Ankylosing spondylitis and bone mineral density--what is the ideal tool for measurement?

The prevalence of vertebral fractures in diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis: A systematic review and meta-analysis

Background

Subjects with ankylosing spinal disorders, including diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) are more prone to vertebral fractures and frequently present with neurological deficit compared to the patients without an ankylosed spine. Moreover, prevalent vertebral fractures are an important predictor for subsequent fracture risk. However, the pooled fracture prevalence for DISH is unknown and less recent for AS. We aimed to systematically investigate the prevalence and risk of vertebral fractures in DISH and AS populations.

Methods

Publications in Medline and EMBASE were searched from January 1980 until July 2023 for cohort studies reporting vertebral fractures in AS and DISH. Data on prevalence were pooled with random effects modeling after double arcsine transformation. Heterogeneity was assessed with I2 statistics and we performed subgroup analysis and meta-regression to explore sources of heterogeneity.

Results

We included 7 studies on DISH (n = 1,193, total fractures = 231) with a pooled vertebral fracture prevalence of 22.6% (95%CI: 13.4%-33.4%). For AS, 26 studies were included (n = 2,875, total fractures = 460) with a pooled vertebral fracture prevalence of 15.2% (95%CI: 11.6%-19.1%). In general, fracture prevalence for AS remained similar for several study-level and clinically relevant characteristics, including study design, diagnostic criteria, spine level, and patient characteristics in subgroup analysis. AS publications from 2010 to 2020 showed higher fracture prevalence compared to 1990 to 2010 (18.6% vs. 11.6%). Fractures in DISH were most common at the thoracolumbar junction, whereas for AS, the most common location was the mid-thoracic spine.

Conclusions

Vertebral fractures are prevalent in AS and DISH populations. Differences in fracture distribution along the spinal axis exist between the 2 disorders. Additional longitudinal studies are needed for incident fracture assessment in patients with ankylosing spinal disorders.

Fractures in the ankylosed spine are associated with poor bone quality and lower hounsfield units

STUDY DESIGN

Retrospective study INTRODUCTION: Patients with ankylosing spinal disorders have a higher risk of fractures, highlighting the need for bone health surveillance. Bone assessment by dual energy x-ray absorptiometry (DXA) is challenging due to abnormal bone formation but measurements by quantitative computed tomography (qCT) have demonstrated higher sensitivity and specificity. However, no studies have analyzed bone quality using qCT in the ankylosed spine population to assess three-column fracture characteristics and subsequent outcomes.

METHODS

106 patients with 115 three-column fractures were identified from 1999 to 2020. Patient demographics, Charlson comorbidity index, and injury severity score were extracted. Bone quality measured in Hounsfield units (HU), fracture characteristics, neurologic injury, and mortality were obtained.

RESULTS

Most injuries occurred in the thoracic spine (70.4%) following a ground level fall (60.5%). HU adjacent to the fracture (127 HU) was significantly lower than the mobile segments (173 HU) (p < 0.001). Fracture adjacent HU was significantly lower in AS patients compared to DISH (109 vs 150 HU, p = 0.02, respectively) and were lower in fractures that resulted in a non-union or revision surgery (88 vs 137 HU, p = 0.04). Patients with longer fused segments were associated with multilevel and displaced fractures.

CONCLUSIONS

Fracture adjacent HUs within the autofused segments were significantly lower than in the mobile segments, and longer fusion segments were associated with displaced, multilevel fractures. This study reinforces the importance of assessing patients for decreased HUs as well as better understand how the length of fused segments is associated with displaced, multilevel fractures.

LEVEL OF EVIDENCE

Level III.

A radiological study of the natural history of diffuse idiopathic skeletal hyperostosis (DISH): a story of incomplete fusion

Introduction: DISH is an ankylosing disease, when fractured can be challenging to manage. A retrospective radiological study was conducted to evaluate the natural history and radiological characteristics of DISH on Computed tomography (CT).Methods: Paired CT scans with DISH that are separated at least two years apart were used to perform the following radiological measurements: Degree of disc space fusion, Osteophyte and vertebral body linear attenuation coefficients (LAC), and Osteophyte axial area size and location.Results: 164 patients were analysed with a mean duration of 4.49 years between scans. 38.14% (442/1159) of disc spaces had at least partial calcification. Most osteophytes were right sided before becoming more circumferential over time. The average fusion score was 54.17. Most of the changes in fusion occurred in the upper and lower thoracic regions. The thoracic region when compared to the lumbar region had a greater proportion of its disc spaced being fully fused. Disc level osteophyte areas were larger than Body level osteophytes. Disc osteophytes size growth rate drops over time from 10.89mm²/year in Stage 1 to 3.56mm²/year in Stage 3. Stage 3 disc spaces (-11.01HU/year) was also found to have had a reduction in their LAC over time when compared to Stage 1 disc spaces (17.04HU/year). This change in osteophyte LAC was not mirrored in the change in vertebral body LAC. We predict that the age of onset and complete thoracolumbar ankylosis of DISH to be 17.96 years and 100.59 years, respectively.Conclusion: DISH ankylosis of the spine a slow process that starts in the mid to lower thoracic region before extending cranially and caudally. After the bridging osteophyte has fully formed, remodelling of the osteophyte occurs.

Vertebral Bone Mineral Density, Vertebral Strength, and Syndesmophyte Growth in Ankylosing Spondylitis: The Importance of Bridging

OBJECTIVE

To examine the relationship between vertebral trabecular bone mineral density (tBMD), vertebral strength, and syndesmophytes in patients with ankylosing spondylitis (AS) using quantitative computed tomography (QCT).

METHODS

We performed QCT of the spine to measure syndesmophytes and tBMD in 5 vertebrae (T11-L3) in 61 patients with AS. Finite element analysis was performed to measure vertebral strength in compressive overload, including in trabecular and cortical compartments. In cross-sectional analyses, we examined associations of syndesmophyte height with tBMD and vertebral strength in each vertebra. In 33 patients followed up for 2 years, we investigated whether baseline tBMD and vertebral strength predicted syndesmophyte growth in the same vertebra, and vice versa.

RESULTS

In the cross-sectional analyses, 126 vertebrae had bridging, 77 vertebrae had nonbridging syndesmophytes, and 83 vertebrae had no syndesmophytes. There were strong inverse associations between syndesmophyte height and tBMD, total strength, and trabecular strength only among bridged vertebrae. In the longitudinal analysis, nonbridged vertebrae with low tBMD (adjusted β = -0.01 [95% confidence interval (95% CI) -0.019, -0.0012]) and low strength (adjusted β = -0.0003 [95% CI -0.0004, -0.0002]) had more syndesmophyte growth over time. Similar associations were absent among bridged vertebrae. Conversely, vertebrae with bridging at baseline had a significant loss in percent tBMD over time (adjusted β = -0.001 [95% CI -0.0017, -0.0004]).

CONCLUSION

Associations between syndesmophytes and vertebral density and strength in AS differ between bridged and nonbridged vertebrae. Among nonbridged vertebrae, low tBMD and strength are associated with syndesmophyte growth. Bridging is associated with large subsequent losses in tBMD, possibly due to mechanical offloading.

The correlation between volumetric bone mineral density and morphological parameters of the proximal femur and clinical outcomes in ankylosing spondylitis patients with hip involvement

Background

To measure volumetric bone mineral density (vBMD) with quantitative computed tomography (QCT) in the proximal femur of ankylosing spondylitis (AS) patients with hip involvement and analyze their correlations with radiographic and clinical parameters.

Methods

Sixty-five AS inpatients were enrolled in this study. The bone mineral density was measured by QCT and dual-energy x-ray absorptiometry (DXA), respectively. The morphological parameters of the proximal femur were measured on digital anteroposterior (AP) radiographs of the pelvis. The correlations between them were analyzed by SPSS software.

