Age-related changes in vertebral height ratios and vertebral fracture

Because no gold standard for the definition of vertebral fracture exists, there has been controversy about whether mild vertebral deformities are truly fractures or simply normal variation in vertebral size and shape. The aim of this study was to assess the associations of mild variations of vertebral height ratios to definite vertebral fractures. In 479 Japanese women (age 53.9±9.1 years) who visited our institute for a medical checkup, we performed lateral lumbar radiographs and morphometric parameters were derived by measuring the anterior (Ha), middle (Hm) and posterior (Hp) height of each vertebral body from T12 to L4. Vertebral height ratios, Ha/Hp, Hm/Hp or Hp/Hp of adjacent vertebrae that were more than 3 SD different from vertebra-specific means of normative data were considered to indicate fractures. Forty-five women were diagnosed with at least one fracture. After excluding the subjects with vertebral fracture, we examined the associations of the variations in vertebral height ratios with age, anthropometric parameters and lumbar bone mineral density (BMD) measured by dual-energy X-ray absorptiometry. Vertebral height ratios, especially Hm/Hp in postmenopausal women, tended to decrease with age and were positively associated with BMD. No significant correlation was observed between anthropometric parameters and vertebral height ratios. Age-related decrease in vertebral height ratios (Ha/Hp and Hm/Hp, each averaged from T12 to L4) was significant even after the correction for BMD. Mean values of height ratios of non-fractured vertebrae adjusted for age and BMD were significantly lower in postmenopausal women with vertebral fracture than in those without vertebral fracture. Logistic regression analysis showed that BMD and height ratios of non-fractured vertebrae were independent predictors of vertebral fracture risk. The results suggest that older women, and women with at least one obvious (3 SD) fracture, tend to have mild deformities which do not qualify using the 3 SD definition. These mild deformities may represent real consequences of osteoporosis, because they are more pronounced among women with obvious fracture.     

Morphometric X-ray Absorptiometry and Morphometric Radiography of the Spine: A Comparison of Analysis Precision in Normal and Osteoporotic Subjects

Morphometric techniques, which use conventional lateral spine radiographs to quantify vertebral body shape (morphometric radiography, MRX), have proved a useful tool in the identification and evaluation of osteoporotic vertebral deformities. Recently a new method of acquiring the images required for vertebral morphometry using dual-energy X-ray absorptiometry scanners (morphometric X-ray absorptiometry, MXA) has been developed. In this study we compare repeat analysis precision of vertebral height measurement using MXA and MRX. Twenty-four postmenopausal women were recruited (mean age 67 + 5.8 years): 12 normal subjects and 12 with osteoporosis and vertebral deformities. Each subject had a MXA scan and lateral thoracic and lumbar radiographs at a single appointment, which were each analyzed quantitatively in a masked fashion, using a standard 6-point method, twice by one observer and once by a second observer. Anterior (Ha), mid (Hm) and posterior (Hp) vertebral heights were measured and wedge (Ha/Hp) and mid-wedge (Hm/Hp) ratios calculated for each vertebral body. Intra- and interobserver precision were consistently poorer in MXA compared with MRX in both normal subjects and those with vertebral deformities, with MXA CV% generally at least 50% higher than corresponding values for MRX. For both MXA and MRX interobserver precision was clearly poorer than intraobserver precision, a problem associated with any morphometric technique. MXA intra- and interobserver precision were significantly poorer for subjects with vertebral deformities compared with those without, with a CV% for deformity subjects up to twice that of normal subjects. Conversely, MRX showed little or no obvious worsening of intra- or interobserver precision for deformity subjects. Comparison of MXA precision in the normal and deformed vertebrae of the deformity subjects demonstrated that the poorer precision in these subjects compared with normal subjects was the result of increased variability in point placement on the deformed vertebrae themselves. However, the precision for normal vertebrae in these subjects was also somewhat poorer than the precision in normal subjects. We conclude that MXA precision is generally poorer than that of MRX and that the presence of vertebral deformities has a more pronounced effect on MXA precision than on MRX precision. Received: 21 July 1998 / Accepted: 13 November 1998     

