or filling with bone—wax, whereas remodeling is inhibited after filling with acrylic bone—cement.

Vertebral postmenopausal bone loss is reduced in overweight women: a longitudinal study in 155 early postmenopausal women.

To study the influence of excess body weight on vertebral postmenopausal bone loss, 155 healthy early postmenopausal women were divided into 2 groups according to their body mass index (BMI = weight/height2) and prospectively followed over a mean 31-month period. Spinal (L2-L4) bone mineral density was measured by dual photon absorptiometry. The annual rate of vertebral bone loss (percentage) was significantly reduced (-0.54 +/- 1.1% vs. -1.46 +/- 1.6%; P < 0.05) in the overweight group (BMI, > or = 25; n = 40) compared to that in the normal weight group (BMI, < 25; n = 115). At baseline, a significant decrease in the urinary calcium/creatinine ratio was observed in the overweight group, which suggested a decrease in bone turnover. A significant correlation was found between the annual rate of bone loss and the BMI (r = 0.21; P < 0.05), but not the body weight. The positive correlation between vertebral postmenopausal rate of bone loss and BMI was confirmed after adjustment for age and time since menopause. Moreover, plasma dehydroepiandrosterone sulfate levels were higher in the high BMI group than in the normal BMI group (P < 0.05). We conclude that within the first years after menopause, moderate excess body weight significantly reduces vertebral postmenopausal bone loss. This effect is probably related to excess adipose tissue through increased conversion of estrogen from adrenal precursors and/or increased production of adrenal androgens.

Intramedullary Nailing and Cortical Bone Mineral Content

A transverse diaphyseal osteotomy of the tibia was stabilized using rigid intramedullary nailing in rabbits. In a 2nd group, nailing was performed without osteotomy. The rabbits were sacrificed 3 to 24 weeks postoperatively, and the nails were removed. The mineral content (BMC) was measured by dual photon absorptiometry and the mineral density (BMD) was calculated. At 24 weeks the osteotomized bones had significantly lower BMC values than did the respective nonosteotomized bones or the intact bones. The BMC of the nonosteotomized bones remained above the control level throughout the experiment. The minimum BMD values of the osteotomized bones were detected at 3 weeks, whereafter they gradually approached the control level over time. The results suggest that rigid intramedullary nailing in connection with osteotomy causes a significant decrease in cortical bone mineral mass, seen at 24 weeks postoperatively. The photon absorption method used seemed sensitive enough to detect changes in cortical bone mineral quantity in these experimental conditions.

Relationship between bone mineral density and dietary intakes in the elderly

Dietary protein and/or calorie insufficiencies represent an important problem in elderly patients. The biological and clinical implications, and particularly the influence on bone mass of undernutrition in the elderly, have not been completely defined, although several studies have demonstrated a high prevalence of dietary insufficiencies in patients with a recent fracture of the proximal femur. In the present study the relationship between dietary intakes, physical performance and bone mineral density (BMD) was examined in hospitalized elderly patients. The study comprised 74 patients (48 women, mean age 82 years; and 26 men, mean age 80 years) who were hospitalized for various medical indications. They were divided into two groups according to their dietary protein intakes, evaluated during the first 28 days in hospital while on a regular diet. The first group consisted of 26 patients (14 women and 12 men) whose protein intake was equal to or greater than 1 g per kilogram of ideal body weight. The second group consisted of 48 patients (34 women and 14 men) who consumed less than 1 g of protein per kilogram of ideal body weight. The two groups differed also in their energy, carbohydrate, lipid and calcium intakes. Patients in the group with the higher protein intake displayed higher BMD at the level of the femoral neck as measured by dual-photon absorptiometry. The men in this group also had higher lumbar spine BMD. After 4 weeks in hospital the women with a higher protein intake had significantly enhanced bicipital and quadricipital muscle strength and better performance as indicated by the increased capacity to climb stairs.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced bone mineral content in adult patients with growth hormone deficiency

