Ultrasound velocity of the tibia in normal German women and hip fracture patients

Correlation of tibial low-frequency ultrasound velocity with femoral radiographic measurements and BMD in elderly women

The ultrasonic axial transmission technique has been proposed as a method for cortical bone characterization. Using a low enough center frequency, Lamb modes can be excited in long bones. Lamb waves propagate throughout the cortical bone layer, which makes them appealing for characterizing bone material and geometrical properties. In the present study, a prototype low-frequency quantitative ultrasonic axial transmission device was used on elderly women (n = 132) to investigate the relationships between upper femur geometry and bone mineral density (BMD) and tibial speed of sound. Ultrasonic velocities (V) were recorded using a two-directional measurement set-up on the midtibia and compared with dual-energy X-ray absorptiometry measurements and plain radiographs of the hip. Statistically significant, but weak, correlations were found between V and femoral shaft cortex thickness measured from radiographs (r = 0.20-0.26). V also correlated significantly with various BMD and bone mineral content parameters (r = 0.20-0.35). Femoral BMD and geometry were found to be significant independent predictors of V (R(2) = 0.07-0.16, p < 0.01). This study showed that femoral geometry and BMD affect significantly the axial ultrasound velocity measured at the tibia. In addition, the results confirmed, for the first time, a relationship between tibial ultrasound velocity and cortical bone thickness at the proximal femur.

Different diagnostic techniques for the assessment of cortical bone on osteoporotic animals

The aim of this study was to assess the capability of ultrasonography and densitometry to predict the mechanical competence of cortical bone in healthy and osteopenic rats, respectively. Thirty 10-month-old Sprague-Dawley retired breeder female rats were used and randomized into three groups of 10 animals each. A group underwent bilateral ovariectomy by dorsal approach (Ovx), another group underwent a simulated ovariectomy (Sham-Ovx), and the last group served as a sham-aged control group (Control). Sixteen weeks after surgery, the animals were euthanized and the femurs of each rat excised for ultrasonographic and densitometric measurements, and mechanical analyses. The Ovx Group had a significantly decreased amplitude dependent speed of sound (AD-SoS-about 7-8%) when compared to the other groups (p<0.0005). For Ovx animals compared with Sham-Ovx and Control rats, significant decreases in densitometric data were observed (6-13%), as well as significant decreases in femoral Max. Load (about 18%) and flexural rigidity (about 30%). The best correlation (R2=0.55, p<0.0005) found was between SoS and femoral shaft bone mineral density (SBMD). The regression coefficient R2 increased when power-law fits were used, particularly from 0.34 (p<0.001) to 0.36 (p<0.0005) in the correlation between SoS and Max. Load and from 0.21 (p<0.05) to 0.25 (p<0.01) in the correlation between SBMD and Max. Load. The ability of QUS or DXA to accurately predict the actual mechanical characteristics of bone, and in particular bone elasticity, remained relatively poor and the improvement of the power-law model did not describe exhaustively the relationships between the variables tested. The DXA and QUS capability to discriminate between ovariectomized and non-ovariectomized rats did not improve when tested together.

Limited diagnostic agreement of quantitative sonography of the radius and phalanges with dual-energy x-ray absorptiometry of the spine, femur, and radius for diagnosis of osteoporosis

OBJECTIVE

The aim of our study was to evaluate the diagnostic agreement of quantitative sonography of the radius and proximal phalanx and dual-energy X-ray absorptiometry (DXA) of the radius, lumbar spine, and femoral neck for the detection of osteoporosis.

MATERIALS AND METHODS

In 95 women (mean age, 53 +/- 13 years) and 26 men (mean age, 53 +/- 13 years), DXA measurements of the lumbar spine (posterior-anterior, L1-L4) and the femoral neck, as well as quantitative sonography of the radius and proximal phalanx of the third finger were obtained. The percentage of patients below a given threshold was calculated for each imaging technique. A T score of less than -2.5 indicated presence of osteoporosis. Diagnostic agreement in identifying individuals with osteoporosis was assessed using kappa scores.

