The impact of degenerative conditions in the spine on bone mineral density and fracture risk prediction

The influence of osteoporosis on mechanical complications in lumbar fusion surgery: a systematic review

Background

Adults undergoing spine surgery often have underlying osteoporosis, which may be a risk factor for postoperative complications. Although these associations have been described, osteoporosis remains profoundly underdiagnosed and undertreated in the spine surgery population. A thorough, comprehensive systematic review summarizing the relationships between bone mineral density (BMD) and specific complications of lumbar fusion surgery could be a valuable resource for raising awareness and supporting clinical practice changes.

Methods

PubMed, Embase, and Web of Science databases were searched for original clinical research articles reporting on BMD, or surrogate measure, as a predictor of complications in adults undergoing elective lumbar fusion for degenerative disease or deformity. Endpoints included cage subsidence, screw loosening, pseudarthrosis, vertebral fracture, junctional complications, and reoperation.

Results

A total of 71 studies comprising 12,278 patients were included. Overall, considerable heterogeneity in study populations, methods of bone health assessment, and definition and evaluation of clinical endpoints precluded meta-analysis. Nevertheless, low BMD was associated with higher rates of implant failures like cage subsidence and screw loosening, which were often diagnosed with concomitant pseudarthrosis. Osteoporosis was also a significant risk factor for proximal junctional kyphosis, particularly due to fracture. Many studies found surgical site-specific BMD to best predict focal complications. Functional outcomes were inconsistently addressed.

Conclusions

Our findings suggest osteoporosis is a significant risk factor for mechanical complications of lumbar fusion. These results emphasize the importance of preoperative osteoporosis screening, which allows for medical and surgical optimization of high-risk patients. This review also highlights current practical challenges facing bone health evaluation in patients undergoing elective surgery. Future prospective studies using standardized methods are necessary to strengthen existing evidence, identify optimal predictive thresholds, and establish specialty-specific practice guidelines. In the meantime, an awareness of the surgical implications of osteoporosis and utility of preoperative screening can provide for more informed, effective patient care.

Clinical Use of Trabecular Bone Score: The 2023 ISCD Official Positions

Osteoporosis can currently be diagnosed by applying the WHO classification to bone mineral density (BMD) assessed by dual-energy x-ray absorptiometry (DXA). However, skeletal factors other than BMD contribute to bone strength and fracture risk. Lumbar spine TBS, a grey-level texture measure which is derived from DXA images has been extensively studied, enhances fracture prediction independent of BMD and can be used to adjust fracture probability from FRAX® to improve risk stratification. The purpose of this International Society for Clinical Densitometry task force was to review the existing evidence and develop recommendations to assist clinicians regarding when and how to perform, report and utilize TBS. Our review concluded that TBS is most likely to alter clinical management in patients aged ≥ 40 years who are close to the pharmacologic intervention threshold by FRAX. The TBS value from L1-L4 vertebral levels, without vertebral exclusions, should be used to calculate adjusted FRAX probabilities. L1-L4 vertebral levels can be used in the presence of degenerative changes and lumbar compression fractures. It is recommended not to report TBS if extreme structural or pathological artifacts are present. Monitoring and reporting TBS change is unlikely to be helpful with the current version of the TBS algorithm. The next version of TBS software will include an adjustment based upon directly measured tissue thickness. This is expected to improve performance and address some of the technical factors that affect the current algorithm which may require modifications to these Official Positions as experience is acquired with this new algorithm.

Risk factors associated with cervical spine lesions in patients with rheumatoid arthritis: an observational study

Background

Few reports have described the association between rheumatoid arthritis (RA) cervical lesions and osteoporosis, especially in patients with vertical subluxation (VS) that could be induced by the collapse of lateral masses in the upper cervical spine. Therefore, this study aimed to investigate the prevalence and risk factors for cervical lesions in patients with RA under current pharmacological treatments with biological agents, and to investigate the relationship between osteoporosis and VS development.

Methods

One hundred eighty-five consecutive patients with RA who underwent both cervical plain radiography and bone mineral density (BMD) scanning were enrolled. RA cervical lesions included atlantoaxial subluxation (AAS), VS, and subaxial subluxation (SAS). We assigned patients with AAS, VS, or SAS to the cervical-lesion group, and all other patients to the non-cervical-lesion group. Radiological findings, BMD, and clinical data on RA were collected. We used multivariate logistic regression analyses to assess the risk factors for cervical lesions in patients with RA.

Results

The cervical-lesion and non-cervical-lesion groups included 106 and 79 patients, respectively. There were 79 patients with AAS, 31 with VS, and 41 with SAS. The cervical-lesion group had a younger age of RA onset, longer RA disease duration, higher RA stage, and lower femoral neck BMD than the non-cervical-lesion group. Multivariate analyses showed that the risk factors for RA cervical lesions were prednisolone usage, biological agent usage, and higher RA stage. Prednisolone usage and femoral neck BMD were the risk factors for VS.

Conclusions

Cervical lesions were confirmed in 57 % of the patients. Prednisolone usage, biological agent usage, and higher RA stage were significant risk factors for cervical lesions in patients with RA. The general status of osteoporosis might contribute to the development of VS.

Prevalent and Incident Vertebral Deformities in Midlife Women: Results from the Study of Women's Health Across the Nation (SWAN)

BACKGROUND

Vertebral fractures are the most common type of osteoporotic fracture among women, but estimates of their prevalence and incidence during middle-age are limited. The development of vertebral morphometry (VM) using dual energy X-ray absorptiometry (DXA) makes it more feasible to measure VM in large, longitudinal, observational studies. We conducted this study to: 1) contribute to the scant knowledge of the prevalence, incidence and risk factors for vertebral deformities in middle-aged women; and 2) to evaluate the performance of DXA-based VM measurement in a large, community based sample.

METHODS

The sample is derived from the Study of Women's Health Across the Nation (SWAN), a multi-site, community-based, longitudinal cohort study of the MT. Using Hologic QDR 4500A instruments, we acquired initial VM measurements in 1446 women during calendar years 2004-2007; in 2012-2013, a follow-up VM was obtained in 1108. Annually, lumbar spine (LS) and femoral neck (FN) bone mineral density (BMD) were measured and participant characteristics were assessed with standardized instruments. Multivariable logistic regression models examined the relations between prevalent deformity and relevant characteristics. Analyses of characteristics associated with prevalent deformity were restricted to 824 women who had not taken bone active medications since SWAN baseline. We calculated incident deformity per person year (PY) of observation, standardized to 1000 person-years.

RESULTS

The cranial portion of the VM image yielded the lowest proportions of readable vertebrae: from T4 through T6, between 43% and 63% of vertebral bodies were evaluable. Greater BMI was associated with fewer readable levels (B = -0.088, p<0.0001). In the baseline sample of 1446 women, the prevalence of vertebral deformity was 3.2% (95% CI: 2.3, 4.1). The relative odds of deformity increased by 61% per SD decrement in baseline LS BMD (p = 0.02) and were 67% greater per SD decrement in baseline FN BMD (p = 0.04). Odds of prevalent deformity increased by 21% per year increment in age (p = 0.02). On average, 1108 women were followed for 6.8 years (SD 0.5 years, range 5.1-8.3 years) and we observed an incidence of 1.98 vertebral deformities per 1000 PY. In the longitudinal sample, 628 participants had never used bone active medications; their vertebral deformity incidence was 2.8 per 1000 PY.

CONCLUSION

Prevalence of vertebral deformity in SWAN participants aged 50-60 years was low and lower bone density at the LS and FN was strongly related to greater risk of prevalent deformity. Only about half of the vertebral levels between T4-T6 could be adequately imaged by DXA. Greater BMI is associated with fewer readable vertebral levels.