The relationship between phalangeal bone density and vertebral deformities

Radiographic absorptiometry (RA) of the phalanges is a convenient and reliable technique for measuring bone mineral density (BMD). It needs only a radiograph of the hand, which can be sent for evaluation to a central facility, whereas other techniques require specialized equipment. We assessed the relationship between RA measurements and the presence of vertebral deformities in a population-based cohort of postmenopausal women, and to compare the results with simultaneously obtained BMD of the hip by dual-energy X-ray absorptiometry (DXA). A total of 389 women aged 55–84 (mean age 67.2 years, SD 8.7) were randomly selected from a large general practice. RA, DXA of the hip, and vertebral deformities in the lateral spine X-rays by vertebral morphometry were assessed. Thirty-eight women (9.8%) had severe (grade II) vertebral deformities, and their BMD at the phalanges and femoral neck was significantly lower than that of women without severe vertebral deformities. Odds ratios for the presence of severe vertebral deformities of 1.5 (95% CI: 1.1–2.1) for RA and 1.3 (95% CI: 0.9–1.9) for DXA, together with similar receiver operating characteristics curves, were found using age-adjusted logistic regression. Phalangeal BMD is related to vertebral deformities at least as closely as BMD of the femoral neck BMD. RA may therefore help to evaluate fracture risk, especially if no DXA equipment is available. Received: 21 July 1998 / Accepted: 1 July 1999     

Vertebral Morphometry: A Comparison of Long-Term Precision of Morphometric X-ray Absorptiometry and Morphometric Radiography in Normal and Osteoporotic Subjects

Vertebral morphometry, the quantification of vertebral body shape, has proved a useful tool in the identification and evaluation of osteoporotic vertebral deformities in both epidemiologic surveys and clinical trials. Although conventionally it has been performed on lateral radiographs of the thoracolumbar spine (morphometric radiography, MRX), it may now be accomplished on morphometric X-ray absorptiometry (MXA) scans, acquired on dual-energy X-ray absorptiometry (DXA) machines. In this study the long-term precision of vertebral height measurement using MXA and MRX was directly compared. Initially 24 postmenopausal women were recruited (mean age 67+/-5.8 years): 12 normal subjects (group 1) and 12 with osteoporosis and known vertebral deformities (group 2). Each subject attended for a baseline visit at which they had a MXA examination and lateral thoracic and lumbar radiographs. Twenty-one subjects then returned 1.7+/-0.4 years later (10 subjects from group 1 and 11 from group 2) for a follow-up visit to repeat both the MXA scans and conventional radiographs. The baseline MXA scans and conventional radiographs were each analyzed quantitatively by two observers in a masked fashion, using a standard six-point method. The follow-up images were then analyzed by the same observers. The MRX observers were masked to the baseline analyses, while the MXA observers utilized the manufacturer's 'compare' facility. On all scans and radiographs anterior (Ha), mid (Hm) and posterior (Hp) vertebral heights were measured and wedge (Ha/Hp) and mid-wedge (Hm/Hp) ratios calculated for each vertebral body, ideally from T4 to L4. MRX analyzed 129 of the 130 available vertebrae in group 1 at both visits and 141 of the 143 available in group 2, while MXA analyzed 124 vertebrae in group 1 at both visits and 127 in group 2. Intra- and inter-observer precision errors, particularly in terms of coefficient of variation (CV%), were larger for MXA than for MRX in both normal subjects and those with vertebral deformities. For example, intra-observer precision errors for vertebral height measurement were 0.62 mm (2.9%) for MXA compared with 0.63 mm (2.2%) for MRX in group 1 (normal) subjects and 0.82 mm (4.2%) for MXA compared with 0.85 mm (3.3%) for MRX for group 2 (osteoporosis and vertebral deformities) subjects. Both MXA and MRX inter-observer precision was clearly poorer than the intra-observer precision, a problem associated with any morphometric technique. This was particularly noticeable for MXA; for example, precision of vertebral height measurement in group 1 subjects was 0.62 mm (2.9%) for intra-observer compared with 0.99 mm (4.6%) for inter-observer analyses. MXA and MRX intra- and inter-observer precision was significantly poorer for subjects with vertebral deformities compared with those without, with the CV% for subjects with vertebral deformity approximately 50% greater than that of normal subjects. For example, MRX intra-observer precision for the midwedge ratio was 2.6% for group 1 subjects compared with 3.8% for group 2 subjects. The precision of vertebral height measurement on deformed vertebrae of group 2 subjects was poorer than that for normal vertebrae in the same subjects using both MXA and MRX, as a result of increased variability in point placement. For example, MXA intra-observer precision (RMS SD) for the wedge ratio precision was 0.037 (3.9%) for normal vertebrae compared with 0.060 (6.6%) for deformed vertebrae. We conclude that MXA precision was generally poorer than MRX, although both techniques were adversely affected by the presence of vertebral deformities and the use of more than one observer. Although precision errors for both techniques were substantially smaller than the 20-25% reduction in vertebral height frequently proposed to identify incident deformities, the poorer precision of MXA may lead to an increased risk of erroneous classification of vertebrae as normal or deformed.     