RESULTS

Between 14% and 22% of the patients were classified as osteoporotic after DXA of the various regions of interest of the radius, 31% after DXA of the spine, 43% after DXA of the femoral neck, 32% after quantitative sonography of the distal radius, and 34% after quantitative sonography of the phalanx of the third finger. Correlation coefficients between T values for quantitative sonography and those for DXA varied between not significant and 0.54 at the different regions. Kappa analysis showed the diagnostic agreement among quantitative sonography and DXA to be fair to moderate (kappa = 0.38-0.48). The highest agreement was between quantitative sonography of the proximal phalanx of the third finger and DXA of the total radius (kappa 0.48; p < 0.05).

CONCLUSION

Considerable diagnostic disagreement exists between quantitative sonography and DXA of the forearm, as is true for most quantitative techniques in the assessment of skeletal status. The lack of correlation makes quantitative sonography impractical for routine diagnostic use but might characterize different parameters related to bone quality.

An in vitro study of the ultrasonic axial transmission technique at the radius: 1-MHz velocity measurements are sensitive to both mineralization and intracortical porosity

The ultrasonic axial transmission technique allows for investigating skeletal sites such as the cortical layer of long bones (radius, tibia, phalanges). Using synchrotron radiation microCT, we investigated, in vitro, the relationships between 1-MHz axial transmission SOS measurements at the radius and site-matched measurements of C.Th, POR, MIN, and vBMD.

INTRODUCTION

The ultrasonic axial transmission technique allows for investigating skeletal sites such as the cortical layer of long bones (radius, tibia, phalanges).

MATERIALS AND METHODS

Using synchrotron radiation microCT, we investigated, in vitro, the relationships between 1-MHz axial transmission speed of sound (SOS) measurements at the radius and site-matched measurements of cortical thickness (C.Th), intracortical porosity (POR), tissue mineralization (MIN), and volumetric BMD (vBMD). SOS measurements were based on bidirectional axial transmission and were performed with a 1-MHz proprietary probe on 39 excised human radii.

RESULTS

The highest correlations between SOS values and bone parameters (R(2)(SOS/POR) = 0.28, p < 10(-3); R(2)(SOS/MIN) = 0.38, p < 10(-4); R(2)(SOS/vBMD) = 0.57, p < 10(-3)) were found for bone parameters assessed in a 1-mm-thick periosteal region of the cortex rather than throughout the whole cortex. The observed moderate correlation between SOS and C.Th values (R(2)(SOS/C.Th) = 0.20, p < 10(-2)) disappeared when controlled for other variables. The two best multilinear predictive models, including either BMD alone or the pair of dependent variables MIN and POR (all assessed in the periosteal cortex), were equally accurate in predicting SOS values (R(2)(SOS/(POR,MIN)) = 0.59, p < 10(-5); R(2)(SOS/vBMD) = 0.57, p < 10(-5)).

CONCLUSION

For the first time, the respective adjusted contributions of POR (-24 m/s%(-1)) and tissue mineralization (+3.5 m/s/mg/cm(-3)) to SOS values were assessed. These results suggest potential sensitivity of axial transmission SOS values to changes in cortical bone status under different pathological conditions or treatments affecting POR and/or tissue mineralization.

Speed of sound in bone at the tibia: is it related to lower limb bone mineral density in spinal-cord-injured individuals?

STUDY DESIGN

A cross-sectional study evaluating BMD at the hip and tibia, and SOS at the radius and mid-tibia in individuals with spinal cord injury (SCI) and a subgroup of non-SCI individuals.

OBJECTIVES

To investigate the speed of sound (SOS) in bone in relation to bone mineral density (BMD).

SETTING

Kinesiology Department, McMaster University, Ontario, Canada.

METHODS

In 14 individuals with SCI and 10 non-SCI individuals, proximal femur and tibia BMD were measured using dual energy X-ray absorptiometry, and radius and tibia SOS were measured with an ultrasonometer. T-scores were calculated using healthy reference databases. Inter-relationships between measurement techniques were determined using Pearson's correlation coefficients. P-values less than 0.05 were considered statistically significant.

RESULTS

: The average ages of the SCI and non-SCI groups were 33+/-9 and 27+/-6 years, respectively. Lesion level ranged from C4 to T12 and average time postinjury was 12 years, with a range of 1.6-25 years. Using the WHO criteria for osteoporosis, nine of 14 SCI subjects were osteoporotic at the hip, with the remainder in the osteopenic range. Tibia SOS T-scores were in the osteoporotic range for one subject with SCI, and two were in the osteopenic range. Among non-SCI individuals, one male had a tibia SOS T-score of -1.4, all others were within the normal range. Hip BMD and tibia SOS were significantly correlated (r=0.46, P<0.01). Hip BMD and tibia BMD were more strongly correlated (r=0.80, P<0.0005). Tibia BMD was not significantly correlated with SOS at the tibia (r=0.35, P=0.09). Radius SOS T-scores were positive and not significantly correlated with any lower limb variable.

