Vertebral deformities and fractures are associated with MRI and pQCT measures obtained at the distal tibia and radius of postmenopausal women

Summary

We investigated the association of postmenopausal vertebral deformities and fractures with bone parameters derived from distal extremities using MRI and pQCT. Distal extremity measures showed variable degrees of association with vertebral deformities and fractures, highlighting the systemic nature of postmenopausal bone loss.

Introduction

Prevalent vertebral deformities and fractures are known to predict incident further fractures. However, the association of distal extremity measures and vertebral deformities in postmenopausal women has not been fully established.

Methods

This study involved 98 postmenopausal women (age range 60–88 years, mean 70 years) with DXA BMD T-scores at either the hip or spine in the range of ?1.5 to ?3.5. Wedge, biconcavity, and crush deformities were computed on the basis of spine MRI. Vertebral fractures were assessed using Eastell's criterion. Distal tibia and radius stiffness was computed using MRI-based finite element analysis. BMD at the distal extremities were obtained using pQCT.

Results

Several distal extremity MRI and pQCT measures showed negative association with vertebral deformity on the basis of single parameter correlation (r up to 0.67) and two-parameter regression (r up to 0.76) models involving MRI stiffness and pQCT BMD. Subjects who had at least one prevalent vertebral fracture showed decreased MRI stiffness (up to 17.9 %) and pQCT density (up to 34.2 %) at the distal extremities compared to the non-fracture group. DXA lumbar spine BMD T-score was not associated with vertebral deformities.

Conclusions

The association between vertebral deformities and distal extremity measures supports the notion of postmenopausal osteoporosis as a systemic phenomenon.     

Vertebral fracture assessment in healthy men: prevalence and risk factors

IntroductionVertebral fracture assessment (VFA) is a technology that can reliably and accurately diagnose vertebral fractures with greater patient convenience, less radiation exposure, and lower cost than standard spine radiography.ObjectiveTo study prevalence and risk factors of vertebral fractures using VFA in healthy men.MethodsThe study cohort consists of a population of 216 healthy men aged between 50 and 79 (mean age, weight and BMI of 63.8 years, 73.3 kg and 25.7 kg/m², respectively). Lateral VFA images and scans of the lumbar spine and proximal femur were obtained by two technologists using a GE Healthcare Lunar Prodigy densitometer. Vertebral fractures were defined using a combination of Genant semiquantitative (SQ) approach and morphometry.ResultsNinety-three percent of vertebrae from T4–L4 and 98% from T8–L4 were adequately visualized on VFA. Vertebral fractures were detected in 29.6% (64/216) of these men: 34/216 (15.7%) had grade 1 and 30/216 (13.8%) had grades 2 or 3. Twenty one of men with VFA-identified fracture (32.8%) had only a single vertebral fracture, while the other 67.2% had two or more. Fractures were most common in the mid-thoracic spine and at the thoraco-lumbar junction. As would be expected, the prevalence of VFA-detected fractures increased with age and as BMD declined. This group of men had a statistically significant lower weight, height, calcium consumption and T-score than those without a VFA-identified vertebral fracture. Regression analysis showed that presence of vertebral fracture was mainly related to the osteoporotic status (OR: 9.0; 95% CI: 3.5–22.8).ConclusionVFA allows evaluation of the majority of vertebral bodies in men. Vertebral fractures are common in healthy men and are related to low BMD.     

Prediction of new clinical vertebral fractures in elderly men using finite element analysis of CT scans