Relationship Between Spine Bone Mineral Density and Vertebral Body Heights

The aim of this study was to investigate the correlation between lumbar spine bone mineral density (LS-BMD) and the vertebral body heights with advancing age and years since menopause. One hundred and sixty-three women ages 39–74 years (77 normal premenopausal, ages 39–54, and 86 normal postmenopausal, ages 46–74 years) were studied. LS-BMD was measured by dual energy X-ray absorptiometry. Vertebral heights were evaluated, using morphometry, as the sum of anterior (AHs), middle (MHs), and posterior (PHs) vertebral body heights from T₄ to L₅. The AHs/PHs ratio at the same level was also calculated. AHs, MHs, PHs, and AHs/PHs ratio directly correlated with LS-BMD; the correlations are AHs r = 0.80, P < 0.0001, MHs r = 0.75, P < 0.0001, PHs r = 0.76, P < 0.0001, and AHs/PHs r = 0.66, P < 0.001. Both LS-BMD and AHs are inversely correlated with age, and the regressions fit with both linear and cubic curves. The statistical significance of the correlations persists while maintaining age constant. The linear regression curve of AHs with age indicates that the spine height decrement rate is 2.12 mm/year, corresponding to 7.4 cm in 35 years. AHs decreases immediately after menopause fitting with a cubic curve model, with a decrement rate of about 3 cm in the first 5 years after menopause. We conclude that the measurement of the sum of vertebral body heights could usefully integrate LS-BMD evaluation in the clinical and epidemiological investigation of osteoporosis. Received: 30 May 1997 / Accepted: 14 November 1997     

Prevalence of Vertebral Fractures in Chinese Men and Women in Urban Taiwanese Communities

Reports on the prevalence (or incidence) rates of vertebral fracture have been available, but they are limited concerning non-white populations and men of all races. This study used the radiomorphometric method to survey the prevalence rate of vertebral fracture for ethnic Chinese women 40 years and older and Chinese men 65 and older who were randomly selected from four major cities in Taiwan. Three sets of reference values of the height ratios were used for middle-aged women, elderly women, and elderly men. The results showed that in Chinese women, the prevalence rate of vertebral fracture was low before age 50 and showed a steady increase thereafter. In men, the increase was small until age 80. The overall adjusted prevalence rate of vertebral fracture for women older than 65 was 20% and that for men, 12.5% (95% confidence interval 18–22% and 11–14%, respectively.) If only severe deformity was counted [height ratio lower than normal mean minus 4 standard deviations (SD), or Grade II deformity], the adjusted prevalence rate was 15.5% for elderly women and 9.5% for elderly men (95% confidence interval 14–17%, and 8–11%, respectively.) The overall adjusted prevalence rate for women aged 40 and over was 6.8% (95% confidence interval 5.7–8%), or 4.5% (95% confidence interval 3.6–5.5%) for Grade II lesions. Moreover, for subjects with fracture, elderly women tended to have more fractured vertebrae per person and more Grade II fractures than elderly men. Thus, Chinese women residing in cities of Taiwan had a relatively high prevalence rate of vertebral fracture, a finding compatible with that for United States or European white women, or for Japanese women residing in America. Elderly Chinese men also have a high prevalence rate of vertebral fracture. The age-specific female-to-male ratio of prevalence rate was about 1.5 to 2.3 between age 65 and 80, and close to unity after age 80. Received: 10 August 1995 / Accepted: 13 February 1996     

Vertebral Dimensions: Influence of X-Ray Technique and Patient Size on Measurements

In this study a new reference value, ``corrected vertebral dimension,' is presented for vertebral height measurements. Of 68 females (age 18–88 years; mean 44.2 years) and 40 males (age 16–81 years; mean 55 years) the projected vertebral dimensions (T₄–L₅) were measured on lateral radiographs. In addition to this, the vertebra-to-film distances (VFD) were measured and a fixed focus-to-film distance (FFD) was used during the study. Corrected dimensions of the thoracic and lumbar vertebrae (T₄–L₅) were calculated using the FFD and VFD. These corrected dimensions were then used to recalculate projected vertebral dimensions at different focus-to-film distances. The applied geometric corrections were verified in a phantom study representing an in vitro situation. The results indicate that studies using different X-ray techniques for making lateral radiographs of the spine can become comparable when using corrected vertebral dimensions.     