Results

The average trabecular vBMD measured at the femoral neck was 136.38 ± 25.58 mg/cm³. According to the BASRI-Hip score, group A consisted of 39 hips (0–2 score) and group B consisted of 26 hips (3–4 score). There were significant differences regarding trabecular CTXA equivalent T-score between group A and B at the femoral neck (p = 0.004); intertrochanteric region (p < 0.001) and greater trochanter (p = 0.001). The trabecular CTXA equivalent T-score at femoral neck had a negative correlation with disease duration (r = − 0.311, p = 0.012) and with CBR (r = − 0.319, p = 0.010).

Conclusions

The low trabecular bone density at the site of the hip was associated with the duration of disease progression and degree of hip involvement. Meanwhile, it had a correlation with hip function status although we failed to confirm a significant relationship between hip vBMD and disease activity.

The bone bridge significantly affects the decrease in bone mineral density measured with quantitative computed tomography in ankylosing spondylitis

INTRODUCTION AND OBJECTIVE

Ankylosing spondylitis (AS) has characteristics of spinal bone bridge and fusion. Although BMD reduction in AS may be presumed to be due to spinal inflammation, this study was designed to confirm whether immobilization of the spine due to syndesmophytes is related to BMD reduction, as immobilization itself is a risk factor for BMD reduction.

METHODS

Among male patients diagnosed with AS according to the modified New York criteria, those who underwent bone density tests with quantitative computed tomography (QCT) were retrospectively analyzed through a chart review. The correlation between the presence or absence of bone bridges for each vertebral body level of the L spine confirmed with radiography and BMD confirmed with QCT was analyzed.

RESULTS

A total of 47 male patients with AS were enrolled. The mean patient age was 46.8 ± 8.2 years, and the mean disease duration was 7.9 ± 6.4 years. The trabecular BMD of the lumbar spine (L1-L4) ranged from 23.1 to 158.45 mg/cm3 (mean 102.2 ± 37 mg/cm3), as measured with QCT. The lumbar BMD measurements showed that 30 patients (63.8%) had osteopenia or osteoporosis. Bone bridge formation showed a negative correlation with BMD. Low BMD was significantly correlated with bone bridge in the vertebral body (p < 0.05). Positive correlations were observed between bone bridge score and BASMI flexion score, whereas significant negative correlations were found between BMD and BASMI flexion score (p < 0.05).

CONCLUSION

Decreased mobility of the vertebrae due to bone bridge formation affects the decrease in BMD in patients with AS.

Gender-specific SBNO2 and VPS13B as a potential driver of osteoporosis development in male ankylosing spondylitis

To identify the critical genes and pathways that related to OP development in male AS patients, bioinformatic gene analysis and qRT-PCR validation were performed. SBNO2 and VPS13B were identified as the potential target for OP development, which may be valuable for the prevention of OP in male AS patients.

INTRODUCTION

Osteoporosis (OP) is common in men with ankylosing spondylitis (AS). The specific pathogenesis of OP in AS, however, is still unclear. The present study attempted to identify potential genes associated with the development of OP in males with AS.

METHODS

Gene expression profiles were downloaded from the GSE73754 and GSE35959 datasets from the Gene Expression Omnibus (GEO). Data from OsteoporosAtlas were downloaded as a supplement. Differentially expressed genes (DEGs) were determined with the limma package. The overlapping DEGs between male AS-related genes and OP-related genes were determined. The DEGs were validated by qRT-PCR in the blood samples of males with AS. Weighted gene co-expression network analysis (WGCNA) was utilized to establish a co-expression network to identify the hub genes.

RESULTS

A total of 17 overlapping DEGs were identified; 6 genes in 17 overlapping DEGs were verified as the essential genes in the pathogenesis of OP in male AS by qRT-PCR analysis. After WGCNA, the modules of MEblue (> 0.6) and MEred (> 0.8) were screened out by the correlation analysis and were determined to function mainly in MAPK signaling pathway and osteoclast differentiation. Analysis of the two modules revealed VPS13B and SBNO2 as key genes due to the high degree of correlation. Both genes play an important role in bone metabolism regulation in male AS. Two hub genes MYD88 in MEblue and NCK1 in MEred with high degree of connectivity were selected.

CONCLUSIONS

Gender-specific SBNO2 and VPS13B may be key genes involved in OP in male AS.

A Contemporary View of the Diagnosis of Osteoporosis in Patients With Axial Spondyloarthritis

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that primarily affects the axial joints. Altered bone metabolism associated with chronic inflammation leads to both new bone formation in the spine and increased bone loss. It is known that patients with axSpA have a high prevalence of osteoporosis and fractures. However, there is no consensus on which imaging modality is the most appropriate for diagnosing osteoporosis in axSpA. Bone mineral density measurement using dual-energy X-ray absorptiometry is the primary diagnostic method for osteoporosis, but it has notable limitations in patients with axSpA. This method may lead to the overestimation of bone density in patients with axSpA because they often exhibit abnormal calcification of spinal ligaments or syndesmophytes. Therefore, the method may not provide adequate information about bone microarchitecture. These limitations result in the underdiagnosis of osteoporosis. Recently, new imaging techniques, such as high-resolution peripheral quantitative computed tomography, and trabecular bone score have been introduced for the evaluation of osteoporosis risk in patients with axSpA. In this review, we summarize the current knowledge regarding imaging techniques for diagnosing osteoporosis in patients with axSpA.

Loss and gain of bone in spondyloarthritis: what drives these opposing clinical features?

The breadth of bone lesion types seen in spondyloarthritis is unprecedented in medicine and includes increased bone turnover, bone loss and fragility, osteitis, osteolysis and erosion, osteosclerosis, osteoproliferation of soft tissues adjacent to bone and spinal skeletal structure weakness. Remarkably, these effects can be present simultaneously in the same patient. The search for a potential unifying cause of effects on the skeleton necessarily focuses on inflammation arising from the dysregulation of immune response to microorganisms, particularly dysregulation of T_H17 lymphocytes, and the dysbiosis of established gut and other microbiota. The compelling notion that a common antecedent pathological mechanism affects existing bone and tissues with bone-forming potential (entheses), simultaneously with variable effect in the former but bone-forming in the latter, drives basic research forward and focuses our awareness on the effects on these bone mechanisms of the increasing portfolio of targeted immunotherapies used in the clinic.

Update on Imaging-Based Measurement of Bone Mineral Density and Quality

PURPOSE OF REVIEW

Patients with inflammatory arthropathies have a high rate of fragility fractures. Diagnostic assessment and monitoring of bone density and quality are therefore critically important. Here, we review standard and advanced techniques to measure bone density and quality, specifically focusing on patients with inflammatory arthropathies.

RECENT FINDINGS

Current standard procedures are dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT). DXA-based newer methods include trabecular bone score (TBS) and vertebral fracture assessment (VFA). More advanced imaging methods to measure bone quality include high-resolution peripheral quantitative computed tomography (HR-pQCT) as well as multi-detector CT (MD-CT) and magnetic resonance imaging (MRI). Quantitative ultrasound has shown promise but is not standard to assess bone fragility. While there are limitations, DXA remains the standard technique to measure density in patients with rheumatological disorders. Newer modalities to measure bone quality may allow better characterization of bone fragility but currently are not standard of care procedures.

The bone mineral density of hip joint was reduced in the initial stage of ankylosing spondylitis?

