Spine deformity index in osteoporotic women: Relations to forearm and vertebral bone mineral measurements and to iliac crest ash density

Bone densitometric measurements are widely used for monitoring therapeutic regimens for osteoporosis. However, it is a matter of debate which measurement site is most appropriate for prediction of individual fracture risk. The aim of this cross-sectional study was to investigate the relationship between bone mineral measurements at various sites and spine deformity index (SDI) in osteoporotic women. The SDI was determined in 37 osteoporotic women aged 56–87 years (mean 70.9 years). Peripheral (single-photon absorptiometry of the distal forearm, and iliac crest ash content) and axial (dual-photon absorptiometry of the lumbar spine) bone mass measurements were obtained. SDI increased with age (r=0.34,p<0.05), whereas forearm BMC (r=–0.52,p<0.002) and forearm BMD (r=–0.62,p<0.0001) decreased. No significant age-related changes were observed in lumbar BMC or iliac crest ash content in these osteoporotic women. A highly significant correlation was found between SDI and lumbar BMC(r=–0.60,p<0.01). A significant, but less pronounced correlation was found between SDI and forearm BMC (r=–0.37,p<0.05), whereas no relation was revealed between SDI and forearm BMD or iliac crest ash content. In a multiple regression model, the relationship between lumbar BMC and SDI remained significant after adjusting for the influence of age, whereas the relationship to forearm BMC disappeared. Furthermore, a multiple regression analysis was performed in order to evaluate the ability of all four bone mass measurements and age to predict variations in SDI. Lumbar BMC was the single significant predictor of SDI in this model (r=–0.68,p<0.01). This study indicates that the risk of vertebral fracture is best estimated by bone mass determined in the spine.     

Diagnostic value of ultrasound analysis and bone densitometry as predictors of vertebral deformity in postmenopausal women

Bone fractures depend not only on bone density, but also on bone quality. Ultrasound (US) has been proposed as a technique for evaluating skeletal status. Speed of sound (SOS) and broadband ultrasound attenuation (BUA) are the US properties currently used to assess bone strength and fragility. In 304 postmenopausal women (age 58.8±5.5 years) we measured: bone mineral density (BMD) of the lumbar spine (by dual-energy X-ray absorptiometry), SOS, BUA and Stiffness in the os calcis (using an Achilles machine). In all subjects we performed lateral lumbar and thoracic radiographs. Morphometric parameters were derived by measuring the anterior, middle and posterior height of each vertebral body, to obtain a semiquantitative grading of vertebral fractures as follows: 0, no vertebral deformity; 1, any vertebral height reduced between 20% and 25%; 2, any vertebral height reduced between 25% and 40%; 3, any vertebral height reduced more than 40%. On the basis of the number and severity of vertebral deformities the women were divided into: group 1 (n=79), normal; group 2(n=80), mild; group 3 (n=85), moderate; and group 4 (n=60), severe. Mean values of SOS, BUA, Stiffness and BMD were significantly lower (p<0.001) in women with vertebral deformity than in normals. In the whole population SOS, BUA and Stiffness values were significantly correlated with BMD. SOS, BUA and Stiffness values were significantly decreased (p<0.001) with vertebral deformity, as was BMD. Receiver operating characteristic (ROC) curve analysis showed BMD to be slightly better than Stiffness in discriminating among groups. Logistic regression analysis showed that BMD, BUA, SOS and Stiffness were independent predictors of vertebral fracture risk. Ultrasound parameters were still significant independent predictors of vertebral fracture even after adjusting for BMD.     