Short-term Precision for Morphometric X-ray Absorptiometry

Morphometric X-ray absorptiometry (MXA) is a low-radiation technique used for the identification of vertebral deformities. The reliability of MXA measurements is dependent on the precision of the technique, and this is influenced by system error, variability associated with morphometric analysis, and variability within study populations. Short-term precision in vivo affects the identification of prevalent deformities, and may vary according to the age and health status of the study population. The aims of this study were to measure short-term precision in vitro and in vivo for MXA, and to compare intraoperator variability for repeat marking of radiographs in morphometric radiography (MRX) and scan images in MXA. For short-term precision in vitro (based on 30 consecutive MXA phantom scans), the coefficient of variation (CV) was approximately 1%. lntraoperator variability for repeat marking of baseline radiographs and MXA scans (marked without the compare facility) in a population-based group of 32 postmenopausal women, was significantly lower for MRX (CV for vertebral heights = 1.5%) than for MXA (CV= 2.9%). The CV for duplicate same-day MXA scans performed in subjects with osteoporosis (n= 20) was 2.2 % for vertebral heights between T8 and L4 using the compare facility, and 4.8% when scans were analyzed without the compare facility. We conclude that short-term precision for MXA is good for vertebrae T8 to L4, but the technique is limited due to poor image resolution in the upper thoracic vertebrae. Intraoperator variability for repeat marking was lower for MRX, but the error associated with marking MXA scans remained below the minimum change required for identification of a vertebral deformity. Received: 31 July 2000 / Accepted: 6 February 2001     

Prediction of Fracture Risk by Radiographic Absorptiometry and Quantitative Ultrasound: A Prospective Study

Recent developments in computer-assisted radiographic absorptiometry (RA) and quantitative ultrasound techniques (QUS) provide readily accessible and relatively inexpensive methods for assessing bone mineral status. However, few population-based studies have investigated the ability of RA and ultrasound to predict fracture risk prospectively. We explored the ability of RA and QUS to predict fracture risk among 560 postmenopausal women from the Hawaii Osteoporosis Study; average follow-up was 2.7 years. An incident vertebral fracture was defined as a decrease of more than 15% in vertebral heights on subsequent films. Self-reported nonspine fractures were verified by medical records. The prospective associations of vertebral fractures, nonspine fractures, and any (spine or nonspine) fractures with bone measurements were examined using logistic regression, adjusting for age. Both phalangeal bone mineral density (BMD) and metacarpal BMD, measured using RA, predicted future fracture risk. The age-adjusted odds ratios (corresponding to 1 SD decrease in BMD) for vertebral fractures, nonspine fractures, and any fractures were 3.41, 1.50, and 1.91, respectively, for phalangeal BMD, and 1.71, 1.49, 1.55, respectively for metacarpal BMD. Calcaneal broadband ultrasound attenuation (BUA) also showed significant association with fracture risk, with age-adjusted odds ratios of 1.50, 1.89, and 1.72 for vertebral fractures, nonspine fractures, and any fractures, respectively. We conclude that hand RA and calcaneal BUA are significant predictors of nonspine fracture, vertebral fracture, and overall fracture risk. The attractive features of these techniques, such as portability, relatively low cost, and ease of use, make them promising alternatives to conventional bone measurement techniques used for the assessment of fracture risk. Received: 26 August 1997 / Accepted: 5 March 1998     

Longitudinal Evaluation of Morphometric X-ray Absorptiometry for the Identification of Vertebral Deformities

Morphometric X-ray absorptiometry (MXA) has not been evaluated for the identification of incident vertebral deformities. The reliability of longitudinal measurements in quantitative vertebral morphometry is influenced by the precision of the technique. Long-term precision in vitro (weekly MXA phantom scans) assessed by retrospective cumulative sum (Cusum) analysis, detected one event during a 6-month period when the measurement process was “out of control”. Inspection of service records revealed that repair work was performed around this timepoint. The coefficient of variation (CV) for long-term precision (vertebral heights) in a population-based sample of postmenopausal women ages 56 to 83, mean 65 ± 6 years (n= 48), was 4.0% for morphometric radiography (MRX), 2.9% for MXA using the compare facility for analysis of serial scans, and 3.2% when “compare” was not used. In women with osteoporosis ages 49 to 87, mean 67 ± 9 years (n= 50), the CV was 5.0% for MRX, 4.1% for MXA using “compare” and 8.5% without “compare”. Precision errors for height ratios (MRX and MXA) were greater than for vertebral heights. Incident deformities were identified by MRX and MXA in the women with osteoporosis, using point prevalence, 20% minimum reduction in vertebral height, and percent least significant change (LSC) in vertebral heights and height ratios. Semiquantitative analysis of radiographs by a radiologist (Genant method) was used as the gold standard. The results were similar for MRX and MXA, and all morphometric criteria identified a similar proportion of true incident deformities, although the false positive rate was generally greater for the height ratio approaches. MXA has good long-term precision and is comparable to MRX for the identification of incident deformities when scans are analyzed with the compare facility. Received: 31 July 2000 / Accepted: 6 February 2001     