Bone mineral content was measured in a follow-up study of adult patients with hypopituitarism and growth hormone deficiency. There were 95 patients (59 males, mean age 54.0 years, range 21-74 years; 36 females, mean age 53.5 years, range 31-73 years). Routine replacement therapy with cortisone acetate and L-thyroxine was given. All males that were gonadal deficient were on proper testosterone therapy, except in four patients who were treated separately. Bone mineral content (g/cm) was measured using dual-photon absorptiometry in the third lumbar vertebra. Bone mineral content in the patients was compared with a control population (N = 413, 25-74 years of age). Bone mineral content was significantly lower in males (N = 55, p < 0.05) compared with controls. In females, bone mineral content was significantly lower both among the subjects with untreated gonadal deficiency (p < 0.001) and among those with treated gonadal deficiency and normal premenopausal gonadal function (p < 0.005) compared with controls. To summarize, patients with hypopituitarism on routine replacement therapy but not growth hormone have a lower bone mineral content than the controls. The reduced bone mineral content might be a result of untreated growth hormone deficiency.

Physical activity as a determinant of bone conservation in the radial diaphysis in rheumatoid arthritis.

To determine if increasing physical activity is protective of diaphysial (cortical) bone mass Fifteen patients attending two rheumatology clinics who had developed seropositive or classical rheumatoid arthritis up to 26 months previously were studied prospectively for two to three years. Rates of loss (or gain) in bone mass in the radial diaphysis and the trabecular bone of the distal radius were measured by quantitative computed tomography, and in the spine by dual photon absorptiometry. Physical activity was assessed by the Framingham physical activity index. Disease activity was followed at three-monthly clinic visits at which the haemoglobin, erythrocyte sedimentation rate, and platelet count were measured. The urinary hydroxyproline to creatinine ratio and plasma osteocalcin were measured at the beginning and end of the observation period. Eleven patients required treatment with disease modifying drugs but none was given corticosteroids. Those whose physical activity did not improve lost radial diaphysial bone at about 4% annually. There was, however, a statistically significant inverse relation, accounting for 48.5% of the variance, between bone loss at this site and improvement in physical activity as assessed by the Framingham index. The other two sites showed much weaker associations. Adjusting for indices of disease activity hardly affected the first relation. Three biochemical indices related to bone turnover showed weak tendencies to decrease with increasing physical activity. Peripheral cortical bone, distant from inflamed joints, is conserved more successfully in patients who achieve higher levels of physical rehabilitation. This may have implications for avoiding long bone fractures later in the disease.

Changes in bone mineral content and density after stroke.

The purpose of this study was to determine whether there are differences in bone mineral content and density between paralyzed and nonparalyzed sides of patients who had sustained strokes associated with unilateral muscle weakness, to determine the relationship between duration of stroke and degree of demineralization and to compare the degree of demineralization in upper and lower limbs. The bone mineral content and density were measured by dual photon absorptiometry (high resolution scanning mode, Lunar DP4) in ambulant patients with a history of single completed strokes associated with unilateral weakness. The bone mineral content and density of each limb was determined by the region of interest analysis program. In the 30 patients included in this study, the bone mineral content and density were significantly less on the paralyzed than on the nonparalyzed side. The degree of demineralization was more pronounced in the upper than in the lower limbs. The mean percentage differences in bone mineral content and density between paralyzed and nonparalyzed arms were 13.8% (P < 0.00001) and 7.95% (P = 0.0003), respectively, and between paralyzed and nonparalyzed legs the differences were 4.5% (P = 0.0012) and 3.42% (P = 0.0028), respectively. A better correlation was noted between the time elapsed since the stroke and the degree of demineralization in the upper limbs (r = 0.75, P < 0.0001), than in the lower limbs (r = 0.60, P = 0.0004). In conclusion, patients who have strokes associated with muscle weakness are at an increased risk of developing osteoporosis on the paralyzed side and particularly in the upper limbs.

Effect of age and osteoarthritis on bone mineral in rhesus monkey vertebrae

We have used vertebrae of free-ranging rhesus macaques to study the effect of age and osteoarthritis on bone mineralization and bone density and to relate these findings to weight, sex, parity, and mineral chemistry. Bone mineralization was determined using the density fractionation technique and bone density using dual-photon absorptiometry. Arthritis was determined osteologically. We found a relationship between mineralization, age, and osteophytes, such that mineralization rose with age in nonarthritics and decreased with age in arthritics. This could also be seen when the females were examined separately. In males, only an increase in mineralization with age could be seen. In females mineralization decreases with parity. Also in females, DPA density decreases with age and increases with parity. No relationships with DPA density could be seen using males and females together or males alone. In conclusion, we have shown that normal skeletal aging in rhesus monkeys is accompanied by an increase in mineralization similar to that in other species, but this is not true in the presence of osteoarthritis. In the females parity has an important effect because it seems to build up bone mass even though the bone present may be undermineralized.

