Radial and ulnar cortical thickness of the second metacarpal

Differential Effect of Long-Term Systemic Exposure of TNFα on Health of the Annulus Fibrosus and Nucleus Pulposus of the Intervertebral Disc

The inflammatory cytokine tumor necrosis factor alpha (TNFα) is considered to play a key role in the pathogenesis of intervertebral disc disease. To evaluate the importance of this cytokine we examined the inflammatory environment and spinal phenotype of 9-month-old human TNFα overexpressing transgenic (hTNFα-TG) mice. The mice evidenced increased circulating levels of interleukin-1β (IL-1β), IL-2, keratinocyte chemoattractant/human growth-regulated oncogene (KC/GRO), and monocyte chemoattractant protein-1 (MCP-1) along with thinning of the cortical and trabecular vertebral bone. Surprisingly, although the nucleus pulposus (NP) of these mice was intact and healthy, the caudal annulus fibrosus (AF) evidenced robust cell death and immune cell infiltration. Despite these differences, there were no obvious alterations in the collagen or aggrecan content in the NP and AF. However, there was a reduction in cartilage oligomeric matrix protein (COMP), suggesting destabilization of the AF matrix. Microarray analysis of the NP from hTNFα-TG mice cells revealed minimal changes in global gene expression. These findings lend support to the notion that NP tissue is isolated from systemic inflammation. In contrast, the severe AF phenotype suggests that systemic inflammation interferes with AF health, predisposing discs to herniation as opposed to directly causing NP degeneration. © 2020 American Society for Bone and Mineral Research.

A New Understanding of the Role of IL-1 in Age-Related Intervertebral Disc Degeneration in a Murine Model

Increased cytokine expression, in particular interleukin-1β (IL-1β), is considered a hallmark of intervertebral disc degeneration. However, the causative relationship between IL-1 and age-dependent degeneration has not been established. To investigate the role of IL-1 in driving age-related disc degeneration, we studied the spine phenotype of global IL-1α/β double knockout (IL-1KO) mice at 12 and 20 months. Multiplex ELISA analysis of blood revealed significant reductions in the concentrations of IFN-γ, IL-5, IL-15, TNF-α, IP-10, and a trend of reduced concentrations of IL-10, macrophage inflammatory protein 1α (MIP-1α), keratinocyte chemoattractant/human growth-regulated oncogene (KC/GRO), and IL-6. However, the circulating level of MIP-2, a neutrophil chemoattractant, was increased in the IL-1KO. The alterations in systemic cytokine levels coincided with altered bone morphology-IL-1KO mice exhibited significantly thicker caudal cortical bone at 12 and 20 months. Despite these systemic inflammatory and bony changes, IL-1 deletion only minimally affected disc health. Both wild-type (WT) and IL-1KO mice showed age-dependent disc degeneration. Unexpectedly, rather than protecting the animals from degeneration, the aging phenotype was more pronounced in IL-1KO animals: knockout mice evidenced significantly more degenerative changes in the annulus fibrosis (AF) together with alterations in collagen type and maturity. At 20 months, there were no changes in nucleus pulposus (NP) extracellular matrix composition or cellular marker expression; however, the IL-1KO NP cells occupied a smaller proportion of the NP compartment that those of WT controls. Taken together, these results show that IL-1 deletion altered the systemic inflammatory environment and vertebral bone morphology. However, instead of protecting discs from age-related disc degeneration, global IL-1 deletion amplified the degenerative phenotype. © 2019 American Society for Bone and Mineral Research.

A longitudinal comparison of appendicular bone growth and markers of strength through adolescence in a South African cohort using radiogrammetry and pQCT

To compare growth patterns and strength of weight- and non-weight-bearing bones longitudinally. Irrespective of sex and ethnicity, metacarpal growth was similar to that of the non-weight-bearing radius but differed from that of the weight-bearing tibia. Weight- and non-weight-bearing bones have different growth and strength patterns.

INTRODUCTION

Functional loading modulates bone size and strength.