绝经后妇女骨质疏松性椎体骨折与腰椎骨密度的关系

目的探讨绝经后妇女骨质疏松性椎体骨折与腰椎骨密度的关系。方法选择骨质疏松性椎体骨折的绝经后妇女23例为骨折组,无椎体骨折的25例绝经后骨质疏松妇女为对照组。两组的年龄、绝经年限、身高、体重、体重指数差异无显著性,均行胸腰椎正侧位X线摄片。用双能X线吸收仪（DXA）测量的腰椎（L2-4）前后位骨密度（BMD）、骨矿含量（BMC）和T值。结果骨折组BMD、BMC和T值均低于对照组（P〈0.01）。结论腰椎BMD降低与绝经后妇女的骨质疏松性椎体骨折相关。绝经后骨质疏松妇女应重视BMD变化,预防椎体骨折的发生。     

Genetic Variation in α2HS-Glycoprotein Is Related to Calcaneal Broadband Ultrasound Attenuation in Older Women

Calcaneal broadband ultrasound attenuation (BUA) is an independent predictor of hip and vertebral fractures. BUA is under genetic control, but the specific genes contributing to BUA are not well defined. We examined the relationship between genetic variation in α₂HS-glycoprotein (AHSG), an abundant noncollagenous protein of bone matrix, and calcaneal BUA. Genetic polymorphism in AHSG was determined in 222 Caucasian women (age 66–92) enrolled in the Pittsburgh Study of Osteoporotic Fractures clinical center by isoelectric focusing of serum samples. Calcaneal BUA and bone mineral density (BMD) were measured on the same foot with a Walker Sonix UBA 575⁺ and single X-ray absorptiometry. Hip and spine BMD were determined with a Hologic QDR-1000 densitometer using dual-energy X-ray absorptiometry. AHSG polymorphism was not significantly related to hip, lumbar spine, or calcaneal BMD. Compared with the homozygous AHSG*2 women, calcaneal BUA was 13% lower in heterozygous (P < 0.05) and 16% lower in homozygous AHSG*1 women (P < 0.05). This relationship persisted after controlling for age, weight, height, walks for exercise, and calcaneal BMD. Current and self-reported height were also lowest in homozygous AHSG*1 women, intermediate in heterozygous women, and highest among homozygous AHSG*2 subjects. These results suggest that the AHSG polymorphism may contribute to the genetic influence on calcaneal BUA and stature. Received: 28 August 1997 / Accepted: 8 January 1998     

Measurement of Vertebral Body Heights: Ex Vivo Comparisons Between Morphometric X-ray Absorptiometry, Morphometric Radiography and Direct Measurements

Morphometric X-ray absorptiometry (MXA) offers some potential advantages over spinal radiography for the quantitative evaluation of vertebral fractures in individuals with spinal osteoporosis. This ex vivo study examined the accuracy of MXA and quantitative morphometry (QM) for the evaluation of vertebral height, in relation to direct measurements from cadaveric vertebral columns. Spinal radiographs and MXA scans were obtained from nine cadaveric vertebral columns (mean age at death 64 years). Anterior, middle and posterior vertebral body heights of all segments from T4 to L4 were measured interactively using MXA software and QM (from the spinal radiographs), and compared with direct measurements derived using digital callipers following cadaveric dissection. Coefficients of variation for repeat QM and MXA scan analysis were less than 2%. The QM and MXA measurements were both strongly correlated (r ²= 0.99) with the direct measurements, with accuracy errors of between 2.6% and 4.3%, and 4.5% and 4.8%, for QM and MXA respectively. At the three measurement sites, analysis of measurement differences showed that QM tended to overestimate the true height and MXA tended towards under-estimation. The mean difference between the direct measurements and QM measurements ranged from 2.7% to 8.7%, and the mean difference between direct and MXA measurements ranged from –2.9% to 4.1%. There was strong linear association between the MXA and QM measurements (r ²= 0.99) with mean differences at the three measurement sites ranging from –4.1% to –5.9%. Under the optimal (ex vivo) scanning conditions used in this study, MXA is comparable to spinal radiography for the assessment of vertebral height. Further studies are required to determine the conditions under which satisfactory MXA image resolution and measurement accuracy can be achieved in a clinical population. Received: 12 May 1998 / Accepted: 13 October 1998     