Vertebral strength, as estimated by finite element analysis of computed tomography (CT) scans, has not yet been compared against areal bone mineral density (BMD) by dual‐energy X‐ray absorptiometry (DXA) for prospectively assessing the risk of new clinical vertebral fractures. To do so, we conducted a case‐cohort analysis of 306 men aged 65 years and older, which included 63 men who developed new clinically‐identified vertebral fractures and 243 men who did not, all observed over an average of 6.5 years. Nonlinear finite element analysis was performed on the baseline CT scans, blinded to fracture status, to estimate L1 vertebral compressive strength and a load‐to‐strength ratio. Volumetric BMD by quantitative CT and areal BMD by DXA were also evaluated. We found that, for the risk of new clinical vertebral fracture, the age‐adjusted hazard ratio per standard deviation change for areal BMD (3.2; 95% confidence interval [CI], 2.0–5.2) was significantly lower (p < 0.005) than for strength (7.2; 95% CI, 3.6–14.1), numerically lower than for volumetric BMD (5.7; 95% CI, 3.1–10.3), and similar for the load‐to‐strength ratio (3.0; 95% CI, 2.1–4.3). After also adjusting for race, body mass index (BMI), clinical center, and areal BMD, all these hazard ratios remained highly statistically significant, particularly those for strength (8.5; 95% CI, 3.6–20.1) and volumetric BMD (9.4; 95% CI, 4.1–21.6). The area‐under‐the‐curve for areal BMD (AUC = 0.76) was significantly lower than for strength (AUC = 0.83, p = 0.02), volumetric BMD (AUC = 0.82, p = 0.05), and the load‐to‐strength ratio (AUC = 0.82, p = 0.05). We conclude that, compared to areal BMD by DXA, vertebral compressive strength and volumetric BMD consistently improved vertebral fracture risk assessment in this cohort of elderly men. © 2012 American Society for Bone and Mineral Research.     

Clinical predictors of incipient vertebral fractures and bone mineral density in kidney transplant patients

Purpose

Kidney transplant recipients are prone to metabolic bone diseases and consequent fractures. This study aimed to evaluate the incidence of incipient vertebral fractures, osteopenia, osteoporosis, and the clinical factors associated with incipient vertebral fractures in a group of kidney transplant patients.

Methods

Two hundred sixty-four patients (F/M 124/140, 45.3 ± 13 years) who had undergone kidney transplantation in tertiary care centers were included. Vertebral fractures were assessed semiquantitatively using conventional thoracolumbar lateral radiography in 202 of the patients.

Results

Vertebral fractures were observed in 56.4% (n = 114) of the study group. The frequency of osteoporosis was 20.0% (53 of 264 patients), and osteopenia was 35.6% (94 of 264 patients). Bone mineral density (BMD) levels were in the normal range in 40.3% (n = 46) of the subjects with vertebral fractures. It was in the osteoporotic range in 20.1% (n = 23) and the osteopenic range in 40.3% (n = 46). Vertebral fractures were associated with age, duration of hemodialysis, BMI, and femoral neck Z score (R² 37.8%, p = 0.027).

Conclusion

As incipient vertebral fractures can be observed in patients with normal BMD levels in kidney transplant recipients, conventional X-ray screening for vertebral fractures may be beneficial for a proper therapy decision of metabolic bone disease in kidney transplant recipients.

     

Vertebral dimensions as risk factor of vertebral fracture in osteoporotic patients: a systematic literature review

Summary This systematic literature review studied the potential association between vertebral fracture risk and vertebral dimensions. Analysis showed that patients with vertebral fractures have smaller non-fractured vertebrae than patients without fractures. Vertebral size is an independent risk factor of vertebral fractures. Introduction Biomechanical factors such as vertebral dimensions may be a risk factor for vertebral fractures beside bone mineral density (BMD). The objective of this study was to evaluate potential association of vertebral size and shape with osteoporotic fracture risk through a systematic literature review. Methods Systematic analysis of published reports comparing vertebral dimensions of patients with and without osteoporotic fractures was performed. Data sources were electronic databases. Data extraction included methods, site, reproducibility and results of vertebral measurement, study population characteristics. It was noted if populations were matched or data were adjusted for age, height, weight and BMD. Results Of 634 reports identified by the literature search, the final review included 13 reports studying 4,428 women and 508 men; median age 64.2 years [range 51.7%–73.0%]. Measurements were performed with computed tomography scan, X-ray, or dual energy X-ray absorptiometry. Vertebral body height, width, depth, area, cross-sectional area (CSA), and volume were 5.5% to 9.5% smaller in fractured group than control group. After adjustment for confounding factors, area, CSA and volume were, respectively, 10.2% [range 7.1%–13.3%], 7.7% [range 1.2%–14.2%] and 9.5% [8.5%–10.5%] smaller in fractured group. Conclusions Vertebral size should be considered as a potential independent vertebral fracture risk factor.     

