Fracture Discrimination Research Articles

Contact quantitative ultrasound: an evaluation of precision, fracture discrimination, age-related bone loss and applicability of the WHO criteria.

The aim of this study was to assess a dry calcaneal quantitative ultrasound (QUS) device by examining: (i) short- and long-term precision; (ii) the ability of the ultrasound parameters to identify women with vertebral fractures; (iii) age- and menopause-related bone loss; (iv) applicability of the WHO criteria in scan interpretation. The study group consisted of 422 healthy women with no risk factors associated with osteoporosis (227 premenopausal and 195 postmenopausal) and 93 women with one or more vertebral fractures. All women had calcaneal QUS and bone mineral density (BMD) measurements of the lumbar spine and hip performed. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) measurements in the heel were combined and expressed as estimated heel BMD. Short-term precision studies yielded coefficient of variations of 0. 3% for SOS, 4% for BUA and 3.3% for estimated heel BMD. Standardized short-term precision values were approximately 0.2 SD. Long-term standardized precision errors ranged from 0.17 to 0.38 SD. All the QUS and BMD measurement parameters showed significant negative relationships with age in the postmenopausal group. Annual losses were 0.35 dB/MHz per year for BUA, 0.56 m/s per year for SOS and 0. 002 g/cm(2) per year for estimated heel BMD. All the QUS and BMD parameters were able to discriminate between healthy postmenopausal women and women with vertebral fracture. Age-adjusted odds ratios for each SD decline in QUS measurements were 3.63, 5.25 and 4.79 for BUA, SOS and estimated heel BMD respectively. Corresponding odds ratios for BMD at the lumbar spine, femoral neck and total hip were 2.39, 2.51 and 2.95 respectively. When the QUS and BMD parameters were expressed as T-scores, estimated heel BMD showed the least age-related decline, while femoral neck BMD displayed the greatest decrease with age. The mean T-score and prevalence of osteoporosis (T<-2.5) for a Caucasian woman aged 60-65 years were -1.35 and 21% respectively for the lumbar spine compared with -0.59 and 2% for estimated heel BMD. In conclusion, this study revealed that contact ultrasound can detect age- and menopause-related influences on bone status and was able to discriminate between healthy individuals and women with vertebral fracture. However, the widely accepted threshold of a T-score of less than -2.5 for the definition of osteoporosis may need modifying for the interpretation of QUS scans.

Hip fracture discrimination by imaging ultrasound measurements of the calcaneus.

Quantitative ultrasound measurements of the os calcis have recently been upgraded with imaging facilities. This has made measurements of a specific region of interest possible and improved the reproducibility of the method, but the diagnostic ability of imaging ultrasound has not yet been investigated thoroughly. We measured broadband ultrasound attenuation (BUA) and speed of sound (SOS) using imaging ultrasound as well as forearm bone mineral density (BMDarm) using dual-energy X-ray absorptiometry in three age-matched groups of women: (1) 25 women who were admitted to hospital due to a hip fracture; (2) 23 women who were admitted to hospital due to a fall without any fracture; and (3) 26 normal women. Furthermore, BMD of the hip (BMDhip) was measured in a subgroup of the hip fracture patients and those who had fallen. All measurements were performed during the index hospitalization in order to avoid any influence from bone loss due to immobilization after the fracture. We found a -0.48 SD deviation from expected age-matched values in BUA among the hip fracture patients, whereas the patients who had fallen showed a +0.16 SD deviance. For SOS, the figures were -0.70 SD for the hip fracture group and -0.06 SD for the patients who had fallen. For BMD of the arm we found values of -0.65 SD and +0.08 SD, respectively, whereas the figures for BMD of the hip were -0.66 SD and +0.13 SD, respectively. All parameters were significantly lower in the hip fracture group compared with the patients who had fallen. None of the parameters in the patients who had fallen deviated significantly from expected normal age-matched values. Neither BMD of the arm or BMD of the hip separated hip fracture patients and patients who had fallen significantly better than ultrasound (BUA or SOS) did. We conclude that imaging ultrasound (BUA or SOS) separates age-matched groups of hip fracture and non-fracture patients as well as BMD measurements do.