Differential Effects of Bone Mineral Content and Bone Area on Vertebral Strength in a Swine Model

Since the biomechanical competence of a vertebral body may be closely related to the content and distribution of the bone mineral, we have evaluated the effects of projected vertebral bone area (BA) and bone mineral parameters [bone mineral content (BMC) or bone mineral density (BMD)] on their biomechanical competence. We used dual-energy X-ray absorptiometry (DXA) to assess the bone mineral parameters of 36 swine thoracic vertebrae (T1–T12) and 15 lumbar vertebrae (L1–L5) after removal of the posterior elements. The failure load, compressive stress, and the stored strain energy of these vertebral bodies were assessed by a uniaxial compressive test using an MTS 810 testing system. Multiple regression analysis showed a significantly negative effect of BA and significantly positive effect of BMC on the biomechanical competence (compressive stress, r²= 0.67, P < 0.0001; failure load, r²= 0.75, P < 0.0001). However, the stored strain energy was only related to the BMC (r²= 0.35, P < 0.0001). The contributory effects of BMC and BA on the biomechanical competence were not equal. The effects of BMC was larger than BA in determining the failure load and stored strain energy, whereas the reverse was found for the compressive stress. Using the log-transformed parameters as the regressors resulted in similar results. These results suggested the differential effects of BA and BMC in determining the biomechanical competence of vertebral bodies. We recommend the use of both parameters instead of BMD alone for evaluation of the vertebral biomechanical competence. Received: 26 June 1997 / Accepted: 8 January 1998     

Visual Assessment of Vertebral Deformity by X-ray Absorptiometry: A Highly Predictive Method to Exclude Vertebral Deformity

The accurate identification of prevalent vertebral fractures is important in both the clinical and research setting as they are associated with increased risk of further fracture and irreversible clinical consequences. This study reports a direct comparison of prevalent vertebral deformity identification using X-ray absorptiometry (XA) scans, acquired on a dual-energy X-ray absorptiometry (DXA) machine, and conventional radiographs in a diverse group of 161 postmenopausal women, ranging from healthy subjects with normal bone mineral density (BMD) to osteoporotic subjects with multiple vertebral deformities. Deformities were identified by a trained operator by visual assessment of the XA scans (VXA) and semiquantitatively by an experienced radiologist on the conventional radiographs (XSQ). Subjects were recruited prospectively and were triaged according to their VXA results into normal, equivocal and definite deformity groups. VXA and XSQ demonstrated good agreement (96.3%, κ= 0.79) in classifying vertebrae as normal or deformed in the 1978 of 2093 vertebrae deemed analyzable on both the XA scans and conventional radiographs. VXA showed good sensitivity (91.9%) in the identification of moderate/severe XSQ deformities and an excellent negative predictive value (98.0%) was produced when VXA was used to distinguish subjects without vertebral deformities from those with possible or definite deformities on a per subject basis. The majority of disagreement between the two methods resulted from different classification of mild wedge and endplate deformities and the poor visualization of upper thoracic vertebrae on the XA scans. Agreement improved, particularly on a per subject basis, when analysis was restricted to the vertebral levels from L4 to T7. Visual triage of XA scans by a trained operator would seem to be swift, convenient and cost-effective method, with excellent negative predictive value, to distinguish subjects with very low risk of vertebral deformities from those with possible deformities. These ‘normal’ subjects can then be excluded prior to performing conventional radiographs and further time-consuming and costly methods of vertebral deformity assessment such as XSQ by an experienced radiologist and/or quantitative morphometry. VXA may prove useful in the clinical evaluation of patients at risk of osteoporosis as an adjunct to BMD scans or in the selection of subjects for osteoporosis-related clinical trials. Received: 27 July 1999 / Accepted: 4 February 2000     

Metacarpal Radiogrammetry by Computed Radiography in Postmenopausal Women with Colles' Fracture and Vertebral Crush Fracture Syndrome