A longitudinal study of supine lateral DXA of the lumbar spine: A comparison with posteroanterior spine,hip and total-body DXA

We report a study to assess whether supine lateral dual-energy X-ray absorptiometry (DXA) scans of the lumbar spine provide better data for monitoring response to treatment than alternative measurement sites such as the posteroanterior (PA) spine, hip and total body. The study population was 152 women enrolled in a placebo-controlled clinical trial of cyclical etidronate therapy. All subjects were 1–10 years after the menopause with bone mineral density (BMD) between 0 and –2 SD of age-matched normal women. Paired PA and lateral spine, left hip and total-body DXA scans were performed at baseline, 1 year and 2 years on a Hologic QDR-2000. One hundred and thirty-one subjects completed the study. Mean percentage change from baseline at 2 years in the treated (n=61) and control (n=70) groups was calculated for vertebral body, width-adjusted (WA) vertebral body, mid-vertebral body and WA mid-vertebral body BMD measurements on the lateral scans and compared with the percentage changes in PA spine, femoral neck, trochanter, Ward's triangle and total-body BMD. The long-term precision for each BMD measurement site was obtained by linear regression analysis in subjects taking placebo. Overall treatment effect, defined as the difference in the percentage change in BMD in the two treatment groups at 2 years, was divided by long-term precision to give an index of the ability of each site to monitor response to treatment. Results (and standard errors) normalized to the ratio of treatment effect/precision for PA spine BMD were as follows: PA spine, 1.00; vertebral body, 0.89 (0.14); WA vertebral body, 0.78 (0.14); mid-vertebral body, 0.65 (0.14); WA mid-vertebral body, 0.60 (0.13); femoral neck, 0.35 (0.15); trochanter, 0.45 (0.15); Ward's triangle, 0.59 (0.22); total body, 0.52 (0.19). Although treatment effect was larger for lateral than for PA spine BMD, this advantage was offset by the greater precision errors. PA spine BMD remains the optimum measurement for longitudinal studies in recently postmenopausal women.     

Does thoracic or lumbar spine bone architecture predict vertebral failure strength more accurately than density?

Summary Trabecular bone microstructure was studied in 6 mm bone biopsies taken from the 10th thoracic and 2nd lumbar vertebra of 165 human donors and shown to not differ significantly between these sites. Microstructural parameters at the locations examined provided only marginal additional information to quantitative computed tomography in predicting experimental failure strength. Introduction It is unknown whether trabecular microstructure differs between thoracic and lumbar vertebrae and whether it adds significant information in predicting the mechanical strength of vertebrae in combination with QCT-based bone density. Methods Six mm cylindrical biopsies taken at mid-vertebral level, anterior to the center of the thoracic vertebra (T) 10 and the lumbar vertebra (L) 2 were studied with micro-computed tomography (μCT) in 165 donors (age 52 to 99 years). The segment T11-L1 was examined with QCT and tested to failure using a testing machine. Results The correlation of microstructural properties was moderate between T10 and L2 (r ≤ 0.5). No significant differences were observed in the microstructural properties between the thoracic and lumbar spine, nor were sex differences at T10 or L2 observed. Cortical/subcortical density of T12 (r ² = 48%) was more strongly correlated with vertebral failure stress than trabecular density (r ² = 32%). BV/TV (of T10) improved the prediction by 52% (adjusted r ²) in a multiple regression model. Conclusion Microstructural properties of trabecular bone biopsies displayed a high degree of heterogeneity between vertebrae but did not differ significantly between the thoracic and lumbar spine. At the locations examined, bone microstructure only marginally improved the prediction of structural vertebral strength beyond QCT-based bone density.     

Failure load of thoracic vertebrae correlates with lumbar bone mineral density measured by DXA

Fractures of the thoracic spine account for a large portion of vertebral fractures in the elderly, yet noninvasive measurements of bone mineral properties are limited to the L2–L4 vertebral bodies. The purpose of this investigation was to determine whether bone mineral properties of the umbar spine correlate with the failure properties of thoracic ertebrae. Cadaveric lumbar segments were scanned using dual-energy x-ray absorptiometry (DXA) from both the latcrol and anteroposterior projections. Three-body segments L1–L3 and T10–T12 were then compressed to create crush tractures in the L2 and T11 vertebral bodies, and linear corelation analyses were performed to compare each DXA measure with the failure properties of L2 and T11. Lumbar BMD from the lateral view correlated significantly with T11 altimate load (r=0.94, P<0.001), as did lumbar BMD from the anteroposterior projection (r=0.83, P=0.001). Significant correlations were also found between both lumbar BMD and BMC and the stiffness and energy to failure of I'll. Furthermore, BMD and BMC measured at L2 correlated significantly with L2 ultimate load, stiffness, and energy to failure. We conclude that bone mineral properties measured at the lumbar spine provide a valid assessment of the compressive strength of both thoracic and lumbar vertebrae. Lumbar BMD may therefore be used to derive an index for the prediction of thoracolumbar fractures to aid in the early intervention of vertebral fractures.Portions of this work were presented at the 40th Annual Meeting of the Orthopaedic Research Society and appeared in abstract form in the conference proceedings.     