Bone Mineral Density and Bone Size in Men With Primary Osteoporosis and Vertebral Fractures

The bone mineral density (BMD) at the lumbar spine, proximal femur, and total skeleton was evaluated in 38 men with primary osteoporosis and vertebral fractures. BMD of the patients was significantly reduced over all skeletal areas compared with controls. The Z-score of the lumbar spine (−2.8 ± 0.9) was less than that of the other areas (P < 0.001) except the legs (−2.5 ± 1.1) (p.n.s.) showing that bone loss had a tendency to be greater over the axial skeleton. Vertebral dimensions compared with age-matched controls were as follows: projected L2–L4 area (cm 2): 45.7 ± 5.6 versus 53.7 ± 3.6 (P < 0.001); vertebral width (cm): 4.37 ± 0.44 versus 4.90 ± 0.36 (P < 0.001). Serum biochemical parameters and testosterone levels were similar between osteoporotic and control men. We conclude that men with vertebral osteoporotic fractures have reduced vertebral BMD and vertebral dimensions compared with age-matched controls. Thus, these findings indicate that the achievement of a reduced bone size at the end of the growth period or a failure of periosteal increase during adult life is likely to contribute to the pathogenesis of the vertebral fractures observed in older men. Received: 31 January 1997 / Accepted: 2 July 1997     

Risk factors for a first-incident radiographic vertebral fracture in women > or = 65 years of age: the study of osteoporotic fractures.

Vertebral fractures in older women signal an increased risk of additional osteoporotic fractures. To identify risk factors for first vertebral fractures, we studied 5822 women > or =65 years of age who had no fracture on baseline radiographs of the spine. Several modifiable risk factors increased an older woman's risk of developing a first vertebral fracture, and women with multiple risk factors and low BMD had the highest risk. Risk factors and low BMD should be useful to help focus efforts to prevent these fractures. INTRODUCTION: Vertebral fractures are a common cause of back pain and disability and signal an increased risk of additional osteoporotic fractures in older women. Little is known about the risk factors for the first occurrence of a vertebral fracture. MATERIALS AND METHODS: To identify risk factors for a first vertebral fracture, we studied 5822 women > or =65 years of age from the Study of Osteoporotic Fractures who had no fracture on baseline radiographs of the spine. We measured potential risk factors and BMD of the wrist and calcaneus at baseline and BMD of the spine and hip halfway through follow-up. Fractures were assessed by standard methods from spine radiographs obtained at baseline and follow-up an average of 3.7 years later. RESULTS AND CONCLUSIONS: In multivariable analyses, older age, previous nonspine fracture, low BMD at all sites, a low body mass index (BMI), current smoking, low milk consumption during pregnancy, low levels of daily physical activity, having a fall, and regular use of aluminum-containing antacids independently increased the risk of a first vertebral fracture. Women using estrogen and those who engaged in recreational physical activity had a decreased risk. The effects of low BMI, smoking, use of estrogen and antacids, and previous fracture were partially mediated by BMD. Women in the lower third of wrist BMD with five or more risk factors had a 12-fold greater risk than women in the highest third of BMD who had zero to three risk factors. The 27% of women at highest risk suffered 60% of the incident fractures. In conclusion, several modifiable risk factors and BMD independently increase an older woman's risk of developing a first vertebral fracture. The combination of risk factors and BMD should be useful for focusing efforts to prevent vertebral fractures.     

Women with low-energy fracture should be investigated for osteoporosis

Introduction?Treatment of osteoporosis is becoming more effective, but methods to identify patients who are most suitable for investigation and treatment are still being debated. Should any type of fracture have higher priority for investigation of osteoporosis than any other? Is the number of previous fractures useful information?

Material and methods?We investigated 303 consecutive women patients between 55 and 75 years of age who had a newly diagnosed low-energy fracture. They answered a questionnaire on previous fractures which also dealt with risk factors. Bone mineral density (BMD) was measured at the hip, lumbar spine, and forearm.

Results?The distribution of fracture location was: distal forearm 56%, proximal humerus 12%, vertebra 18%, and hip 13%, all with similar age. Half of the subjects had had at least one previous fracture before the index fracture, 19% had had two previous fractures, and 6% had had three or more previous fractures. Patients with vertebral or hip fracture had lower BMD and had had more previous fractures than patients with forearm or humerus fractures. There was an inverse correlation between number of fractures and BMD. Osteoporosis was present in one-third of patients with forearm fracture, in one-half of those with hip or humerus fracture, and in two-thirds of those with vertebral fracture.