Based on the hypothesis that the underlying osteoporotic mechanism of Colles' fracture in postmenopausal women is similar to that of other osteoporotic fractures, that is, cortical bone resorption as opposed to cancellous bone resorption, the rate of corticoendosteal bone loss was compared in 40 normal postmenopausal women [average age 68.4 ± 7.1 years; 20 ± 4 years since menopause (YSM)], in 35 postmenopausal women with Colles' fracture (age 69.4 ± 7.5 years, 22 ± 8 YSM), in 35 normal postmenopausal women with vertebral crush fracture (age 69.4 ± 7.5 years, 22 ± 8 YSM, and in 35 normal premenopausal women (age 36.1 ± 7.9 years). Radiogrammetry by digital radiography of the second metacarpal was used to measure external (ED) and internal (ID) diameter, cortical thickness (CCT), cortical area (CA), and the ratio of cortical area to total area (CA/TA). The ID values of the groups of postmenopausal women were subtracted from the ID value of the premenopausal women and the result was divided by YSM to obtain the rate of corticoendosteal resorption/year (ΔC), CA resorption year (ΔCA) and CA/TA resorption/year (ΔCA/TA). ID, ΔC, ΔCA, and ΔCA/TA all were larger in the postmenopausal women with Colles' and vertebral crush fractures than in the normal postmenopausal women (ANOVA: all P < 0.0001). ID, CCT, ΔC, CA, ΔCA, and ΔCA/TA did not differ between the two groups of postmenopausal women with fractures. ΔC was 87% greater in postmenopausal women with vertebral crush fracture and 116% greater in women with Colles' fracture than in normal postmenopausal women. These results indicate that the loss of cortical bone is an important factor in Colles' fracture in postmenopausal women. Received: 10 October 1996 / Accepted: 15 October 1997     

Identification of Vertebral Deformities in Men: Comparison of Morphometric Radiography and Morphometric X-ray Absorptiometry

Osteoporotic vertebral deformities may be detected by morphometric radiography (MR) using spinal radiographs, and by morphometric X-ray absorptiometry (MXA) using dual-energy X-ray absorptiometry. Reference values for MR may not be appropriate for MXA, and reference values may be affected by gender and age. The aims of this study were to (1) compare mean deformity of vertebral height ratios for MR and MXA in men, (2) compare mean deformity for MXA in men and women, (3) compare mean wedge angle measured by MXA in men and women and (4) assess the effect of aging on MXA values in men. We studied a general practitioner sample of 115 men aged 22–81 years (mean 53 years) and 124 women aged 55–89 years (mean 68 years). Subjects had MXA of T4 to L4 using the Hologic QDR 4500A. Women and men over age 50 years had radiographs of the thoraco-lumbar spine. Scans and radiographs were marked in the same way by one operator and vertebral height ratios and mean deformity were calculated for MR and MXA. The mean wedge angle, θ, was calculated for MXA in all subjects. Mean wedge and biconcavity deformity and standard deviation (SD) in men were greater for MXA than for MR. The mean wedge and biconcavity deformity measured by MXA tended to be greater for men than for women. Vertebral deformity in men increased with age, and was associated with degenerative change seen on spinal radiographs. The mean wedge angle was greater for men than for women, and it increased with age in men. We conclude that sex- and age-specific reference ranges should be established separately for MXA. Received: 14 September 1998 / Accepted: 28 January 1999     

Differing Lumbar Vertebral Mineralization Rates in Ambulatory Pediatric Patients with Osteogenesis Imperfecta

The purpose of this study was to evaluate serial changes in bone mineral density (BMD) of the lumbar spine in individual children and adolescents with untreated osteogenesis imperfecta (OI) using dual X-ray absorptiometry (DXA). Twenty-seven pediatric patients with OI who had no historical or radiographic evidence of lumbar fracture, required no assistive device for mobility, and were taking no medications known to affect skeletal mineralization during the study period comprised the investigational group. Absolute BMD and age- and gender-matched BMD (Z-scores) were assessed relative to standard parameters of growth (height, weight, age, height adjusted for age and gender and body surface area) and severity of disease (lifetime fracture rate). The spinal mineralization rate (SMR) between examinations for 15 patients with more than one measurement (n= 20 intervals) was expressed as the magnitude of the change in BMD Z-score per year. Both BMD and BMD Z-score were closely correlated with height, height Z-score, weight and body surface area and were inversely related to fracture rate (P < 0.001 for all comparisons). BMD was also highly correlated with patient age (P < 0.001). Stepwise regression analysis showed that together height Z-score and lifetime fracture rate improved the prediction of BMD Z-score (r= 0.71; P < 0.001). SMRs ranged from −0.5 to 3.5. The average change in SMR between sequential measurements was 168% for the five children who had more than two DXA examinations. Linear regression showed a significant negative correlation between SMR and height Z-score (r=−0.79, P < 0.001). We conclude that vertebral body size is a critical determinant of BMD and BMD Z-score in OI because DXA results are expressed per unit area, not per unit volume. Pediatric patients with OI mineralize their lumbar vertebrae at rates similar to healthy children but tend to lag behind in overall mineralization. The rate of mineralization at any age appears to be related to the patient's height (adjusted for age- and gender-matched controls) and inversely related to the patient's lifetime rate of fractures. Our data suggest that vertebral mineralization in children with OI is related primarily to rapid increases in vertebral volume and only secondarily to increases in vertebral mineral density. Received: 2 March 1997 / Accepted: 5 June 1997     

