Biomedical subjects

D Felsenberg

Publications and source records attributed to D Felsenberg.

At least 73 records · Page 4Linked to original sources

PubMed1998

Measurements of vertebral shape by radiographic morphometry: sex differences and relationships with vertebral level and lumbar lordosis.

OBJECTIVE: To examine sex-related and vertebral-level-specific differences in vertebral shape and to investigate the relationships between the lumbar lordosis angle and vertebral morphology. DESIGN AND PATIENTS: Lateral thoracic and lumbar spine radiographs were obtained with a standardized protocol in 142 healthy men and 198 healthy women over 50 years old. Anterior (Ha), central (Hc) and posterior (Hp) heights of each vertebra from T4 to L4 were measured using a digitizing technique, and the Ha/Hp and Hc/Hp ratios were calculated. The lumbar lordosis angle was measured on the lateral lumbar spine radiographs. RESULTS: Ha/Hp and Hc/Hp ratios were smaller in men than women by 1.8% and 0.7%, respectively, and these ratios varied with vertebral level. Significant correlations were found between vertebral shape and the lumbar lordosis angle. CONCLUSIONS: These results demonstrate that vertebral shape varies significantly with sex, vertebral level and lumbar lordosis angle. Awareness of these relationships may help prevent misdiagnosis in clinical vertebral morphometry.

Aged↗

PubMed1998

Bone densitometry: applications in sports-medicine.

Physical exercise and sports increase muscular mass and the remodelling process of bones. The increment of bone depends on the type and the quality of sport. Short-term high-performance activities such as sprint, tennis, fencing lead to increased bone mineral density as well as weight lifting or heavy athletics. Swimming, bicycling, walking are associated with good musculature conditioning without an increase of bone mass. The effects on the bone by performing endurance activities are controversially discussed. Excessive sport leads to an increase of fatigue fractures. Low bone mass may result from hormonal disregulation in female athletes.

Absorptiometry, Photon↗

PubMed1998

Linearity and accuracy errors in bone densitometry.

This investigation was undertaken to quantify accuracy errors and identify possible linearity errors in dual energy X-ray absorptiometry (DXA) of bone, based on studies of commercially available bone densitometers for planar densitometry. The following was found in a combination of in vitro phantom studies and in vivo investigations of human volunteers: (1) Pronounced differences between the instruments when measuring vertebral size and contours of the projected bone regions. (2) Falsely low bone mineral content (BMC in terms of g) in cases of low nominal bone mass, due to the fact that edge regions were omitted by the calculation software of some devices. (3) An increase in the projected bone area secondary to an increase in nominal bone mass with some instruments. (4) Clinically and statistically significant errors of accuracy of BMC and to a lesser extent bone mineral density (BMD). (5) Substantial linearity errors with some osteodensitometers for BMC, a phenomenon that reduces the usefulness of this parameter. It is concluded that DXA devices are affected by a combination of accuracy errors and linearity errors, some more than others, and that linearity errors influence their ability to monitor change in BMC and to a lesser extent in BMD, making system intercomparison difficult.

Adult↗

PubMed1998

Measures of complexity for cancellous bone.

The problem of quantifying the structure of cancellous bone has been addressed in the past by histomorphometry and more recently by imaging techniques using X-ray attenuation. The current approaches compute and describe parts of the construction of the trabecular net. We developed a new technique which quantifies cancellous bone of human lumbar vertebrae as a whole. The interactions, transactions, and interrelationships of all parts of the structural composition of the trabeculae are accounted for and quantified. The method is based on the concept of structural complexity within the framework of nonlinear dynamics. The methodology was developed by using axial high resolution computed tomography images. The technique was transferred to quantitative computed tomography images and is based on the non-invasive assessment of 50 human L3 specimens. The value of Houndsfield units per pixel representing trabecular bone of the vertebrae was transformed into color-encoded and alphabet-encoded symbols. The procedure of transformation of the X-ray attenuation pixels into symbols was necessary as a basis on which measures of complexity were introduced to assess the composition of symbols within the images. The development of a generalization of symbolic dynamics, a mathematical method, to work with two-dimensional images was a prerequisite. The results of this study demonstrate that the structural composition of cancellous bone declines more rapidly than bone mineral density during the loss of bone. This outcome strongly suggests an exponential relationship between bone mineral density and the architectural composition of cancellous bone. Normal trabecular bone has a complex ordered structure. The structural composition during the osteopenic phase of bone loss is characterized by lower structural complexity and a significantly higher level of architectural disorder. A high grade of osteoporosis leads again to an ordered structure, although its structural complexity is minimal.

