Biomedical subjects

C M Langton

Publications and source records attributed to C M Langton.

At least 19 recordsLinked to original sources

PubMed2006

Three dimensional stereolithography models of cancellous bone structures from muCT data: testing and validation of finite element results.

Stereolithography (STL) models of complex cancellous bone structures have been produced from three-dimensional micro-computed tomography data sets of human cancellous bone histological samples from four skeletal sites. The STL models have been mechanically tested and the derived stiffness compared with that predicted by finite element analysis. The results show a strong correlation (R2 = 0.941) between the predicted and calculated stiffnesses of the structures and show promise for the use of STL as an additional technique to complement the use of finite element models, for the assessment of the mechanical properties of complex cancellous bone structures.

Biomimetics↗

PubMed2003

Stereo visualization of 3D trabecular bone structures produced by bone remodelling simulation.

Adult human bone is constantly being renewed by a process known as remodelling. For cancellous bone this renewal process occurs at the interface between bone and marrow where bone is depleted by osteoclasts and rebuilt by osteoblasts. This remodelling process allows bone to repair itself. Software simulators for bone remodelling provide insight into the bone remodelling process; they allow investigation into bone form and structural properties, and they also allow the emulation of bone diseases and possible treatments for these diseases over long periods of time. BONESIM is a software that simulates bone remodelling in terms of Basic Multi-cellular Units (BMUs). 3D visualization of trabecular bone and its attributes is an essential tool in understanding this remodelling process for cancellous bone. It enables the bone researcher to quickly understand the dynamic behaviour of remodelling, the resulting geometry of the bone structure and it allows alternative remodelling scenarios to be compared. This paper presents the volume visualization technique that has been developed to provide this visualization tool.

Adult↗

PubMed2002

Smoothing of pixelated finite element models of cancellous bone structures and the effect on the predicted structural properties of the bone.

Many areas of biomedical engineering involve the modelling of biological systems, often using data from medical scanning techniques such as computed microtomography (microCT), and the prediction of the mechanical properties of these systems via finite element models. These models, and also those produced from remodelling simulations on idealized bone structures, are inherently highly pixelated and therefore have a high degree of surface roughness. The purpose of this paper is to demonstrate that this surface roughness need not necessarily have an influence on the predicted properties of the object under examination. To demonstrate this, two-dimensional idealized models of cancellous bone structures were used that were initially depleted and then rebuilt stochastically. A hysteresis effect was observed such that a significant amount of rebuilding beyond the original density was required to regain the initial intact stiffness. To ensure that this effect was not an artefact of the high degree of surface roughness of the rebuilt structures, a two-stage smoothing procedure was applied to assess if this had any effect on the stiffness of the structures. The superpixelation of the structures appeared to have a more profound effect than the smoothing procedures, although the smoothed structures still had stiffness and density values similar to those of the original structures, with a hysteresis effect still evident. This proves that the pixelization of the structures does not have a significant effect on the predicted mechanical properties of the structures. This work has important implications for other models that exhibit a high degree of surface roughness.

Artifacts↗

PubMed2001

An investigation into the feasibility of implementing fractal paradigms to simulate cancellous bone structure.

Cancellous bone consists of a framework of solid trabeculae interspersed with bone marrow. The structure of the bone tissue framework is highly convoluted and complex, being fractal and statistically self-similar over a limited range of magnifications. To date, the structure of natural cancellous bone tissue has been defined using 2D and 3D imaging, with no facility to modify and control the structure. The potential of four computer-generated paradigms has been reviewed based upon knowledge of other fractal structures and chaotic systems, namely Diffusion Limited Aggregation (DLA), Percolation and Epidemics, Cellular Automata, and a regular Grid with randomly relocated nodes. The resulting structures were compared for their ability to create realistic structures of cancellous bone rather than reflecting growth and form processes. Although the creation of realistic computer-generated cancellous bone structures is difficult, it should not be impossible. Future work considering the combination of fractal and chaotic paradigms is underway.

Algorithms↗

PubMed2001

Computer and experimental simulation of a cortical end-plate phase cancellation artefact in the measurement of BUA at the calcaneus.