METHODS

To compare growth patterns and strength of weight- and non-weight-bearing bones longitudinally, we performed manual radiogrammetry of the second metacarpal on hand-wrist radiographs and measured peripheral quantitative computed tomography images of the radius (65%) and tibia (38% and 65%), annually on 372 black and 152 white South African participants (ages 12-20 years). We aligned participants by age from peak metacarpal length velocity. We assessed bone width (BW, mm); cortical thickness (CT, mm); medullary width (MW, mm); stress-strain index (SSI, mm³); and muscle cross-sectional area (MCSA, mm²).

RESULTS

From 12 to 20 years, the associations between metacarpal measures (BW, CT and SSI) and MCSA at the radius (males R² = 0.33-0.45; females R² = 0.12-0.20) were stronger than the tibia (males R² = 0.01-0.11; females R² = 0.007-0.04). In all groups, radial BW, CT and MW accrual rates were similar to those of the metacarpal, except in white females who had lower radial CT (0.04 mm/year) and greater radial MW (0.06 mm/year) accrual. In all groups, except for CT in white males, tibial BW and CT accrual rates were greater than at the metacarpal. Tibial MW (0.29-0.35 mm/year) increased significantly relative to metacarpal MW (- 0.07 to 0.06 mm/year) in males only. In all groups, except white females, SSI increased in each bone.

CONCLUSION

Irrespective of sex and ethnicity, metacarpal growth was similar to that of the non-weight-bearing radius but differed from that of the weight-bearing tibia. The local and systemic factors influencing site-specific differences require further investigation. Graphical abstract.

Bone robusticity in two distinct skeletal dysplasias diverges from established patterns

Achondroplasia (ACH) is a heritable disorder of endochondral bone formation characterized by disproportionate short stature. Osteogenesis imperfecta (OI) is a heritable bone and connective tissue disorder characterized by bone fragility. To investigate bone morphology of these groups, we retrospectively reviewed 169 de-identified bone age films from 20 individuals with ACH, 39 individuals with OI and 37 age- and sex-matched controls (matched to historical measurements from the Bolton-Brush Collection). We calculated robustness (Tt.Ar/Le) and relative cortical area (Ct.Ar/Tt.Ar) from measurements of the second metacarpal, which reflect overall bone health. Relative cortical area (RCA) is a significant predictor of fracture risk and correlates with robustness at other sites. Individuals with OI had RCH values above and robustness values below that of the control population. Bisphosphonate treatment did not significantly impact either robustness or RCA. In contrast to that reported in the unaffected population, there was no sexual dimorphism found in OI robustness or relative cortical area. We suggest that the underlying collagen abnormalities in OI override sex-specific effects. Individuals with ACH had robustness values above and RCA values below that of the control population. Sexual dimorphism was found in ACH robustness and RCH values.

CLINICAL SIGNIFICANCE

Identifies morphologic trends in two distinct skeletal dysplasia populations (OI and ACH) to better understand development of bone robusticity and slenderness in humans. Understanding these patterns of bone morphology is important to predict how individuals will respond to treatment and to increase treatment effect. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2392-2396, 2017.

Radiogrammetry and radiographic absorptiometry

Metacarpal morphometry and radiogrammetry are the oldest methods for quantitative assessment of the skeleton. The historical aspects of these measurements are reviewed. Although they were inexpensive and widely available and provided useful research and epidemiologic information, they were labor intensive and imprecise. They were replaced with the current established methods of bone mineral densitometry. With the application of modern computer vision techniques, metacarpal morphometric analysis has been rejuvenated, with improvement in precision and evidence that the method can be applied to studies in adults and children. Evidence for limited normal reference data and the ability to predict future fractures in osteoporosis and reflect activity and predict outcomes in rheumatoid arthritis are presented.