Algorithms↗

PubMed1998

Prevalence of vertebral deformities according to the diagnostic method.

Vertebral deformities are a major complication of osteoporosis. Although their prevalence is known to increase with age, the absence of reference criteria complicates their radiologic diagnosis. We evaluated variations in the prevalence of vertebral deformities according to the diagnostic method used in 291 men and 262 women older than 50 years included in the European Vertebral Osteoporosis Study. Lateral radiographs of the thoracic and lumbar spine were obtained in all subjects using standardized parameters. Six morphometric and quantitative methods were used to detect vertebral deformities. The prevalence of vertebral deformities, the number of vertebral deformities per 100 subjects and the prevalence of deformities for each vertebra varied according to the method used. With most methods, the percentage of subjects with vertebral deformities and the number of vertebral deformities were similar among the men and among the women. In the women, the prevalence and the number of vertebral deformities increased with age; beyond 70 years of age, however, the prevalence remained stable with advancing age, although the number of deformities per patient increased. In men, the prevalence of vertebral deformities remained stable with advancing age, suggesting that osteoporosis was not the only cause of vertebral deformity in this group. In conclusion, the prevalence of vertebral deformities varies according to the diagnostic method used. In men, none of the six methods evaluated in this study adequately differentiates osteoporotic deformities from deformities due to other causes.

Age Factors↗

PubMed1997

[Prevalence of vertebral deformity in Hungary: the European Vertebral Osteoporosis Study].

Prevalence and distribution of vertebral deformity regarded as classic marker of osteoporosis are reported on the basis of the results of the first Hungarian cross-sectional population-based survey. The clinical-epidemiological project is conducted by the National Institute of Rheumatology and Physiotherapy in Hungary in the frame of the European Vertebral Osteoporosis Study which comprises 19 countries and 36 centres. A random sample of 324 females and 300 males aged 50 years and over stratified in 5-year age bands was recruited. Lateral spinal X-rays were evaluated centrally by two different morphometric methods. Based on the McCloskey-Kanis criteria the prevalence of all deformities was 16.7% in females and 18.7% in males. These values from Hungary have been considered high compared to the prevalence rates of other European countries, approaching, and in males exceeding, the highest rates gained from Sweden. In females the prevalence increased with age, men aged 50-59 years and women aged 75 years and over had higher prevalence of deformity compared to the other sex. In females vertebra thoracic 11, in males that of lumbar 3 were mostly affected, wedge deformities occurred most frequently. Extrapolating the results we can conclude that vertebral deformity found in both sexes similarly, affects approximately 500,000 individuals in Hungary along with the potential deterioration of quality of life. This enormous burden requires the consistent fulfillment of the National Osteoporosis Program and other preventive-curative strategies.

Aged↗

PubMed1997

Anthropometric measurements and vertebral deformities. European Vertebral Osteoporosis Study (EVOS) Group.

To investigate the association between anthropometric indices and morphometrically determined vertebral deformity, the authors carried out a cross-sectional study using data from the European Vertebral Osteoporosis Study (EVOS), a population-based study of vertebral osteoporosis in 36 European centers from 19 countries. A total of 16,047 EVOS subjects were included in this analysis, of whom 1,973 subjects (915 males, 1,058 females) (12.3%) aged 50 years or over had one or more vertebral deformities ("cases"). The cases were compared with the 14,074 subjects (6,539 males, 7,535 females) with morphometrically normal spines ("controls"). Data were collected on self-reported height at age 25 years and minimum weight after age 25 years, as well as on current measured height and weight. Body mass index (BMI) and height and weight change were calculated from these data. The relations between these variables and vertebral deformity were examined separately by sex with logistic regression adjusting for age, smoking, and physical activity. In females, there was a significant trend of decreasing risk with increasing quintile of current weight, current BMI, and weight gain since age 25 years. In males, subjects in the lightest quintile for these measures were at increased risk but there was no evidence of a trend. An ecologic analysis by country revealed a negative correlation between mean BMI and the prevalence of deformity in females but not in males. The authors conclude that low body weight is associated with presence of vertebral deformity.

Age Factors↗

PubMed1997

Population-based geographic variations in DXA bone density in Europe: the EVOS Study. European Vertebral Osteoporosis.