Comparisons of Different Screening Tools for Identifying Fracture/Osteoporosis Risk Among Community-Dwelling Older People

A prospective study was conducted to compare criterion, predictive, and construct validities of 9 fracture/osteoporosis assessment tools, including calcaneal quantitative ultrasonography (QUS), Age Bulk One or Never Estrogens (ABONE), body weight criterion (BWC), Fracture Risk Assessment Tool (FRAX), Garvan fracture risk calculator (GARVAN), Osteoporosis Risk Assessment Instrument (ORAI), Osteoporosis Index of Risk (OSIRIS), Osteoporosis Self-Assessment Tool for Asians (OSTA), and Simple Calculated Osteoporosis Risk Estimation (SCORE), among older men and women in Taiwan.Using the femoral neck dual-energy x-ray absorptiometry (DXA) T-score as an external criterion, the sensitivity, specificity, positive and negative predictive values, positive and negative likelihood ratios, and the area under the receiver operating characteristic curve (AUC) for each tool were calculated. The ability of these tools to predict injurious falls was examined. A principal component analysis was applied to understand whether these tools were measuring the same underlying construct.The FRAX, BWC, ORAI, OSIRIS, OSTA, and SCORE had AUCs of ≥0.8 in men, while the GARVAN, OSIRIS, OSTA, and SCORE had AUCs of ≥0.8 in women. The sensitivity, negative predictive value, and likelihood ratio of the ABONE, BWC, ORAI, OSIRIS, OSTA, and SCORE tools in both men and women were 100%, ≥90%, and 0.0, respectively; the specificity and positive predictive value and likelihood ratio were far from satisfactory. The GARVAN displayed the best predictive ability of a fall in both men (AUCs, 0.653-0.686) and women (AUCs, 0.560-0.567), despite being smaller in women. The 9 screening tools and 2 central DXA measurements assessed 5 different factors, while the ABONE, BWC, ORAI, OSIRIS, OSTA, and SCORE measured the same one.Simple self-assessment tools can serve as initial screening instruments to rule out persons who have osteoporosis; however, these tools may measure a different construct other than fracture/osteoporosis risk.

Additive association of vitamin D insufficiency and sarcopenia with low femoral bone mineral density in noninstitutionalized elderly population: the Korea National Health and Nutrition Examination Surveys 2009-2010

Vitamin D insufficiency and sarcopenia are crucial risk factors for osteoporosis. In a study of noninstitutionalized elderly subjects, we investigated the simultaneous effect of vitamin D and sarcopenia on bone mineral density (BMD) and found that sarcopenia was associated with low BMD in the femur, especially in those with suboptimal vitamin D levels.

INTRODUCTION

Although vitamin D insufficiency and sarcopenia are prevalent in the elderly population worldwide, their possible influence on BMD has not been determined. We aimed to investigate the different effect of vitamin D insufficiency and sarcopenia on BMD in the elderly Korean population.

METHODS

Individuals aged 60 or older were selected from those who participated in the Fourth and Fifth Korea National Health and Nutrition Examination Surveys conducted in 2009 and 2010; 1,596 males and 1,886 females were analyzed. Appendicular skeletal muscle mass (ASM) and BMD were assessed by dual-energy X-ray absorptiometry; serum 25-hydroxyvitamin D [25(OH)D] and a panel of clinical and laboratory parameters were also measured.

RESULTS

The study population was divided into four groups according to their vitamin D and sarcopenic status. BMD in total femur and in the femoral neck but not the lumbar spine was markedly decreased in sarcopenic subjects with vitamin D insufficiency [25(OH)D < 20 ng/ml] comparing to other groups, regardless of gender. Multivariable linear regression models showed that BMD was significantly associated with ASM and high daily calcium intake as well as conventional risk factors such as age, body mass index (BMI), and history of fracture. Independent predictors for low femur BMD included sarcopenia, low daily calcium intake, low 25(OH)D levels, age, and BMI.

CONCLUSIONS

These data showed that an association between vitamin D insufficiency and low BMD was more prominent in elderly subjects with sarcopenia.

Degenerative spondylolisthesis is associated with low spinal bone density: a comparative study between spinal stenosis and degenerative spondylolisthesis

Spinal stenosis and degenerative spondylolisthesis share many symptoms and the same treatment, but their causes remain unclear. Bone mineral density has been suggested to play a role. The aim of this study was to investigate differences in spinal bone density between spinal stenosis and degenerative spondylolisthesis patients. 81 patients older than 60 years, who underwent DXA-scanning of their lumbar spine one year after a lumbar spinal fusion procedure, were included. Radiographs were assessed for disc height, vertebral wedging, and osteophytosis. Pain was assessed using the Low Back Pain Rating Scale pain index. T-score of the lumbar spine was significantly lower among degenerative spondylolisthesis patients compared with spinal stenosis patients (−1.52 versus −0.52, P = 0.04). Thirty-nine percent of degenerative spondylolisthesis patients were classified as osteoporotic and further 30% osteopenic compared to only 9% of spinal stenosis patients being osteoporotic and 30% osteopenic (P = 0.01). Pain levels tended to increase with poorer bone status (P = 0.06). Patients treated surgically for symptomatic degenerative spondylolisthesis have much lower bone mass than patients of similar age treated surgically for spinal stenosis. Low BMD might play a role in the development of the degenerative spondylolisthesis, further studies are needed to clarify this.

Intervertebral T-score differences in younger and older women

The T-score discordance among skeletal sites is an important aspect of dual-energy X-ray absorptiometry (DXA) measurements. In the spine, large T-score differences between vertebrae are frequently seen in elderly patients owing to degenerative disease. However, it is unclear how often such differences occur in younger adults with healthy spines. The T-scores for individual lumbar vertebrae were compared for 2391 female singletons (18-79 yr) recruited to the Twins UK Adult Twin Register. Women were divided into 6 age bands and 5 bands by body weight, respectively, and the T-score differences between the pairs of vertebrae were examined using correlation coefficients and the standard error of the estimate (SEE) from linear regression analysis. Correlations between the T-scores for adjacent lumbar vertebrae were r = 0.92 decreasing to r = 0.79 between L1 and L4. When plotted as a function of age, r-values were constant for the 5 younger age bands, but decreased in the oldest group. In contrast, the T-score SEE values increased progressively with age from 0.4 to 0.5 for the younger groups to 0.7 for the oldest. Similar trends were seen when women were divided according to body weight. Both increasing age and higher body weight were statistically significantly associated with a higher T-score SEE. The incidence of large T-score differences between vertebrae varies with age and body weight, but is common even among younger women. Clinically significant T-score differences can occur in the absence of osteoarthritis, and visual assessment of spine DXA scans for evidence of degenerative disease is advised before vertebrae are omitted from scan analyses.

Evaluation of bone mineral density in patients with chronic low back pain

Study Design

This was designed as a retrospective study.

Purpose

We investigated the relationship between bone mineral density (BMD) and chronic lower back pain (LBP).

Overview of Literature

In spite of a large number of epidemiological surveys on the prevalence of LBP and BMD measurements completed separately in the general population, the relationship between the two has not been well documented.

Methods

The study included 171 patients with chronic LBP who underwent the BMD study. The control group was selected from our database regarding BMD without LBP.

Results

A total of 678 subjects, aged 18 to 100 years (mean, 49.9±12.9 years) were included in the study, 25% (n=171) of the subjects had LBP. Compared to those patients without LBP, patients exhibiting LBP had statistically significant lower mean weight, hip and spine BMD and T-score. Lower BMD and T-scores were significant regardless of the age group, gender, menopausal status, and obesity classification.

Conclusions

Chronic LBP has a negative correlation with hip and spine bone mineral density.

Positioner and clothing artifact can affect one-third radius bone mineral density measurement

This report identifies a radius dual-energy X-ray absorptiometry (DXA) confounder and technical approach to avoid this inaccuracy. Initially, a precision study revealed substantial differences (p<0.001) in radius bone mineral density (BMD) least significant change ranging from 0.038 to 0.073g/cm(2) between 3 technologists that each performed assessments in 30 men and 30 women. Subsequently, visual examination of all 360 forearm DXA images, including bone, soft tissue, neutral, and air point-typing was performed. Errors in automated "soft tissue" identification were observed; compared with the manufacturer's ideal depiction, suboptimal soft tissue point-typing was present in 30/360 scans (8.3%) involving 27 individuals. These point-typing deviations appeared to result from inclusion of forearm positioner slots at the scan field edges or clothing covering the forearm. Twenty-four individuals had a paired scan appropriately point-typed, thus allowing evaluation of the effect on BMD measurement. In those with incorrect point-typing associated with positioner slots, the mean one-third radius BMD was ∼7% higher. In conclusion, positioner slots at the edges of the distal scan field can lead to automated soft tissue identification inaccuracies and consequent erroneous one-third radius BMD measurement. DXA technologists should avoid slot inclusion in forearm scans and evaluate point-typing as part of routine analysis.

A European multicenter comparison of quantitative ultrasound measurement variables: the OPUS study

Quantitative ultrasound (QUS) measurement variables vary between European countries in a different way to hip bone mineral density. Standardization of data can be achieved through statistical approaches to reduce any between-center differences in QUS measurement variables. However, further validation of this method is required before it can be widely applied.