CONCLUSION

Lower-limb bone mass is reduced in spinal cord-injured individuals, but SOS at the mid-tibia is not. It remains to be determined whether ultrasound measurements can predict fracture in the SCI population.

Bone quantitative ultrasound and nutritional status in severely handicapped institutionalized children and adolescents

BACKGROUND & AIMS

Children with cerebral palsy (CP) have a high prevalence of pathologic fractures. Bone quantitative ultrasonography (QUS) has emerged as a radiation-free method for the assessment of bone quality and fracture risk. In this study, we applied QUS technique in order to investigate bone status in handicapped institutionalized children and adolescents.

METHODS

This cross-sectional study included 87 handicapped institutionalized patients. Measurements of the velocity of ultrasound wave, speed of sound (SOS), at distal radius and midshaft tibia, were performed using Omnisense 7000S analyser (Sunlight Ltd., Tel Aviv, Israel). In addition, all the participants had a thorough evaluation of nutritional status, demographic and clinical characteristics.

RESULTS

Forty-five of patients had either radius or tibia bone SOS lower than -1 SD, and 21% had either radius or tibia bone SOS lower than -2.5 SD. Using step-wise regression analysis, female gender (P=0.003) and stature (P=0.008) were correlated with radius SOS. Age (P=0.03) and fracture history (P=0.04) were negatively correlated with tibia SOS.

CONCLUSION

In this group of children and adolescents with CP one-fifth had poor bone status as suggested by low tibia/radius SOS assessed by QUS. Female gender, stature, age and fracture history were significantly correlated with poor bone status.

Tibial ultrasound velocity in women with wrist fracture

The aim of the study was to determine whether cortical midtibial speed of sound (Soundscan 2000, Myriad Ultrasound Systems, Israel) was able to discriminate women who sustained a fracture of the distal radius from normal women and to compare the performance of tibial speed of sound with dual-energy X-ray absorptiometry (DXA) of the distal radius, hip, and lumbar spine. The study population consisted of 40 women with a wrist fracture and 41 healthy age-matched controls. Tibial ultrasound velocity correlated with bone mineral density of the distal forearm (rS = 0.64, p < 0.001), the hip (rS = 0.46, p < 0.001), and the lumbar spine (rS = 0.51, p < 0.001). The mean speed of sound value at the mid-tibia of the wrist fracture patients (3873 m/s) was lower than that of the controls (3913 m/s), but the difference was not statistically significant (p = 0.12). All DXA values were significantly lower in fracture cases. Receiver operating curve analysis showed that mid-tibial ultrasound velocity was less effective than DXA of the distal forearm to discriminate wrist fracture patients from age-matched controls.

Relationship among MRTA, DXA, and QUS

Dual-energy X-ray absorptiometry (DXA) and quantitative ultrasound (QUS) are the accepted modalities for the evaluation of fracture risk in the clinical setting. However, neither method provides a direct measurement of bone mechanics. In this study, we investigated a prototype device, known as a mechanical response tissue analyzer (MRTA), which provides direct mechanical measurements of mechanical properties of bone. A total of 56 healthy volunteers (20 men and 36 women) between the ages of 18 and 83 were recruited. The MRTA was used to measure the cross-sectional bending stiffness (EI) of the ulna bone. Axial speed of sound (SOS) at the ulna bone was determined by QUS; bone mineral content (BMC) and bone mineral density (BMD) were determined by DXA. Correlations, regression analysis, and analyses of variance (ANOVAs) were used to compare the three modalities. These analyses revealed that although there are strong linear relationships among the data collected by the various technologies, the bone properties reflected by MRTA are not fully explained by DXA and QUS. We conclude that the total information conveyed by MRTA measurements is unique. Further research is needed to delineate the different qualities of bone strength that are captured by MRTA, but not by DXA or QUS.