The osteoporosis was common complication of ankylosing spondylitis (AS), but it was frequently unrecognized in the initial stage of the disease. This study was to compare areal bone mineral density (BMD) of hip joints in early AS patients with that in healthy controls, to explore the progress of bone loss in cortex and spongiosa in early AS.Quantitative computed tomography (QCT) of hip was performed in 60 AS patients (modified New York criteria for AS, with grade 2 sacroiliitis in computed tomography) and 57 healthy controls. The QCT measurements of AS patients were compared with the measurements of healthy controls.The AS patients had lower areal BMD in cortical bone and total bone of proximal femur in early AS patients (P < .01), than the controls. But there were not significant different of areal BMD in spongiosa of proximal femur between the early AS patients and healthy controls. Strong correlations were found between body mass index BMI, areal BMD in cortical bone (rs = 0.410, P < .001; rs = 0.422, P < .001) and total bone (rs = 0.368, P < .001; rs = 0.266, P = .003) both in AS patients and healthy controls.The results indicate that osteopenia/osteoporosis is general in early stage of AS. What is more, the osteopenia/osteoporosis in cortex is earlier than in spongiosa of proximal femur in early AS.

Clinical practice recommendations for the use of imaging in the diagnosis and management of axial spondyloarthritis in Taiwan

OBJECTIVE

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease bearing challenges in early diagnosis. To improve clinical diagnosis and management of axSpA, recommendations were developed with current axSpA classification criteria and recent advances in medical imaging applications.

METHODS

A systematic literature review was conducted by 10 rheumatologists and radiologists in Taiwan to retrieve research evidence on the utilization of imaging modalities, including conventional radiography (CR), magnetic resonance imaging (MRI), computed tomography (CT), ultrasound (US), quantitative sacroiliac scintigraphy (QSS), and dual-energy X-ray absorptiometry (DXA). The panel of experts proposed six key issues on the role of imaging in early diagnosis of axSpA, monitoring of disease activity and structural changes, predicting treatment effects, and assessing complications such as osteoporosis and spinal fracture. The consensus was established on the basis of research evidence, clinical experiences and expert opinions. For each recommendation statement, the level of evidence was evaluated, the strength of recommendation was graded and the final level of agreement was determined through voting.

RESULTS

In total, four overarching principles and 13 recommendations were formulated. These recommendations outlined different imaging approaches in the diagnosis and management of axSpA disease progression. Considering CT is easy to perform when MRI is less available in Taiwan, the expert panel proposed a concise and practical diagnostic scheme to strengthen the valuable role of MRI and CT in the diagnostic evaluation of axSpA without evident radiographic features.

CONCLUSION

These modified recommendations provide guidance for rheumatologists, radiologists and healthcare professionals on timely diagnosis of axSpA and disease management with appropriate imaging modalities.

Cortical bone loss is an early feature of nonradiographic axial spondyloarthritis

Background

In the present study, we investigated bone geometry, microstructure, and volumetric bone mineral density (vBMD) in a cohort of patients with nonradiographic axial spondyloarthritis (nr-axSpA) in order to define the early bone changes occurring in axial spondyloarthritis (axSpA) and to define potential factors for deterioration of bone microstructure.

Methods

Patients with axSpA (n = 107) and healthy control subjects (n = 50) of similar age and sex were assessed for geometric, volumetric, and microstructural parameters of bone using high-resolution peripheral quantitative computed tomography (HR-pQCT) at the radius. Additionally, demographic and disease-specific characteristics of patients with axSpA were recorded.

Results

Patients with nr-axSpA and control subjects were comparable in age, sex, and body mass index. Geometric and microstructural analysis by HR-pQCT revealed a significantly reduced cortical area (p = 0.022) and cortical thickness (p = 0.006) in patients with nr-axSpA compared with control subjects. Total and cortical vBMD were significantly reduced in patients with nr-axSpA (p = 0.042 and p = 0.007, respectively), whereas there was no difference in trabecular vBMD. Patients with a short disease duration (< 2 years; n = 46) also showed significant reduction of cortical thickness and cortical area compared with control subjects. Patients with disease duration > 2 years (n = 55) additionally developed a decrease of cortical and total vBMD. Multiple regression models identified male sex to be associated with lower cortical vBMD and female sex to be associated with lower trabecular vBMD.

Conclusions

Bone microstructure in patients with nr-axSpA is characterized primarily by deterioration of cortical bone. Cortical bone loss starts early and is evident within the first 2 years of the disease.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1620-1) contains supplementary material, which is available to authorized users.

The Fascinating Paradox of Osteoporosis in Axial Spondyloarthropathy

Low bone mineral density (BMD) is a recognized feature of axial spondyloarthropathy (axSpA). However, the osteoproliferation inherent in axSpA can make traditional dual-energy x-ray absorptiometry assessment inaccurate, particularly in structurally advanced disease. As a result, much about osteoporosis in axSpA is unknown. There is a wide variation in prevalence figures for low BMD in the literature. There is also no consensus regarding risk factors for developing low BMD in axSpA. It is accepted that there is an excess of vertebral fractures in patients with axSpA, but the role of low BMD in contributing to this risk is virtually unknown. This article provides a comprehensive review of the current knowledge regarding low BMD in axSpA. It highlights our current BMD measurement techniques along with their potential pitfalls, and discusses the significance of BMD in vertebral fractures. It also identifies gaps in our knowledge and makes recommendations for future research.

Bone Mineral Density and Fracture Risk in Ankylosing Spondylitis: A Meta-Analysis

We conducted a meta-analysis of studies to examine the risk of vertebral and non-vertebral fractures in patients with ankylosing spondylitis (AS). Additionally, we evaluated the risk factors of vertebral fractures in AS. Two authors independently searched Embase and Medline for studies that had assessed the risk of fractures in patients with AS. Twenty-two studies were eligible for the meta-analysis. Patients with AS had high frequency of vertebral fractures [OR (95% CI): 1.96 (1.52-2.51)]. Major risk factors for vertebral fractures in patients with AS include low BMD at the femoral neck and total hip, male gender, longer disease duration, higher BASDAI, higher BASRI, and possibly inflammatory bowel disease. The risk of non-vertebral fractures [OR (95% CI) 1.10 (1.04-1.15)] was 10% higher in AS patients than in controls. The risk of hip fractures in AS patients was not statistically significant [OR (95% CI) 1.17 (0.71-1.92)] in our pooled analysis. We found that patients with AS are at high risk of vertebral fractures. Male sex, duration of AS, mSASSS, BASRI, and low BMD at the hip and distal forearm were associated with the risk of vertebral fractures. Current evidence on the risk of hip fractures in patients with AS is inconsistent. Data about the effect of NSAIDs and TNF inhibitors on fracture risk in AS are limited.

Analysis of the Literature on Cervical Spine Fractures in Ankylosing Spinal Disorders

STUDY DESIGN

Narrative literature review.

OBJECTIVE

The numbers of low-energy cervical fractures seen in patients suffering from ankylosing spondylitis (also known as Bechterew disease) or diffuse idiopathic skeletal hyperostosis (also known as Forestier disease) have greatly increased over recent decades. These fractures tend to be particularly overlooked, leading to delayed diagnosis and secondary neurological deterioration. The aim of the present evaluation was to summarize current knowledge on cervical fractures in patients with ankylosing spinal disorders (ASDs).

METHODS

The literature was analyzed through an extensive PubMed search focusing on cervical fractures, especially with delayed diagnosis.

RESULTS

In ASDs, it was mainly the cervical spine that was found to be affected by fractures. Fifty percent of ASD patients had neurological deficits at admission, with a high probability of secondary deterioration due to an initially missed diagnosis. Multislice high-resolution imaging techniques should be the radiological standard of care if a vertebral fracture is suspected. Nevertheless, many of these spinal fractures are overlooked, leading to feared secondary deterioration of existing unstable fractures. Long posterior instrumentations were found to be the treatment of choice, followed by anterior and combined anterior-posterior instrumentations.