INTRODUCTION

European between-center differences in hip bone mineral density (BMD) have been shown to exist; however, little is known about the geographical heterogeneity of QUS measurement variables. We aimed to examine the differences in QUS variables between three different European countries.

METHODS

Five calcaneal and phalangeal QUS devices in Sheffield, Aberdeen (UK), Kiel and Berlin (Germany), and three devices in Paris (France) were used to measure QUS variables in younger (n = 463, 20-39 years old) and older (n = 2,399, 55-79 years old) women participating in the European multicenter Osteoporosis and Ultrasound (OPUS) study. Broadband ultrasound attenuation, speed of sound, stiffness index, amplitude-dependent speed of sound, bone transmission time, and ultrasonic bone profiler index data were collected. Between-center differences were examined using ANOVA followed by post hoc Fisher's least significant difference tests, and ANCOVA with linear contrasts. p < 0.05 indicated statistical significance.

RESULTS

Between-center differences in nonstandardized QUS measurement variables existed for younger (p = 0.0023 to p < 0.0001) and older women (p < 0.001). Anthropometric characteristics exerted a significant influence on nonstandardized data (p = 0.045 to p < 0.001). However, following statistical standardization, based on height and weight or based on measurements made in young people, geographical heterogeneity in QUS measurement variables was no longer apparent.

CONCLUSIONS

QUS measurement variables vary between European countries in a different way to those for hip BMD. Standardization of data can be achieved through statistical approaches to reduce any between-center differences in QUS measurement variables. However, further validation of this method is required before it can be widely applied.

Regional distribution of spine and hip QCT BMD responses after one year of once-monthly ibandronate in postmenopausal osteoporosis

In the published placebo-controlled Ibandronate Quality (IQ) study, 12 months of once-monthly oral ibandronate increased femoral and vertebral integral and trabecular bone mineral density (BMD) measured by quantitative computed tomography (QCT). Ibandronate showed significant improvements versus placebo in finite element analysis of femoral and vertebral strength. This post hoc analysis examined QCT BMD changes in novel superior and inferior vertebral volumes of interest (VOIs) and femoral and vertebral subcortical, extended cortical, and extended trabecular VOIs. Ninety-three postmenopausal women (BMD(a)T-scores< or =-2.0 at lumbar spine, total hip, or femoral neck) received ibandronate 150 mg/month (n=47) or placebo (n=46) for 12 months. QCT with Medical Imaging Analysis Framework (MIAF)-Spine and MIAF-Femur used automated segmentation and coordinate system-based identification of integral, cortical, subcortical, and trabecular VOIs and combinations (extended cortical=cortical+subcortical; extended trabecular=trabecular+subcortical). Between-group differences in mean percentage changes from baseline were determined by treatment- and center-adjusted analysis of variance. P values were post hoc, exploratory, descriptive, and unadjusted for multiple comparisons. Ibandronate increased vertebral superior and inferior trabecular and extended cortical midsection BMD (4.9%, p=0.032; 4.6%, p=0.055; 3.9%, p=0.014, respectively) versus placebo. Femoral BMD treatment differences (ibandronate versus placebo) were significant in total hip (extended trabecular 4.0%, p=0.005; extended cortical 1.5%, p=0.047; subcortical 3.7%, p=0.009), trochanter (extended trabecular 5.2%, p=0.007; extended cortical 2.4%, p=0.01), and extended trabecular femoral neck (4.0%, p=0.02). Monthly oral ibandronate for 12 months improved QCT BMD versus placebo in the vertebral periphery, subcortical total hip, and all femoral extended trabecular regions.

Bone mineral density, arterial stiffness, and coronary atherosclerosis in healthy postmenopausal women

OBJECTIVE

The aim of this study was to assess the correlation between bone mineral density (BMD), arterial stiffness, and coronary atherosclerosis in healthy postmenopausal women.

METHODS

We performed a retrospective review of 152 postmenopausal women who visited the health promotion center for a routine checkup, after excluding participants who had factors affecting BMD and coronary artery disease. BMD was evaluated by dual-energy x-ray absorptiometry in the lumbar spine and femur. Arterial stiffness was measured by brachial-ankle pulse wave velocity (baPWV), and coronary atherosclerosis was assessed by 64-row multidetector computed tomography.

RESULTS

Women with osteoporosis had a significantly higher baPWV than those in the osteopenia and normal BMD groups. Higher baPWV was also associated with the presence of atherosclerosis. The baPWV was significantly positively correlated with age, systolic blood pressure, diastolic blood pressure, and neutrophil to lymphocyte ratio and negatively correlated with femur BMD. The optimum predictive value of baPWV in coronary atherosclerosis was estimated using the receiver operating characteristic curve. A cutoff of 1,506 cm/second would give a sensitivity of 83.3% and specificity of 82.9%. A higher overall risk for coronary atherosclerosis emerges with higher baPWV levels (>1,500 cm/s) after controlling for age and cardiovascular risk factors.

CONCLUSIONS

Arterial stiffness by measuring baPWV can be a useful independent predictor for coronary atherosclerosis. In addition, our results suggest that postmenopausal women with osteoporosis should be considered for further evaluation of coronary atherosclerosis.

Measuring and interpreting age-related loss of vertebral bone mineral density in a medieval population

This study investigates the age- and sex-related patterns in vertebral bone mineral density (BMD) and the relationship between BMD and vertebral osteophytosis (VO), using a specialized peripheral densitometer in a skeletal sample excavated from the British medieval village Wharram Percy. A total of 58 individuals were divided by sex into three broad age categories (18-29, 30-49, 50+ years.). Each fourth intact vertebral centra was scored for VO and 5-mm thick coronal sections scanned in a specialized peripheral densitometer (GE Lunar Piximus DXA). Changes in BMD associated with age, sex, and VO severity were examined in the whole vertebral section, a strictly trabecular region, and a primarily cortical region of bone separately. Significant change in vertebral BMD was found to occur by middle age with little or no statistical change in BMD between middle and old age. Females appear to suffer greater bone loss at an earlier age with no change in BMD between middle and old age, whereas males show a more steady loss of BMD across the age groups. The bone mineral content and BMD of the cortical region is higher in individuals with pronounced/severe osteophytosis. The unusual age- and sex-related patterns of change in vertebral BMD at Wharram Percy are compared with the patterns of age-related change from recent longitudinal population-based studies. The results emphasize the different pattern of bone loss in young adulthood seen in trabecular regions of the skeleton and highlight the importance of consideration of degenerative joint disease in BMD studies. The influence of lifestyle factors on vertebral BMD in this medieval population is also discussed.

Bone mineral density measurement at both spine and hip for diagnosing osteoporosis in Japanese patients

In Japan, spinal dual-energy X-ray absorptiometry (DXA) has been commonly performed for diagnosing osteoporosis but scanning the proximal femur is not done widely. The latest Japanese guidelines for prevention and treatment of osteoporosis, revised in 2006, recommend bone mineral density (BMD) measurement at both spine and hip for diagnosing osteoporosis, although there have been no reports that proved the necessity of those measurements. One thousand forty-one women and 485 men with clinical suspicion of osteoporosis were enrolled in this study, and DXA was performed at both spine and hip. The proportions of the patients who had inconsistency between diagnosis of osteoporosis from spinal DXA and that of hip were estimated. As a result, 22% of women and 15% of men had an inconsistency with the diagnosis of osteoporosis using DXA at each measurement site. There was inconsistency in diagnosing osteoporosis using DXA at the spine and proximal femur measurement sites. Because spine and femoral DXA measurements complement each other in the diagnosis of osteoporosis, BMD measurement at both spine and hip should be performed for all Japanese patients who are suspected osteoporosis, regardless of age and sex.

Effect of dexrazoxane and amifostine on the vertebral bone quality of Doxorubicin treated male rats

Doxorubicin (DOX) is widely used in combination cocktails for treatment of childhood hematological cancers and solid tumors. A major factor limiting DOX usage is DOX-induced cardiotoxicity. However, it is not known whether protectants like dexrazoxane (DXR) and amifostine (AMF) can prevent DOX-mediated bone damage. The present study investigated whether administration of AMF alone or in combination with DXR would prevent any DOX-mediated bone damage. Male rat pups were treated with DOX, DXR, AMF, and their combinations. On neonate day 38, the bone mineral density (BMD), bone mineral content (BMC) and the micro-architecture of the lumbar vertebrae were analyzed. We have shown that when male rats are treated with DOX, DXR, DOX+DXR, AMF, DOX+AMF or DOX+DXR+AMF, there is a decrease in lumbar vertebral BMD (p<0.05). Furthermore, the relative bone volume (BV/TV) was decreased by DXR, DOX+DXR, and DOX+AMF treatments. Interestingly, DOX+AMF significantly increased BV/TV when compared to DXR treatment (p<0.04). The trabecular number (Tb.N) decreased with DXR and DOX+DXR and increased with DOX+AMF treatments. This information will be useful in designing better cancer combination therapies that do not lead to vertebrae deterioration.