Roentgenographic procedure for selecting proximal femur allograft for use in revision arthroplasty

A roentgenographic scoring system was developed to help orthopaedic surgeons and bone banks estimate the quality of bone stock in proximal femoral allografts inteded to use in revision arthroplasty. This system scores a standardized anteroposterior roentgenograph of the proximal femur using four indices representing morphological features of cancellous and cortical bone known to be clinically associated with bone strength. The indices were combined to give a weighted score, which was though to reflect the ability of a bone to carry in vivo loads. Thirty bones were evaluated for bone mineral density using dual-photon absorptiometry. They were then sent to another institution and evaluated using the newly devised roentgenographic scoring system. The results showed that the bone score roentgenographic method is a a reasonable technique for selecting allograft femurs for transplantation. This roentgenographic technique and scoring system has now been packaged into kits and is available to orthopaedic surgeons and bone banks for evaluation bone stocks quality in proximal femoral allografts intended for transplantation.

NON-WEIGHTBEARING EXERCISE MAY INCREASE LUMBAR SPINE BONE MINERAL DENSITY IN HEALTHY POSTMENOPAUSAL WOMEN

Seven postmenopausal women exercised regularly at moderate intensities (60-80% of maximum heart rate) for eight months on bicycle ergometers. Evaluation of bone mineral density by dual photon absorptiometry revealed a significant (P < 0.01) + 3.55 +/- 1.43% (mean +/- SE) increase in lumbar spine density in the exercisers compared with the 2.44 +/- 0.81% decrease noted in seven sedentary controls. No significant difference in change in femoral neck density was noted between the two groups (+2.51 +/- 2.10% v -0.74 +/- 0.72% for exercisers and controls, respectively; P > 0.10). Dietary intake of calcium and vitamin D was similar in both groups, as was previous exposure to estrogen replacement therapy. These data provide evidence of a prospective nature that non-weightbearing exercise may be effective in reversing bone loss in healthy postmenopausal women.

Influence of patient's weight on dual-photon absorptiometry and dual-energy X-ray absorptiometry measurements of bone mineral density

Lumbar spine bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) (Hologic QDR 1000) and by 153Gd dual-photon absorptiometry (DPA) (Novo Lab 22a) in 120 postmenopausal women. Though a high correlation existed between the two techniques, the ratio between DXA and DPA values was not constant. Using DXA we observed a higher dependence of BMD on weight than in the DPA measurements. To investigate the different behaviour of DXA and DPA machines with weight, we analysed the effects of increasing thickness of soft tissue equivalents on the BMD of the Hologic spine phantom and on the BMD equivalent of an aluminium standard tube. Increasing tissue-equivalent thickness caused the phantom BMD measured by DPA to decrease significantly but had not effect on the DXA measurements. The different behaviour of DPA and DXA equipment with regard to the phantoms could account for the differences observed in the relations between BMD and weight in the patients. Using multiple regression we studied the influence of weight and body mass index on the relation between BMD measured by the two techniques. The introduction of either of these variables into the regression resulted in an improvement of the prediction of the DXA values from the DPA values. However, the residual standard error of the estimate was still higher than the combined precision errors of the two methods, so that no simple relation allows a conversion of BMDDPA into BMDDXA. Our results confirm that BMD is positively correlated with weight in postmenopausal women; the influence of weight on BMD is blunted when the Novo Lab 22a DPA machine is used for measuring bone mineral.