The contribution of serum osteoprotegerin to bone mass and vertebral fractures in postmenopausal women

Regulation of osteoclastic activity is critical for understanding bone loss associated with the postmenopausal period. In vitro and animal studies have revealed the role of OPG as a decoy receptor that neutralizes the effect of RANKL on the differentiation and activation of osteoclasts. However, the role of the OPG-RANKL system in postmenopausal osteoporosis is controversial. Thus, the aim of this study was to investigate the relationship among circulating levels of OPG, RANKL, bone turnover markers (BTM), bone mineral density (BMD) and vertebral fractures in postmenopausal women. We determined anthropometric parameters, circulating OPG and RANKL, BTM, estradiol, BMD by dual X-ray absorptiometry at the lumbar spine (LS) and femoral neck (FN), and pre-existing vertebral fractures in 206 ambulatory postmenopausal women of a mean age of 62 years (SD 7). Circulating OPG was significantly related to age ( r =0.158; P =0.023), years since menopause ( r =0.167; P =0.016) and BMD (LS Z-score: r =0.240; P =0.001, FN Z-score: r =0.156; P =0.025). Over half of the women had undetectable RANKL ( n =113; 54.9%). There were no significant differences in clinical variables, BTM or BMD among women with detectable vs. undetectable RANKL. OPG was found to be independently associated with osteoporosis (OR: 2.9, 1.4–5.9) and prevalent vertebral fractures (OR: 2.5, 1.2–5.4). We conclude that serum OPG levels are independently associated with bone mass and prevalent vertebral fractures in postmenopausal women.     

Bone mineral density and prevalent vertebral fractures in men and women

To test the hypothesis that the association between bone mineral density (BMD) and estimated volumetric BMD and prevalent vertebral fractures differs in men and women, we studied 317 Caucasian men and 2,067 Caucasian women (average age 73 years). A total of 43 (14%) men and 386 (19%) women had a vertebral fracture identified on lateral spine radiographs using vertebral morphometry. Hip and spine areal BMD was about 1/3 standard deviation lower among men and women with a vertebral fracture. A 0.10 g/cm² decrease in areal BMD was associated with 30–40% increased odds of having a fracture in men and 60–70% increased likelihood in women. Low bone mineral apparent density (BMAD) was also associated with 40–50% increased odds of a vertebral fracture in both genders. The probability of a man having a fracture was observed at higher absolute areal BMD values than observed for women (P=values for interaction of BMD × gender: trochanter, P=0.05; femoral neck, P=0.10; total hip, P=0.09). In contrast, the probability of fracture was similar in men and women across the range of estimated volumetric BMD (BMAD). In conclusion, low BMD and low BMAD are associated with increased odds of vertebral fracture in both men and women. Measures of bone mass that partially correct for gender differences in bone size may yield universal estimates of fracture risk. Prospective studies are needed to confirm this observation.     

Dual-energy X-ray absorptiometry of the spine in anteroposterior and lateral projections

