Risk Of Osteoporosis Fractures Research Articles

Risedronic acid reduces hip fracture risk in osteoporosis

Risedronic acid reduces hip fracture risk in osteoporosis

Apoptosis and osteoporosis

During normal bone remodeling, the rate of supply of new osteoblasts and osteoclasts and the timing of the death of osteoclasts, osteoblasts, and osteocytes by apoptosis are critical determinants of the initiation of new BMUs and the extension or reduction of the lifetime of existing ones. Disruption of the fine balance among these processes may be an important mechanism behind the deranged bone turnover found in most metabolic disorders of the adult skeleton. Like most armies, the amount 5 of work done by bone cells is far more dependent on numbers than vigor. Therapeutic agents that alter the prevalence of apoptosis of osteoblasts and osteoclasts can correct the imbalance in cell numbers that is the basis of the diminished bone mass and increased risk of fractures in osteoporosis.

Ultrasound measurements at the proximal phalanges in healthy women and patients with hip fractures.

Measurements of bone mineral density (BMD) are useful for the assessment of fracture risk in osteoporosis. First prospective studies showed that quantitative ultrasound as measured at the calcaneus also predicts future hip fracture risk, independently of BMD and as accurately as BMD. The aim of this study was to compile a reference population for a new ultrasound device that determines amplitude-dependent speed of sound (AD-SOS) through the proximal phalanges of the hand and to prove its ability to distinguish between health volunteers and osteoporotic patients. In a case-control study we examined 139 healthy women aged 21-94 years and a group of 24 female patients aged 69-94 years with recent hip fractures. In the healthy reference population additional BMD measurements were performed with dual-energy X-ray absorptiometry (DXA) and quantitative ultrasound measurements at the calcaneus were carried out. In vivo precision of AD-SOS measurements through the phalanges was 0.52% CV. Simple regression analyses showed a negative correlation with age (r = -0.73, p < 0.001); modest significant correlations with BMD of the lumbar spine (r = 0.36, p < 0.001) and BMD of the femoral neck (r = 0.37, p = 0.002) as measured with DXA were shown. The comparison with another ultrasound device measuring SOS and broadband ultrasound attenuation (BUA) through the calcaneus showed correlation with SOS (r = 0.50, p < 0.001); no significant correlation was found with BUA measurements. Furthermore a dependency of AD-SOS values in anthropometric factors such as body mass index (r = 0.37, p < 0.001), height (r = 0.40, p < 0.001) and weight (r = 0.23, p < 0.05) was shown. First study results on 24 clinically diagnosed osteoporotic patients, defined as patients with recent (< 1 week) pertrochanteric or femoral neck fractures, showed a good separation between age- and sex-matched controls and osteoporotic patients (Z = -2.0 SD). Receiver operating characteristic (ROC) curves showed an area under the fitted curve of 0.83 +/- 0.06. These results are powerful for a device measuring AD-SOS through the proximal phalanges of the hand, and further prospective studies have proven the capability of phalangeal ultrasound in fracture risk assessment.

Second metacarpal cross-sectional geometry: Rehabilitating a circular argument.

Radiogrammetry of the second metacarpal has long served as a measure of normal and abnormal bone growth and aging, functional asymmetry, and fracture risk in osteoporosis. The method relies on algebraic interpretation (circular or elliptical models) of uni- or biplanar radiographic images. This paper tests the conformance of these models with actual measures of metacarpal geometric variation in a sample of 356 bones from an historic archaeological sample. Both the circular and elliptical models significantly over-estimate actual values for all variables (e.g., total area (3.05% and 9.42%, respectively) and cortical area (7.25% and 12.25%), bending rigidity about the mediolateral (13.88% and 20.92%) and anteroposterior axes (17.35% for the elliptical model). The greater degree of systematic bias found for the elliptical model is contrary to results of an earlier study (Lazenby, 1997), and suggests that sample composition can influence the method error associated with a particular approach. The import of radiogrammetric bias will depend on the degree of shape variation among samples compared (e.g., left vs right, male vs female, etc.), which in most cases cannot be predetermined. Consequently, reduced major axis equations were derived from regressing actual on estimated values for total area (TA), cortical area (CA) and two measures of bending rigidity (Ix, Iy) in order to permit adjustment for radiogrammetric error associated with these algebraic models. Application of these formulae to a hold-out sample showed no significant differences between actual and predicted values. Am. J. Hum. Biol. 10:747-756, 1998. © 1998 Wiley-Liss, Inc.