Interindividual variation in functionally adapted trait sets is established during postnatal growth and predictable based on bone robustness

Adults acquire unique sets of morphological and tissue-quality bone traits that are predictable based on robustness and deterministic of strength and fragility. How and when individual trait sets arise during growth has not been established. Longitudinal structural changes of the metacarpal diaphysis were measured for boys and girls from 3 mo to 8 yr of age using hand radiographs obtained from the Bolton-Brush collection. Robustness varied approximately 2-fold among boys and girls, and individual values were established by 2 yr of age, indicating that genetic and environmental factors controlling the relationship between growth in width and growth in length were established early during postnatal growth. Significant negative correlations between robustness and relative cortical area and a significant positive correlation between robustness and a novel measure capturing the efficiency of growth indicated that coordination of the subperiosteal and endocortical surfaces was responsible for this population acquiring a narrow range of trait sets that was predictable based on robustness. Boys and girls with robust diaphyses had proportionally thinner cortices to minimize mass, whereas children with slender diaphyses had proportionally thicker cortices to maximize stiffness. Girls had more slender metacarpals with proportionally thicker cortices compared with boys at all prepubertal ages. Although postnatal growth patterns varied in fundamentally different ways with sex and robustness, the dependence of trait sets on robustness indicated that children sustained variants affecting subperiosteal growth because they shared a common biological factor regulating functional adaptation. Considering the natural variation in acquired trait sets may help identify determinants of fracture risk, because age-related bone loss and gain will affect slender and robust structures differently.

Semi-automated evaluation of the cortico-medullar index on radius radiographs: a study in prepubertal girls

The aim of the study was to validate a non-invasive method allowing a semi-automatic cortico-medullar index (CMI) computation from standard radiographs. Fifty-five radiographs of the non-dominant radius of prepubertal girls (aged 10.12+/-1.47 years) were scanned (100 microm scanning resolution) by the same observer. To detect the grey level peaks, we used the Deriche's recursive filter applied to the grey level gradients and we defined the cortical areas by thresholding (iterative contour detection). The CMI was calculated as cortical areas divided by the total bone area. The reproducibility was tested through the analysis of ten radiographs scanned twice, on 5, 10, 15, 20, 30 and 40 lines at each side of a reference line located at the distal third part of the radius. We used the root mean square coefficient of variation (RMS-CV) as verification. Dual-Energy X-ray (DXA) was used for densitometry measurements of the whole body, and non dominant radius (mid-, distal third and ultra distal). The result attaining the best reproducibility concerned the 15-line position (Mean CMI=0.58+/-0.005 with a 1.36% RMS-CV). CMI correlated significantly with Bone Mineral Density (BMD) (r=0.40, 0.33 and 0.50, P<0.01, respectively, at the whole body, mid- and third distal of the radius), Bone Mineral Content (BMC) (r=0.32, 0.36, 0.34 and 0.35, respectively, at the whole body (P=0.01), mid- (P=0.007), third distal (P=0.01) and ultra distal of the radius (P=0.01)) but not with BMD at the ultra distal of the radius (r=-0.01, P=0.9). This semi-automated new method has been easily implemented, reproducible, and therefore, could be useful tool for the bone CMI computation.

Population variation in second metacarpal sexual size dimorphism

This paper contrasts levels of sexual size dimorphism in second metacarpal osteometric and geometric morphology in two bioculturally distinctive populations: 19th century Euro-Canadian settlers, and proto/historic central Canadian Inuit. Significant within-group sexual size dimorphism is found for all variables, though few show significant interpopulation differences. However, in every case the Euro-Canadian sample is more dimorphic than the Inuit sample. Notably, differences reside in geometric measures (total area, Imax) sensitive to variation in functional strain, and thus are interpretable in light of proximate causal models, i.e., activity profiles distinct from generalized mode of subsistence. Other proximate factors, such as nutritional stress acting to diminish Inuit sexual size dimorphism, may also play a role. However, models often cited to explain dimorphism, such as marriage practice (e.g., polygyny) or division of labor situated in mode of subsistence, do not. The higher sexual size dimorphism in the 19th century settler sample belies the notion that technological progress inevitably leads to reduced dimorphism.