CONCLUSIONS

Delayed diagnosis of cervical fractures in ASDs contributes to initially misinterpreted clinical symptoms, inadequate imaging techniques, and a lack of knowledge about this disease entity due to its peculiarities. Thorough assessment of the patients' neurological morbidity at admission might reduce the occurrence of the associated fractures. The biomechanical behavior of ASD fractures is completely different from that of non-ASD fractures, so that the treatment strategy for these patients should be at least surgical, in combination with long dorsal instrumentations or combined anterior-posterior approaches.

Bone edema on magnetic resonance imaging is highly associated with low bone mineral density in patients with ankylosing spondylitis

OBJECTIVE

This study aimed to assess the relationship between bone marrow edema (BME) on magnetic resonance imaging (MRI) and bone mineral density (BMD) in patients with ankylosing spondylitis (AS).

METHODS

The study included 333 patients with AS who underwent BMD measurements and axial MRI. Additionally, 106 normal controls were included. The modified New York criteria were used as the classification criteria of AS. Clinical, laboratory, and imaging data were collected and analyzed. Lumbar spine and proximal femur BMD were assessed using dual-energy X-ray absorptiometry. Low BMD was defined by a Z-score ≤-2. The Spondyloarthritis Research Consortium of Canada (SPARCC) MRI index was used to assess inflammation at the sacroiliac joint (SIJ) and spine.

RESULTS

Among the 333 patients, the male:female ratio was 4.6:1, mean patient age was 28.5±10.6 years, and mean disease duration was 7.3±6.8 years. The prevalences of low BMD, osteopenia, and osteoporosis were significantly higher among AS patients than among controls (19.8%, 62.8%, and 5.7% vs. 4.7%, 33.0%, and 0%, respectively, P = 0.000). The BMD values were significantly lower and prevalences of low BMD at both the spine and femur were significantly higher among patients with BME on MRI than among those without BME. Multivariate logistic regression analysis showed that male sex (OR 3.87, 95% CI 1.21-7.36, P = 0.023), high ASDAS-CRP score (OR 2.83, 95% CI 1.36-4.76, P = 0.015), the presence of BME on sacroiliac MRI (OR 2.83, 95% CI 1.77-6.23, P = 0.000) and spinal MRI (OR 4.06, 95% CI 1.96-8.46, P = 0.000), and high grade of sacroiliitis (OR 2.93, 95% CI 1.82-4.45, P = 0.002) were risk factors for low BMD (any site). The SPARCC scores of the SIJ were negatively correlated with femoral BMD (r = -0.22, 95% CI -0.33 to -0.10, P = 0.000). Additionally, the SPARCC scores of the spine were negatively correlated with BMD values (r = -0.23, 95% CI -0.36 to -0.09, P = 0.003) and Z-scores (r = -0.24, 95% CI -0.36 to -0.12, P = 0.001) at the spine.

CONCLUSION

Low BMD is common in AS patients. BME on MRI is highly associated with low BMD at both the spine and femur.

Imaging in osteoporosis in rheumatic diseases

Osteoporosis is a common comorbidity of all major rheumatic diseases, and manifests itself both systemically and locally. Systemic bone loss manifests because of several factors, primarily inflammation, immobility, and commonly used medical treatment for rheumatic diseases. Local bone loss manifests as periarticular demineralization and bone erosion due to local release of inflammatory agents and cytokines, which promote bone resorption. All these factors contribute to the phenomenon of arthritis-associated osteoporosis. This review summarized the currently available and used methods that play a role in the diagnosis and monitoring of osteoporosis and in the detection of osteoporotic fractures.

Osteoporosis Management in Ankylosing Spondylitis

Low bone mineral density (BMD) is increasingly recognized as a common comorbid condition in ankylosing spondylitis (AS). As low BMD increases fracture risk, it is important to identify and treat low BMD in patients with AS who have been shown to be at increased risk for fractures above the population normal. Since low BMD occurs early in disease, we screen during the first year of diagnosis with dual energy x-ray absorptiometry (DXA). If patients are found to have osteoporosis by T-score of less than -2.5 or if their Z-score on DXA is more than two standard deviations below the mean, we initiate therapy with bisphosphonates in males and in females who are not planning any future pregnancies. While reduction in fracture risk with bisphosphonate therapy has not been clearly defined in patients with AS, reduction in vertebral and hip fractures has been well established in primary osteoporosis and thus it is our first line treatment. If there are contraindications to the use of bisphosphonates in the treatment of low BMD, we will consider the use of denosumab. If the patient is not receiving a TNF-alpha inhibitor (TNFi) and has active disease, we also favor early initiation of TNFi due to their positive effects on BMD though the outcome on reduction in vertebral fractures remains unclear. We counsel all patients regarding the importance of adequate intake of vitamin D and calcium per the Institute of Medicine guidelines. All patients should be encouraged to participate in weight-bearing activities with a focus on core strength and gait training.

Higher Level of Dickkopf-1 is Associated with Low Bone Mineral Density and Higher Prevalence of Vertebral Fractures in Patients with Ankylosing Spondylitis

Patients with ankylosing spondylitis (AS) have an increased risk of bone loss and vertebral fractures. In this study, we explored the hypothesis that the excess bone loss and vertebral fractures might be related with the activity of the Wingless signaling pathway, and in particular with the serum levels of its circulating inhibitors, Sclerostin and Dickkopf-1 (DKK1). We recruited 71 patients diagnosed with AS. Lateral radiographs of the total spine were analyzed to detect the presence of vertebral fractures, and bone mineral density (BMD) was assessed in all patients using dual X-ray absorptiometry at lumbar spine and proximal femoral site. Blood samples were obtained and levels of C-reactive protein (CRP), DKK1, and Sclerostin were measured. Blood samples from 71 healthy sex- and age-matched volunteers were collected to be used as controls. Vertebral fractures were detected more commonly among men than in women (29 vs 8 %, respectively). DKK1, but not Sclerostin serum levels, were inversely correlated to lumbar spine Z-score BMD. Patients with one or more prevalent vertebral fractures had significantly higher DKK1 levels, without significant difference in Sclerostin serum levels. A significant positive correlation was found between DKK1 serum levels and CRP (r = 0.240, p = 0.043). The association we found between serum DKK1 levels and BMD values and vertebral fracture prevalence suggests that DKK1 might contribute to the severity of osteoporosis in AS.

Utility of DXA scanning and risk factors for osteoporosis in ankylosing spondylitis-A prospective study

BACKGROUND

Conventional DXA imaging of spine and hip to measure bone mineral density (BMD) has limitations in patients with ankylosing spondylitis (AS). We investigated the correlation of hip and spine BMD measurements in patients with AS to determine if hip DXA will prove clinically useful while avoiding the confounding effect of spinal disease. Also, we studied risk factors for osteoporosis (OP) and osteopenia in AS.

METHODS

We randomly identified patients from our validated AS registry ≥18 years of age who met the Modified New York Classification criteria for AS. BMD was measured and interpreted using ISCD 2007 guidelines and diagnosis of OP was based on WHO criteria. ESR, CRP, urinary N-telopeptide, and 25-hydroxy vitamin D were also measured. Correlation between the BMD (total hip and/or femoral neck) and lumbar spine was calculated. Statistical comparisons between the 2 sites, lumbar spine (AP) and hip (total hip and or femoral neck) were made using Bowker's test for symmetry and kappa statistics. Chi-square and odds ratio using logistic regression were used to assess the association of the purported risk factors for OP in these patients.