The effect of cement augmentation on the geometry and structural response of recovered osteopenic vertebrae: an anterior-wedge fracture model

STUDY DESIGN

The efficacy of cement augmentation in restoring the geometry and structural competence of failed thoracic and lumbar human vertebrae under mechanical loads was studied.

OBJECTIVES

To quantify whether cement augmentation restores and maintains the geometry and structural competence of failed osteopenic vertebrae and to assess the contribution of vertebral geometry to the achieved augmentation.

SUMMARY OF BACKGROUND DATA

Cement augmentation of failed vertebrae was clinically shown to alleviate significant pain and functional impairments associated with vertebral fragility fractures. However, the procedure's efficacy in restoring the structural response of the failed vertebrae and maintaining the achieved geometry under functional loads remains unclear.

METHODS

Nineteen thoracic and lumbar human vertebrae were tested to failure under compression-flexion loading. The vertebrae were allowed to recover, were retested to failure, augmented with Polymethylmethacrylate and again retested to failure. Repeated measures analysis was used to compare the change in vertebral geometry and structural response, defined as the multiplanar force and moment response of the vertebra to the imposed deformation, at each of the test stages. Linear regression was used to assess the role of the geometry of the failed vertebrae in affecting the outcome of augmentation.

RESULTS

Augmentation significantly increased the compressive (228%) and flexion (118%) strength of the failed vertebrae and achieved a significant, albeit partial, restoration of vertebral geometry. However, the structural response of the failed vertebrae was markedly altered, whereas under applied loads, the achieved height restoration was significantly diminished. Although the geometry of the fractured vertebral body was associated with the degree of restoration of the vertebral body afteraugmentation, it was not correlated with the change in the structural parameters.

CONCLUSION

Augmentation increases the structural competence of failed vertebrae and to a degree, restores their geometry. However, the structural response of the augmented vertebrae was significantly modified. Furthermore, the augmented vertebrae were unable to maintain the degree of geometry restoration under load.

Comprehensive osteoporosis management with easy access to bone mineral density measurements

BACKGROUND

The majority of people with osteoporosis are never evaluated even though effective treatments are available. The County Council of Värmland in Sweden has implemented an osteoporosis management model that has been shown to be effective in promoting awareness and providing care for osteoporosis patients. Discussions among a prevention group on osteoporosis in the county council were opened in 1997. The county of Värmland covers a large area, and the distances from the peripheral parts to the main city are approximately 300 km and cumbersome for the inhabitants. The importance of having an osteoporosis service that could reach the county inhabitants in a convenient way was therefore recognized.

METHODS

Three thousand four hundred patients were evaluated between March 2001 and December 2003. Guidelines for patient selection for bone density testing and treatment guidelines were formulated. Promoting awareness was an important prerequisite for the model to function. This was accomplished by having the measurement devices where the patients showed up and by regular education of the primary care doctors.

RESULTS AND CONCLUSIONS

A multidisciplinary team was established and consisted of primary care doctors, orthopaedic surgeons, internists, physiotherapists, a patient organization member, a county health care representative and nurses. Team members met every third month and agreed upon clinical guidelines for implementing the system. The presented osteoporosis management system is not a screening approach as all patients had risk factors for osteoporosis before they were suggested for bone density testing. This study shows that providing a comprehensive package of measures makes it possible to establish an effective osteoporosis management system with limited economical resources.

Preferred skeletal site for osteoporosis screening in high-risk populations

OBJECTIVES

The current World Health Organization (WHO) definition of osteoporosis, which is based on densitometry of lumbar and femoral regions, is extensively used for decision-making in clinical practice. Discordance in diagnosis of osteoporosis using this definition is a known phenomenon. The aim of this study was to evaluate the impact of such discordance and to assess the diagnostic value of using one skeletal site for screening purposes as opposed to the two sites required in the WHO criteria.

STUDY DESIGN

Data was collected from 4188 individuals (3848 female); mean age=53.4 years (standard deviation 11.8) referred to a community-based outpatient osteoporosis testing centre in Tehran, Iran.

METHODS

Dual-energy X-ray absorptiometry (DXA) was performed on L1-L4 lumbar spine and total hip for all cases. The DXA results were categorized according to WHO criteria. Sensitivity for each site was calculated as number of cases with T-score < -2.5 at that site divided by the total number of cases with T-score < -2.5 at any site.

RESULTS

Prevalence of osteoporosis diagnosis using lumbar DXA, femoral DXA, and WHO criteria (either of the sites) were 24.7%, 12.4%, and 27.8%, respectively. Sensitivity of lumbar DXA for diagnosis of osteoporosis (88.9%) was significantly higher than femoral DXA (44.6%, P<0.001); but this difference became non-significant for men > or = 60 and women > or = 70 (P=0.615 and P=0.077, respectively). Agreement of the procedures in different sites (kappa) was 0.40 (0.37 to 0.43). When proximal femur was considered as the reference, positive likelihood ratios of lumbar DXA to detect cases were 4.7 and 2.0 in younger and older groups, respectively.

CONCLUSIONS

Concerning the high rate of discordance and low agreement between DXA results, the data obtained from each anatomical site cannot predict the condition of the other site. However, if use of a single assessment is intended for screening programs, public health authorities can develop different strategies for different age groups of their population. We propose lumbar DXA for the younger group (men < 60 and women < 70) and femoral densitometry for the older.

Safety and Efficacy of Teriparatide in Elderly Women with Established Osteoporosis: Bone Anabolic Therapy from a Geriatric Perspective

OBJECTIVES

To assess the safety and efficacy of teriparatide in patients aged 75 and older and compare these findings with those of women younger than 75 using data from the Fracture Prevention Trial (FPT).

DESIGN

The FPT was a randomized, multicenter, double-blind, placebo-controlled study.

SETTING

The FPT multicenter international study.

PARTICIPANTS

Postmenopausal women aged 42 to 86 were randomized to placebo (N=544) or teriparatide 20 mug (N=541) by daily self-injection for a median of 19 months. Patients received daily oral supplements of 1,000 mg calcium and 400 to 1,200 IU vitamin D. For this analysis, subgroups were defined according to patient age younger than 75 (N=841) and 75 and older (N=244).

MEASUREMENTS

The effects of teriparatide on bone mineral density (BMD) of the lumbar spine and femoral neck; the incidence of new vertebral and new nonvertebral fragility fractures; bone turnover markers, including bone-specific alkaline phosphatase; and urinary deoxypyridinoline corrected for creatinine clearance, as well as the safety of teriparatide, were investigated.

RESULTS

There were no significant treatment-by-age interactions for the bone turnover markers, femoral neck BMD, vertebral fractures, nonvertebral fragility fractures, height loss, hyperuricemia, or hypercalcemia. A significant treatment-by-age interaction for lumbar spine BMD (P=.08) was due to an increase in BMD observed in the placebo group aged 75 and older. There were no treatment-by-age interactions for important treatment-emergent adverse events (TEAEs), including back pain, nausea, leg cramps, and dizziness. The most important TEAEs in women aged 80 and older (23 patients from the placebo group and 25 patients from the teriparatide group) were also reviewed; no unexpected TEAEs were found in the patients treated with teriparatide. These results indicate that the clinical effects of teriparatide were consistent in the older and younger women.

CONCLUSION

Age does not affect the safety and efficacy of teriparatide in postmenopausal women with osteoporosis.