Circumferential variation in human second metacarpal cortical thickness: sex, age, and mechanical factors

Variation in cortical thickness (CT) in four quadrants of the human second metacarpal was investigated in a sample (100 males and 72 females, skeletal age 20 to 50+ years) from a 19th-century cemetery. Both left and right elements were studied (total N = 344). Multivariate analysis of covariance (MANCOVA) (for age, sex, and side, controlling for absolute size) was used to test the hypothesis of equality of thickness in the dorsal, palmar, medial, and lateral quadrants. Differences in regional CT posits localized regulation of resorption and formation adapting bone shape to functional loads, with implications for activity-modulation of skeletal senescence. The palmar cortex was found to be uniformly thicker in both sexes and both sides, and at all ages (young, middle, and old adult); the medial, lateral, and dorsal cortices did not differ significantly. Patterns of age-related loss occurring preferentially at the endocortical surface differed between men and women, with women showing significant declines across all age groups for all quadrants, and males only small decrements after middle age. The greater CT in the palmar quadrant corresponds to the region of maximum compressive strain in the second metacarpal for functions involving full flexion (grasping). Although the palmar cortex is thicker at all ages, women lose mass in that quadrant at the same rate as in other quadrants, suggesting that function does not offer protection against endocrinologically-mediated depletion of bone mass (postmenopausal osteopenia).

Prediction of cross-sectional geometry from metacarpal radiogrammetry: a validation study

Regression models have been developed to adjust algebraic estimates of second metacarpal cortical bone geometry to actual values (as determined through invasive analysis). These models, derived from an archaeological sample of European origin, have high efficacy in predicting actual values but have not been validated on non-European samples. This paper reports a validation study for these models applied to a historic/proto-historic sample of Inuit from the central Canadian Arctic (n = 166; ages and sexes pooled as per the original study). In that the Inuit sample has been argued to exhibit distinct skeletal biology, this represents a robust test of the predictive models. The algebraic models again produced biased overestimates of actual values, whereas the predictive regression models were found to provide good estimates of actual values for measures of bone strength (Total Area, bending about the Ix and Iy axes), but not for estimates of mass (Cortical Area). This difference may exist in either functional or systemic differences in skeletal physiology and aging bone loss in the Inuit.

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.

Age and menopause-related changes in phalangeal bone density of Japanese women, measured by a digital image processing method

The bone density (BD), phalangeal index (PLI), and metacarpal index (MCI) of the proximal phalangeal and metacarpal bones of the index finger of the nondominant hand were measured, using a digital image processing (DIP) method, in a total of 345 normal Japanese women. In this study, two different locations were measured and the BD, PLI, and MCI decreased significantly after the age of 50 years (P < 0.01 vs values for women in their third decade). The BD, PLI, and MCI of the proximal phalangeal and metacarpal bones showed a significant decrease in postmenopausal groups compared with the pre-menopause group (P < 0.01), which indicated that not only trabecular bone but also cortical bone had an accelerative bone loss in the postmenopausal women. The BD in proximal phalangeal and metacarpal bones decreased by 0.69% and 0.74% / per year, respectively, and there were no significant differences between these annual decreases. The BD of proximal phalangeal bone had a good correlation with that of the metacarpal bone (r = 0.77; P < 0.01), which suggested that the measurement of proximal phalangeal BD was as useful as the measurement of metacarpal BD in screening for osteoporosis (coefficient of variation; CV, 0.64%). The data suggest that DIP has a potential application in screening for osteoporosis.

The metacarpal index revisited: a brief overview

Metacarpal index (MCI) is combined cortical thickness (both sides)) normalized with regard to outer bone diameter of the measuring site, the midshaft of the second metacarpal, or the three midmetacarpals of both hands. MCI is reduced with age, particularly in postmenopausal women. It correlates with axial bone mass in group studies. Measurement of the MCI in its modern version, digital X-ray radiogrammetry (DXR), requires only a plain analog radiograph, a PC, a film scanner, and reliable software. MCI can be used diagnostically and longitudinally for monitoring changes. MCI measured with DXR has few problems regarding accuracy and precision errors, and MCI is presently regaining lost territories among tests for quantification of bone mass and bone strength. It can be measured inexpensively and swiftly. MCI and other geometrical variables of bone can be measured on old radiographs, thus enabling estimation of cortical bone loss from the time of earlier recordings.