The purpose of this study was to investigate variations in bone density between 16 European populations, 13 of which were participants in the European Vertebral Osteoporosis Study (EVOS). Men and women aged 50-80 years were recruited randomly from local population registers, stratified in 5-year age bands. The other three centres recruited similarly. Random samples of 20-100% of EVOS subjects were invited for dual-energy X-ray absorptiometry (DXA) densitometry of the lumbar spine and/or proximal femur using Hologic, Lunar or Norland pencil beam machines or, in one centre, a Sopha fan-beam machine. Cross-calibration of the different machines was undertaken using the European Spine Phantom prototype (ESPp). Highly significant differences in mean bone density were demonstrated between centres, giving rise to between centre SDs in bone density that were about a quarter of a population SD. These differences persisted when centres using Hologic machines and centres using Lunar machines were considered separately. The centres were ranked differently according to whether male or female subjects were being considered and according to site of measurement (L2-4, femoral neck or femoral trochanter). As expected, bone mineral density (BMD) had a curvilinear relationship with age, and apparent rates of decrease slowed as age advanced past 50 years in both sexes. In the spine, not only did male BMD usually appear to increase with age, but there was a highly significant difference between centres in the age effect in both sexes, suggesting a variability in the impact of osteoarthritis between centres. Weight was consistently positively associated with BMD, but the effects of height and armspan were less consistent. Logarithmic transformation was needed to normalize the regressions of BMD on the independent variates, and after transformation, all sites except the femoral neck in females showed significant increases in SD with age. Interestingly, the effect of increasing weight was to decrease dispersion in proximal femur measurements in both sexes, further accentuating the tendency in women for low body mass index to be associated with osteoporosis as defined by densitometry. It is concluded that there are major differences between BMD values in European population samples which, with variations in anthropometric variables, have the potential to contribute substantially to variations in rates of osteoporotic fracture risk in Europe.

Absorptiometry, Photon↗

PubMed1997

Influence of hormonal and reproductive factors on the risk of vertebral deformity in European women. European Vertebral Osteoporosis Study Group.

The aim of this study was to determine whether variation in the level of selected hormonal and reproductive variables might explain variation in the occurrence of vertebral deformity across Europe. A population-based cross-sectional survey method was used. A total of 7530 women aged 50-79 years and over were recruited from 30 European centres. Subjects were invited to attend for an interviewer-administered questionnaire and lateral spinal radiographs which were taken according to a standard protocol. After adjusting for age, centre, body mass index and smoking, those in the highest quintile of menarche (age > or = 16 years) had an increased risk of vertebral deformity (odds ratio [OR] = 1.48; 95% confidence interval [CI] 1.16, 1.88). Increased menopausal age (> 52.5 years) was associated with a reduced risk of deformity (OR = 0.78; 95% CI 0.60, 1.00), while use of the oral contraceptive pill was also protective (OR = 0.76; 95% CI 0.58, 0.99). There was a smaller protective effect associated with one or more years use of hormone replacement therapy, though the confidence limits clearly embraced unity. There was no apparent effect of parity or breast-feeding on the risk of deformity. We conclude that oestrogen status is an important determinant of vertebral deformity. Ever use of the oral contraceptive pill was associated with a 25% reduction in risk of deformity though the effect may be a result of the higher-dosage oestrogen pills used in the past. Parity and breast-feeding do not appear to be important and would appear to have little potential for identification of women at high risk of vertebral deformity.

Age Factors↗

PubMed1997

[Vertebral morphometry with DXA/MXA equipment--an equipment comparison. Dual x-ray absorptiometry/morphometric x-ray absorptiometry].

PURPOSE: The accuracy and reproducibility of morphometric measurements (Morphometric X-ray Absorptiometry = MXA) of vertebrae were determined. The significant difference of the change in height of vertebral bodies in follow-up studies was computed for MXA methods and digitised spinal radiographs as well. MATERIAL AND METHODS: The measurements were carried out on two new Dual X-ray Absorptiometry (DXA) devices (device A = Expert, Lunar Corp., device B = QDR 2000 Plus, Hologic Inc.). The data were obtained by using the European Spine Phantom (ESP) and lumbar spine specimens. RESULTS: The accuracy of vertebral morphometry performed on radiographs is 2.0%, on the device A 2.3%, and on the device B 4.9%. Measurements taken with the ESP showed a reproducibility of 1.0 to 3.0%, whereas measurements of fractured vertebrae resulted in 5.1 to 6.0%. CONCLUSION: The results of the morphometric measurements demonstrate that a reliable fracture analysis in phantoms and specimens is possible. Further in-vivo studies are necessary.