Dual-energy X-ray absorptiometry (DXA) of the lumbar spine provides an estimation of the bone mineral content (BMC) corrected by the projected area of the spine and expressed in g/cm². This two-dimensional estimate of the bone mineral density (BMD) is influenced by the skeletal size, assessed by the subject's height. In order to obtain an estimate of the volumetric BMD, we measured BMC with a new DXA device (Sophos L-XRA) equipped with 24 detectors and a rotating arm, thus allowing scanning of the lumbar spine in both an anteroposterior (AP) projection and a lateral (LAT) projection with the patient in a supine position. Comparison between the results obtained on the third (L3) and fourth (L4) lumbar vertebrae with automatic or manual analysis showed that the best precision was obtained with the lateral measurement of L3 alone with an automatic soft tissue baseline determination. Results were expressed in g/cm² and in g/cm³ (by dividing the g/cm² value by the width (AP area divided by the height of the vertebra) of L3), and were compared with those obtained by conventional AP scanning of L2–4 (g/cm²). The in vivo precision error evaluated by triplicate measurements on 10 controls was 17 mg/cm² (1.96%) and 5.2 mg/cm³ (2.31%) for LAT L3 as compared with 13 mg/cm² (1.15%) for AP L2–4. Volumetric BMD (g/cm³) measurement, assessed in vitro on a calibrated hydroxyapatite phantom, and the absolute values obtained in normal women were similar to those obtained by quantitative computed tomography (QCT). In 39 healthy adults (27±4 years) BMD expressed in g/cm² was correlated with height (r=0.36 for AP L2–4 andr=0.39 for LAT L3;p<0.05 for both) but not with LAT L3 BMD expressed in g/cm³ (r=0.02; NS). The age-related bone loss between 30 and 80 years of age, derived from the normal values for 101 healthy women (age range 19–73 years) was 36% for AP L2–4, 52% for LAT L3 (g/cm²) and 60% for LAT L3 (g/cm³). In a group of 22 women with untreated postmenopausal vertebral osteoporosis (one or more non-traumatic vertebral crush fractures) the mean decrease in BMD, expressed as a percentage of the age-adjusted normal value, was more pronounced (p<0.001) for LAT L3 BMD (–21% in g/cm²,Z-score –1.08; –22% in g/cm³,Z-score –0.94) than for AP L2–4 BMD (–9%,Z-score –0.66). We conclude that: 1) BMD measurement restricted to the vertebral body of L3 can be achieved with a low precision error with this new DXA device; 2) it allows an estimate of the volumetric density (g/cm³) which does not seem to be influenced by skeletal size; 3) lateral BMD appears to be more sensitive than conventional AP scanning for assessing age-related bone loss and should be useful in the investigation of trabecular osteoporosis.     

Prevalent vertebral deformities: Relationship to bone mineral density and spinal osteophytosis in elderly men and women

The aims of this study were to ascertain vertebral deformity prevalence in elderly men and women and to describe the association between bone mineral density (BMD) at the lumbar spine and femoral neck, severity of spinal degenerative disease and vertebral deformity prevalence. We performed standardized spinal radiographs in a random sample of 300 elderly men and women participating in the Dubbo Osteoporosis Epidemiology Study, a population-based study of fracture risk factors. Radiographs were read independently by masked observers for the prevalence of vertebral deformity and severity of osteophytosis. BMD was measured by dual-energy X-ray absorptiometry. The prevalence of vertebral deformities was critically dependent on the criterion used. The less strict criteria seemed to overestimate deformities at either end of the spine region analysed. However, irrespective of the criterion used, prevalence of deformity was higher in men than in women (25% vs 20% for the 3 SD criterion, 17% vs 12% for the 4 SD criterion and 27% vs 25% for the 25% criterion). Femoral neck BMD was more strongly associated with vertebral deformities than spinal BMD for the 25% criterion (OR/SD change in BMD 1.39 (p=0.02) vs 1.20 (p=0.19)), 3 SD criterion (OR/SD change in BMD 1.45 (p=0.01) vs 1.10 (p=0.34)) and 4 SD criterion (OR/SD change in BMD 1.98 (p=0.0002) vs 1.68 (p=0.008)). BMD was also more strongly associated with biconcave deformities than either wedge or crush deformities and more so in men than in women. Severity of spinal osteophytosis was not associated with vertebral deformity. In conclusion, femoral neck BMD is at least equivalent to the lumbar spine BMD in strength of association with prevalent vertebral fractures. Spinal osteophytosis falsely elevates BMD without a concomitant decrease in fracture risk, indicating that any interpretation of spinal BMD needs to be adjusted for osteophytosis. These findings support the use of femoral neck bone densitometry in older men and women. Moreover, these data indicate that current criteria for radiological assessment of vertebral deformity are sufficiently loose to include a substantial proportion of non-fractures in the elderly, with important implications for the design of clinical trials. However, irrespective of the criterion used, vertebral deformities in men are at least as common, if not more so, than in women, suggesting that vertebral osteoporotic fractures are overlooked in men.     