It has been experimentally demonstrated that for the measurement of broadband ultrasound attenuation (BUA) at the human calcaneus the cortical end-plate creates a measurement artefact of the order of 7 dB MHz(-1). It has been suggested that the origin of this artefact may be a phase cancellation of the ultrasound pulse resulting from inconsistencies in propagation time across the ultrasound beam. Experimental and computer simulations were performed on samples of varying degrees of curvature and hence varying propagation times across the ultrasound beam. The experimental simulation incorporated Perspex samples of 35, 50 and 75 mm radius. The computer simulation was implemented using Matlab and Simulink, with the propagation time represented by a transport delay. The wavelet-based simulation incorporated a digitized transmitted ultrasound pulse derived from the experimental simulation. The experimental and computer-derived frequency spectra for the varying radii samples were comparable, demonstrating, firstly, that there is a significant dependence of measured BUA upon radius of curvature and, secondly, that the response in measured BUA to radius of curvature is similar in magnitude and trend for both experimental and computer simulations. The current study suggests that the BUA artefact observed in vitro corresponds to a radius of approximately 58 mm. Although the radius of curvature was not recorded in the original in vitro study, this value appears to be reasonable. This study indicates that the assumptions within the computer simulation were manifested within the experimental validation, and, hence, the observed BUA measurement artefact is related to the presence of the calcaneal cortical end-plate and is due to phase cancellation of the propagating ultrasound pulse.

Artifacts↗

PubMed2000

Stochastically simulated assessment of anabolic treatment following varying degrees of cancellous bone resorption.

The aim of this study was to investigate the recovery in cancellous bone stiffness resulting from anabolic treatment following varying degrees of resorption, using a stochastic simulation applied to a simplistic structure consisting of five vertical and five horizontal trabeculae. The structure was initially resorbed, and "bone" elements were stochastically removed until nominal resorptions of 10%, 15%, 20%, 25%, and 30% were achieved. A stochastic simulation of anabolic treatment was then applied where bone elements were added, continuing until the original stiffness had been regained, for example, simulating treatment of a patient with an anabolic agent after a period of postmenopausal resorption. The resorption and anabolic simulations were repeated three times for each of the nominal resorptions. The stiffness of the bone structure decreased linearly with resorption, with a slope of approximately -2 and an R(2) of 97.0%; hence, the stiffness fell at approximately twice the rate of the reduction in density. When the various structures regained their original density, the resultant stiffness also had a linear relationship with the original resorption, with a slope of -1 and a lower R(2) of 86.1%. This implies that the reduction in stiffness, when original density was regained, fell proportionately with the degree of initial resorption and, therefore, after a resorption of 30%, when original density was regained, the stiffness of the resultant structure was approximately 30% less than that of the original structure. The density required for the original stiffness to be regained increased linearly with the degree of initial resorption, with a slope of approximately 0.5 and an R(2) of 65.2%, lower than that observed for the previous relationships. This indicates a greater spread of data and suggests greater variability in the formation phase beyond the point of regained original density. Because irreversible connectivity reduction is widely considered to be one of the earliest manifestations of estrogen loss, these findings, although obtained on a simulation of a simplistic cancellous bone structure, support the concept of early intervention to prevent potentially irreversible deterioration of trabecular architecture after menopause.

Bone Resorption↗

PubMed2000

Comparison of bone mineral density and quantitative ultrasound of the calcaneus: site-matched correlation and discrimination of axial BMD status.