Autocorrelation and cepstral methods for measurement of tibial cortical thickness

Cortical thickness of the tibia is related to stress fracture risk and overall skeletal status. Two methods are proposed for estimating tibial cortical thickness based on power spectra of ultrasonic echoes containing reflections from front and back surfaces of the cortex. The locations of the peaks in the autocorrelation function and the cepstrum are related to cortical thickness. Data were acquired on plastic plates in order to validate the methodology. These data indicate high correlations between estimated and true thickness with correlation coefficients r = 0.99, (95% confidence interval: 0.993-1.00) for the autocorrelation method and r = 0.99 (95% CI: 0.996-1.00) for the cepstral method. Data on six tibia samples in vitro indicate correlation coefficients of r = 0.92 (95% CI: 0.72-1.00) for the autocorrelation method and r = 0.85 (95% CI: 0.62-0.94) for the cepstral method. Estimates of precisions of the two methods were 0.3 +/- 0.1 mm (autocorrelation method) and 0.5 +/- 0.2 mm (cepstral method). One measurement in a human volunteer in vivo demonstrated clinical feasibility of the measurement and good agreement with cortical thickness assessed using peripheral quantitative computed tomography (QCT). This technology offers the promise of an inexpensive, fast, portable, simple, nonionizing technique for assessing skeletal status.

Ultrasound velocity in the tibia in Japanese patients with hip fracture

The speed of sound in the tibia (tibial SOS) was measured in elderly women to determine whether the tibial SOS declined with age, similarly to bone mineral density (BMD), as determined by dual-energy X-ray absorptiometry (DXA), and whether the tibial SOS in elderly hip fracture patients was lower than that in a control group. The subjects in this study included 38 female patients with hip fracture aged 65 years or more and 38 age-matched women living in a nursing home as the control group. There was a significant decline in the tibial SOS with age in women in the control group, but not in those with hip fracture. In all subjects aged under 80 years, the tibial SOS in women with hip fracture was significantly lower than that in women in the control group. In all subjects who were 80 years or older, the tibial SOS was not significantly different between women with hip fracture and the control group; thus, the tibial SOS in both groups was low, and they were considered to have progressive osteoporosis. The tibial ultrasound velocity can be expected to be useful as an indicator of the risk of limb fracture in the elderly.

Phalangeal ultrasonography in forearm fracture discrimination

Over the last decade, the use of ultrasounds has been developed into an effective tool for investigating bone tissue and predicting the risk of fracture in osteoporosis. Studies have focused on hip and vertebral fractures while no information is available on the use of phalangeal ultrasonography to identify patients with forearm fractures. Thus, the current authors decided to compare 50 postmenopausal women with low energy forearm fractures (Fractured Group) with a control age-matched group of 94 women (Control Group). Measurements were taken at the distal metaphysis of the proximal phalanxes of the hand of the non-fractured arm using the DBM Sonic Bone Profiler. The reproducibility of the method was assessed by amplitude-dependent speed of sound (AD-SoS) CV% = 0.64 and by Ultrasound Bone Profiler Index (UBPI) CV% = 2.38. In the Control Group, the AD-SoS and UBPI mean values and standard deviations were significantly higher compared to the group with fractures (P < 0.0005). The receiver operating characteristic (ROC) curves were calculated and the areas under the curve (AUC) were 0.78 +/- 0.04 for AD-SoS and 0.77 +/- 0.05 for UBPI, respectively. Logistic regression analysis adjusted to age revealed that both AD-SoS (78.2%, ORAD-SoS = 12.03, P < 0.0005) and UBPI (76.0%, ORAD-SoS = 7.39, P < 0.0005) parameters discriminated correctly between fractured and non-fractured control women whereas the association of both parameters could not allow better discrimination. The present results showed that ultrasound investigation at the phalanxes is reproducible and efficiently discriminates between subjects with forearm fractures and those in the control subjects.