The effect of measurement of the contralateral hip if the spine is not included in the bone mineral density analysis

The aim of this study was to determine if measurement of the contralateral femora has an effect on osteoporosis diagnosis and treatment classification if the spine is not included in the bone mineral density (BMD) scan. The method used was the T-score discordance from the dual femur BMD scans of 537 women (mean age: 61.2 yr; standard deviation: 10.5; age range: 32-90 yr) who were evaluated to determine if inclusion of the contralateral hip in the BMD study made a difference in clinical diagnosis and treatment classification when the spine was not included in the BMD scan. Clinical diagnosis and treatment classification was based on the lowest T-score at each hip of three femur sites: the neck, the trochanter, and the total femur. The results of the diagnosis classification (i.e., normal, osteopenia, and osteoporosis) differed in the right versus the left femora in 28% of subjects at one or more sites, and in 14%, 15%, and 10% of subjects at the neck, trochanter, and total femur, respectively. Diagnosis discordance increased in subjects who were aged 65 yr and older. Treatment classification (T>or=-1.5; T<-1.5; T<-2.0) differed in the right versus the left femora in 33% of subjects at one or more sites, and in 18%, 14%, and 12% of subjects at the neck, trochanter, and total femur, respectively. Treatment discordance increased in subjects age 65 yr and older. Using the lowest T-score for clinical diagnosis classification, when the contralateral hip was considered, a clinical difference in diagnosis from normal-->osteopenia occurred in 3.9% of subjects, and from osteopenia-->osteoporosis in 1.3% of subjects. A clinical difference in treatment category from T>or=-1.5-->T<-1.5 occurred in 2.7% of subjects, and from T>or=-2-->T<-2 in 2.7% of subjects. In conclusion, inclusion of the bilateral hip in the BMD study made a clinical difference in diagnosis classification in 5.2% of subjects and in treatment classification in 5.4% of subjects. T-score differences between the contralateral hips increased with age. In the subgroup of subjects age 65 yr and older, a clinical difference in classification to a more severe diagnosis or treatment category occurred in 5.35% and 7.25% of subjects, respectively.

Bone mineral density and estimated height loss based on patients' recalls

INTRODUCTION

Height loss has been shown to be an indicator of incident vertebral fractures. However, the relationship between height loss and bone mineral density (BMD) in different skeletal regions, as well as the power of human memory in estimation of height loss across the life span, has not yet been established. Given that the variation in BMD between populations is substantially less than the variation in fracture risk, we studied the relationship between height loss based on patient's recalls and BMD in Iranian men and women of all ages.

METHODS

Randomized clustered sampling from all regions of Tehran was performed to recruit the study population. Participants were asked about their maximum recalled previously measured height, if they were confident. In the 457 participants included, the difference between the participants' maximum recalled and current measured height was calculated.

RESULT

L1-L4 lumbar BMD, femoral neck BMD, and young adjusted T-scores were significantly lower in the group of participants with estimated height reduction of greater than 5 cm. In simple linear regression analysis, height loss was a significant predictor of femoral neck T-score (standardized beta coefficient=-0.15; p0.003) and L1-L4 lumbar T-score (beta=-0.08; p0.048). After adjustment for age, gender, and weight, height loss remained a significant predictor for femoral neck T-score (beta=-0.078; p0 .043). In multivariate models for lumbar T-score, height loss was an independent predictor only in participants equal to or younger than 50 years of age (beta=-0.144; p0.033).

CONCLUSION

Higher estimated height loss according to patients' recalls was an indicator of lower BMD in our sample. Especially in the femoral neck region, this factor might be considered as a substitute case-finding tool for low BMD. Considering relatively young nature of our study group and biological differences between populations, our findings need to be validated in future prospective studies.

Radiographic features of lumbar disc degeneration and bone mineral density in men and women

OBJECTIVES

To determine the association between individual radiographic features of lumbar disc degeneration and bone mineral density (BMD) at the spine and hip.

METHODS

SUBJECTS

were recruited from a population register for a screening survey of vertebral osteoporosis. BMD was assessed at the spine and hip using dual energy x ray absorptiometry. Lateral spinal radiographs were evaluated for features of lumbar disc degeneration. Each vertebral level from L1/2 to L4/5 was assessed for the presence and severity of osteophytes, end plate sclerosis, and disc space narrowing. Linear regression was used to determine the association between each of these features and BMD at the spine and hip, with adjustments for age, body mass index, and levels of physical activity. Analyses were done separately in men and women.

RESULTS

250 women and 256 men (mean age around 65 years) were studied. At the lumbar spine, after age adjustment there was an increase in BMD with increasing grade for all radiographic features of disc degeneration in both men and women. At the femoral neck, after age adjustment there was an increase in BMD with increasing osteophyte and end plate sclerosis grade though not disc space narrowing. Adjusting for body mass index and physical activity did not influence the strength of the associations.

CONCLUSIONS

Radiographic features of lumbar disc degeneration are associated with an increase in BMD at the spine. Osteophytes and end plate sclerosis, but not disc space narrowing, are associated with an increase in BMD at the hip.

Fracture prediction by bone density measurements at sites other than the fracture site: the contribution of BMD correlation

It is widely believed that the most reliable BMD measurement for predicting fracture risk at any given skeletal site is one made at the fracture site itself. This study examines the hypothesis that the ability of BMD measurements at other distant sites in the skeleton remote from the fracture site to predict fracture risk is due to their correlation with the BMD measurements at the fracture site. We refer to this assumption as the correlation hypothesis. We show that the correlation hypothesis predicts the relationship betadist = rbetafrac, where beta is the gradient of the exponential relationship between fracture risk and Z-score, betafrac is the beta-value for the fracture site, betadist the beta-value for the distant BMD site, and r is the correlation coefficient between the Z-scores at the two sites. In practice it is important to consider the effect of BMD measurement errors on the (r, beta) relationship. We show that the effect of errors at the distant site is to reduce betadist and r in a way that preserves their original relationship. When errors at the fracture site are taken into account the effect on the (r, beta) plot is for the point representing the fracture site to fall below the extrapolation of the straight-line relationship predicted for the points representing the distant BMD sites. We tested the correlation hypothesis by using data from the Study of Osteoporotic Fractures to examine the (r, beta) plots for hip, spine and forearm fractures. For the hip the data are consistent with a straight-line relationship and suggest that measurements made at other sites provide no additional information about fracture risk over and above that provided by hip BMD itself. For spine and forearm fractures the data show that distant sites do provide additional information about fracture risk in a way that is quantitatively consistent with the BMD measurement errors reported in cadaver studies. It is clear that random BMD errors at the fracture site cause loss of information about fracture risk and that some of this lost information is recoverable from measurements made at other sites in the skeleton. Overall, this study points to BMD correlation as an important factor in explaining the ability of measurements made at distant sites to predict fracture risk.

Complex segregation analyses of bone mineral density in Chinese

China has the largest population in the world; approximately 7% of the total population suffers from primary osteoporosis. Osteoporosis is mainly characterized by low bone mineral density (BMD). In the present study, familial correlation and segregation analyses for spine and hip BMDs have been undertaken for the first time in a Chinese sample composed of 401 nuclear families with a total of 1260 individuals. The results indicate a major gene of additive inheritance for hip BMD, whereas there is no evidence of a major gene influencing spine BMD. Significant familial residual effects are found for both traits, and heritability estimates (+/-SE) for spine and hip BMDs are 0.807(0.099) and 0.897(0.101), respectively. Sex and age differences in genotype-specific average BMD are also observed. This study provides the first evidence quantifying the high degree of genetic determination of BMD variation in the Chinese.

Positive relationship between bone mineral density and low back pain in middle-aged women

There have been a large number of epidemiological studies demonstrating various primary factors that cause musculoskeletal disorders in middle-aged and older women. However, the relationship between low back pain and bone mineral density is not well documented, and no evidence for any direct relationship between the two has been found. To investigate the relationship, we conducted a cross-sectional study, on a population of 2,244 Japanese women aged 25-85 years who were participating in a regional health screening program. Information on lifestyle, reproductive characteristics and the presence of current low back pain was collected by self-administered questionnaires, and bone mineral density at the distal radius was measured. We found increasing bone mineral density to be significantly associated with low back pain in middle-aged women using a logistic regression analysis. Exercise and smoking were also significantly associated with low back pain. This association remained even after entering other lifestyle and reproductive factors into the final model. Accordingly, high bone mineral density would seem to be as important a public health problem as low bone mineral density and osteoporosis when considering the musculoskeletal symptoms and disabilities that appear in middle-aged women.