Interpretation?Vertebral fractures were the strongest marker of low BMD and forearm fractures the weakest. The number of previous fractures is helpful information for finding the most osteoporotic patient in terms of severity. Investigation of osteoporosis therefore seems warranted in every woman between the ages of 55 and 75 with a recent low-energy fracture, with highest priority being given to those with vertebral, hip, or multiple fractures.     

Vertebral fractures in males with type 2 diabetes treated with rosiglitazone

ObjectiveTo investigate the relationship between osteoporotic vertebral fractures and rosiglitazone treatment and the influence on this association of bone mineral density (BMD) and duration of diabetes.Research design and methodsIn this cross-sectional study, we evaluated BMD by DXA and the prevalence of radiological vertebral fractures identified by a quantitative morphometric analysis in 43 males with type 2 diabetes under metformin alone (22 cases) or associated with rosiglitazone (21 cases) and in 22 control non-diabetic subjects attending an out-patient bone clinic.ResultsVertebral fractures were found in 46.5% of diabetic males (p = 0.06 vs. control subjects) with higher prevalence in patients treated with rosiglitazone plus metformin as compared with those under treatment with metformin alone (66.7% vs. 27.3%; p = 0.01). The patients on rosiglitazone plus metformin were significantly younger and with greater body mass index (BMI). Multivariate logistic regression analysis demonstrated that rosiglitazone plus metformin treatment maintained the significant correlation with the occurrence of vertebral fractures (odds ratio 6.5, C.I. 1.3–38.1, p = 0.03) even after correction for age and BMI. Within the rosiglitazone-exposed group, the occurrence of vertebral fractures was not correlated with BMD, age, duration of diabetes, duration of medical treatment, dose of rosiglitazone, serum glycosylated hemoglobin and total testosterone values.ConclusionsThe use of rosiglitazone is associated with an increased prevalence of vertebral fractures in males with type 2 diabetes. These findings call for a wide screening of bone status in diabetic patients treated with rosiglitazone and the use of spine X-ray in combination with DXA in this assessment.     

Physical Performance and Radiographic and Clinical Vertebral Fractures in Older Men

In men, the association between poor physical performance and likelihood of incident vertebral fractures is unknown. Using data from the MrOS study (N = 5958), we describe the association between baseline physical performance (walking speed, grip strength, leg power, repeat chair stands, narrow walk [dynamic balance]) and incidence of radiographic and clinical vertebral fractures. At baseline and follow‐up an average of 4.6 years later, radiographic vertebral fractures were assessed using semiquantitative (SQ) scoring on lateral thoracic and lumbar radiographs. Logistic regression modeled the association between physical performance and incident radiographic vertebral fractures (change in SQ grade ≥1 from baseline to follow‐up). Every 4 months after baseline, participants self‐reported fractures; clinical vertebral fractures were confirmed by centralized radiologist review of the baseline study radiograph and community‐acquired spine images. Proportional hazards regression modeled the association between physical performance with incident clinical vertebral fractures. Multivariate models were adjusted for age, bone mineral density (BMD, by dual‐energy X‐ray absorptiometry [DXA]), clinical center, race, smoking, height, weight, history of falls, activity level, and comorbid medical conditions; physical performance was analyzed as quartiles. Of 4332 men with baseline and repeat radiographs, 192 (4.4%) had an incident radiographic vertebral fracture. With the exception of walking speed, poorer performance on repeat chair stands, leg power, narrow walk, and grip strength were each associated in a graded manner with an increased risk of incident radiographic vertebral fracture (p for trend across quartiles <0.001). In addition, men with performance in the worst quartile on three or more exams had an increased risk of radiographic fracture (odds ratio [OR] = 1.81, 95% confidence interval [CI] 1.33–2.45) compared with men with better performance on all exams. Clinical vertebral fracture (n =149 of 5813, 2.6%) was not consistently associated with physical performance. We conclude that poorer physical performance is associated with an increased risk of incident radiographic (but not clinical) vertebral fracture in older men. © 2014 American Society for Bone and Mineral Research.     