Assessment of bone status using speed of sound at multiple anatomical sites

Studies in vitro and in vivo have shown that quantitative ultrasound (QUS) is a valid tool for the assessment of bone status. Current QUS methods using the transmission technique are limited to one peripheral bone site. A new system, Sunlight Omnisense (Omnisense, Sunlight Medical Ltd., Rehovot, Israel), measures speed of sound (SOS, in m/s) along the surface of the bone based on an axial transmission technique. The Omnisense can measure SOS at several anatomical sites. This study evaluated the SOS at different anatomical sites in a healthy population. A total of 334 adult women from three research centers in the USA and Canada with a mean (+/- SD) age of 48.8 (+/- 17.4) years were enrolled in this study. SOS was measured at the proximal third phalanx, distal one third radius, midshaft tibia, and fifth metatarsal. The mean SOS (+/- SD) values for the phalanx, radius, tibia and metatarsal were 3984 (+/- 221), 4087 (+/- 147), 3893 (+/- 150) and 3690 (+/- 246) m/s, respectively. Each anatomical site SOS was significantly different (p < 0.001) from that of the other sites. SOS at the different anatomical sites was modestly, but significantly, correlated (r = 0.31 to 0.56, p < 0.001). Similar correlation coefficients were obtained for the T scores. The mean T scores for subjects over the age of 60 years were -1.94, -2.01, -0.97 and -1.42 for the phalanx, radius, tibia and metatarsal, respectively. The age of peak SOS and the rate of change thereafter varied with anatomical site, implying that the prevalence of osteopenia and osteoporosis was site-dependent if only one T score cut-off point was used. Comparing individuals, 10% to 17% of patients had T scores that differed by more than a factor of 2 between sites. Weight and age were some of the contributing factors to this heterogeneity. The Omnisense provides an opportunity to assess bone status at different anatomical sites. Whether or not combining measurements from all these anatomical sites will improve osteoporosis management still needs to be determined.

Effect of estrogen replacement therapy on speed of sound at multiple skeletal sites

OBJECTIVES

To evaluate the effect of estrogen replacement therapy (ERT) on postmenopausal bone loss by multi-site ultrasound measurement.

METHODS

A cross-sectional comparison of postmenopausal women, ERT users and non-users. The two study groups were enrolled for the reference database collection for the Sunlight Omnisense (Omnisense) and were matched by years since menopause. Speed of sound (SOS) was measured at the distal radius (RAD), mid-shaft tibia (TIB), fifth metatarsus (MTR) and proximal phalanx (PLX).

RESULTS

143 ERT users for 5.2+/-3.6 years were compared with 139 ERT non-users (age: 57.0+/-5.3 and 57.5+/-5.5, respectively). Both groups were 7.1+/-5.0 years since menopause. SOS, expressed in T-score units, was higher at the RAD in ERT users as compared to ERT non-users (-0.55+/-1.30 and -1.36+/-1.60, respectively, P<0.0001), and at the TIB (-0.73+/-1.34 and -1.28+/-1.45, respectively, P=0. 003). Same trend was observed at the MTR and PLX, but not statistically significant because of fewer observations. In early post menopause period, the ERT-non users RAD data shows an annual SOS decrease of 0.17 versus annual increase of 0.12 T-score units (P=0.037). Similar effect is observed at the TIB, though not statistically significant (non-users decrease of 0.20 vs. users increase of 0.08 T-score units/year, P=0.086).

CONCLUSIONS

SOS measurements by Omnisense at multiple skeletal sites support the ERT protective effect on bone.

Prediction of bone strength of distal forearm using radius bone mineral density and phalangeal speed of sound

This investigation compares quantitative ultrasound (QUS) measurement of the phalanges with peripheral quantitative computed tomography (pQCT) and dual X-ray absorptiometry (DXA) measurement of the forearm, to estimate the strength of the distal radius in 13 cadaveric forearms. The cadavers were scanned at the distal radius by pQCT and DXA for bone mineral density (BMD) and at the approximate phalanges by QUS for speed of sound (SOS). The distal radii were subjected to a simulated Colles fracture produced with a materials testing machine. The load at which the distal radius was fractured was considered as a representation of bone strength. The bone strength correlated significantly with SOS at different phalanges (r = 0.63-0.72), BMD at different regions of interest by DXA (r = 0.67-0.75), and cortical BMD at different sites by pQCT (r = 0.61-0.67). Standard stepwise regression analysis showed that adding phalangeal SOS into forearm densitometric variables significantly enhanced the statistical power for prediction of the strength of the distal radius. Our results suggest that, for assessment of site-specific distal forearm strength, QUS measurement of the phalanges is comparable to forearm densitometry. Phalangeal QUS may add clinical value if distal forearm strength has a high priority.