Osteoarthritis and osteoporosis: clinical and research evidence of inverse relationship

The etiology of osteoporosis (OP) and osteoarthritis (OA) is multifactorial: both constitutional and environmental factors, ranging from genetic susceptibility, endocrine and metabolic status, to mechanical and traumatic injury, are thought to be involved. When interpreting research data, one must bear in mind that pathophysiologic factors, especially in disorders associated with aging, must be regarded as either primary or secondary. Therefore, findings in end-stage pathology are not necessarily the evidence or explanation of the primary cause or event in the diseased tissue. Both aspects of research are important for potentially curative or preventive measures. These considerations, in the case of our topic--the inverse relationship of OP and OA--are of particular importance. Although the inverse relationship between two frequent diseases associated with aging, OA and OP, has been observed and studied for more than 30 years, the topic remains controversial for some and stimulating for many. The anthropometric differences of patients suffering from OA compared with OP are well established. OA cases have stronger body build and are more obese. There is overwhelming evidence that OA cases have increased BMD or BMC at all sites. This increased BMD is related to high peak bone mass, as shown in mother-daughter and twin studies. With aging, the bone loss in OA is lower, except when measured near an affected joint (hand, hip, knee). The lower degree of bone loss with aging is explained by lower bone turnover as measured by bone resorption-formation parameters. OA cases not only have higher apparent and real bone density, but also wider geometrical measures of the skeleton, diameters of long bones and trabeculae, both contributing positively to better strength and fewer fragility fractures. Not only is bone quantity in OA different but also bone quality, compared with controls and OP cases, with increased content of growth factors such as IGF and TGFbeta, factors required for bone repair. Furthermore, in vitro studies of osteoblasts recruited from OA bone have different differentiation patterns and phenotypes. These general bone characteristics of OA bone may explain the inverse relationship OA-OP and why OA cases have fewer fragility fractures. The role of bone, in particular subchondral bone, in the pathophysiology, initiation and progression of OA is not fully elucidated and is still controversial. In 1970, it was hypothesized that an increased number of microfractures lead to an increase in subchondral bone stiffness, which impairs its ability to act as a shock absorber, so that cartilage suffers more. Although subchondral bone is slightly hypomineralized because of local increased turnover, the increase in trabecular number and volume compensates for this, resulting in a stiffer structure. There is also some experimental evidence that osteoblasts themselves release factors such as metalloproteinases directly or indirectly from the matrix, which predispose cartilage to deterioration. Instead, the osteoblast regenerative capacity of bone in OP is compromised compared with OA, as suggested by early cell adhesion differences. The proposition that drugs which suppress bone turnover in OP, such as bisphosphonates, may be beneficial for OA is speculative. Although bone turnover in the subchondral region of established OA is increased, the general bone turnover is reduced. Further reduction of bone turnover, however, may lead to overmineralized (aged) osteons and loss of bone quality, resulting in increased fragility.

Biomechanics of the aging spine

The human spine is composed of highly specific tissues and structures, which together provide the extensive range of motion and considerable load carrying capacity required for the physical activities of daily life. Alterations to the form and composition of the individual structures of the spine with increasing age can increase the risk of injury and can have a profound influence on the quality of life. Cancellous bone forms the structural framework of the vertebral body. Individual trabeculae are oriented along the paths of principal forces and play a crucial role in the transfer of the predominantly compressive forces along the spine. Age-related changes to the cancellous core of the vertebra includes a loss of bone mineral density, as well as morphological changes including trabecular thinning, increased intratrabecular spacing, and loss of connectivity between trabeculae. Material and morphological changes may lead to an increased risk of vertebral fracture. The vertebral endplate serves the dual role of containing the adjacent disc and evenly distributing applied loads to the underlying cancellous bone and the cortex of the vertebra. With aging, thinning of the endplate, and loss of bone mineral density increases the risk of endplate fracture. Ossification of the endplate may have consequences for the nutritional supply and hydration of the intervertebral disc. The healthy intervertebral disc provides mobility to the spine and transfers load via hydrostatic pressurization of the hydrated nucleus pulposus. Changes to the tissue properties of the disc, including dehydration and reorganization of the nucleus and stiffening of the annulus fibrosus, markedly alter the mechanics of load transfer in the spine. There is no direct correlation between degenerative changes to the disc and to the adjacent vertebral bodies. Furthermore, advancing age is not the sole factor in the degeneration of the spine. Further study is crucial for understanding the unique biomechanical function of the aging spine.

Finite element modeling of the human thoracolumbar spine

STUDY DESIGN

Biomechanical properties within cadaveric vertebral bodies were parametrically studied using finite element analysis after calibration to experimental data.

OBJECTIVES

To develop and validate three-dimensional finite element models of the human thoracolumbar spine based on quantitative computed tomography scans. Specifically, combine finite element modeling together with biomechanical testing circumventing problems associated with direct measurements of shell properties.

SUMMARY OF BACKGROUND DATA

Finite element methods can help to understand injury mechanisms and stress distribution patterns within vertebral bodies as an important part in clinical evaluation of spinal injuries. Because of complications in modeling the vertebral shell, it is not clear if quantitative computed tomography-based finite element models of the spine could accurately predict biomechanical properties.

METHODS

We developed a novel finite element modeling technique based on quantitative computed tomography scans of 19 radiographically normal human vertebra bodies and mechanical property data from empirical studies on cylindrical trabecular bone specimens. Structural properties of the vertebral shell were recognized as parametric variables and were calibrated to provide agreement in whole vertebral body stiffness between model and experiment. The mean value of the shell properties thus obtained was used in all models to provide predictions of whole vertebral strength and stiffness.

RESULTS

Calibration of n = 19 computer models to experimental stiffness yielded a mean effective modulus of the vertebral shell of 457 +/- 931 MPa ranging from 9 to 3216 MPa. No significant correlation was found between vertebral shell effective modulus and either the experimentally measured stiffness or the average trabecular modulus. Using the effective vertebral shell modulus for all 19 models, the predicted vertebral body stiffness was an excellent predictor of experimental measurements of both stiffness (r2= 0.81) and strength (r2 = 0.79).

CONCLUSION

These findings indicate that modeling of the vertebral shell using a constant thickness of 0.35 mm and an effective modulus of 457 MPa, combined with quantitative computed tomography-based modeling of trabecular properties and vertebral geometry, can accurately predict whole vertebral biomechanical properties. Use of this modeling technique, therefore, should produce substantial insight into vertebral body biomechanical behavior and may ultimately improve clinical indications of fracture risk of this cohort.

Automated assessment of exclusion criteria for DXA lumbar spine scans

Modern bone densitometry systems using dual-energy X-ray absorptiometry (DXA) automatically analyze lumbar spine scans and provide clinically important information concerning spine bone mineral density (BMD) and fracture risk. Lumbar spine BMD accurately reflects skeletal health and fracture risk in most cases, but degenerative diseases associated with aging may lead to the formation of reactive bone (osteophytes) and other confounding conditions that elevate BMD without a concomitant increase in bone strength or decrease in fracture risk. Automated densitometry software known as computer-aided densitometry (CAD) (GE Medical Systems Lunar) assists the user in identifying scans with common acquisition and analysis irregularities known to influence BMD values. Visual examination of 231 female spine scans measured with DXA found abnormal conditions that could influence BMD results in 29% of scans. The sensitivity and specificity of several criteria for identifying scans with conditions that could influence BMD were determined. A good criterion for identifying scans with abnormal conditions was a T-score difference of greater than 0.9 or 1.0 between L1-L4 mean and individual vertebrae. Criteria for excluding affected vertebrae were determined. Exclusion of affected vertebrae resulted in a mean BMD decrease of nearly 0.6 SD (T-score) among affected scans.

Effects of bone cement volume and distribution on vertebral stiffness after vertebroplasty

STUDY DESIGN

The biomechanical behavior of a single lumbar vertebral body after various surgical treatments with acrylic vertebroplasty was parametrically studied using finite-element analysis.

OBJECTIVES

To provide a theoretical framework for understanding and optimizing the biomechanics of vertebroplasty. Specifically, to investigate the effects of volume and distribution of bone cement on stiffness recovery of the vertebral body.

SUMMARY OF BACKGROUND DATA

Vertebroplasty is a treatment that stabilizes a fractured vertebra by addition of bone cement. However, there is currently no information available on the optimal volume and distribution of the filler material in terms of stiffness recovery of the damaged vertebral body.

METHODS

An experimentally calibrated, anatomically accurate finite-element model of an elderly L1 vertebral body was developed. Damage was simulated in each element based on empirical measurements in response to a uniform compressive load. After virtual vertebroplasty (bone cement filling range of 1-7 cm3) on the damaged model, the resulting compressive stiffness of the vertebral body was computed for various spatial distributions of the filling material and different loading conditions.