Longitudinal study of age- and menopause-related metacarpal index changes in Japanese adult females

To establish a comprehensive mode for cortical bone thinning rate, the metacarpal index (MCI) of the index finger of the nondominant hand was measured using computed X-ray microdensitometry. Statistical analysis was used to study the MCI data in relation to age and menopausal status. A total of 383 healthy Japanese women ranging in age from 30 to 79 yr were investigated in 1996 and 1999. The MCI was generally decreased by 1.11% per year. However, accelerative decreases of 1.78 and 2.05% per year were observed within both the age 50-59 yr group and the early postmenopausal period, respectively. In addition, analysis of age-based longitudinal data showed that the age-related loss of MCI in the age 50-59 yr category was significantly higher than that in the other age categories (p < 0.01), indicating that the changes in MCI were more dependent on menopausal status than on aging. Our study suggests that the cortical bone thinning rate is affected by both aging and menopausal status, but the latter may be a predominant factor.

Digital X-ray radiogrammetry: a new appendicular bone densitometric method with high precision

The precision of any given method for measurement of bone mineral density (BMD) is important in relation to the interpretation of repeated measurements over time, e.g. to monitor the course of suspected osteoporosis or follow the effect of therapy. In the present study a new bone densitometer using the digital X-ray radiogrammetry (DXR) method (Pronosco X-posure Systemtrade mark) is investigated with respect to its short-term precision. The study was carried out on two groups of females, one consisting of 20 women between the ages of 30 and 40, and the other of 20 post-menopausal women above the age of 64. The mean age of the premenopausal women was 35.2 years and the mean DXR BMD was 0.578 g cm-2. The mean age of the post-menopausal women was 68.2 years and the mean DXR BMD was 0.489 g cm-2. The short-term precision of the two groups was evaluated using the coefficient of variation (CV%) and corresponding 90% confidence intervals. The coefficient of variation in the premenopausal group was 0.68% with a 90% confidence interval of 0. 57%-0.83%. The coefficient of variation in the postmenopausal group was 0.61% with a 90% confidence interval of 0.52-0.75%. It can be concluded from the present study that the short-term in vivo precision error of the DXR method is low in both pre- and post-menopausal women. When the results of the study are compared to data reported in the literature, the performance of the DXR method seems to be at least equivalent with peripheral DXA.

Cross-sectional assessment of age-related bone loss in men: the MINOS study

There are few data on osteoporosis in men, but cross-sectional studies have shown that age-related bone loss in men is of lower magnitude than in women. To elucidate some controversies related partially to methodological aspects, we measured bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA) at various skeletal sites (spine, hip, and whole body using a Hologic QDR-1500 device; forearm using an Osteometer DTX 100 device) in a large cohort of 1040 men, aged 19-85 years. The final investigation was performed on 934 men, aged 19-85 years, after exclusion of 106 men with disease or treatment known to affect bone metabolism. Peak BMD was achieved at 25 and 29 years at the lumbar spine and hip, respectively, but only at 40 and 37 years at the distal forearm and whole body, respectively. The magnitude of bone loss between peak bone mass and 80 years of age was linear at most sites and averaged 13%-18%; that is, SD of 1.1-1.8 from peak BMD, except for Ward's triangle, which showed a marked bone loss of 43% (i.e., 2.5 SD), and for the lumbar spine. In the entire cohort, increase of the average lumbar spine BMD after the age of 55 years was related to the development of osteoarthritis, because, in men without severe arthritis, lumbar spine BMD continued to decrease. Height-adjusted partial correlations indicate that both the mineral content and the area of long bones of the limbs increased with age up to 50 years, followed by a significant decrease of BMD without change of bone surface. SD of mean BMD increased significantly with age at most skeletal sites. In summary, age-related change of BMD varied according to skeletal site in men with peak bone mass achieved earlier at sites rich in trabecular bone than at those rich in cortical bone. Bone loss varied according to skeletal site from 14% to 43%. The variability of BMD increased with age, which may reflect interindividual variability of age-related bone loss.