Assessment of Bone Mineral at Appendicular Sites In Females With Fractures of the Proximal Femur

The prediction of hip fractures by measurements at remote sites or the improvement of predictive power by measurements at multiple sites could potentially increase the success of osteoporosis screening programs. In a cross-sectional study on 137 postmenopausal women, we tested the hypothesis that bone assessment at the hip, the forearm, and the tibia are independently associated with osteoporotic fractures of the hip. Bone mineral densities, geometric features, and ultrasound properties were determined with hip dual X-ray absorptiometry, forearm peripheral quantitative computed tomography (QCT), and tibia speed of sound measurement. While the odds ratios for fracture discrimination per standard deviation decrease ranged between 3 and 4 for measurements at the hip, they were only 1.8 at the forearm and 1.4 at the tibia. Measurements at the tibia or the forearm were neither independently associated with osteoporotic hip fractures ( p > 0.05) nor could any combination of measurements significantly increase the power for the identification of fractures as measured with receiver operating curves. Women who sustained trochanteric fractures were characterized by a generalized loss of bone mineral. Cervical fractures were associated with a decrease of bone mineral density at the hip, but no significant alterations in bone mass or geometric properties were observed at the tibia or at the forearm. Fracture risk prediction at the hip is therefore preferably performed by measurements at the hip itself. Peripheral QCT at the distal radius and tibial ultrasound seem capable of depicting women with an increased risk for trochanteric but not for cervical fractures. The risk assessment appears not to be improved by including information of cortical or geometric properties of the forearm.

Discrimination of spinal fracture with various bone mineral measurements.

For several different bone mineral measurements and various skeletal sites, we compared capability to discriminate between women in various age decades with and without spinal fracture, and attempted to identify the most effective cutoff level in discrimination of spinal fracture. The subjects were 88 women aged 50-59 years (including 32 with fracture), 95 women aged 60-69 years (including 54 with fracture), and 34 women aged 70-79 years (including 18 with fracture). Spinal trabecular and cortical bone mineral density (BMD) were measured using quantitative computed tomography (CT), and spinal, radial (ultra-distal, 10% distal and 33% distal), and calcaneal BMD were measured by dual X-ray absorptiometry. These BMD values were obtained in each subject on the same day. Three statistical techniques-Student's t-test, the logistic regression analysis, and the receiver operating characteristics (ROC) analysis- were applied and accuracy was calculated using the various cutoff values. The capability to discriminate between women with and those without fracture using these BMD values was different among the three age groups. In women aged 50-59 and 60-69 years, all measurements showed good capabilities for discriminating women with fracture. In women aged 70-79 years, these measurements showed lower capability than in those aged 50-59 and 60-69 years, but among them, the calcaneal and ultradistal radial BMD showed relatively good capability. The 10% and 33% distal radial BMD values were not useful in the detection of the high risk women with fracture. The cutoff BMD values for discrimination of women with fracture varied according to the sites and methods of measurement. For each specific age group, the most suitable measurement methods and the appropriate skeletal sites should be considered, and the effective cutoff values to discriminate those with fracture may differ according to the measurement methods, the skeletal sites examined, and age.

Quantitative CT assessment of the lumbar spine and radius in patients with osteoporosis.

We undertook this study to quantify the relationship between bone mineral assessments of the lumbar spine using quantitative CT (QCT) and of the radius using peripheral QCT (pQCT) and to test the sensitivity of both techniques in detecting changes in bone mass that are related to age and osteoporosis. Forty-two healthy premenopausal, 38 healthy postmenopausal, and 97 osteoporotic postmenopausal women were examined with pQCT of the distal radius and with QCT of the lumbar spine (L1-L4). The bone mineral density (BMD), bone mineral content (BMC), and a cross-sectional area of cortical bone were assessed at the distal radius. The BMD of trabecular and total bone and the BMC of total bone were assessed at the midvertebral bodies of the lumbar spine. In the healthy women, correlations of radial BMD with spinal trabecular and total BMD were modest (r = .39 and r = .49, respectively) but were higher for total BMC (r = .79). All correlations in osteoporotic women (r = .19 for trabecular BMD, r = .31 for total BMD, and r = .47 for total BMC) were lower than those in healthy women. For measurement of spinal bone mass in healthy women, trabecular BMD showed a higher correlation with age (r = .81) and a larger relative annual decrease (1.2%) than did total BMD (r = .75, .78%) or total BMC (r = .54, .55%). At the radius, the highest correlations with age were found for total BMC (r = .57, .53%), cortical area (r - .52, .67%), and cortical BMC (r = .48, .78%). Age-adjusted odds ratios for prevalent vertebral fractures were highest for total (4.5) and trabecular (4.4) spinal BMD. For radial measurements, odds ratios were highest for both total BMD (2.3) and cortical area (2.3). QCT of spinal trabecular bone showed the strongest capability for assessment of age-related bone loss and for discrimination of osteoporotic vertebral fractures. In comparison, pQCT of radial trabecular bone showed the weakest capability for these applications, and pQCT of radial cortical or total bone showed intermediate capability.