RESULTS

Frequency of OP among AS patients ≥50 years of age was 23%, and that of osteopenia was 41%. Among patients <50 years of age, the frequency of low bone mass for expected age (Z-score ≤-2.0) was 14.7%. There was moderate correlation (ρ = 0.59) and a fair agreement (κ = 0.26; 95% CI: 0.10-0.42) between the lowest T-values of hip and lumbar spine (AP view). OP was significantly associated with elevated CRP level [OR = 4.2 (95% CI: 1.13-15.9), p < 0.03] and African American race [OR = 7.2 (95% CI: 1.18-44.99), p < 0.03].

CONCLUSION

Our results demonstrated a moderate correlation and fair agreement between the T-scores of hip and the lumbar spine (AP view) in patients with AS, suggesting that DXA of the hip and the lumbar spine (AP view) may both be useful for OP and osteopenia screening in patients with AS without fused spines. We confirm the previous reports of an association of elevated CRP level with an increased risk of OP in patients with AS, but this is the first study to demonstrate that African American patients with AS may be at a higher risk of developing OP compared to Caucasians.

The prevalence of vertebral fractures in spondyloarthritis: relation to disease characteristics, bone mineral density, syndesmophytes and history of back pain and trauma

Introduction

An increased risk of vertebral fracture (VF) is one of the extra-articular manifestations of spondyloarthropathy (SpA). The prevalence of moderate to severe VFs visualized by radiography (Rx) in patients with SpA in daily practice is unknown until imaging of the full spine is available, as most VFs do not present with clinical signs and symptoms of an acute fracture.

Methods

We evaluated the prevalence of VFs (>25 % loss in height) on available Rx and dual-energy X-ray absorptiometry (DXA) images in 390 consecutive patients with SpA in daily practice. We assessed their association with disease characteristics, bone mineral density, the modified Stoke Ankylosing Spondylitis Spinal Score, and history of trauma.

Results

Forty-six patients (11.8 %) had Rx VF (56.4 % men, 93.5 % in the thoracic spine), and 44.5 % had multiple VFs. Compared with patients without VF, patients with VF were older (52.2 vs. 47.3 years, p < 0.01; range 25–84 years), had lower femoral neck T-scores (−1.1 vs. −0.7; p < 0.05), and had a marginally higher modified Stoke Ankylosing Spondylitis Spinal Score (11.7 vs. 7.0; p = 0.06). Among patients with VFs, 15.2 % had a history of trauma with acute back pain (p < 0.001 vs. no VF). The reliability of DXA for diagnosing radiographic VFs was high (κ 0.90).

Conclusions

Moderate to severe VFs are found in more than 10 % of patients with SpA before the age of 40 years in 5 % of women and 9 % in men. Most VFs are located in the thoracic region, are related to low femoral neck bone mineral density and to stiffening of the spine, and are only rarely related to trauma history. DXA is a useful alternative for diagnosing VFs.

EULAR recommendations for the use of imaging in the diagnosis and management of spondyloarthritis in clinical practice

A taskforce comprised of an expert group of 21 rheumatologists, radiologists and methodologists from 11 countries developed evidence-based recommendations on the use of imaging in the clinical management of both axial and peripheral spondyloarthritis (SpA). Twelve key questions on the role of imaging in SpA were generated using a process of discussion and consensus. Imaging modalities included conventional radiography, ultrasound, magnetic resonance imaging, computed tomography (CT), positron emission tomography, single photon emission CT, dual-emission x-ray absorptiometry and scintigraphy. Experts applied research evidence obtained from systematic literature reviews using MEDLINE and EMBASE to develop a set of 10 recommendations. The strength of recommendations (SOR) was assessed by taskforce members using a visual analogue scale. A total of 7550 references were identified in the search process, from which 158 studies were included in the systematic review. Ten recommendations were produced using research-based evidence and expert opinion encompassing the role of imaging in making a diagnosis of axial SpA or peripheral SpA, monitoring inflammation and damage, predicting outcome, response to treatment, and detecting spinal fractures and osteoporosis. The SOR for each recommendation was generally very high (range 8.9–9.5). These are the first recommendations which encompass the entire spectrum of SpA and evaluate the full role of all commonly used imaging modalities. We aimed to produce recommendations that are practical and valuable in daily practice for rheumatologists, radiologists and general practitioners.

Bone mass in axial spondyloarthritis: A literature review

AIM: To review the published literature reporting bone loss in patients with axial spondyloarthritis (SpA) particularly those studies using dual X-ray absorptiometry (DXA) methods.

METHODS: This literature review examines the reported bone mass in patients with ax-SpA, particularly those using the DXA methods. The MEDLINE, Web of Science and Scopus databases were searched for relevant articles published between September 1992 and November 2013. Some of used search terms were ankylosing spondylitis (AS), SpA, spondyloarthropathy, bone loss, bone mass, osteopenia, bone mineral density, osteoporosis (OP), densitometry. Studies in which bone loss was investigated by using DXA in patients with SpA were eligible. Each article was reviewed and the key elements were noted.

RESULTS: There were 286 hits on MEDLINE, 200 on Web of Science and 476 on Scopus. After applying inclusion and exclusion criteria, we identified 55 articles in our systematic search. The sample size of the studies varied from 14 to 332 patients with SpA. The reported age range varied from 25 to 56 years in the reviewed studies. The symptom duration of patients with axSpA varied from 1.6 to 49 years. There were more males than females in these studies. Most of the recruited females were premenopausal women. Reported HLA-B27 positivity changed between 19% to 95%. The prevalence of OP and osteopenia in patients with SpA varied from 3%-47% to 5%-88%, respectively, in the included studies. In particular, the prevalence of OP and osteopenia ranged from 2.0%-47.0% and 5.0%-78.3%, respectively, in patients with AS. There are conflicting results regarding the relationship among disease activity, acute phase response and bone mass. Some studies suggest good correlation of bone mass with disease activity and acute phase reactants.

CONCLUSION: Bone loss may be determined in patients with axSpA at the lumbar spine or proximal femur even in the early phase of the disease and may be associated with inflammation (bone marrow edema) at the vertebral colon.

Opportunistic computed tomography screening shows a high incidence of osteoporosis in ankylosing spondylitis patients with acute vertebral fractures

Advanced ankylosing spondylitis is associated with reductions in bone mineral density (BMD), contributing to pain and predisposing to fractures. Quantifying this reduction is complicated because overgrowth of bone and loss of trabecular bone occur concurrently. Traditional methods such as dual-energy X-ray absorptiometry struggle to generate accurate estimates of BMD in these patients. The aim of this study was to evaluate the utility of computed tomography (CT) attenuation in generating estimates of BMD in patients with severe AS who had sustained vertebral fractures. Patients with severe AS and bridging syndesmophytes who presented, with acute fractures of the spine, were reviewed to assess whether they had a CT scan in the 6 mo before or after injury that included an image of the L1 vertebra; if it did, the scans were selected for analysis. A total of 17 patients were evaluated. Using a CT attenuation threshold of 135 HU balanced for sensitivity and specificity, 14 of 17 (82%) patients were osteoporotic. Using a CT attenuation threshold for higher sensitivity (160 HU), 15 of 17 (88%) patients were osteoporotic. Even using the L1 CT attenuation threshold of 110 HU for higher specificity, 14 of 17 (82%) patients were osteoporotic. CT attenuation demonstrates that a high proportion of AS patients who sustain fractures have osteoporosis. This overcomes some of the difficulties that have been encountered with the use of dual-energy X-ray absorptiometry in this group of patients. This simple and accessible method saves on time, cost, and exposure to radiation and can help in the planning of a patient's management.

Bone microarchitecture in ankylosing spondylitis and the association with bone mineral density, fractures, and syndesmophytes

Introduction

Osteoporosis of the axial skeleton is a known complication of ankylosing spondylitis (AS), but bone loss affecting the peripheral skeleton is less studied. This study on volumetric bone mineral density (vBMD) and bone microarchitecture in AS was conducted to compare peripheral vBMD in AS patients with that in healthy controls, to study vBMD in axial compared with peripheral bone, and to explore the relation between vertebral fractures, spinal osteoproliferation, and peripheral bone microarchitecture and density.