Second metacarpal midshaft geometry in an historic cemetery sample

Study of bone mass at the second metacarpal midshaft has contributed to our understanding of skeletal growth and aging within and between populations and has relied extensively on noninvasive techniques and in particular radiogrammetric data. This study reports age, sex, and side variation in size and shape data acquired from direct measurement of cross-sections obtained from a large (n = 356), homogeneous skeletal sample. Correlation analysis and three-way ANOVA of size-adjusted data confirm general impressions of patterned variation in this element: males have absolutely but not necessarily relatively larger bones than females; the right side is larger than the left, though a larger than expected proportion (approximately 25%) of left metacarpals exhibits greater values than the right; and bone mass but not strength (in males) declines with age. Contrary to the widely accepted assumption of circularity for this location, direct measurement of cross-sectional geometry confirms previous biplanar radiogrammetric conclusions regarding the noncircularity of the second metacarpal midshaft and identifies a significant difference between males and females, with the latter having a more cylindrical diaphysis. Deviation of the axes of maximum and minimum bending strength associated with noncircularity suggests a distribution of bone mass to resist bending moments perpendicular to the distal palmar arch, though this conclusion awaits more robust study of the functional anatomy of the metacarpal diaphysis.

Age-related cortical bone loss at the metacarpal

In order to evaluate in vivo the entity of endosteal and periosteal changes with age in the two sexes, and their relative contribution to age-related cortical bone loss, we undertook a cross-sectional study on a population of normal Caucasian subjects. The group included 189 women and 107 men who were studied by photodensitometry and radiogrammetry of the second metacarpal bone, derived from the same standard hand X-ray. Of the subjects, 134 were 65 years of age or older (75 women and 59 men). Metacarpal bone mineral density (BMD) correlated with age in both sexes, with an annual bone loss rate of 0.5% in women and 0.15% in men. In the over 65 group, correlation was significant only in women, who underwent an acceleration in the rate of bone loss (1% per year). Marrow cavity width (M), cortical index at the second metacarpal shaft (MI) and external width (W) all correlated with age in both sexes, although generally better in the female than in the male sex. M almost doubled from the fourth to the ninth decade in women and increased 50% in men. In the same age interval, MI showed an annual decrease of 0.49% in females and 0.33% in males. In the over 65 group, cortical thinning rate was significant in women (0.39% per annum) but not in men (0.14% per annum), whereas correlation of W was not significant in either sex. Finally, MI correlated with BMD in the whole study population and in the over 65, with a female prevalence in correlation strength maintained throughout life. The following conclusions can be derived for metacarpal aging: (1) an acceleration in cortical bone loss occurs in females after age 65; (2) age-related growth in periosteal diameter, although significant in the whole population, is negligible in the elderly of both sexes; (3) age-related cortical bone loss is generally more dependent on cortical thinning in women than in men.

Bias and agreement for radiogrammetric estimates of cortical bone geometry

RATIONALE AND OBJECTIVES

Radiogrammetry of the second metacarpal assumes a circular or elliptical model, which does not conform to reality. This study assesses the degree of bias and limits of agreement (error) resulting from deviations from these assumed models for estimates of bone mass and strength.

METHODS

Forty-six left metacarpals were radiographed in orthogonal posteroanterior and mediolateral views for calculation of algebraic estimations of area and bending moments of area. The bones were then sectioned at midshaft and digitized for determination of actual values of these properties. Bias was determined as the mean difference between methods, and error as +/-2 standard deviation.

RESULTS

Radiogrammetric methods significantly (P < 0.05) overestimate actual values for measures of cortical area and bending strength. Elliptical models are less biased and prone to smaller ranges of error than are uniplanar circular models.

CONCLUSIONS

Radiogrammetric estimation of metacarpal bone mass is subject to considerable method error arising from use of an overly simplistic circular model for its midshaft geometry.