Jos Nijs

Assessment of the strength of proximal femur in vitro : Relationship to femoral bone mineral density and femoral geometry

Femoral neck axis length, neck width, and neck-shaft angle were measured on radiographs of right proximal femora from 64 cadavers (28 female, 36 male). Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry (DXA) for various regions of interest, and quantitative computed tomography (QCT) was used to determine BMD and bone areas for cortical and trabecular bone at the trochanter and femoral neck. The strength of the femur was determined by a mechanical test simulating a fall on the greater trochanter, and the fracture type (cervical or trochanteric) was subsequently determined from radiographs. Twenty-six cervical fractures and 38 trochanteric fractures were observed, with no significant sex difference in the distribution of fracture types. Femoral strength was significantly elevated in males compared to females. DXA trochanteric BMD was more strongly (p < 0.05) correlated with femoral strength (r2 = 0.88) than were any of the other DXA BMD measurements (r2 = 0.59-0.76). In multiple regression models, a combination of different DXA BMD measurements produced only a small increase (1%) in the explained variability of femoral strength. Of the QCT measurements, trochanteric cortical area yielded the optimal correlation with femoral strength (r2 = 0.83). Weak, but significant, correlations were observed between femoral strength and cortical BMD at trochanteric (r2 = 0.28) and neck regions (r2 = 0.07). In multiple regression models, combining QCT parameters yielded, at best, an r2 of 0.87. Of the geometrical parameters, both neck axis length and neck width were significantly correlated with femoral strength (r2 = 0.24, 0.22, respectively), but no significant correlation was found between strength and the neck-shaft angle. Combining DXA trochanteric BMD with femoral neck width resulted in only a small increase in the explained variability (1%) compared to trochanteric BMD alone. The results demonstrated that DXA and QCT had a similar ability to predict femoral strength in vitro. Trochanteric BMD was the best DXA parameter, and cortical area (not cortical BMD) was the optimal QCT parameter. Geometric measurements of the proximal femur were only weakly correlated with the mechanical strength, and combinations of DXA, QCT, and geometric parameters resulted in only small increases in predictive power compared to the use of a single explanatory variable alone.

Improving Risk Assessment: Hip Geometry, Bone Mineral Distribution and Bone Strength in Hip Fracture Cases and Controls. The EPOS Study

Abstract: Hip geometry and bone mineral density (BMD) have previously been shown to relate independently to hip fracture risk. Our objective was to determine by how much hip geometric data improved the identification of hip fracture. Lunar pencil beam scans of the proximal femur were obtained. Geometric and densitometric values from 800 female controls aged 60 years or more (from population samples which were participants in the European Prospective Osteoporosis Study, EPOS) were compared with data from 68 female hip fracture patients aged over 60 years who were scanned within 4 weeks of a contralateral hip fracture. We used Lunar DPX ‘beta’ versions of hip strength analysis (HSA) and hip axis length (HAL) applied to DPX(L) data. Compressive stress (Cstress), calculated by the HSA software to occur as a result of a typical fall on the greater trochanter, HAL, body mass index (BMI: weight/(height)2) and age were considered alongside femoral neck BMD (FN-BMD, g/cm2) as potential predictors of fracture. Logistic regression was used to generate predictors of fracture initially from FN-BMD. Next age, Cstress (as the most discriminating HSA-derived parameter), HAL and BMI were added to the model as potentially independent predictors. It was not necessary to include both HAL and Cstress in the logistic models, so the entire data set was examined without excluding the subjects missing HAL measurements. Cstress combined with age and BMI provided significantly better prediction of fracture than FN-BMD used alone as is current practice, judged by comparing areas under receiver operating characteristic (ROC) curves (p<0.001, deLong’s test). At a specificity of 80%, sensitivity in identification was improved from 66% to 81%. Identifying women at high risk of hip fracture is thus likely to be substantially enhanced by combining bone density with age, simple anthropometry and data on the structural geometry of the hip. HSA might prove to be a valuable enhancement of DXA densitometry in clinical practice and its use could justify a more pro-active approach to identifying women at high risk of hip fracture in the community.

Mineral Metabolism and Bone Mass at Peripheral and Axial Skeleton in Diabetes Mellitus

Bone mineral content (BMC), mineral homeostasis, and diabetes control were evaluated in 31 Caucasian insulin-dependent diabetic patients (disease duration 18.3 ± 7.7 yr, mean ± SD) with normal kidney function. To evaluate bone mass, we performed radiogrammetry and single- and dual-photon absorptiometry. In women, a significantly lower mean BMC was found in the distal radius, at a mixed trabecular-cortical (P < .01) and a cortical (P < .05) site, as well as in the lumbar spine (P < .02). In diabetic men, mean BMC was significantly reduced at the trabecularcortical (P < .01) and cortical (P < .05) sites of the radius but not in the lumbar spine. When expressed as densities (i.e., BMC/width or lumbar BMC/area), only the BMC/width at the radius cortical area was significantly reduced in women (P < .05). The results of the radiogrammetry showed a larger endosteal diameter in the diabetic women, resulting in a significantly lower cortical thickness (P < .05). Diabetic men did not show abnormalities on radiogrammetry. Diabetic patients had diminished serum calcium and phosphorus concentrations (P < .001), whereas serum parathyroid, 25-hydroxyvitamin D3, and concentrations of both total and free 1,25-dihydroxyvitamin D3 were normal. No correlation between parameters of diabetes control (HbA1, insulin dose, and triglycerides) or calcium-regulating hormones and BMC were found. These data confirm that, despite large overlap of individual values, mean bone mass at the peripheral skeleton is significantly decreased in diabetic patients. Moreover, we report that the BMC of the lumbar spine is significantly reduced in female diabetic patients.