Methods

High-resolution peripheral quantitative computed tomography (HRpQCT) of ultradistal radius and tibia and QCT and dual-energy x-ray absorptiometry (DXA) of lumbar spine were performed in 69 male AS patients (NY criteria). Spinal radiographs were assessed for vertebral fractures and syndesmophyte formation (mSASSS). The HRpQCT measurements were compared with the measurements of healthy controls.

Results

The AS patients had lower cortical vBMD in radius (P = 0.004) and lower trabecular vBMD in tibia (P = 0.033), than did the controls. Strong correlations were found between trabecular vBMD in lumbar spine, radius (r_S = 0.762; P < 0.001), and tibia (r_S = 0.712; P < 0.001).

When compared with age-matched AS controls, patients with vertebral fractures had lower lumbar cortical vBMD (-22%; P = 0.019), lower cortical cross-sectional area in radius (-28.3%; P = 0.001) and tibia (-24.0%; P = 0.013), and thinner cortical bone in radius (-28.3%; P = 0.001) and tibia (-26.9%; P = 0.016).

mSASSS correlated negatively with trabecular vBMD in lumbar spine (r_S = -0.620; P < 0.001), radius (r_S = -0.400; p = 0.001) and tibia (r_S = -0.475; p < 0.001) and also with trabecular thickness in radius (r_S = -0.528; P < 0.001) and tibia (r_S = -0.488; P < 0.001).

Adjusted for age, syndesmophytes were significantly associated with decreasing trabecular vBMD, but increasing cortical vBMD in lumbar spine, but not with increasing cortical thickness or density in peripheral bone. Estimated lumbar vBMD by DXA correlated with trabecular vBMD measured by QCT (r_S = 0.636; P < 0.001).

Conclusions

Lumbar osteoporosis, syndesmophytes, and vertebral fractures were associated with both lower vBMD and deteriorated microarchitecture in peripheral bone. The results indicate that trabecular bone loss is general, whereas osteoproliferation is local in AS.

The epidemiology of osteoporosis and fractures in ankylosing spondylitis

Bone is a target in many inflammatory rheumatic diseases. Inflammation leads to a wide range of changes in bone, and especially bone remodeling. In ankylosing spondylitis (AS) bone loss has been documented, but measuring bone density in the spine is hampered by new bone formation in syndesmophytes, periost and within the vertebrae. The risk of vertebral fractures is increased in AS. The diagnosis of vertebral fractures requires imaging and adequate evaluation of vertebral heights. In addition, in the ankysosed spine segments, additional imaging is often needed to diagnose spinal fractures at unusual locations (cervical spine) or in the posterior arch structures. Risk factors for vertebral fractures are helpful for case finding. Fracture prevention is indicated in high risk patients with AS, especially when they have already a vertebral fracture or in the presence of osteoporosis.

Vertebral fractures in ankylosing spondylitis are associated with lower bone mineral density in both central and peripheral skeleton

OBJECTIVE

To study the prevalence and risk factors for vertebral fractures (VF) in ankylosing spondylitis (AS) and the relation between VF, measures of disease activity, and bone mineral density (BMD) in different measurement sites.

METHODS

Patients with AS (modified New York criteria) underwent examination, answered questionnaires, and gave blood samples. Lateral spine radiographs were scored for VF (Genant score) and syndesmophyte formation through modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). BMD was measured with dual-energy x-ray absorptiometry in the hip, radius, and lumbar spine in anteroposterior and lateral projections with estimation of volumetric BMD (vBMD).

RESULTS

Two hundred four patients (57% men) with a mean age of 50 ± 13 years and disease duration 15 ± 11 years were included. VF were diagnosed in 24 patients (12%), but were previously noted clinically in only 3 of the 24. Patients with VF were significantly older (p = 0.004), had longer disease duration (p = 0.011), higher Bath Ankylosing Spondylitis Metrology Index (p = 0.011), mSASSS (p = 0.035), and Bath Ankylosing Spondylitis patient global score-2 (BASG-2) (p = 0.032) and were more often smokers (p = 0.032). All women with a VF were postmenopausal. BMD was significantly lower at all measuring sites in the patients with VF. In logistic regression, high BASG-2, low BMD in femoral neck, and low lumbar vBMD were independently associated with presence of VF.

CONCLUSION

VF in AS are common but are often not diagnosed. VF are associated with advanced age, longstanding disease, impaired back mobility, syndesmophyte formation, and lower BMD in both the central and peripheral skeleton. BMD in the femoral neck, total hip, and estimated vBMD showed the strongest association with VF.

Osteoporosis in ankylosing spondylitis - prevalence, risk factors and methods of assessment

Introduction

Osteoporosis can be a complication of ankylosing spondylitis (AS), but diagnosing spinal osteoporosis can be difficult since pathologic new bone formation interferes with the assessment of the bone mineral density (BMD). The aims of the current study were to investigate prevalence and risk factors for reduced BMD in a Swedish cohort of AS patients, and to examine how progressive ankylosis influences BMD with the use of dual-energy x-ray absorptiometry (DXA) of the lumbar spine in different projections.

Methods

Methods of assessment were questionnaires, back mobility tests, blood samples, lateral spine radiographs for syndesmophyte grading (mSASSS), DXA of the hip, radius and lumbar spine in anteroposterior (AP) and lateral projections with estimation of volumetric BMD (vBMD).

Results

AS patients (modified New York criteria), 87 women and 117 men, mean age 50 ± 13 years and disease duration 15 ± 11 years were included. According to World Health Organization (WHO) criteria 21% osteoporosis and 44% osteopenia was diagnosed in patients > = 50 years. Under age 50 BMD below expected range for age was found in 5%. Interestingly lateral lumbar DXA showed significantly lower BMD and revealed significantly more cases with osteoporosis as compared with AP DXA. Lumbar vBMD was not different between sexes, but women had significantly more lumbar osteoporosis measured with AP DXA (P < 0.001). Men had significantly higher mSASSS (P < 0.001). Low BMD was associated with high age, disease duration, mSASSS, Bath Ankylosing Spondylitis Metrology Index (BASMI), inflammatory parameters and low body mass index (BMI). Increasing mSASSS correlated significantly with decreasing lateral and volumetric lumbar BMD, while AP lumbar BMD showed tendency to increase.

Conclusions

Osteoporosis and osteopenia is common in AS and associated with high disease burden. Lateral and volumetric lumbar DXA are more sensitive than AP DXA in detecting osteoporosis and are less affected by syndesmophyte formation.

Osteoimmunology and osteoporosis

The concept of osteoimmunology is based on growing insight into the links between the immune system and bone at the anatomical, vascular, cellular, and molecular levels. In both rheumatoid arthritis (RA) and ankylosing spondylitis (AS), bone is a target of inflammation. Activated immune cells at sites of inflammation produce a wide spectrum of cytokines in favor of increased bone resorption in RA and AS, resulting in bone erosions, osteitis, and peri-inflammatory and systemic bone loss. Peri-inflammatory bone formation is impaired in RA, resulting in non-healing of erosions, and this allows a local vicious circle of inflammation between synovitis, osteitis, and local bone loss. In contrast, peri-inflammatory bone formation is increased in AS, resulting in healing of erosions, ossifying enthesitis, and potential ankylosis of sacroiliac joints and intervertebral connections, and this changes the biomechanical competence of the spine. These changes in bone remodeling and structure contribute to the increased risk of vertebral fractures (in RA and AS) and non-vertebral fractures (in RA), and this risk is related to severity of disease and is independent of and superimposed on background fracture risk. Identifying patients who have RA and AS and are at high fracture risk and considering fracture prevention are, therefore, advocated in guidelines. Local peri-inflammatory bone loss and osteitis occur early and precede and predict erosive bone destruction in RA and AS and syndesmophytes in AS, which can occur despite clinically detectable inflammation (the so-called 'disconnection'). With the availability of new techniques to evaluate peri-inflammatory bone loss, osteitis, and erosions, peri-inflammatory bone changes are an exciting field for further research in the context of osteoimmunology.