Estimation of vertebral body strength by dual photon absorptiometry in elderly individuals: Comparison between measurements of total vertebral and vertebral body bone mineral

The aim of the present study was to investigate the predictive value of bone mineral measurements by dual photon absorptiometry (DPA) in vitro for strength and ash weight of lumbar vertebral bodies in elderly, otherwise nonselected individuals. The material comprised 46 individuals: 26 males (43–95 years) and 20 females (63–95 years) without malignant diseases. Spinal segments, including L 2, L 3, and L 4, were removed en bloc at autopsy. Bone mineral content (BMC) measurements imitating the normal DPA procedure were performed on the segments suspended in a water bath. The segments were measured in toto (BMC T) and remeasured after removal of the posterior elements (BMC B). The second lumbar vertebral body (L 2) was then dissected and sawed below the endplates to obtain samples with pianoparallel ends before compression in a materials testing machine. Finally, the bone specimens were incinerated for ash weight estimations. BMC T showed significant correlations to vertebral body ash weight ( r = 0.79), compressive strength (load, r = 0.69), and stress (load per unit area, r = 0.47). The correlations were unproved by removing the posterior elements (BMC Bash weight, r = 0.86, BMC B-load, r = 0.74, BMC B-stress, r = 0.49). Correction of BMC for differences in vertebral body height (BMC/cm) further increased the correlation coefficients (BMC B/cm-ash weight, r = 0.92, BMC B/cm-load, r = 0.78, BMC B/cm-stress, r = 0.55). We conclude that lumbar BMC is predictive for lumbar vertebral body compressive strength in vitro and ash weight. The correlation coefficient is improved by removing the posterior non-weight-bearing element. Both BMC B and BMC T corrected for vertebral height give a slightly improved correlation for vertebral body compressive strength.

Effects of chronic heroin abuse on bone and mineral metabolism

Though the chronic use of opiates can modify several body functions, only a few data are available on the effects of opioid drugs on mineral metabolism. We have examined the possible consequences of chronic opiate abuse on bone mass, bone turnover and calcium metabolism in 13 male chronic heroin users, examined 1-2 days after the last administration of the drug (group A), 14 former male heroin addicts, examined 4-24 months after drug discontinuation (group B), and 22 healthy, age- and sex-matched control subjects. In group A, the vertebral bone mineral density (measured by Dual-Photon Absorptiometry) was significantly lower (p < 0.05) than in the control subjects, despite similar values of total body bone mineral, lean body and fat mass. Blood-ionised calcium and urinary calcium and hydroxyproline were significantly increased (p < 0.01), whereas parathyroid hormone was lower than in controls (p < 0.01). Bone alkaline phosphatase and osteocalcin, however, were not significantly different from the control values. LH and testosterone levels were low (p < 0.01 vs controls). In contrast, group B subjects did not show significant differences from the control group. The chronic abuse of opioid drugs may be associated with altered bone metabolism and reduced trabecular bone mass, attributable, at least in part, to gonadal deficiency. These alterations seem reversible after drug discontinuation.

Effect of long‐term administration of progestogen on post‐menopausal bone loss: result of a two‐year, controlled randomized study

We determined whether a progestogen given alone to post-menopausal women may prevent bone loss. Thirty-five early post-menopausal women who had not received any form of treatment to prevent bone loss were randomly assigned to a 2-year regimen of 500 micrograms/day of a gestagen derived from 19-norprogesterone (Promegestone) or a placebo for 21 days out of a 28-day treatment cycle. Bone mineral density of the spine was measured by dual photon absorptiometry. After 2 years of treatment bone mineral density decreased significantly in the placebo group by a mean of 4.5%. In the gestagen group, the rate of bone change was significantly lower as compared to the placebo group (-1.3% +/- 1.2% vs -4.5% +/- 2% (mean +/- SEM), P < 0.05). There were no changes in the biochemical bone turnover parameters in the placebo group but in the gestagen group a significant decrease was observed in the urinary calcium excretion after 2 years. The results suggest that a gestagen with no androgenic action can partly counteract early post-menopausal bone loss.

The development of juxta-articular osteoporosis after synovectomy of the knee. A prospective study by double photon absorptiometry.

In a prospective study 9 patients, who were going to have a synovectomy for rheumatoid arthritis of the knee, underwent dual photon absorptiometry before, and at intervals after, operation. This determined the degree of juxta-articular osteoporosis quantitatively. The density was compared to a control group with normal knees. The follow up measurements showed an improvement in the juxta-articular bone mineral content after the 6th month. This demonstrates that bone densitometry is an objective indicator of the development of juxta-articular osteoporosis in inflammatory joint disease.