Relationship Between Baseline Insulin-Like Growth Factor-I (IGF-I) and Femoral Bone Density in Women Aged Over 70 Years: Potential Implications for the Prevention of Age-Related Bone Loss

OBJECTIVE: To test the hypothesis that the decline in femoral bone mass associated with healthy aging is partially accounted for by deficiency of the growth hormone‐insulinlike growth factor‐I (IGF‐I) axis.

Aging of the thoracic spine: Distinction between wedging in osteoarthritis and fracture in osteoporosis—A cross-sectional and longitudinal study

Thoracic kyphosis is clinically associated with osteoporosis as well as with osteoarthritis. Because misinterpretation of thoracic spine deformities on X-rays may lead to overdiagnosis of vertebral fracture, we studied morphological changes of the thoracic spine in a cross-sectional (n = 89) and longitudinal study (n = 38) in 30 women with established osteoporosis (OP), in 31 women with spinal osteoarthritis (OA), and in 28 normal women. Vertebral deformation was assessed on lateral roentgenograms of the thoracic spine from T-4-T-12. The anterior, middle, and posterior heights were measured using six points corresponding to the four corners of the vertebral body excluding osteophytes and the midpoints of the endplates. For the thoracic T-6-T-9 region, the mean anterior/posterior height ratio was 7.7% in the controls, 13% in osteoarthritis, and 21% in osteoporosis. For the mid-height/posterior height ratio the respective values were 13%, 12%, and 22%. The osteoporosis group differed significantly from the control and osteoarthritis group in anterior and in midheight reduction. The yearly mean anterior height reduction in the osteoarthritis group was 0.7% compared with 1.5% in the osteoporosis group. The mean yearly midheight reduction was, respectively, 0.5% versus 2.9%. The differences between the groups were significant. We conclude that vertebral deformity, in particular wedging, of the thoracic spine is not exclusively characteristic for osteoporosis and that certain vertebral deformities develop by mechanisms other than fracture. Osteoporotic fracture of the thoracic spine is characterized by an exaggerated reduction of the midheight to posterior height in addition to reduction of the anterior to posterior height.(ABSTRACT TRUNCATED AT 250 WORDS)

Timing and quantification of bone loss in cardiac transplant recipients

To evaluate osteopenic bone disease in heart transplant patients, we prospectively measured bone mineral density (BMD) in 33 consecutive male recipients before hospital discharge and 1 year later, using dual photon absorptiometry. At hospital discharge BMD measurement at the lumbar spine was only 90% of that expected in healthy age- and sex-matched controls (P=0.005). One year later BMD had further decreased by 8.5% at the lumbar spine and by 10.4% at the femoral neck (P=0.0001). Five patients suffered vertebral compression fractures during the 1st post-operative year. Our results indicate that osteopenia of the lumbar spine is already present at the time of hospital discharge after transplantation and that further bone loss occurs at a considerable rate during the 1st postoperative year at the lumbar spine and at the femoral neck.

Seasonal variation in bone metabolism in young healthy subjects

SummarySerum vitamin D metabolites and urinary calcium excretion; parameters of bone formation (serum alkaline phosphatase, serum osteocalcin); parameters of bone resorption (24 hour hydroxyprolinuria, 2 hour fasting urinary hydroxyproline/creatinine ratio); and parameters of cortical and trabecular bone density, parathyroid hormone (iPTH, COOH terminal assay), and serum minerals (calcium, phosphorus) were followed serially in 55 young adults (21 women and 34 men) from December 1985 until January 1987 at four different times during the year. The effect of a low-dose cyclooxygenase inhibitor (piroxicam 5 mg daily) on the same parameters of bone density and bone turnover when given from December until May, was also evaluated in this study. At the end of the treatment period parameters of bone turnover and bone density were comparable between placebo and piroxicam-treated groups. Therefore, the results of all subjects were pooled in order to investigate seasonal variation. In both sexes, seasonal variation was found not only for 250HD3 but also for 1,25(OH)2D3, serum calcium and phosphorus, urinary calcium excretion, and for bone density at the lumbar spine. Parameters of bone formation (serum osteocalcin and alkaline phosphatase), bone resorption (24 hour urinary hydroxyprolinuria and fasting urinary hydroxyproline/creatinine ratio) and PTH were influenced by this seasonal variation. We conclude that in young adults, a significant seasonal variation occurs, with low winter and high summer values, for serum 25 and 1,25(OH)2D3 for urinary calcium apparently without important influence on parameters of bone turnover or parathyroid activity and for lumbar spine density. Treatment with a low-dose cyclooxygenase inhibitor was without influence on the observed changes.