Unraveling the Role of Structure and Density in Determining Vertebral Bone Strength

The strength of bone is determined not only by bone density but also by structure. Therefore, quantification of the structure in radiographs by texture parameters may result in a better prediction of fracture risk. Since in radiographs density and structure are strongly correlated, the predictive power of texture parameters should be corrected for the influence of BMD to determine the additional information conveyed by these parameters. In this study, we evaluated the predictive power of various texture parameters based on the Grey-Level Dependence Method and the Morphological Gradient Method. This study was performed on 67 vertebrae obtained from 20 male and 12 female human cadaver thoracolumbar spines. BMD and area of the vertebral body were determined from QCT images and texture parameters were derived from direct magnification (DIMA) radiographs. The fracture force, measured under conditions simulating the in vivo situation, was corrected with the area of the vertebra to yield the fracture stress (FS). Results of the study indicate that BMD correlates significantly with FS r= 0.82 (P < 0.001, n= 24) and r= 0.94 (P < 0.001, n= 43) for female and male vertebrae, respectively. Correlation coefficients of the investigated texture parameters were as high as 0.80 (P < 0.001) and 0.67 (P < 0.001) for the female and male vertebrae, respectively. Multiple regression analysis showed that in female vertebrae, the addition of one texture parameter to BMD results in a better prediction of strength. The multiple correlation coefficient was 0.87 (P < 0.001) in this case. In male vertebrae, BMD was the best predictor of fracture stress. These results suggest that texture parameters, as measured in magnification radiographs, can predict bone strength. Whereas in all cases BMD is the best single predictor of bone strength, for women texture parameters contain useful additional information. Received: 9 July 1996 / Accepted: 24 March 1997     

Effectiveness of instant vertebral assessment to detect prevalent vertebral fracture

Introduction Vertebral fracture is currently underdiagnosed, despite its common severity and its value to predict further osteoporotic fracture. Morphometry using dual X-ray absorptiometry (DXA) [vertebral fracture assessment (VFA)] is a new technique that may facilitate detection of many vertebral fractures, as images are obtained at the same time as bone mineral density (BMD) measurement, and would also allow avoiding spine radiographs.Methods We conducted a cross-sectional study to assess the diagnostic value of Instant Vertebral Assessment (IVA), which is a morphometry scan using the Hologic Delphi densitometer, to detect prevalent vertebral fracture in postmenopausal women. Interobserver precision was assessed, then IVA scans were compared with lateral spine radiographs, considered the gold standard, to test diagnostic agreement between the two techniques. Sensitivity, specificity and predictive values were calculated, as well as the likelihood ratio of the positive test, using sensitivity and specificity at each vertebral level.Results Among 85 patients of whom 50% had at least one vertebral fracture identified with radiographs, we found that interobserver precision was moderate, with frequent difficulties in discerning upper thoracic vertebrae. On a per-vertebra basis, sensitivity was around 70% from L4 to T11 and lower above T11 whereas specificity was above 90% for all vertebrae, and the negative predictive value remained above 80% from L4 to T7 and decreased above T7. On a per-patient basis, sensitivity was 0.69, specificity 0.74, positive predictive value equalled 0.72 and negative predictive value 0.71. When only grades 2 and 3 fractures were considered, results were comparable, with slightly improved specificity. Then, with the likelihood ratios calculated in our sample, we obtained posttest probabilities using the prevalence of vertebral fracture at lumbar and thoracic levels in a large sample of postmenopausal women with osteopenia and osteoporosis with and without vertebral fracture [baseline data in women of the Multiple Outcomes on Raloxifene Evaluation (MORE) trial]. At levels where fractures were most common, likelihood ratios of the positive test were good or excellent, associated with sizeable posttest probabilities.Conclusion IVA allowed diagnosis of vertebral fracture at levels where vertebral fracture were most common, i.e., the lumbar and mid and lower thoracic levels, but its value was weaker at the upper thoracic levels.