A new method for quantitative ultrasound measurements at multiple skeletal sites: first results of precision and fracture discrimination

We investigated a new multisite quantitative ultrasound device that measures the acoustic velocity in axial transmission mode along the cortex. Using a prototype of the Omnisense (Sunlight Ultrasound Technologies, Rehovot, Israel), we tested the performance of this instrument at four sites of the skeleton: radius, ulna, metacarpal, and phalanx. Intraobserver (interobserver) precision errors ranged from 0.2% to 0.3% (0.3% to 0.7%) for triplicate measurements with repositioning. Fracture discrimination was tested by comparing a group of 34 women who had previously suffered a fracture of the hip, spine, ankle, or forearm to a group of 28 healthy women who had not suffered a fracture. Age-adjusted standardized odds ratios ranged from 1.6 to 4.5. Except for the ulna the sites showed a significant fracture discrimination (p < 0.01). The areas under the receiver operating curves (ROC) curves were from 0.88 to 0.89 for radius, metacarpal, and phalanx. A combination of the results from the three sites showed a significant increase of the ROC area to 0.95 (p < 0. 05). Our results show promising performance of this new device. The ability to measure a large variety of sites and the potential to combine these measurements are promising with regard to optimizing fracture risk assessment.

Use of quantitative ultrasound to assess bone status in children with juvenile idiopathic arthritis: a pilot study

Periarticular osteoporosis around inflammed joints and generalized osteoporosis have been shown to be markers of disease activity and severity in children with juvenile idiopathic arthritis (JIA). Bone mineral density (BMD) in adults can be assessed precisely by dual X-ray absorptiometry (DXA), but this technique has not been used widely in children. Quantitative ultrasound (QUS) may provide an alternative method for assessment of bone status. The aim of this pilot study was to compare QUS to DXA in assessing generalized osteoporosis in a cohort of patients JIA. Twenty-two Caucasian children (15 females, 7 males) with JIA of duration 19-142 months (mean 71 mo) and age 7-17 yr were recruited. Total body and lumbar spine BMD and bone mineral content (BMC) were measured by DXA using standard procedures on a Lunar DPX-L scanner. QUS was performed using Myriad SoundScan 2000. Speed of sound (SOS) was measured at the right midtibia. The DXA results were compared to QUS using linear regression analysis. Spine and total body BMD measured by DXA correlated significantly with tibia SOS (spine: r = 0.57, p < 0.007; total body: r = 0.68, p < 0.001). Spine BMC was similarly related to SOS as BMD (r = 0.58, p < 0.007). Individual patient weight and height were strong predictors of BMD, but only moderate predictors of SOS. The mean spine BMD was lower in the JIA patients compared to the normal ranges (mean Z-score of -1.19). BMD Z-scores were negatively associated with disease duration. Patients taking steroids were associated with lower Z-scores. In conclusion, SOS shows a significant correlation with BMD as measured by DXA, albeit with wide 95% confidence intervals in this small pilot study. QUS was also well tolerated and was technically easy to perform in these children. With the added advantage that it is free from radiation risk, further assessment of this potentially valuable tool for measuring bone status in children is warranted.

Prediction of the strength of the elderly proximal femur by bone mineral density and quantitative ultrasound measurements of the heel and tibia

Quantitative ultrasound (QUS) of the heel and tibia have recently been approved in the United States for diagnostic evaluation of low bone mass. The goal of this study was to use human cadaveric specimens to compare correlations among: a) strength of the proximal femur; b) bone mineral density of the femur, tibia, and heel; and c) QUS of the tibia and heel. We obtained 26 proximal femurs and intact lower limbs from 16 female and 10 male cadavers, with a mean age of 81+/-12 years. Bone mineral density (BMD, g/cm2) of the proximal femur and tibia were assessed using dual-energy x-ray absorptiometry, and BMD (g/cm) of the heel was measured using single-energy x-ray absorptiometry. Ultrasound velocity at the mid-tibia was determined using a contact, gel-coupled ultrasound device. Broadband ultrasound attenuation (BUA) and speed of sound (SOS) of the heel were determined using a transmission ultrasound device with water-based coupling. The femurs were tested to failure in a configuration designed to simulate a fall to the side with impact to the greater trochanter. As in previous studies, the strength of the proximal femur was very strongly correlated with femoral BMD and heel BMD (r2 = 0.78-0.92, p < .0001 for all). BUA and SOS of the heel were also strongly correlated to femoral strength (r2 = 0.70 and 0.67, respectively, p < 0.0001 for both), whereas tibia SOS was only weakly correlated (r2 = 0.19, p = 0.03). The average coefficient of variation for triplicate tibial SOS measurements was 0.50%. This study indicates that, although tibial SOS measurements are precise, they are not strongly correlated with femoral BMD or strength. In contrast, heel QUS measurements are strongly correlated with the strength of the proximal femur. These findings imply that tibial SOS may be of limited use for assessing hip fracture risk. Prospective fracture risk data are needed to define further the clinical utility of tibia ultrasound measurements.