Bone Mineral Density in Cystic Fibrosis: Benefit of Exercise Capacity

The aim of this study was to evaluate the association between bone mineral density (BMD) and objective maximal exercise measurements in adults with cystic fibrosis (CF). Twenty-five CF patients (19 males, 6 females, mean age 25.5 yr, range: 17–52) underwent BMD assessment and maximal-cycle ergometer exercise testing. We examined the relationship between gas exchange (% peak-predicted O₂ uptake, CO₂ output, O₂ saturation), exercise performance (maximum power, exercise duration), and respiratory mechanics (tidal volume, rate) with lumbar spine and total proximal femur BMD. The strongest clinical correlate with BMD was forced expiratory volume at 1 s (lumbar spine Z-score, r = 0.36; total proximal femur Z-score, r = 0.68, p < 0.01). The strongest exercise correlate was % peak-predicted O₂ uptake (lumbar spine Z-score, r = 0.44, p < 0.01; total proximal femur Z-score, r = 0.59, p < 0.01). There was a closer association between exercise parameters and total proximal femur BMD (r = 0.43–0.60) than with lumbar spine BMD (r = 0.04–0.45). Multiple regression analysis revealed VO₂ to be the strongest independent predictor of BMD (R² = 0.86, p < 0.001) followed by petCO₂ and body mass index (R² = 0.7 and 0.5, respectively, p < 0.01). Exercise appears to influence total proximal femur BMD more than lumbar spine BMD in CF. Exercise rehabilitation programs focusing on peripheral strength training may benefit those CF patients with low total proximal femur BMD.     

Radiographic outcome of vertebral bone bruise associated with fracture of the thoracic and lumbar spine in adults

Bone bruising associated with long bone injury is a defined entity with known radiological, pathologic and clinical features. Vertebral bone bruise (VBB) has been described through magnetic resonance imaging (MRI) of the injured spine, but to date the consequences of this entity are unknown. The objective of this retrospective study was to describe the plain radiographic outcome of MRI-defined VBB associated with thoracic and lumbar spine fracture in adults, and to assess whether VBBs caused abnormalities of the bone–implant interface at instrumented levels. Levels of VBB were identified through analysis of the full spine MRI in a consecutive series of adult patients admitted to a spinal injuries unit for thoracic and lumbar spine fractures. The anterior wedge angles (AWAs) of thoracic and lumbar vertebrae demonstrating VBB were measured on radiographs taken at time of injury and at follow-up. Abnormalities of the bone–implant interface were recorded at instrumented levels associated with VBB on follow-up radiographs. Thirty VBBs were identified in 18 adult patients who had suffered 21 vertebral fractures. At an average follow-up of 19 months (range, 12–30 months), the mean AWAs of the VBB vertebrae at the time of injury and at the most recent follow-up were 3.5° and 3.8°, respectively (p=0.33, paired t-test). A total of 12 out of 30 (40%) bruised levels were instrumented in 13 out of 18 (72%) operated patients. No bone–implant interface failure was observed at these levels. It is concluded that VBB associated with thoracic and lumbar vertebral fracture in adult patients does not appear to cause significant progressive vertebral deformity or bone–implant interface failure.An erratum to this article can be found at     

The fracture risk index and bone mineral density as predictors of vertebral structural failure