Measurement of bone mineral density at the spine and proximal femur by volumetric quantitative computed tomography and dual-energy X-ray absorptiometry in elderly women with and without vertebral fractures.

The goal of this study was to determine the effect of vertebral fracture status on trabecular bone mineral density (BMD) measurements obtained in the proximal femur and spine by helical volumetric quantitative computed tomography (vQCT). The study population consisted of 71 Italian women (average age 73 +/- 6) years. This group included 26 subjects with radiographically confirmed atraumatic vertebral fractures and 45 controls. The subjects received helical CT scans of the L1 and L2 vertebral bodies and the hip. The three-dimensional CT images were processed using specialized image analysis algorithms to extract measurements of trabecular, cortical, and integral BMD in the spine and hip. To compare the vQCT results with the most widely used clinical BMD measurement, dual X-ray absorptiometry (DXA) scans of the anteroposterior (AP) spine and proximal femur were also obtained. The difference between the subjects with vertebral fractures and the age-matched controls was computed for each BMD measure. All BMD measurements showed statistically significant differences, which ranged from 7% to 22% between subjects with fractures and controls. Although, given our small sample size, we could not detect statistically significant differences in discriminatory power between BMD techniques, integral BMD of the spine measured by vQCT and DXA tended to show stronger associations with fracture status (0.001 < p < 0.004). Measurements by QCT and DXA at the hip were also associated with vertebral fracture status, although the association of DXA BMD with fracture status was explained largely by differences in body weight between subjects with vertebral fractures and controls.     

Association of Visceral and Subcutaneous Fat Mass With Bone Density and Vertebral Fractures in Women With Severe Obesity

Introduction: The aim of this study was to evaluate the association of visceral and subcutaneous adipose tissue with bone mineral density (BMD), geometric indices of femoral neck strength and vertebral fractures in pre- and postmenopausal women with severe obesity. Methods: A cross-sectional study was conducted with pre- (n = 37) and postmenopausal (n = 21) women with body mass index higher than 40 kg/cm². BMD at total body, lumbar spine, hip and forearm, presence of vertebral fractures, lean mass, visceral, and subcutaneous adipose tissue were assessed by DXA. Geometric indices of femoral neck strength were calculated by DXA. Serum bone turnover markers (CTX and osteocalcin) and 25(OH)D were also measured. Results: BMD at all studied sites was similar in pre- and postmenopausal women. In postmenopausal women, total subcutaneous adipose tissue was inversely associated with BMD at total femur (β = −0.009; 95% confidence interval [CI] −0.017; −0.002) and with strength index (β = −0.03; 95% CI −0.04; −0.01). In premenopausal women, visceral adipose tissue was inversely associated with cross-sectional moment of inertia (β = −0.95; 95%CI −1.89; −0.01). Vertebral fractures were highly prevalent in premenopausal (32%), and even more frequent among postmenopausal women (55%). Conclusion: Taken together, our results suggest that both visceral and subcutaneous fat may be detrimental for bone health in pre- and postmenopausal women, and that severe obesity may increase the risk of vertebral fractures, even in young women.     

Ex vivo estimation of thoracolumbar vertebral body compressive strength: The relative contributions of bone densitometry and vertebral morphometry