Cyclical etidronate increases bone density in the spine and hip of postmenopausal women receiving long term corticosteroid treatment. A double blind, randomised placebo controlled study

OBJECTIVE To study the effect of cyclic etidronate in secondary prevention of corticosteroid induced osteoporosis. METHODS A double blind, randomised placebo controlled study comparing cyclic etidronate and placebo during two years in 37 postmenopausal women receiving long term corticosteroid treatment, mainly for polymyalgia rheumatica (40% of the patients) and rheumatoid arthritis (30%). Bone density was measured in the lumbar spine, femoral neck, and femoral trochanter. RESULTS After two years of treatment there was a significant difference between the groups in mean per cent change from baseline in bone density in the spine in favour of etidronate (p=0.003). The estimated treatment difference (mean (SD)) was 9.3 (2.1)%. Etidronate increased bone density in the spine (4.9 (2.1)%, p<0.05) whereas the placebo group lost bone (−2.4 (1.6)%). At the femoral neck there was an estimated difference of 5.3 (2.6)% between the groups (etidronate: 3.6 (1.4)%, p<0.05, placebo: −2.4 (2.1)%). The estimated difference at the trochanter was 8.2 (3.0) (etidronate: 9.0 (1.5)%, p<0.0001, placebo: 0.5 (2.3)%). No significant bone loss occurred in the hip in placebo treated patients. CONCLUSIONS Cyclic etidronate is an effective treatment for postmenopausal women receiving corticosteroid treatment and is well tolerated.

Effects of anteversion on femoral bone mineral density and geometry measured by dual energy x-ray absorptiometry : A cadaver study

The effect of femoral neck anteversion on bone mineral density (BMD) and geometry as measured by dual energy X-ray absorptiometry (DXA) was assessed using 64 right proximal femora from 36 male and 28 female cadavers. The anteversion angle was measured on computed tomography (CT) images, and DXA measurements were made both in the neutral position (i.e, at 0 degree anteversion, femoral neck axis parallel to the table) and in the simulated anteverted position (i.e., femoral shaft axis parallel to the table, greater and lesser trochanters in contact with the table, and femoral neck free). The mean anteversion angle measured by CT was 19.3 degrees (range 6 degrees-38 degrees). Anteversion was associated with a significant elevation in femoral neck BMD of +2.8% (range -5.3%-(+)9.8%) (p < 0.05), and the femoral neck BMD increased with increasing anteversion (p < 0.01). Trochanteric BMD was less affected by anteversion, with an average increase of only 0.2% (range -5%-5.9%) (p = n.s.) in the anteverted position, but there was a significant positive association between the change in trochanteric BMD and the anteversion angle (p < 0.01). Anteversion produced a mean reduction of -2.4% (range -7.6%-(+)4.3%) (p < 0.001) in apparent femoral neck axis length, while femoral neck width remained generally unaffected. These data confirm that femoral BMD as measured by DXA is affected by femoral anteversion with a lesser magnitude than previously reported. The use of trochanteric BMD may minimize the influence of anteversion. While the mean changes in BMD and neck axis length attributable to anteversion are modest, the considerable interindividual variability in the magnitude of the effects demonstrates that other factors, such as, the complex geometry of femoral neck modifies the effect of anteversion on BMD measurements. The error in BMD introduced femoral anteversion may represent a significant confounding influence in cross-sectional and longitudinal studies. Careful repositioning of the foot and leg is essential in monitoring changes in BMD longitudinally. Knowledge of the effects of femoral anteversion may assist in understanding the relation of femoral BMD and neck axis length to hip fracture.

Factors determining the final outcome of treatment of idiopathic scoliosis with the Boston brace: a longitudinal study.

This study tries to determine factors influencing the final outcome of treatment of idiopathic scoliosis with the Boston brace and to compare the results with the natural history. One hundred and fifty-one patients, 130 girls and 21 boys, treated between 1982 and 1991, were reviewed. A series of continuous and categorical variables were measured, allowing for the construction of a multiple regression equation. Continuous variables were age at discovery of the curve, time of interval between discovery and treatment and age at the beginning of treatment. Furthermore age of menarche, duration of treatment, duration of weaning and age and time of follow-up were noted. Continuous numerical variables were the Cobb angle, the apical vertebral rotation, and the Risser stage. Categorical variables consisted of the results of a questionnaire and the Kings classification of the curve. Good results are achieved in older children, with low Cobb angles and advanced maturity, who are, however, the very ones not expected to progress, as also indicated in studies on natural history. Brace treatment seems not to alter the natural history in general, and especially not in the older child; this is the case from age 12 years and Risser stage 2 onwards. In the younger child, a brace is probably still indicated, because it has been proved that a scoliosis is more prone to progress and that a possible positive result can still not be ruled out, as long as randomized control trials are not conducted.