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.

[Osteosonography of the phalanges of men]

BACKGROUND

The distal metaphysis of the first phalanx of the fingers II to V is, like the vertebral body, a useful site for the measurement of mineralisation and structure of the bone, because of the simultaneous presence of compact and trabecular bone.

METHOD

With an osteosonographic device (DBM sonic 1200, IGEA, Italy) we measured in 38 young and healthy men, 14 elderly and healthy men, 18 men with osteopenia, 8 men with osteoporosis and vertebral fractures and 10 men with long-standing cortisone medication, the adSOS (amplitude-dependent speed of sound) and the UBPS (ultrasound bone profile score) at the phalanges, as well as bone mineral density (BMD) at lumbar spine using dual-X-ray absorptiometry (DXA).

RESULTS

There was no correlation between adSOS or UBPS and lumbar BMD (DXA). There was a significant positive correlation between adSOS and UBPS, r = 0.826 (p < 0.00001). AdSOS declined with age (r = 0.694, p = 0.021); the UBPS was not age-dependent (r = -0.15, p = n.s.), as expected. AdSOS and UBPS could discriminate significantly between the young and healthy controls and the men with osteopenia/vertebral fractures or oral steroids (p < 0.00001). The DXA could be significantly discriminate all healthy controls from the patients with osteopenia or vertebral fractures. It could not significantly discriminate the healthy controls from the patients taking oral glucoconticoids. Only the UBPS could significantly discriminate this group from the healthy controls.

CONCLUSION

These results show, that adSOS and UBPS are precise parameters to be measured at the phalanges. The detection level of pathological changes in osteoporosis are similar between adSOS and lumbar BMD (DXA) and improved by using UBPS. This might be explained by the influence of structural changes in bone on UBPS, rather than changes in bone mineral alone. Prospective studies have to clarify the role of adSOS and UBPS in fracture prediction.

Utility of ultrasound to assess risk of fracture

Traditional assessments of bone properties have utilized densitometry techniques such as Dual Energy X-ray Absorptiometry (DXA). Recently, quantitative ultrasound (QUS) has been introduced as an alternative method of assessing bone properties. Advantages of QUS over X-ray techniques include low costs, portability, and nonionizing radiation. Proponents of QUS have claimed that this technology can provide information not only about the density but also about the structure and mechanical properties of bone. There are two major questions that need to be answered for those who seek to diagnose bone disorders with ultrasound: (1) what does quantitative ultrasound actually measure, and, even more importantly, (2) what is its clinical utility? In this review we will briefly examine the first question and will focus on the utility of ultrasound in clinical trials to discriminate between fractures and non-fractures and to predict the risk of fractures.

Quantitative ultrasound techniques for the assessment of osteoporosis: expert agreement on current status. The International Quantitative Ultrasound Consensus Group

Quantitative ultrasound (QUS) methods have been introduced in recent years for the assessment of skeletal status in osteoporosis. The performance of QUS techniques has been evaluated in a large number of studies. Reviewing existing knowledge, an international expert panel formulated the following consensus regarding the current status of this technology. To date, evidence supports the use of QUS techniques for the assessment of fracture risk in elderly women. This has been best established for water-based calcaneal QUS systems. Future studies should include the predictive validity of other QUS systems. Additional clinical applications of QUS, specifically the assessment of rates of change for monitoring disease progression or response to treatment, require further investigation. Its low cost and portability make QUS an attractive technology for assessing risk of fractures in larger populations than may be suitable or feasible for bone densitometry. Additional investigations that assess innovative QUS techniques in well defined research settings are important to determine and utilize the full potential of this technology for the benefit of early detection and monitoring of osteoporosis.