The performance of quantitative ultrasound (QUS) and dual energy X-ray absorptiometry (DXA) bone densitometry of the calcaneus have been compared, both in terms of site-matched correlation and their discriminatory ability to identify osteoporotic and osteoporotic or osteopenic subjects. 91 female subjects (aged 56.9 +/- 9.6 years, 31-84 years) who were routinely referred for axial BMD assessment of the lumbar spine and femoral neck by DXA (Lunar DPX-L), consented to have additional measurements of QUS (McCue CubaClinical Mk II) and DXA (Lunar PIXI) of their left calcaneus. The site-matched correlation between calcaneal BMD with QUS parameters were: (a) broadband ultrasound attenuation (BUA) alone, adj-R2 = 62.7%, p < 0.0001; (b) velocity (VOS) alone, adj-R2 = 48.4%, p < 0.0001; and (c) BUA and VOS combined, adj-R2 = 65.2%, p < 0.0001. The site-matched correlations are towards the higher end of data reported by other researchers, indicative of the exacting measurement protocol implemented here. 30 subjects were categorized as normal, 38 being osteopenic and 23 being osteoporotic. Optimum accuracies and odds ratios were obtained using logistic regression. The differences in accuracy between calcaneal BMD and calcaneal QUS parameters were statistically insignificant, with zero included within the confidence intervals, for the identification of both (a) osteoporotic and (b) osteoporotic or osteopenic subjects. The odds ratios for the discrimination of subject status achieved with calcaneal BMD were higher, although statistically insignificant, than achieved with the QUS parameters. Receiver operator characteristic (ROC) analysis for the identification of subjects into the categories (a) and (b) above was performed. Areas under the ROC curve (AUC) (95% confidence intervals) for the logit of the probability that a subject would be osteoporotic were: 0.814 (0.700, 0.928) for calcaneal BMD; 0.791 (0.673, 0.909) for BUA; 0.717 (0.588, 0.846) for VOS; and 0.793 (0.675, 0.911) for BUA and VOS combined. For the identification of osteoporotic or osteopenic subjects, the ROC areas were: 0.851 (0.774, 0.928) for calcaneal BMD; 0.773 (0.678, 0.868) for BUA; 0.783 (0.690, 0.877) for VOS; and 0.778 (0.685, 0.871) for BUA and VOS combined. Again, calcaneal BMD provided a higher, yet statistically insignificant, AUC than any QUS parameter. In conclusion, for the identification of subjects defined by World Health Organization criteria for axial BMD, the performance of BMD and QUS calcaneal parameters were statistically comparable. The choice of peripheral bone densitometry modality should therefore be made upon factors external to their discriminatory performance.

Absorptiometry, Photon↗

PubMed1999

Development and evaluation of a phantom for morphometric X-ray absorptiometry.

Morphometric X-ray absorptiometry (MXA) provides the potential to assess vertebral deformity using a technique with much lower radiation dose to the patient than standard radiographic procedures. MXA overcomes many other limitations such as cone beam distortion observed in conventional plane radiographs. A phantom has been designed to assess the accuracy of the MXA technique, to monitor long-term precision and to assess inter- and intra-operator variability. The phantom consists of two columns of 12 cylinders representing the vertebral bodies, one of regular components and one representing vertebral deformities. Each column may be inserted, as required, into a Perspex torso-mimicking block. Initial assessment on the Lunar Expert-XL demonstrates that the phantom provides image parameters reflecting those found clinically. Measurement of vertebral height was found to be consistently underestimated by 4.9%. Operator precision ranged from 0.6% for posterior height measurement to 1.0% for middle height measurement of the regular component column. The corresponding precision range for the column representing vertebral deformation was 0.6% (posterior) and 1.1% (middle). Analysis of 10 scans of each column by two independent operators demonstrated a few significant differences in height assessment confined to the 'thoracic' region of the regular column. However, inter-operator variability was found to increase with increasing complexity of vertebral shape producing several differences, particularly in posterior height assessment of the deformed column.

Absorptiometry, Photon↗

PubMed1999

Biot theory: a review of its application to ultrasound propagation through cancellous bone.

To facilitate an understanding of the dependence of ultrasound velocity and attenuation upon the material and structural properties of cancellous bone, several theoretical concepts for ultrasound propagation have been adapted or developed, including the Biot theory and several scattering theories. Biot theory considers wave propagation through an elastic porous solid interspersed with fluid, considering the separate motion of the trabecular framework and morrow, respectively. The success achieved with the Biot theory has, to date, tended to be greater for the prediction of velocity than for attenuation. This article provides a review of the relevant literature, describing the physical parameters required for the Biot theory and their experimental determination. It is suggested that future developments should consider additional attenuation mechanisms, in particular, those due to scattering, local flow in microcracks, and surface roughness of the trabeculae.

Biophysical Phenomena↗

PubMed1999

Acoustic and ultrasonic tissue characterization--assessment of osteoporosis.