The estimation of vertebral fracture risk in individuals with suspected osteopenia is commonly based on measurements of lumbar spine bone density. The efficacy of vertebral size and deformity, as assessed by vertebral morphometry, in the prediction of fractures has been less studied. In an ex vivo investigation the regional relationships between vertebral size, vertebral deformity, bone density and compressive strength throughout the thoracolumbar spine were examined. In 16 vertebral columns (T1–L5) the bone mineral content (BMC) and bone mineral density (BMD) of each segment were measured using lateral projection dual-energy X-ray absorptiometry, and the vertebral cancellous density (VCD) and mid-vertebral cross-sectional area (CSA) measured using quantitative computed tomography. Vertebral body heights were determined from mid-sagittal CT scans, and vertical height ratios calculated for each segment. The failure load and failure stress of the isolated vertebral bodies were determined using a material testing device. Separate analyses were performed for the upper (T1–4), middle (T5–8) and lower (T9–12) thoracic, and lumbar (L1–5) segments. In all regions, failure load was strongly correlated with BMD (r=0.82–0.86), moderately correlated with VCD (r=0.60–0.71) and vertebral height (r=0.22–0.49), and poorly correlated with the height ratios (r=0.04–0.33). Failure stress was best predicted by BMD (r=0.73–0.78) and VCD (r=0.70–0.78) but was poorly correlated with all morphometric variables (r=0.01–0.33). The segmental correlations between BMD and VCD ranged fromr=0.49 tor=0.79. For all regions, BMD and VCD were included in the stepwise regression models for predicting failure load and failure stress. Either the mid-vertebral height or CSA were included in all the failure load models, while mid-vertebral height was included in only one of the failure stress models. The results suggest that vertebral deformity and size (as assessed by vertebral morphometry) make only a minor contribution to the prediction of vertebral strength additional to that provided by bone densitometry alone. The consistent regional relationships between variables appear to support the practice of global fracture risk assessment based on lumbar spine densitometry.     

Relative strength of thoracic vertebrae in axial compression versus flexion

Background contextNoninvasive strength assessment techniques are the clinical standard in the diagnosis and treatment of osteoporotic vertebral fractures, and the efficacy of these protocols depends on their ability to predict vertebral strength at all at-risk spinal levels under multiple physiological loading conditions.PurposeTo assess differences in vertebral strength between loading modes and across spinal levels.Study design/settingThis study examined the relative strength of isolated vertebral bodies in compression versus flexion.MethodsDestructive biomechanical tests were conducted on 30 pairs of donor-matched, isolated thoracic vertebral bodies (T9 and T10; F=19, M=11; 87+5 years old, max=97 years old, min=80 years old) in both uniform axial compression and flexion using previously described protocols. Quantitative computed tomography (QCT) scans were taken before mechanical testing and used to obtain bone mineral density (BMD) and “mechanics of solids” (MOS) measures, such as axial and bending rigidities.ResultsCompressive strength was higher than flexion strength for each donor by 940+152 N (p<.001, paired t test), and vertebral strengths in the two loading modes were moderately correlated (adjusted R²=0.50, p<.001). For both compression and flexion loading modes, adjacent-level BMD and MOS metrics had approximately half the predictive capacity as same-level measurements, and BMD and MOS values were only moderately correlated across spinal levels.ConclusionsThe results of this study are important in designing clinical test protocols for assessing vertebral fracture risk. Because vertebral body flexion and compressive strength are not strongly correlated and flexion strength is significantly less than compressive strength, it is imperative to investigate a patient's spinal structural capacity under bending loading conditions. Furthermore, our work suggests that clinicians using QCT-based measures should perform site-specific strength assessments on each at-risk spinal level. Future work should focus on improving the accuracy of densitometric measures in predicting vertebral strength in flexion and also on examining same- versus adjacent-level strength assessment for radiographic techniques with lower X-ray dosage, such as dual-energy X-ray absorptiometry.     

骨水泥椎间渗漏与椎体成形术术后再发椎体压缩骨折相关性研究

目的 评估骨水泥椎间渗漏与椎体成形术（percutaneous vertebroplasty,PVP）术后再发椎体压缩骨折风险的相关性.方法对2009年6月～2011年6月行PVP手术治疗的153例骨质疏松性椎体压缩骨折患者进行回顾性研究,根据椎体再发骨折情况分为再发骨折组与对照组,记录2组患者骨密度、骨水泥注射量与骨水泥椎间隙渗漏情况.结果共124例患者（148个椎体）获得完整随访,平均随访18个月;24例患者（32个椎体）再发椎体压缩骨折.再发椎体压缩骨折患者骨水泥椎间渗透率为25.0%（6/24）与对照组的21.0%（21/100）差异无统计学意义（P＞0.05）.再发椎体压缩骨折患者骨密度低于对照组,差异有统计学意义（P＜0.05）.结论 骨水泥椎间渗漏并不增加PVP术后再发椎体压缩骨折风险,低骨密度是再发椎体骨折的危险因素.     