Peripheral measurement techniques for the assessment of osteoporosis

Peripheral measurement techniques have been the first to be developed for the assessment of osteoporosis, and they remain useful. Besides traditional approaches such as radiographic absorptiometry (RA), radiogrammetry, and single-photon absorptiometry (SPA), new peripheral approaches have been developed that offer powerful ways to assess skeletal status in osteoporosis. These include single x-ray absorptiometry (SXA), peripheral dual x-ray absorptiometry (pDXA), peripheral quantitative computed tomography (pQCT), quantitative ultrasound (QUS) techniques, and magnetic resonance imaging (MRI) approaches. This review describes the current role of peripheral imaging techniques vis-à-vis their central imaging counterparts. Peripheral measurement techniques are attractive because equipment cost is substantially lower, radiation exposure is small, and the devices require less space and sometimes are even portable. Additionally, QUS and MRI offer the potential to measure aspects of bone status beyond the limits of bone densitometry. Peripheral techniques represent important diagnostic methods for the assessment of osteoporosis.

Tibial ultrasound velocity measured in situ predicts the material properties of tibial cortical bone

Quantitative ultrasound (QUS) is currently being investigated as a possible alternative or adjunct to X-ray-based methods for assessing osteoporosis and fracture risk. It has been proposed that QUS may allow measurement of bone "quality," such as bone architecture or material properties. In this study, we used human cadaveric specimens to evaluate whether ultrasound velocity measurements performed in situ at the midtibia were correlated with the mechanical properties of tibial cortical bone. We obtained 26 human lower limbs (10 men and 16 women) with a mean (+/-SD) age of 81 +/- 12 and range of 53-98 years. The longitudinal ultrasound velocity of the cortical bone at the anteromedial midtibia (tUV, meters per second) was assessed in the intact legs (SoundScan 2000, Myriad Ultrasound, Rehovot, Israel). Then a cylinder of cortical bone was removed from the anterior tibia at the site of QUS scanning, scanned using peripheral quantitative computed tomography to determine bone density, and mechanically tested in tension to failure. We found that tUV of the intact legs correlated strongly with bone density of the cortical bone specimens (r2 = 0.74, p < 0.0001). Both bone density (r2 = 0.89, p < 0.0001) and tUV (r2 = 0.84, p < 0.0001) were very strongly correlated with the cortical bone elastic modulus. In addition, both tUV (r2 = 0.75) and bone density (r2 = 0.80) were highly correlated with the ultimate strength of the cortical bone specimens. In summary, tibial ultrasound velocity measured in situ correlated with the material properties of tibial cortical bone nearly as strongly as did bone density. (Bone 21:119-125; 1997).

Three-year longitudinal study with quantitative ultrasound at the hand phalanx in a female population

A longitudinal study was conducted to assess the value of quantitative ultrasound (QUS) measurement in predicting the risk of fracture and to evaluate how QUS parameters change with ageing and the climacteric. A group of 211 female subjects underwent assessment by QUS at the distal metaphysis of the first phalanx of the last four fingers of the hand on two occasions 3 years apart. The subjects were selected from outpatients attending the orthopaedic clinic, provided they were not affected by metabolic disease or under treatment with drugs known to interfere with bone metabolism. In vivo the coefficient of variation and the standardized coefficient of variation of the QUS device were respectively 0.5% and 3.5%. The correlation between the values of the amplitude-dependent speed of sound (AD-SoS) in the two measurements was r = 0.92. In 77.3% of the subjects during the observation period we recorded a reduction in AD-SoS. During the study 22 fractures were observed in peripheral sites, 8 of which were associated with 'low-energy trauma'. By multiple logistic regression analysis we found that the relative risk of fracture for a 1 SD reduction in AD-SoS was 1.5 (95% CI 1.1-1.7) (p < 0.03). The percentage of low-energy fractures significantly increased among those subjects with an AD-SoS value lower than 1850 m/s (T-score < -3.5) at the first examination (p <0.0001). QUS investigation proved to be especially sensitive to hormonal changes associated with the climacteric: we observed a mean decrease of 56 m/s in the AD-SoS for women who entered the menopause between the first and the second QUS test (average time since menopause 2 years), as against 10 m/s in subjects remaining premenopausal. In a group of 146 subjects with 'normal' Ad-SoS at the first examination, we observed a significant reduction in AD-SoS only after 40 years of age. This study demonstrates that measurement of the AD-SoS at the phalanx is reproducible, can be employed to assess the risk of fracture, and is able to detect age-related alterations in bone tissue.