RESULTS

Vertebral stiffness recovery after vertebroplasty was strongly influenced by the volume fraction of the implanted cement. Only a small amount of bone cement (14% fill or 3.5 cm3) was necessary to restore stiffness of the damaged vertebral body to the predamaged value. Use of a 30% fill increased stiffness by more than 50% compared with the predamaged value. Whereas the unipedicular distributions exhibited a comparative stiffness to the bipedicular or posterolateral cases, it showed a medial-lateral bending motion ("toggle") toward the untreated side when a uniform compressive pressure load was applied.

CONCLUSION

Only a small amount of bone cement ( approximately 15% volume fraction) is needed to restore stiffness to predamage levels, and greater filling can result in substantial increase in stiffness well beyond the intact level. Such overfilling also renders the system more sensitive to the placement of the cement because asymmetric distributions with large fills can promote single-sided load transfer and thus toggle. These results suggest that large fill volumes may not be the most biomechanically optimal configuration, and an improvement might be achieved by use of lower cement volume with symmetric placement.

Bone mineral density, osteopenia, and osteoporosis in the rhesus macaques of Cayo Santiago

This cross-sectional study investigates metabolic bone disease and the relationship between age and bone mineral density (BMD) in males and females of a large, well-documented skeletal population of free-ranging rhesus monkeys (Macaca mulatta), from the Caribbean Primate Research Center Museum collection from Cayo Santiago, Puerto Rico. The sample consists of 254 individuals aged 1.0-20+ years. The data consist of measurements of bone mineral content and bone mineral density, obtained from dual-energy X-ray absorptiometry (DEXA), of the last lumbar vertebra from each monkey. The pattern of BMD differs between male and female rhesus macaques. Females exhibit an initial increase in BMD with age, with peak bone density occurring around age 9.5 years, and remaining constant until 17.2 years, after which there is a steady decline in BMD. Males acquire bone mass at a faster rate, and attain a higher peak BMD at an earlier age than do females, at around 7 years of age, and BMD remains relatively constant between ages 7-18.5 years. After age 7 there is no apparent effect of age on BMD in the males of this sample; males older than 18.5 years were excluded due to the presence of vertebral osteophytosis, which interferes with DEXA. The combined frequency of osteopenia and osteoporosis in this population is 12.4%. BMD values of monkeys with vertebral wedge fractures are generally higher than those of virtually all of the nonfractured osteopenic/osteoporotic individuals, thus supporting the view that BMD as measured by DEXA is a useful but imperfect predictor of fracture risk, and that low BMD may not always precede fractures in vertebral bones. Other factors such as bone quality (i.e., trabecular connectivity) should also be considered. The skeletal integrity of a vertebra may be compromised by the loss of key trabeculae, resulting in structural failure, but the spine may still show a BMD value within normal limits, or within the range of osteopenia.

Lumbar osteoarthritis, bone mineral density, and quantitative ultrasound

Low bone mass is a major risk factor for osteoporotic fractures. Thus, bone density evaluation, performed by Dual Energy X-ray Absorptiometry (DXA) is important for diagnosis and monitoring treatment of osteoporosis. The accuracy of DXA, particularly at the lumbar spine, can be affected by several factors such as degenerative diseases. To evaluate the effects of vertebral osteophytosis on densitometric measurements, we examined 198 women, aged 32-81 years, who had undergone lateral X-ray of the lumbar spine. We classified patients according to different grades of osteophytosis, and evaluated bone density at the lumbar spine and the proximal femur by DXA. We also performed quantitative ultrasound at the heel (QUS). Patients with severe osteophytosis were significantly older (p < 0.0005), and values were adjusted for this parameter. We observed a significant increase in lumbar bone density with worsening osteophytosis (p < 0.02). On the contrary, no significant differences were found at the femur and QUS. According to bone density at the femoral neck, we subdivided patients into two groups: osteoporotic (group A) and non-osteoporotic (group B). Both groups showed increasingly high bone density at the spine with worsening osteophytosis (A: p < 0.01; B: p < 0.02). No differences were found in all the other evaluations. In conclusion, lumbar spine measurement is dramatically influenced by osteophytosis, particularly in the elderly. Consequently, other strategies should be performed such as evaluation of the hip and also measurement of the heel by ultrasound, which could be an interesting approach in these cases.

Posterior-anterior and lateral dual-energy x-ray absorptiometry for the assessment of vertebral osteoporosis and bone loss among older men

Lateral spine dual-energy x-ray absorptiometry (DXA) selectively measures the trabecular-rich vertebral bodies without the contributions of the cortical-rich posterior elements of the spine and is less affected by spinal degenerative disease than posterior-anterior DXA. We tested whether lateral DXA detects vertebral osteoporosis more often and is more sensitive to age-related bone loss than posterior-anterior DXA in 193 healthy, community-dwelling men aged 51-81 years (mean +/- SD; 67 +/- 8 years). All men had supine lateral, posterior-anterior, and proximal femur DXA scans on a Hologic QDR 2000 densitometer. A subset (n = 102) had repeat scans after 4 years to determine annualized rates of change in bone mineral density (BMD). Age was inversely and significantly associated with BMD in the midlateral (r = -0.27) and lateral (r = -0.24) but not posterior-anterior (r = 0.04) projections. Midlateral (-1.43 +/- 3.48% per year; p = 0.0001), lateral (-0.27 +/- 1.68% per year; p = 0.12), and hip (-0.19 +/- 1.02% per year; p = 0.06) BMD decreased, whereas posterior-anterior BMD increased (0.73 +/- 1.11% per year; p = 0.0001) during follow-up. When compared with normal values in 43 men aged 21-42 years, mean T scores were significantly lower with lateral (-1.47 +/- 1.32) and midlateral (-1.57 +/- 1.36) than posterior-anterior (-0.12 +/- 1.30; p < 0.0001) DXA. Only 2.6% of the older men were considered osteoporotic (T score < or = -2.5) at the posterior-anterior spine, whereas 11.0% were osteoporotic at the femoral neck, 22.5% at the lateral spine, and 24.6% were osteoporotic at the midlateral spine. We conclude that supine lateral DXA identifies considerably more men as osteoporotic and is more sensitive to age-related bone loss than posterior-anterior DXA. Spinal osteoporosis may represent a substantially greater health problem among older men than previously recognized.

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

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

Bone density and fracture risk in men

We evaluated different definitions of osteoporosis in a population-based sample of 348 men (age 22-90 years) compared with 351 women (age 21-93 years). Thirty-six men (10%) and 46 women (13%) had a history of osteoporotic fracture (hip, spine, or distal forearm due to moderate trauma at >/= age 35). In logistic regression analysis, osteoporotic fracture risk was associated with bone mineral density (BMD) at all sites (neck, trochanter, total hip, lumbar spine, and total wrist) in both genders (p < 0.001) except spinal BMD in men. After adjusting for age, total hip BMD was the strongest predictor of fracture risk in women (odds ratio [OR] per 1 SD decline, 2.4; 95% confidence interval [CI], 1.6-3.7), while wrist BMD was best in men (OR, 1.5; 95% CI, 1.1-2.0). Among men but not women, bone mineral apparent density (BMAD) was a better predictor of fracture than BMD (wrist BMAD OR, 1.7; 95% CI, 1.3-2.3). Hip BMD/BMAD decreased linearly from age 20 years onward in both genders, while spinal BMD/BMAD declined after age 40 in women but not in men. In both genders, total wrist BMD/BMAD decreased after age 50. By World Health Organization criteria, the age-adjusted prevalence of osteoporosis at the hip, spine, or wrist was 35% among women >/=50 years of age. A similar approach (BMD > 2.5 SD below the young male mean) produced an osteoporosis prevalence rate in men >/=50 years of age of 19%. Thus, bone density predicts fracture risk in men as it does in women, and the prevalence of osteoporosis in men, using sex-specific normal values, is substantial. These observations indicate a need for better prevention and treatment strategies for men.