Osteoporosis, often termed the 'silent epidemic', has been defined as 'a decrease in bone mass and architectural deterioration of bone tissue, leading to enhanced bone fragility and consequent increase in fracture risk'. In the United Kingdom alone, the annual health costs are in excess of 750 million Pounds, with 60,000 patients suffering a hip fracture each year. A quarter of these will die within 12 months of their fracture, half of the remainder will never regain independent living. The established procedure for assessing the risk of osteoporotic fracture is via bone mineral density (BMD) assessment using dual-energy X-ray absorptiometry (DXA). However, DXA is an expensive technique and is not widely available. Within the past 15 years, ultrasound assessment of bone has rapidly advanced in scientific understanding, technical development and clinical utility. Measurements of cancellous bone (particularly at the calcaneus) are generally performed in preference to those of cortical bone (tibial cortex). There are currently 15 commercial systems available and over 3500 systems are in use world-wide. The low cost and portability offered by ultrasound systems should enable an integrated community-based screening programme to be established in the near future. Ultrasound measurements of bone are generally obtained using transmission rather than pulse-echo techniques owing to its highly attenuating nature. Ultrasound velocity and attenuation measurements are utilized. For velocity, there are well-defined fundamental relationships describing the dependence upon the elasticity and density of bone.

Absorptiometry, Photon↗

PubMed1999

Comparison of accuracy and cost effectiveness of clinical criteria and BUA for referral for BMD assessment by DXA in osteoporotic and osteopenic perimenopausal subjects.

A pilot study of 107 women aged 60-69 years recently suggested that the measurement of broadband ultrasound attenuation (BUA) provides a superior cost effective pre-screen referral method for bone mineral density (BMD) measurement by DXA (dual-energy X-ray absorptiometry) than can be achieved by clinical criteria (CC). The aim of this study was to compare the accuracy and cost effectiveness of BUA and clinical criteria in a younger cohort. 599 women aged 50-54 years (52.18 +/- 1.35) had previously been measured by DXA at lumbar spine and right femoral neck, along with BUA measurement of the right calcaneus. Each subject had also completed an extensive clinical and social questionnaire to ascertain those who would have met one or more of the six general clinical criteria adopted by our Centre. Each subject was classified by DXA using the WHO criteria as normal, osteopenic or osteoporotic, defined at lumbar spine or femoral neck. Sensitivity, specificity and accuracy were calculated for BUA and the clinical criteria, noting that analysis was undertaken with and without the oestrogen deficiency clinical criterion (CC1): "Any oestrogen deficient woman who would want to be treated or would want to continue treatment if found to be osteopenic or osteoporotic". The accuracy for identifying osteoporotic subjects was 72.8% for BUA (at the point of matched sensitivity and specificity, 75 dB MHz(-1)), 30.7% for CC(1-6) and 64.3% for CC(2-6). When osteopenic subjects were incorporated, the accuracies were 63.8% for BUA (at the point of matched sensitivity and specificity, 82 dB MHz(-1)), 60.3% for CC(1-6) and 55.7% for CC(2-6). The minimum cost per osteoporotic subject correctly identified was pound sterling 573.50 by DXA alone, pound sterling 325 by BUA, pound sterling 458 by CC(1-6) and pound sterling 416 by CC(2-6). When osteopenic subjects were incorporated, the costs were pound sterling 87, pound sterling 83.50, pound sterling 78 and pound sterling 74, respectively. The overall cost, dependent upon the prevalence of osteoporosis (or osteopenia) within the population, more accurately indicates the feasibility of a population-based screening programme. For the identification of either osteoporotic or osteopenic subjects from the general population by DXA, the prevalence-compensated cost (cost per subject correctly identified multiplied by prevalence) is pound sterling 45, irrespective of age cohort. If CC(2-6) were adopted for the identification of osteoporotic subjects alone, the prevalence-compensated cost would be pound sterling 32 and pound sterling 42 for the 50-54 and 60-69 aged cohorts, respectively. For BUA, the prevalence-compensated cost falls to pound sterling 25 and pound sterling 43 for the 50-54 and 60-69 aged cohorts, respectively. If osteoporotic or osteopenic subjects were to be identified in the 50-54 aged cohort, both CC(2-6) (pound sterling 38) and BUA (pound sterling 43) perform similarly to DXA alone. BUA appears to provide a valuable population pre-screen for the identification of osteoporotic subjects, less so for osteopenic. It is suggested that if both osteopenic and osteoporotic women are to be identified for clinical management incorporating DXA, then neither BUA nor clinical criteria are satisfactory referral methods. An unanswered question from this study, however, is whether ultrasound has an independent role in the assessment of fracture risk for perimenopausal women who do not have the benefit of referral for DXA.

Absorptiometry, Photon↗

PubMed1998

Prevalence of osteoporosis and related risk factors in UK women in the seventh decade: osteoporosis case finding by clinical referral criteria or predictive model?