Baseline new bone formation does not predict bone loss in ankylosing spondylitis as assessed by quantitative computed tomography (QCT): 10-year follow-up

Background

To evaluate the relationship between bone loss and new bone formation in ankylosing spondylitis (AS) using 10-year X-ray, dual-energy x-ray absorptiometry (DXA) and quantitative computed tomography (QCT) follow-up.

Methods

Fifteen AS patients free from medical conditions and drugs affecting bone metabolism underwent X-ray, DXA and QCT in 1999 and 2009.

Results

In spine QCT a statistically significant (p = 0,001) decrease of trabecular bone mineral content (BMC) was observed (change ± SD: 18.0 ± 7.3 mg/cm³). In contrast, spine DXA revealed a significant increase of bone mineral density (change ± SD: -0.15 ± 0.14 g/cm²). The mean BMC, both at baseline and follow-up was significantly lower (p = 0.02 and p = 0.005, respectively) in advanced radiological group as compared to early radiological group. However, in multiple regression model after adjustment for baseline BMC, the baseline radiological scoring did not influence the progression of bone loss as assessed with QCT (p = 0.22, p for BMC*X-ray syndesmophyte scoring interaction = 0.65, p for ANOVA-based X-ray syndesmophyte scoring*time interaction = 0.39). Baseline BMC was the only significant determinant of 10-year BMC change, to date the longest QCT follow-up data in AS.

Conclusions

In AS patients who were not using antiosteoporotic therapy spine trabecular bone density evaluated by QCT decreased over 10-year follow-up and was not related to baseline radiological severity of spine involvement.

The relation between bone mineral density, bone turnover markers, and vitamin D status in ankylosing spondylitis patients with active disease: a cross-sectional analysis

SUMMARY

Osteoporosis is a well recognized complication of ankylosing spondylitis (AS). This study indicates that increased bone turnover, inflammation, and low vitamin D levels are important in the pathophysiology of AS-related osteoporosis, and that bone turnover markers (BTM) are valuable markers to detect bone loss in AS.

INTRODUCTION

The aim of this study was to elucidate the pathophysiology of AS-related osteoporosis by investigating the relation between bone mineral density (BMD), BTM, vitamin D, and clinical assessments of disease activity and physical function, as well as to identify parameters that are related to low BMD (osteopenia or osteoporosis) in AS patients with active disease.

METHODS

One hundred twenty-eight consecutive Dutch AS outpatients were included in this cross-sectional study. Bath AS Disease Activity Index (BASDAI), erythrocyte sedimentation rate (ESR), C-reactive protein, ASAS-endorsed disease activity score (ASDAS), Bath AS Functional Index (BASFI), bone formation markers procollagen type 1 N-terminal peptide (PINP) and osteocalcin (OC), bone resorption marker serum C-telopeptides of type I collagen (sCTX), 25-hydroxyvitamin D (25OHvitD), lumbar spine and hip BMD, and vertebral fractures were assessed. Z-scores of BTM were calculated using matched 10-year cohorts of a Dutch reference group to correct for the normal influence that age and gender have on bone turnover.

RESULTS

sCTX Z-score, OC Z-score, BASDAI, age, and gender were independently related to low BMD. In addition, PINP Z-score, ESR, 25OHvitD, age, and gender were independently related to sCTX and/or OC Z-score.

CONCLUSIONS

This study indicates that increased bone turnover, inflammation, and low vitamin D levels are important in the pathophysiology of AS-related osteoporosis. Furthermore, sCTX and OC Z-scores seem to be valuable markers to detect bone loss in AS patients in daily clinical practice where BMD of the lumbar spine, measured by DXA, may be overestimated due to osteoproliferation in patients with advanced AS.

Osteoporosis in ankylosing spondylitis

Osteoporosis (OP) is a frequent complication of ankylosing spondylitis (AS), even in early stages of the disease, and is associated with elevated levels of biochemical markers of bone turnover, proinflammatory cytokines, and acute-phase reactants. This suggests that systemic inflammatory mediators, such as interleukin-6 and tumor necrosis factor-alpha, may be involved. Various factors that conceivably work in conjunction with one another also cause bone loss in AS (eg, genetic polymorphisms of vitamin D, low levels of osteoprotegerin and sex steroid hormones, and impaired calcium and vitamin D absorption). Dual x-ray absorptiometry for assessing bone mineral density (BMD) has limitations in patients with AS because of unreliability of spinal measurements, particularly in advanced disease with new bone formation. Femoral neck BMD is reduced and correlates with increased risk of vertebral fractures. Hence, measurement of BMD at the femoral neck may provide the most accurate means of detecting osteopenia and OP and could assess fracture risk in AS patients. No guidelines are available for detection and treatment of OP in AS, and most patients are young men, who are less likely to be screened. The only evidence-based recommendation is that optimal control of disease activity in AS prevents bone loss. A recent study showed a beneficial effect of infliximab therapy on bone turnover markers and BMD in AS. Also, bisphosphonates may be useful in managing OP in AS.

[Bone densitometry in inflammatory rheumatic diseases : Characteristics of the measurement site and disease-specific factors]

Bone densitometry should be performed earlier in patients with inflammatory arthritis, since factors such as inflammation and drug therapy, in particular treatment with glucocorticoids, have an important impact on the development of osteoporosis. DXA (Dual energy X-ray Absorptiometry) is considered the gold standard for bone densitometry. According to the German guidelines for osteoporosis, bone densitometry plays a crucial role in the choice of therapy.In patients with rheumatoid arthritis, measurement of peripheral bone (forearm) density in addition to lumbar spine and hip is recommended, since local bone loss is pathognomonic for this disease. DXA measurements of the hand enable the diagnosis of juxtaarticular osteoporosis at an earlier stage; however, this has not yet been established in routine practise.Bone measurement in patients with ankylosing spondylitis can be performed in the lumbar spine and the hip at disease onset. In systemic lupus erythematosus, bone loss is more frequent in patients with high inflammatory activity. Patients with psoriasis arthritis frequently have osteoporosis in the case of a destructive development of the joints.

Relationship Between Bone Mineral Density and Disease Activity in Patients with Ankylosing Spondylitis

Objective: This retrospective study was planned to determine the relationship between bone mineral density (BMD) and clinical, radiological and laboratory parameters in patients with ankylosing spondylitis (AS).

Materials and Methods: The study group consisted of 28 patients with a mean disease duration of 11.9±6.1 years. In addition to clinical and demographic variables, lumbar and femoral BMD were evaluated with dual energy X-ray absorbtiometry. Lumbar spine score (LSS) and sacroiliac score (SIS) were calculated by grading of standard radiographs. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level were determined as laboratory parameters.

Results: The rate of osteoporosis and osteopenia were 7.1% and 25% at the lumbar spine, and 14.2% and 17.8% at the femoral neck, respectively. LSS was significantly correlated with lumbar BMD (r=0.70, p<0.001), but not with femoral neck BMD (r=-0.11, p=0.55). SIS was negatively correlated with femoral neck BMD (r=-0.79, p<0.001), but not correlated with lumbar BMD (r=0.19, p=0.32). While lumbar BMD was positively correlated with disease duration (r=0.37, p=0.05), femoral neck BMD showed negative correlation with disease duration (r=-0.46, p=0.01). The evaluation of clinical paramaters and BMD showed that morning stiffness, spinal pain, ESR and CRP were not correlated with BMD. Only modified Schober's test was related to BMD on both lumbar spine and femoral neck.