Absorptiometry, Photon↗

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↗

PubMed1997

Influence of physical activity on vertebral deformity in men and women: results from the European Vertebral Osteoporosis Study.

Physical activity is associated with an increased bone mass and a reduced risk of hip fracture. There are, however, no data from population samples of men and women concerning the effect of regular levels of physical activity on the risk of vertebral deformity. The aim of this study was to determine the relationship between regular physical activity and vertebral deformity in European men and women. A population survey method was used. Thirty-six centers from 19 European countries participated. Each center recruited a population sample of men and women aged 50 years and over. Those who took part received an interviewer-administered questionnaire and lateral thoracolumbar radiographs. Subjects were asked about two dimensions of physical activity: (1) the level of physical activity undertaken either at work or at home on a daily basis at three different age periods: 15-25 years, 25-50 years, and 50+ years; and (2) the amount of time spent walking or cycling out of doors each day. Spinal radiographs were evaluated morphometrically and the presence of vertebral deformity was defined according to the McCloskey method. In total, 14,261 subjects, aged 50-79 years, from 30 centers were studied, of whom 809 (12.0%) men and 884 (11.7%) women had one or more deformities. After adjusting for age, center, smoking, and body mass index, very heavy levels of activity in all three age groups were associated with an increased risk of vertebral deformity in men (odds ratios, age adjusted [OR], 1.5-1.7; with all 95% confidence intervals [CI] excluding unity). No increased risk was observed in women. Current walking or cycling more than 1/2 h/day was associated with a reduced risk of vertebral deformity in women (OR 0.8; 95% CI 0.7-1.0). We conclude that regular walking in middle-aged and elderly women is associated with a reduced risk of vertebral deformity. By contrast, heavy levels of physical activity in early and middle adult life are associated with an increased risk in men. These differences are of relevance in understanding the epidemiology of vertebral deformity and planning programs of prevention.

Adolescent↗

PubMed1996

The prevalence of vertebral deformity in european men and women: the European Vertebral Osteoporosis Study.

Our aim was to determine the prevalence of radiographically defined vertebral deformity, as a marker of vertebral osteoporosis, in different regions and populations within Europe. We used a cross-sectional population-based survey. Population-based sampling frames were obtained from 36 centers in 19 European countries. Stratified random sampling was used to recruit 15,570 males and females aged 50-79 years. Lateral spinal radiographs were taken according to a standardized protocol, and all X-rays were evaluated centrally. Vertebral deformity was morphometrically defined according to the published methods of McCloskey and Eastell. Based on the McCloskey method, the mean center prevalence of all deformities was 12% in females (range 6-21%) and 12% in males (range 8-20%). The prevalence increased with age in both sexes though the gradient was steeper in females. There was substantial geographical variation, with the highest rates in Scandinavian countries. Radiographically defined vertebral deformity is a common disorder and equally frequent in males and females. Using standardized methodology, there is important variation in occurrence across Europe, which might suggest clues to pathogenesis.

Age Distribution↗

PubMed1996

Radial cortical and trabecular bone densities of men and women standardized with the European Forearm Phantom.

We previously showed that it is possible to cross-calibrate peripheral bone densitometers using the European Spine Phantom (ESP). We have now performed a multinational study of cross-calibrated radius bone density based on normal subjects of both sexes in eight European centers. Six centers were equipped with machines made by Scanco or Stratec for determining distal radial trabecular bone density by quantitative computed tomography (QCT) and two were equipped with Lunar SP2 single photon absorptiometry (SPA) equipment for measuring midshaft cortical bone density. Subjects recruited ranged from 20 to over 80 years of age. Over one hundred and fifteen men were studied by QCT and a different cohort of 104 men were studied with SPA; the equivalent figures for women were 235 and 123. Reference ranges were derived for bone density against age for each of the four groups, and their applicability is discussed in relation to between-center differences in the results obtained. There were insignificant differences (P > 0.05 with Bonferroni correction) between centers in the values obtained by QCT in the different populations. However, there were considerably larger and highly statistically significant differences between midshaft cortical bone density values of about 10% of overall means between subjects from eastern Finland and central Belgium (P < 0.001), with higher Finnish values. Women had considerably lower radial trabecular bone density values than men at all ages, a result that differentiates the radius from the spine. This sex difference widened after menopause. These results have important implications for understanding the contribution of bone density to the differential risk of Colles' fracture in the two sexes and suggest that further work is needed to establish young normal reference ranges for radial bone density in Europe.