The objectives of the study were: to determine the prevalence of osteoporosis in women in their seventh decade; to determine the number of women who conformed to at least one of the current East Yorkshire Clinical Referral Criteria for Osteoporosis; and to determine the sensitivity and specificity of these referral criteria in the diagnosis of osteoporosis and to compare this with the receiver operating characteristic (ROC) curve of a logistic regression model incorporating variables that were significantly associated with the risk of osteoporosis. An observational study was carried out at the Centre for Metabolic Bone Disease, Hull Royal Infirmary, on women in their seventh decade from three general practices. Densitometric assessment of lumbar spine and femoral neck was carried out using dual-energy X-ray absorptiometry (DXA) and a detailed medical history taken. The main outcome measures were prevalence of osteoporosis in women in their seventh decade and efficacy of agreed clinical referral criteria at osteoporosis case finding. Of 823 Caucasian women who underwent DXA, 24% proved to have osteoporosis at hip, spine or both according to WHO criteria. A further 49% had osteopenia detected at hip, spine or both. At least one of the referral criteria was present in 47% of the women assessed. The sensitivity of the clinical referral criteria for detection of osteoporosis was 58% with a corresponding specificity of 60%. This point lies below the ROC curve (area under fitted curve, Az = 0.73) of a logistic regression model incorporating weight, age at menopause and current use of hormone replacement therapy. In conclusion, osteoporosis according to WHO criteria was found in almost 25% of women in their seventh decade. A simple logistic regression model provided a more sensitive method of osteoporosis case finding than the selective screening component of the clinical referral criteria employed in our practice.

Absorptiometry, Photon↗

PubMed1998

A comparison of porosity, fabric and fractal dimension as predictors of the Young's modulus of equine cancellous bone.

The purpose of this study was to compare the structural parameters of fabric and fractal dimension as predictors of the Young's modulus of equine cancellous bone. Eight 15 mm cubes of cancellous bone were obtained from three equine third metacarpal bones. Young's modulus was determined for the three orthogonal directions. The fabric and fractal dimension were calculated for each of the six exposed faces of each cube. Fractal dimension plus porosity provided a higher explanatory power for Young's modulus (R2 = 78.7%. P < 0.0001) than fabric plus porosity (R2 = 69.2%, P < 0.0001). Fractal dimension was also significantly correlated with fabric (R2 = 53.8%, P < 0.0001). Although this novel method for combining fractal dimension data into a pseudo-directionally dependent predictor of Young's modulus requires further validation over a greater range of porosities and differing cancellous bone tissues, its potential has been demonstrated.

Animals↗

PubMed1998

Dynamic stochastic simulation of cancellous bone resorption.

A stochastic simulation of cancellous bone resorption was developed and applied to a simple two-dimensional lattice structure representing the vertebral body. The simulation is based upon the concept of a basic multicellular unit (BMU) where net resorption (-deltaB.BMU) is considered at bone/marrow surfaces. The cancellous bone structure is defined as a binary matrix with the size of the pixels corresponding to a square element of approximately 20 microm dimension. The simulation considers both the probability that any surface pixel will be activated into a BMU and, if activated, the length of the resorption cavity. The relationship between relative stiffness and density for the simulation was predicted by finite element analysis. The stochastic simulation was iterated eight times with the mechanical properties assessed after each stage. Perforation of a single trabeculae was first observed at step 2, the structure completely lacking connectivity and mechanical integrity by step 8. The slope of the stiffness-porosity graph was greater than unity for the first five steps, but thereafter approached zero because the structure had lost connectivity and effectively collapsed. The eight-step simulation was repeated five times and demonstrated that, although the stiffness/density relationships were similar at the extremes of density, the dependence of stiffness upon density varied. This clearly demonstrates the stochastic nature of the simulation upon cancellous bone structure, and is probably indicative of a significant dependence of mechanical integrity upon perforation effects.

Biomechanical Phenomena↗

PubMed1998

Fractal dimension predicts broadband ultrasound attenuation in stereolithography models of cancellous bone.