胸腰椎爆裂骨折椎体后壁与椎弓根关系的CT观察

目的探讨胸腰椎(T11~L2)爆裂骨折(thoracolumbar burst fracture,TLBF)椎体后壁与椎弓根的关系及临床意义。方法根据CT扫描观察伤椎椎体后壁与椎弓根的联系并将其分为5种类型,通过X线片测量各型椎体前缘的压缩百分比、后凸Cobb角,CT薄层横断面扫描测量各种类型椎管占位程度,MRI评估各类型后方韧带复合体的损伤情况,对各种类型的脊髓损伤程度按美国脊髓损伤协会(American spinal injury association,ASIA)标准分级,分析椎体后壁与椎弓根的关系及其与各观察指标的相关性。结果本组患者100例,A型19例;B型9例;C型10例;D型35例;E型27例,除无连接型外完整及部分连接共73例。A~D型与E型ASIA分级比较差异有统计学意义,即椎体后壁与双侧椎弓根无联系的患者脊髓损伤更严重,A~D型椎体后壁与椎弓根完全或部分相连对脊髓有较好的保护作用。椎体后壁与双侧椎弓根或单侧椎弓根连接的患者椎管占位程度较轻,而椎体后壁与双侧椎弓根无连接及与椎弓根上方/下方皮质连接的患者椎管占位程度较重。结论大多数TLBF患者椎体后壁与椎弓根有完整及部分连接,椎体后壁与椎弓根有连接的患者脊柱生物力学更稳定。     

Heritability of prevalent vertebral fracture and volumetric bone mineral density and geometry at the lumbar spine in three generations of the Framingham study

Genetic factors likely contribute to the risk for vertebral fractures; however, there are few studies on the genetic contributions to vertebral fracture (VFrx), vertebral volumetric bone mineral density (vBMD), and geometry. Also, the heritability (h²) for VFrx and its genetic correlation with phenotypes contributing to VFrx risk have not been established. This study aims to estimate the h² of vertebral fracture, vBMD, and cross‐sectional area (CSA) derived from quantitative computed tomography (QCT) scans and to estimate the extent to which they share common genetic association in adults of European ancestry from three generations of Framingham Heart Study (FHS) families. Members of the FHS families were assessed for VFrx by lateral radiographs or QCT lateral scout views at 13 vertebral levels (T₄ to L₄) using Genant's semiquantitative (SQ) scale (grades 0 to 3). Vertebral fracture was defined as having at least 25% reduction in height of any vertebra. We also analyzed QCT scans at the L₃ level for integral (In.BMD) and trabecular (Tb.BMD) vBMD and CSA. Heritability estimates were calculated, and bivariate genetic correlation analysis was performed, adjusting for various covariates. For VFrx, we analyzed 4099 individuals (148 VFrx cases) including 2082 women and 2017 men from three generations. Estimates of crude and multivariable‐adjusted h² were 0.43 to 0.69 (p < 1.1 × 10^?2). A total of 3333 individuals including 1737 men and 1596 women from two generations had VFrx status and QCT‐derived vBMD and CSA information. Estimates of crude and multivariable‐adjusted h² for vBMD and CSA ranged from 0.27 to 0.51. In a bivariate analysis, there was a moderate genetic correlation between VFrx and multivariable‐adjusted In.BMD (?0.22) and Tb.BMD (?0.29). Our study suggests vertebral fracture, vertebral vBMD, and CSA in adults of European ancestry are heritable, underscoring the importance of further work to identify the specific variants underlying genetic susceptibility to vertebral fracture, bone density, and geometry. © 2012 American Society for Bone and Mineral Research.     

Risk factors for prevalent vertebral fractures in black and white female densitometry patients.

This cross-sectional study compared risk factors for prevalent vertebral fractures (diagnosed using densitometric spine image Vertebral Fracture Assessment [VFA]) in 176 black and 345 white women recruited during their clinical bone mineral density (BMD) testing at the University of Chicago Hospitals. We used logistic regression to assess the association of prevalent vertebral fractures and risk factors (age, height loss, history of nonvertebral fractures, BMD, and use of corticosteroids). The prevalence of vertebral fractures was 21% for both races. All risk factors of interest were significantly associated with vertebral fractures in white women. Among black women, only age and corticosteroid use were found to be significant predictors of presence of vertebral fracture(s). In women without history of corticosteroid use, the probability of having vertebral fracture(s) given age was lower (p=0.02) in black subjects. In 77 patients with a history of corticosteroid use, the probability of having vertebral fracture(s) was higher in black than in white women after adjustment for age (p=0.045), BMD (p=0.045), or cumulative corticosteroid dose (p=0.08). Fewer black women were prescribed pharmacologic therapy for osteoporosis, regardless of their BMD level and corticosteroid use. We conclude that use of corticosteroids may be associated with relatively greater vertebral fracture risk in blacks than in whites.     