Absorptiometry, Photon↗

PubMed1996

[Cost and effectiveness of different strategies in diagnosis of osteoporosis].

Osteoporosis represents one of the most common disorders in Germany. Because of the general aging of the population and due to several secular trends (less exercise, nutritional deficits, higher standard of living) the prevalence of osteoporosis will increase substantially. Therefore, it is important to develop preventive strategies and analyze them according to both medical and economical criteria. During the last couple of years substantial progress has been made both in the area of diagnostic approaches as well as treatment modalities. Thus, from a medical point of view important conditions for a positive assessment of the cost-benefit-ratio of diagnostic approaches in osteoporosis are now fulfilled. Currently, a strategy for selective screening of well-defined high risk groups appears to be most appropriate. These include 1. women with subnormal hormonal status provided that other risk factors are present, 2. patients with low-trauma fractures, 3. patients under prolonged steroid therapy, and 4. patients with secondary osteoporosis due to other causes. International studies have demonstrated that even more far-reaching preventive strategies can be conceived that could be both medically and economically effective. Currently, however, data for a detailed cost-benefit-analysis are lacking or based on outdated diagnostic equipment or treatment agents. New Studies on this topic are critically needed to evaluate preventive strategies, specifically for Germany.

Absorptiometry, Photon↗

PubMed1996

Clinical utility of bone mass measurements in adults: consensus of an international panel. The Society for Clinical Densitometry.

Low bone mass predicts future fracture risk as well as high cholesterol or high blood pressure can predict the risk of heart disease or stroke. Prevention of the first fracture should be a clinical goal. In patients without fractures, osteopenia and osteoporosis can be diagnosed based on the extent of reduction in bone mass below mean peak bone mass of young healthy individuals. As bone mass decreases, fracture risk increases exponentially. Clinical situations in which an assessment of bone mass and fracture risk affects therapeutic decisions include estrogen deficiency, vertebral abnormalities, radiographic osteopenia, asymptomatic primary hyperparathyroidism, and long-term corticosteroid therapy. Serial measurements can also be used to monitor the effects of osteoporosis treatments. The appropriate technique and skeletal site for bone mass measurements should be chosen based on the patient's circumstances and the precision of measurement. A clinical interpretation can enhance the value of computer-generated bone mass measurement reports and improve decision making.

Absorptiometry, Photon↗

PubMed1996

[Systematics of osteodensitometric methods and acronyms].

The radiological diagnosis of osteoporosis is primarily based on osteodensitometry. The continuous development of new methods requires persistent analysis of its potential and limits. The knowledge of the differences of osteodensitometric methods is essential for understanding patient reports. The acronyms are internationally established, their correct usage is advocated.

Abbreviations as Topic↗

PubMed1996

[CT osteodensitometry in the area immediate to hip endoprostheses].

UNLABELLED: The value of metal artifact reduction in quantitative bone density determination in the vicinity of metallic implants was studied. METHOD: Ten cadaver femora with hip endoprostheses implanted intra vitam were examined in CT with varying slice thicknesses, tube voltage, scan time and magnification factor. The artifact-laden images were then processed using a metal artifact reduction programme (MAR). The metallic implant was removed, allowing the bone slices to be examined again with the same imaging parameters, but without the bothersome metal artifacts. This allowed comparison of bone density values obtained before and after application of MAR with data obtained after implant removal. RESULTS: A comparison of the bone density measurements between the sample group without implants and the group with indwelling implants prior to MAR showed an unexpected correlation coefficient r = 0.975-0.977. The correlation coefficients after MAR rose to r = 0.987-0.992 in 125 kV and r = 0.989-0.991 in 85 kV modes. The reproducibility of the density measurements for the groups without implants and with implants following MAR showed variation coefficients (VC) of 1.16% and 0.75% respectively. The reproducibility of the manual definition of the region of interest (ROI) in bone showed a VC = 2.19%. CONCLUSIONS: Bone density in the vicinity of metallic implants can be reliably and reproducibly determined using MAR.

Artifacts↗