There has been considerable debate on the relative dependence of broadband ultrasound attenuation (nBUA, dB MHz(-1) cm(-1)) upon the density and structure of cancellous bone. A nonlinear relationship between nBUA and porosity has recently been demonstrated using stereolithography models, indicating a high structural dependence for nBUA. We report here on the measurement of trabecular perimeter and fractal dimension on the two-dimensional images used to create the stereolithography models. Adjusted coefficients of determination (R2) with nBUA were 94.4% (p < 0.0001) and 98.4% (p < 0.0001) for trabecular perimeter and fractal dimension respectively. The feature of fractal dimension representing both the porosity and connectivity of a given structure is most exciting. Further work is required to determine the relationship between broadband ultrasound attenuation and fractal dimension in complex three-dimensional cancellous bone structures.

Bone and Bones↗

PubMed1998

A phantom based study on the effect of subject positioning on morphometric X-ray absorptiometry using the Lunar Expert-XL.

Morphometric X-ray absorptiometry (MXA) relies on accurate measurement of vertical dimensions of vertebrae from a lateral perspective. Deviations resulting from scoliotic curvature or poor patient positioning produce distortions of visible vertebral dimensions and may lead to analysis error. This study utilized a phantom developed at this centre to assess the effect of vertebral malalignment on the accuracy of the MXA technique on the Lunar Expert-XL. Measured vertebral heights were found to be consistently underestimated by an average of 3.7%. Precision ranged from 0.79% for anterior height measurement to 1.03% for middle height measurement. Vertebral malalignment was investigated as the effect of rotation around the anteroposterior, lateral and superoinferior axes. Rotation around the lateral axis produced little discernible effect. However, superoinferior axial rotation showed a change of more than two standard deviations in the mid/posterior ratios of biconcave vertebrae at comparatively small angles of rotation. Anteroposterior axial rotation produced an increase in observed height at small angles of rotation, and a rapid decrease in vertebral height as rotation increased. The results suggest that whilst kyphosis or lordosis of up to at least 5.8 degrees has a minimal effect on MXA, scoliosis of 4.6 degrees or above produces a distinctive effect on the defining crush height ratios.

Absorptiometry, Photon↗

PubMed1998

Sound-tissue interaction: the physical basis of bone ultrasonometry and limitations of existing methods.

Ultrasound measurements of bone are generally obtained using transmission rather than pulse-echo techniques because of its highly attenuating nature. Ultrasound velocity and attenuation measurements are utilized. For velocity, there are well-defined fundamental relationships describing the dependence on the elasticity and density of bone. However, the practical implementation and signal processing of velocity measurements has led to a significant variability in results from different commercial systems. We may measure either phase of group velocity, for the latter, adopting a range of pulse arrival definitions. We are offered bone velocity, heel velocity, time of flight, and amplitude-dependent velocity. For attenuation measurements, however, the reverse is true. We generally record the increase in attenuation with frequency (0.2-0.6 MHz), termed broadband ultrasound attenuation (BUA). Although first described in 1984, because of the complex interplay of attenuation mechanisms, there still lacks a fundamental understanding of the dependence of BUA on the material and structural properties of cancellous bone. With the increasing number of commercial systems available, there is an urgent need to understand the intrinsic (artefact free) and system estimation of ultrasound velocity and attenuation parameters that may be implemented to characterise bone and provide clinical information.

Journal Article↗

PubMed1997

The role of ultrasound in the assessment of osteoporosis: a review.

Osteoporosis is now being recognized as a "silent epidemic" and there is an increasing need to improve its diagnosis and management. Quantitative ultrasound (QUS) measurement [broadband ultrasound attenuation (BUA) and velocity] is emerging as an alternative to photon absorptiometry techniques in the assessment of osteoporosis. The fundamental principles governing ultrasound measurements are discussed, and some of the commercially available clinical systems are reviewed, particularly in relation to data acquisition methods. A review of the published in vivo and in vitro data is presented. The general consensus is that ultrasound seems to provide structural information in addition to density. The diagnostic sensitivity of ultrasound measurement of the calcaneus in the prediction of hip fracture has been shown by recent large prospective studies to be similar to hip bone mineral density (BMD) measured with dual-energy X-ray absorptiometry (DXA) and superior to spine BMD. Ultrasound has also been shown to correlate better with the type of hip fracture (intertrochanteric or cervical) than BMD and to provide comparable diagnostic sensitivity to spine BMD in vertebral fractures. It has also been observed that combining the results of both ultrasound and DXA BMD significantly improved hip fracture prediction. Areas where further research is required are identified.

Biophysical Phenomena↗