Structural failure becomes increasingly likely as the load on bone approximates or exceeds the bones ability to withstand it. The vertebral fracture risk index (FRI) expresses the risk for structural failure as a ratio of compressive stress (load per unit area) to estimated failure stress, and so should be a more sensitive and specific predictor of vertebral fracture than spine areal BMD (aBMD) or volumetric BMD (vBMD), surrogates of bone strength alone. To address this issue, we analyzed the results of a case-control study of 89 postmenopausal women with vertebral fractures and 306 controls in Melbourne, Australia, and a 10-year community-based prospective study in which 30 postmenopausal women who had incident vertebral fractures were compared with 150 controls in Lyon, France. The FRI and vBMD of the third lumbar vertebral body and spine aBMD were derived using dual X-ray absorptiometry. In the cross-sectional analysis, each SD increase in FRI was associated with 2.1-fold (95% confidence interval [CI], 1.55–2.73) increased vertebral fracture risk, while each SD decrease in aBMD or vBMD was associated with 4.0-fold (95% CI, 2.69–6.18 and 2.65–6.94, respectively) increase in risk. Using receiver operating characteristic (ROC) analysis, the FRI was less sensitive and specific than aBMD in discriminating cases and controls (area under ROC, 0.76 vs 0.84, p <0.01). The area under ROC curve did not differ between FRI and vBMD (0.76 vs 0.79, NS). In the prospective data set, the FRI was not predictive [hazard ratio, HR, 1.20 (95% CI, 0.9–1.7)] and was in contrast to aBMD [HR, 2.4 (95% CI, 1.5–3.8)] and vBMD [HR, 2.1 (95% CI, 1.39–3.17)]. There was also lower sensitivity using a cutoff value of FRI 1 compared with aBMD T -score of –2.5 SD in both studies. There was poor agreement (kappa=0.13–0.18) between FRI and aBMD T -scores in detecting fractures; each method only identified around 50% of fractured cases. Within the constraints of the sample size, we concluded that applying a biomechanical index such as FRI at the spine is no better in discriminating fracture cases and controls than conventional aBMD or vBMD. The FRI may not predict incident vertebral fractures.     

Distal radius fracture is an early sign of general osteoporosis: Bone mass measurements in a population-based study

To evaluate the bone mass by bone density measurements in patients with distal radius fracture, a prospective open case-control study was carried out in the county of Uppsala, Sweden, with population-based cases and controls. There were 111 patients with a distal radius fracture who were otherwise healthy and aged 53–76 years, together with 60 healthy controls of similar age, sex and menopausal status. The main outcome measures were bone mineral density (BMD) in the lumbar spine and hip measured with dual-energy X-ray absorptiometry, and in the (non-fractured) distal forearm determined by single-photon absorptiometry. It was found that at all measuring sites BMD was significantly lower in cases than in controls. The difference in the distal forearm was around 20% (p<0.001) and in the spine and hip 5%–8% (p<0.05–0.001). In the healthy subjects there were positive correlations (r=0.39–0.65;p<0.002) between the forearm BMD and that of both the spine and hip, whereas in the patients with distal radius fracture there was only a weak correlation between the forearm and spine BMD (r=0.28;p<0.05) and no association between the BMD of the forearm and hip (r<0.01). It is concluded that patients with distal radius fracture who are otherwise healthy have a preferential bone loss at the distal forearm but also a generally low bone mass. Patients with fracture of the distal radius fracture should be considered for prophylactic measures against osteoporosis.     

Treatment of postmenopausal vertebral osteopenia with monofluorophospate: A long-term calcium-controlled study

The aim of the present study was to assess the effects of the new fluorine pro-drug monofluorophos-phate (MFP) in postmenopausal women with vertebral osteopenia and high bone turnover. We enrolled postmenopausal women (PMW, 43–59 years) who had had a natural menopause 2–5 years before the study, had vertebral bone mineral density (BMD) <13 SD from the premenopausal mean, and had at least one of the biochemical markers of bone remodeling >1 SD over the mean for premenopausal women. Patients were randomly divided into two treatment groups (group 1, 500 mg/day of oral calcium; group 2, MFP at the dose of 20 mg F-equivalents + 600 mg calcium/day) for 2 years (n=21 in each group). The lumbar vertebral (L2–4) BMD and total body bone mineral (TBBM) were measured by dual-energy X-ray absorptiometry (Lunar DPX, Lunar Corporation, USA). Urinary hydroxyproline excretion (OH-P/Cr), plasma bone Gla protein (BGP) and serum alkaline phosphatase (AP) were assayed. In group 1 the markers of bone turnover and vertebral BMD did not show any significant modification, while TBBM showed a significant (p<0.05) decrease after 24 months. In group 2 a significant (p<0.05) decrease in OH-P/Cr (–23.9±2.0%), and an increase in both BGP (+19.4±2.6%) and AP(+10.3±2.6%) levels were observed after 24 months of MFP administration. In this group, both vertebral BMD (+5.01±0.9%,p<0.01) and TBBM (+4.0±0.6%,p<0.05) showed a significant increase after 24 months. Present results suggest that, in osteopenic PMW, MFP administration induces a significant increase in vertebral BMD without impairment of cortical bone, with a reduction in bone resorption and an increase in bone formation rate.     