Alendronic acid reduces additional fracture risk in osteoporosis

Alendronic acid reduces additional fracture risk in osteoporosis

Risk Factors in Spinal Bone Mineral Densitometry

Absorptiometric methods have gained widespread use in quantification of bone mineral density, particularly for the assessment of fracture risk in osteoporosis. The aim of the present study was to determine the radiation burden to patients and operators related to the assessment of bone mineral status in the spine using either dual X ray absorptiometry (DXA), or single energy spectrum quantitative computed tomography (SE-QCT). Effective dose to adult patients from spinal bone mineral density measurement was found to be in the order of 1 μSv in DXA and 100 μSv in SE-QCT. The radiation burden to the operators was found to be low.

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.

Multifractal radiographic analysis of osteoporosis

An important complication of osteoporosis is fracture. Alteration in bone structure, as well as decreased bone mass, contribute to the tendency to fracture in osteoporosis. Current methods that measure bone mass alone show substantial overlap of the measurements of osteoporotic patients who fracture with those that do not. Our aim is to develop noninvasive methods of evaluating bone structure on plain film radiographs to better predict fracture risk in osteoporosis. Regions of interest (ROIs) were selected from digitized lateral lumbar spine radiographs of 43 patients being seen in an osteoporosis clinic. The fractal dimension of these ROIs was estimated using a surface area method. The ability of fractal dimension to distinguish between cases that had fracture elsewhere in the spine from those that did not, was evaluated using receiver operating characteristic (ROC) analysis. These results were compared with ROC analysis for these same patients using bone mineral density (BMD) measurements (bone mass). Significantly larger Az (area under ROC curve) values were obtained using fractal dimension (0.87) than from using BMD (0.58), indicating a better test performance using fractal dimension. Therefore, computerized radiographic methods to evaluate bone structure, such as fractal analysis, may be helpful in better determining fracture risk in osteoporosis.

A critical review of bone mass and the risk of fractures in osteoporosis

The usefulness of various bone mineral measurement techniques is a subject of current controversy. In order to explore whether disparate conclusions may have arisen from differences in analytic methodology, data from published reports of bone mass and nonviolent fractures have been reanalyzed in terms of fracture risk. In the large majority of studies, reduced bone mass was associated with an increased risk of fractures. However, the magnitude of the relationship varied much more among cross-sectional studies than among prospective studies, suggesting that bias related to subject selection and/or postfracture bone loss may have strongly influenced the cross-sectional findings. We conclude that more emphasis should be given to the results of prospective studies, and that more attention should be paid to subject selection in all investigations. Analyzing and presenting results in terms of fracture risk would probably reduce the level of confusion in the field and provide more clinically relevant information. These issues are also applicable to studies of potential fracture risk factors other than bone mass, such as bone structure and bone quality.

Predicting Femoral Neck Strength From Bone Mineral Data

An interactive computer program was developed to derive femoral neck geometry from raw bone mineral image data for an estimate of hip strength using single plane engineering stress analysis. The program, which we call Hip Strength Analysis (HSA), was developed as an attempt to improve the predictive value of hip bone mineral data for osteoporosis fracture risk assessment. We report a series of experiments with an aluminum phantom and with cadaver femora, designed to test the accuracy of derived geometric measurements and strength estimates. Using data acquired with both Lunar DP3 (DPA) and Hologic QDR-1000 (x-ray) scanners, HSA computed femoral neck cross-sectional areas (CSA) and cross-sectional moments of inertia (CSMI) on an aluminum phantom were in excellent agreement with actual values (r greater than .99). Using Lunar DP3 data, CSA and CSMI measurements at mid-femoral necks of 22 cadaver specimens were in good general agreement with literature values. HSA computed cross-sectional properties of three of these specimens were compared with measurements derived from sequential CT cross-sectional images. Discrepancy between the two methods averaged less than 10% along the length of the femoral neck. Finally, breaking strengths of 20 of the femora were measured with a materials testing system, showing better agreement with HSA predicted strength (r = .89, percent standard of the estimate (%SEE) = 21%) than femoral neck bone mineral density (r = .79, %SEE = 28%).