The degree of osteoporosis in patients with vertebral fracture and patients with hip fracture: Relationship to incidence of vertebral fracture

The most typical fracture that occurs in osteoporotic patients is a vertebral fracture, whereas hip fractures are thought to occur in the most severe osteoporotic patients. The purpose of this study was to compare the degree of osteoporosis between patients with vertebral fractures and patients with hip fracture by examining bone mineral density, biochemical markers of bone metabolism, and the incidence of vertebral fractures. Subjects were 50 female patients with vertebral fractures (VX) and 60 female patients with hip fracture (HX). Bone mineral densities (BMD) of the lumbar spine, femoral neck (Neck), and one-third of the radius were determined by DXA. Total and bone alkaline phosphatase, osteocalcin, N-MID osteocalcin, PICP, free deoxypyridinoline, and CTx were measured. All z-scores of BMD in the three areas of VX and HX patients were negative, meaning those BMDs were lower in VX and HX than a decade-matched normal reference. The z-score of Neck BMD was significantly lower in HX than in VX. Deoxypyridinoline and CTx were significantly higher in HX than in VX. N-MID osteocalcin was significantly lower in HX than in VX. VX and HX patients were divided into four subgroups according to the number of their vertebral fractures: VX, with a single fracture; VX, with multiple fractures; HX, without vertebral fractures; and HX, with vertebral fractures. VX with multiple fractures and HX with vertebral fractures had lower z-scores at all skeletal sites. HX with vertebral fractures had the lowest median z-score at spine and Neck, whereas HX without vertebral fractures had a low z-score only at Neck compared to VX with a single fracture. There was no significant difference in markers among the subgroups. The number of vertebral fractures was negatively correlated with z-scores of BMD at all three sites. We concluded that uncoupling between bone formation and resorption is greater in hip fractures than in vertebral fractures. Vertebral fractures are associated with general osteopenia of the total skeleton. We suggest that there are two types of osteoporosis in patients with hip fractures: one is that the bone mass of the femoral neck is specifically reduced, and the other is a terminal stage of osteoporosis which follows osteoporosis with vertebral fractures. Received: Aug. 24, 1998 / Accepted: Dec. 4, 1998     

Finite element models predict in vitro vertebral body compressive strength better than quantitative computed tomography

The correlation between bone mineral density and vertebral strength is not based on mechanical principles and thus the method cannot reflect the effects of subtle geometric features and densitometric inhomogeneities that may substantially affect vertebral strength. Finite element models derived from quantitative computed tomography (QCT) scans overcome such limitations. The overall goal of this study was to establish that QCT-based "voxel" finite element models are better predictors of vertebral compressive strength than QCT measures of bone mineral density with or without measures of cross-sectional area. QCT scans were taken of 13 vertebral bodies excised from 13 cadavers (L1-L4; age: 37-87 years; M = 6, F = 7) and used to calculate bone mineral density (BMD(QCT)). The QCT voxel data were converted into linearly elastic finite element models of each vertebra, from which measures of vertebral stiffness and strength were computed. The vertebrae were biomechanically tested in compression to measure strength. Vertebral strength was positively correlated with the finite element measures of strength (r(2) = 0.86, P < 0.0001) and stiffness (r(2) = 0.82, P < 0.0001), the product of BMD(QCT) and vertebral minimum cross-sectional area (r(2) = 0.65, P = 0.0008), and BMD(QCT) alone (r(2) = 0.53, P = 0.005). These results demonstrate that highly automated "voxel" finite element models are superior to correlation-based QCT methods in predicting vertebral compressive strength and therefore offer great promise for improvement of clinical fracture risk assessment.