Comparison of trabecular bone density at vertebral and radial sites using quantitative computed tomography

Trabecular volumetric bone mineral density (VMD) was measured at the lumbar spine using quantitative computed tomography (QCT) and at the distal radius using peripheral QCT (pQCT) in 60 Japanese women aged 21–86 years. The age-dependent decrease between age 20 and 80 years was found to be almost identical between vertebral trabecular VMD and radial trabecular VMD, averaging 2.5±0.26 (SE) and 2.5±0.30 mg/cm³ per year, respectively. A highly significant correlation was found between vertebral and radial trabecular VMD (r=0.806,p<0.001) with a prediction error of ±9.6% (± SD/mean). In the present study, a relatively constant trabecular VMD ratio was found between the vertebral and distal radial sites, despite the relatively small study population. This may indicate a close parallelism between vertebral and radial trabecular bone.     

椎体内部强化术后术椎塌陷的危险因素分析

目的 :探讨椎体内部强化术,包括经皮椎体成形术(PVP)、椎体后凸成形术(PKP),术后术椎塌陷的发生率、独立危险因素以及预防措施。方法:回顾性分析2012年1月至2013年6月经椎体内部强化术治疗并获得随访的154例单节段骨质疏松性椎体压缩骨折(OVCF)患者的临床资料,其中男65例,女89例,年龄57~90岁,平均(76.20±9.35)岁。随访时间6~30个月,平均(15.43±6.81)个月,术后随访患者均接受X线检查,部分患者接受MRI检查。分析与术椎塌陷相关的可能危险因素,包括性别、年龄、手术方式(PVP或PKP)、骨质疏松程度T评分、术椎节段水平、是否合并椎体骨坏死、术椎骨水泥填充模式、术椎前缘高度恢复率。并将可能的危险因素作为研究对象,采用多因素Logistic逐步回归分析法筛选影响术椎塌陷的独立危险因素。结果:随访周期内共发现29例发生术椎塌陷,术椎塌陷的发生率为18.83%。多因素Logistic逐步回归分析显示手术方式(OR=0.171,P=0.010),骨质疏松程度T评分(OR=0.242,P=0.024),是否合并椎体骨坏死(OR=12.225,P=0.003),术椎骨水泥填充模式(OR=10.461,P=0.000)以及术椎前缘高度恢复率(OR=0.316,P=0.019)是影响术椎塌陷的独立危险因素。结论:椎体内部强化术后术椎塌陷的发生率较高,其发生率与多种因素相关,其中手术方式、骨质疏松程度T评分、是否合并椎体骨坏死、术椎骨水泥填充模式、术椎前缘高度恢复率是影响术椎塌陷的独立危险因素。术前严格筛选患者,术中注重骨水泥的对称性均匀分布,术后积极抗骨质疏松治疗,可降低术后术椎塌陷的发生率。     