Prediction of vertebral failure loads from spinal and femoral dual-energy X-ray absorptiometry, and calcaneal ultrasound: an in situ analysis with intact soft tissues

The objective of the current study was to determine the correlation of spinal and femoral dual-energy X-ray absorptiometry (DXA) and calcaneal ultrasound, measured in situ with intact soft tissues, with the in vitro failure loads of lumbar vertebral bodies. Forty-nine cadavers with intact skin and soft tissues (32 men aged 82.1 +/- 9.0 years, 17 women aged 83.1 +/- 10.1 years) were examined. The bone mineral content (BMC), the projectional area, and the bone mineral density (BMD) of the lumbar spine and proximal femur were determined with DXA, and the ultrasonic properties of the calcaneus with quantitative calcaneal ultrasound. The fourth lumbar vertebra was then excised with adjacent intervertebral disks and its mechanical failure load determined, using a materials testing machine. Absolute fracture loads were significantly higher in men than in women, but they were similar after adjusting for body weight and height. Spinal DXA was significantly associated with vertebral failure load (r = 0.62 combined; r = 0.54 men; r = 0.58 women). Femoral DXA (r = 0.46) and calcaneal ultrasound (r = 0.48) showed somewhat lower correlation coefficients, with the speed of sound (SOS) being able to add predictive information in a stepwise regression model. Normalizing the vertebral failure loads to body weight and height reduced the correlations, with only spinal DXA yielding a significant relationship. Our data suggest that previous in vitro studies may have overestimated the association between spinal DXA and vertebral failure loads, presumably because measurements were performed on excised bones, but not in situ in the presence of soft tissue inhomogeneity. The results indicate that, even in a population of old age and under in situ conditions, spinal DXA may still be somewhat better than femoral DXA and calcaneal ultrasound in predicting vertebral failure loads.

Short-term and long-term fracture prediction by bone mass measurements: a prospective study

Prospective and cross-sectional studies have demonstrated that bone mass predicts fracture risk. However, most prospective studies have been limited to a few years of follow-up. We investigated the long-term associations of bone mass with vertebral fractures using longitudinal data collected from more than 500 postmenopausal Japanese-American women in the Hawaii Osteoporosis Study. New vertebral fractures were identified during an average of 2.7 years between 1992 and 1995. Short-term fracture prediction was evaluated using bone mass (spine, calcaneus, distal radius, and proximal radius) measured at the beginning of follow-up. Long-term prediction was evaluated using bone mass measured before the follow-up period (11 years earlier for nonspine bone mass and 8 years earlier for spine). All four bone mass measurements were significant predictors of vertebral fractures identified during the subsequent 2.7 years (short-term prediction), with odds ratios (ORs) ranging from 1.5 to 1.9. The ORs for long-term prediction were slightly lower in magnitude, but the confidence intervals overlapped the short-term ORs considerably, suggesting that both long-term and short-term associations are similar in magnitude. Furthermore, cross-sectional analyses based on bone mass measurements performed at the end of follow-up (after fractures had occurred) yielded results similar to those based on prospective data (bone mass measured prior to fractures), suggesting that the relatively quick and inexpensive cross-sectional studies are useful for preliminary evaluations of new bone mass measurement techniques. The results suggest that bone mass measurements made up to 11 years earlier can predict vertebral fractures almost as well as measurements made more recently.

Epidemiology of spinal osteoporosis

Approximately 30% of postmenopausal white women in the United States have osteoporosis, and 16% have osteoporosis of the lumbar spine in particular. Bone density of the spine is positively associated with greater height and weight, older age at menopause, a history of arthritis, more physical activity, moderate use of alcoholic beverages, diuretic treatment, and current estrogen replacement therapy, whereas later age at menarche and a maternal history of fracture are associated with lower levels of density. Low bone density leads to an increased risk of osteoporotic fractures. Fracture risk also increase with age. Vertebral fractures affect approximately 25% of postmenopausal women, although the exact figure depends on the definition used. Recent data show that vertebral fracture rates are as great in men as in women but, because women live longer, the lifetime risk of a vertebral fracture from age 50 onward is 16% in white women and only 5% in white men. Fracture rates are less in most nonwhite populations, but vertebral fractures are as common in Asian women as in those of European heritage. Other risk factors for vertebral fractures are less clear but include hypogonadism and secondary osteoporosis; obesity is protective of fractures as it is of bone loss. Compared with hip fractures, vertebral fractures are less disabling and less expensive, costing approximately $746 million in the United States in 1995. However, they have a substantial negative impact on the patient's function and quality of life. The adverse effects of osteoporotic fractures are likely to increase in the future with the growing number of elderly people.

Decrease of bone formation in adult women with fragility fractures

OBJECTIVES

To compare bone mineral density (BMD) and some markers of bone metabolism in women with fragility fractures and in normal age-matched subjects.

METHODS

A 100 women with at least one vertebral deformity > 25%, and 219 age-, BMI- and parity-matched healthy women, were recruited for the study. In all the patients fractures were symptomatic and occurred at least 1 year before densitometric measurement. Forearm bone mineral density (BMD) as well as biochemical assessment of some markers of bone turnover were measured in all the subjects.

RESULTS

BMD was significantly lower in the fracture than in the control group (0.326 +/- 0.073 vs. 0.379 +/- 0.079; P < 0.001). Fractured women showed alkaline phosphatase (ALP) and osteocalcin (OC) serum levels significantly lower than controls, while no differences were found in fasting urinary calcium and hydroxyproline excretion. Women without fractures showed a significant correlation between ALP and both age and years since menopause (YSM). Such a correlation is lacking in the fracture group.

CONCLUSIONS

Women with vertebral deformities likely due to a fracture had a forearm BMD and markers of bone formation lower than normal. Whether low bone density is due to a low peak of bone mass or to an increased postmenopausal bone loss sustained by an uncoupling between the two bone remodelling processes is still unclear.

How can we measure bone quality?

Osteoporosis is a systematic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue. This leads to diminished biomechanical competence of the skeleton and is associated with low-trauma or atraumatic fractures. In the past decade, considerable progress has been made in the development of methods for assessing the skeleton non-invasively, so that osteoporosis can be better managed. While dual X-ray absorptiometry (DXA) is still the preferred methodology, several limitations will be addressed. Another densitometric technique which is widely accepted for diagnosis of spinal osteoporosis is single energy QCT. Measurements of vertebral trabecular bone mineral density (BMD) demonstrate larger percentage decrements between vertebrally-fractured subjects and normal controls, and confer higher relative risks for vertebral fracture than either anteroposterior or lateral DXA measurements. As an emerging alternative to photon absorptiometry techniques, there is a growing interest in the use of quantitative ultrasound (QUS) measurements for the non-invasive assessment of osteoporotic fracture risk in the management of osteoporosis. The attractiveness of QUS lies in the fact that indirect and in vitro experience has suggested that ultrasound may give information not only about BMD but also about architecture and elasticity. Whether or not combining QUS and DXA improve fracture prediction is still unclear and needs further analysis. Due to the growing evidence supporting the use of QUS in osteoporosis and the large number of QUS devices already on the market, a general clinical consensus on the application of QUS is urgently needed. Other techniques that are less widely used for the management of osteoporosis. For example, peripheral quantitative computed tomography, quantitative magnetic resonance (QMR) and magnetic resonance microscopy are promising tools for the evaluation of the skeleton. For example, the ability of QMR and high resolution magnetic resonance imaging has been explored and shows promise as a technique for assessing trabecular bone structure in osteoporosis.

Hormone replacement therapy and prevention of osteoporosis: risk assessment and practical advice

A review of the Debrecen Regional Osteoporosis Program (DROP) in Hungary is given, with special reference to the detection of postmenopausal osteoporosis (PMOP) and its treatment by hormone replacement therapy (HRT). The new definition of osteoporosis by focusing on bone mineral density (BMD) measurements has the major advantage of practical usefulness. The algorithm of managing osteoporotic patients can be easily constructed from the result of bone densitometry as the primary diagnostic tool. The DROP serves a total population of 550,000, is equipped with a DXA bone densitometer, a bone metabolism laboratory and backed by a multidisciplinary team of clinicians from gynecology, radiology, rheumatology, internal medicine, and orthopedic surgery. In 1995 the total number of patients undergoing densitometry was 3170. In 2045 patients T scores of -1 or below were found. From this total number, 348 patients received HRT for 1 year or longer. The results of the treatment showed a positive response (i.e. no bone loss, or net gain) in 65%, while half of the 'non responders' proved in fact non compliant. The contradiction between risk assessment and early diagnosis is explained and replacing 'risk assessment' by 'selection criteria for bone densitometry' is proposed. 'Prevention of osteoporosis' is also to be replaced by 'prevention of complications', i.e. osteoporotic fractures. One of these measures is HRT. Its rational use in the prevention and treatment of osteoporosis and its relation to other treatment methods in the authors' own experience is discussed.