Scanning electron microscope fractography in failure analysis of steels

For many failure cases, macroscopic examination of the fracture surface permits discrimination of fatigue fractures from overload fractures. For clarifying fatigue fractures, the practical significance of microfractography is limited to an investigation of the crack initiation areas. Scanning electron microscopy is successfully used in tracing local material abnormalities that act as fatigue crack initiators. The task for the scanning electron microscope, however, is much more substantial in failure analysis of overload fractures, especially for steels. By revealing specific fractographic characteristics, complemented by information about the material and the loading conditions, scanning electron microscopy provides a strong indication of the probable cause of failure. A complete dimple fracture is indicative of acceptable bulk material properties; overloading, by subdimensioning or excessive external loading, has to be verified. The presence of cleavage fracture makes the material properties questionable if external conditions causing embrittlement are absent. Intergranular brittle fracture requires verification of grain-boundary weakening conditions—a sensitized structure, whether or not combined with a local stress state or a specific environment. The role of scanning electron microscopy in failure analysis is illustrated by case histories of the afore-mentioned fracture types.

Current methods and advances in bone densitometry

Bone mass is the primary, although not the only, determinant of fracture. Over the past few years a number of noninvasive techniques have been developed to more sensitively quantitate bone mass. These include single and dual photon absorptiometry (SPA and DPA), single and dual X-ray absorptiometry (SXA and DXA) and quantitative computed tomography (QCT). While differing in anatomic sites measured and in their estimates of precision, accuracy, and fracture discrimination, all of these methods provide clinically useful measurements of skeletal status. It is the intent of this review to discuss the pros and cons of these techniques and to present the new applications of ultrasound (US) and magnetic resonance (MRI) in the detection and management of osteoporosis.

Better discrimination of hip fracture using bone density, geometry and architecture

Bone density predicts the risk of hip fracture. Because hip strength is determined by bone geometry and architecture as well as density, we tested which variables in geometry and architecture were independent discriminators of hip fracture and, if combined with density, improved the discrimination of fracture from non-fracture over bone density alone. The design was a case-control study. The subjects were Caucasian women over the age of 60 years who had sustained a hip fracture after the age of 58 years (n = 22), and controls matched for age and weight (n = 43) and unmatched controls (n = 317) with no history of hip fracture. Variables in density, geometry and architecture were obtained from dual-energy X-ray absorptiometry images and from radiographs of the upper end of the femur. In a univariate model, of the measures of bone mass, the best discriminator of hip fracture was bone mineral density of the neck of femur; of the geometric measurements, it was hip axis length; and of the measurements of bone architecture, it was Singh grade. In a multivariate model, these three variables were shown to be independent discriminators of hip fracture. When hip axis length was combined with bone mineral density, there was significant improvement in discrimination of hip fracture (p = 0.014), and when Singh grade was combined with hip axis length and bone mineral density there was a further significant improvement (p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Measurement of bone mineral density: Current status

0 steoporosis has been traditionally defined as a condition of low bone mass accompanied by atraumatic fractures. Recently, more emphasis has been placed on patient bone mineral density in the attempt to identify those at high risk for osteoporotic fracture before these fractures have occurred. As a result, bone densitometry techniques have become increasingly important. Four general methods have been developed and are currently being used for noninvasively measuring bone mineral density at various anatomic sites, both in the axial and in the peripheral skeleton (Table I). While differing in the particular anatomic sites they measure and in their precision, accuracy, and fracture discrimination, all of these methods provide clinically useful measurements of skeletal status and represent major advances in our ability to noninvasively measure bone mass.

Studies on collision-protective structures in nuclear powered ships

For the purpose of obtaining design formulae of collision-protective side structures installed in nuclear powered ships, various series of tests and theoretical analyses were carried out. Fracture types of side structures could be grouped into two types such as deformation and crack ones. Discrimination of fracture, estimation of load, and absorbed energy against penetration depth were formulated. The dynamic effects could be explained well with the rise of yield stress of steel. Relationship between added mass of water and elapsed time of collision was analyzed. The influence of the strength of a stem of striking ship could be examined with strength ratio of stem to side structure and semi-experimental formulae of the energy absorption were obtained. The influence of the stem angle and penetration angle to the energy absorption was clarified to be small. The condition of the side structures required to have large absorbed energy was discussed using the model tests of various side structures.