Bone mineral density and bone turnover in patients with Bartter syndrome

The aim of this investigation was to evaluate bone mineral density (BMD), by use of DXA, and bone turnover, in patients with Bartter syndrome (BS). Ten patients (2 with BS type II and 8 with BS type III) were included in the procedure. Age at study varied between 2 and 30 years. During the studies usual treatment with indomethacin, spironolactone, and potassium chloride was maintained. Results were compared with those obtained in the 20 asymptomatic parents. Height of the patients at the time of the study did not differ from reference values (Z-score –1.2 to +0.8). Three patients (1 with BS type II and 2 with BS type III) presented reduced lumbar spine BMD or overt osteopenia (BMD Z-scores: –2.3, –1.3, and –1.1). BMD did not correlate significantly with age. Paternal and maternal femoral neck BMD values correlated significantly with lumbar spine BMD of the patients (r=0.65, P<0.05, and r=0.80, P<0.01). Lumbar spine BMD Z-scores correlated negatively with urinary Ca excretion when values both from patients and parents were jointly analyzed (r=–0.43, P<0.05). Plasma calcium concentration was significantly higher (P<0.001) and plasma phosphate Z-score was significantly lower (P<0.05) in the patients than in the parents. However, no significant differences were observed in values for intact PTH, 1,25 (OH)₂D₃ and 25 (OH)D₃. Intact PTH values correlated positively with BMD Z-scores at lumbar spine (r=0.45, P<0.05) and at femoral neck (r=0.63, P<0.01). Age-corrected biochemical markers of bone formation (plasma alkaline phosphatase and osteocalcin concentrations) were normal whereas age-corrected markers of bone reabsorption (urinary PYD and DPD excretion) were significantly higher than parental values (P<0.01 and <0.05, respectively). We conclude that: (1) reduced BMD is not an exclusive feature of neonatal BS and it can be also observed in classic BS; (2) the loss of bone mineral is not progressive, probably because of the hypocalciuric effect of indomethacin therapy; and (3) this study did not determine whether loss of bone mass is the cause or the consequence of hypercalciuria although the beneficial effect of indomethacin therapy implies the latter.     

Vitamin D and bone mineral density

Bone mineral density (BMD) at the lumbar spine and the neck of femur and serum concentrations of 25-hydroxyvitamin D (25OHD), intact parathyroid hormone (PTH), alkaline phosphatase, calcium, albumin, creatinine and phosphate were measured in a group of 166 postmenopausal women (30–79 years) attending a bone clinic for bone density measurements. Four subjects with suspected primary hyperparathyroidism were excluded from analysis. BMD at the lumbar spine was correlated with body mass index (BMI) (r=0.278,p=0.0003), age (r=−0.194,p=0.0134) and serum 25OHD (r=0.188,p=0.0167). BMD at the neck of femur correlated with BMI (r=0.391,p<0.0001), age (r=−0.356,p<0.0001), PTH (r=−0.156,p=0.047) and serum 25OHD (r=0.231,p=0.0031). Stepwise multiple regression analysis showed that age, BMI and serum 25OHD contributed to the variation in BMD at lumbar spine. At the neck of femur, PTH was an additional contributor. We conclude that serum 25OHD makes a contribution to BMD a lumbar spine and neck of femur.     

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     

Body segment lengths and arm span in healthy men and women and patients with vertebral fractures

We studied 112 healthy men and 261 healthy women aged 18–92 years, and 34 men and 73 postmenopausal women with vertebral fractures aged 45–90 years to determine (i) whether patients with vertebral fractures have shorter stature before fracture, and (ii) whether the difference between arm span and standing or sitting height can be used to identify patients with fractures. Arm span was measured by using a calibrated extended ruler. Standing height, sitting height and leg length were measured by using a Holtain stadiometer. The results were expressed in absolute term and standard deviation (SD) or Z-scores (mean±SEM). Advancing age was associated with decreased sitting height (r=–0.37 to –0.41, both P<0.01) and a trend towards decreased arm span (r=–0.12 to –0.17, P=0.06 and 0.07) in healthy men and women; leg length was independent of age in both sexes (r=–0.09 to –0.12, NS). In patients with vertebral fractures, sitting height was reduced in women (Z=–0.83±0.14 SD, P<0.01) and men (Z=–1.37±0.21 SD, P<0.01) but only the women had reduced leg length (Z=–0.46±0.15 SD, P<0.01) and arm span (Z=–0.76±0.15 SD, P<0.01). Univariate and multivariate analyses suggest that the predictive ability of the difference between arm span and standing or sitting height to identify patients with vertebral fractures is limited. We concluded that women, not men, with vertebral fractures may come from a population with short stature. The difference between arm span and standing or sitting height cannot be used to predict vertebral fracture risk.