Conclusion: Ankylosing spondylitis patients are at risk for developing osteoporosis. In advanced disease, the lumbar BMD is misleadingly high because of paravertebral calcification and ossification. Therefore, it is more rational to evaluate the BMD at the femoral neck. (Turk J Rheumatol 2010; 25: 24-8)

Insights in to the pathogenesis of axial spondyloarthropathy based on gene expression profiles

Introduction

Axial spondyloarthropathy (SpA) is a group of inflammatory diseases, with ankylosing spondylitis as the prototype. SpA affects the axial skeleton, entheses, joints and, at times, the eyes. This study tested the hypothesis that SpA is characterized by a distinct pattern of gene expression in peripheral blood of affected individuals compared with healthy controls.

Methods

High-density, human GeneChip^® probe arrays were used to profile mRNA of peripheral blood cells from 18 subjects with SpA and 25 normal individuals. Samples were processed as two separate sets at different times (11 SpA + 12 control subjects in primary set (Set 1); 7 SpA+ 13 control subjects in the validation set (Set 2)). Blood samples were taken at a time when patients were not receiving systemic immunomodulatory therapy. Differential expression was defined as a 1.5-fold change with a q value < 5%. Gene ontology and pathway information were also studied.

Results

Signals from 134 probe sets (representing 95 known and 12 unknown gene transcripts) were consistently different from controls in both Sets 1 and 2. Included among these were transcripts for a group of 20 genes, such as interleukin-1 (IL-1) receptors 1 and 2, Nod-like receptor family, pyrin domain containing 2 (NLRP2), secretory leukocyte peptidase inhibitor (SLPI), secreted protein acidic and rich in cysteine (SPARC), and triggering receptor expressed on myeloid cells 1 (TREM-1) that are clearly related to the immune or inflammatory response and a group of 4 transcripts that have a strong role in bone remodeling.

Conclusions

Our observations are the first to implicate SPARC, SLPI, and NLRP2, a component of the innate immune system, in the pathogenesis of SpA. Our results also indicate a possible role for IL-1 and its receptors in SpA. In accord with the bone pathology component of SpA, we also found that expression levels of transcripts reflecting bone remodeling factors are also distinguishable in peripheral blood from patients with SpA versus controls. These results confirm some previously identified biomarkers implicated in the pathogenesis of SpA and also point to novel mediators in this disease.

The relation between osteoporosis and vitamin D levels and disease activity in ankylosing spondylitis

In this study, the relation between osteoporosis and vitamin D and the disease activity in patients with ankylosing spondylitis (AS) was investigated. A hundred patients with AS and 58 healthy individuals were included in the study. In addition to the routine blood and urine tests, serum 25-(OH)D3, parathormone (PTH), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), total calcium, ionized calcium, and phosphorous levels of all participants were also measured. Bone mineral density (BMD) measurements were performed at the anterior-posterior and lateral lumbar and femur regions. Anterior-posterior and lateral thoracic and lumbosacral radiography was performed on all participants. The disease activity was evaluated by Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), functional status by Bath Ankylosing Spondylitis Functional Index (BASFI), and mobility by Bath Ankylosing Spondylitis Metrology Index (BASMI). In the patient group, BMD values obtained from the lateral lumbar and femur regions and serum vitamin D levels were lower than the control group. A negative relation was determined between the lateral lumbar BMD values and ESR, CRP, and BASDAI scores of patients with AS. The ESR, CRP levels, and BASMI scores of the AS patients with osteoporosis were significantly higher, when compared to patients without osteoporosis. The negative correlation between serum 25-(OH)D3 level and ESR, CRP levels did not reach a statistically significant level in patients with AS; the positive correlation between PTH levels and ESR, and the negative correlation between CRP and BASDAI also did not reach a statistically significant level. Vitamin D deficiency in AS may indirectly lead to osteoporosis by causing an increase in the inflammatory activity. The present authors believe that it would be beneficial to monitorize vitamin D levels together with BMD measurements in order to determine the patients under osteoporosis risk.

Prevalence and risk factors of osteoporosis and vertebral fractures in patients with ankylosing spondylitis

Ankylosing spondylitis (AS) is characterized by inflammation of the entheses and paravertebral structures, leading in time to bone formation at those sites. As well, vertebral bone loss is also a recognized feature of AS Objective: To calculate the prevalence and risk factors of osteoporosis and vertebral fractures in patients with AS.

METHODS

Eighty patients with AS were enrolled in the study. Clinical, biological and radiological status was assessed by the Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), ESR and C-reactive protein (CRP), Bath AS Radiology Index (BASRI) and modified stoke AS spine score (mSASSS). BMD of the hip and spine was measured and vertebral fractures were defined using a combination of Genant semiquantitative (SQ) approach and morphometry by VFA (fracture vertebral assessment).

RESULTS

The years+/-11.8. The mean BMI was 22.8 kg/m(2)+/-4.1 and the mean disease duration was 10.8 years+/-6.6. Prevalence of osteoporosis was 25%. 18.8% of patients had a vertebral fracture (grades 2 and 3). Factors associated with osteoporosis were low weight and BMI and longer disease duration, higher ESR, CRP, BASFI and BASDAI. Vertebral fractures were associated with advanced age, longer disease duration, higher BASFI, BASRI and mSASSS and reduced BMD and T-score at the hip site, presence of osteoporosis at any site. Multiple logistic regression analysis (Table 4) revealed that parameters significantly associated with osteoporosis were BASDAI (OR=1.05, 95% confidence interval [CI]: 1.03-1.09); disease duration (OR=1.13, 95%CI: 1.03-1.25); and BMI (OR=0.82, 95%CI: 0.69-0.93). The presence of VFs (grades 2 and 3) were independently associated with disease duration (OR=1.50, 95%CI: 1.07-2.10); and mSASSS (OR=1.17, 95%CI: 1.05-1.30).

CONCLUSION

Osteoporosis is common in patients with AS and seems to be related to disease activity while vertebral fractures appear to be related to the duration and structural severity of the disease rather than BMD.

Osteoporosis and vertebral fractures in ankylosing spondylitis

PURPOSE OF REVIEW

To review recent data, in the context of what is already known, about an increased risk of vertebral fractures in ankylosing spondylitis patients.

RECENT FINDINGS

Osteoporosis and fractures of the vertebral body and its dorsal arch are now well recognized features in patients with ankylosing spondylitis, but their diagnosis is still often a challenge. The risk factors and clinical consequences for fractures in ankylosing spondylitis are increasingly understood in the context of osteoimmunology and of spinal biomechanical changes in material and structural components in the spine that result in bone failure.

SUMMARY

Diagnosing fractures of the vertebral body and its dorsal arch remains a challenge in studies and in clinical practice. Prospective studies are needed to evaluate to what degree such fractures can be prevented in ankylosing spondylitis.

Is osteoporosis generalized or localized to central skeleton in ankylosing spondylitis?

BACKGROUND

Osteoporosis at the lumbar spine and at the femur is a well-established complication in ankylosing spondylitis (AS), but the exact mechanism and the distribution of osteoporosis are not known absolutely.

OBJECTIVE

To determine whether the osteoporosis is generalized or localized to central skeleton and to examine the relation between bone mineral density (BMD) and disease activity and radiologic progression in patients with AS.

METHODS

In this study, 26 patients with AS and 33 healthy controls matched for age and sex were recruited to the study. Hip and forearm BMD were measured by dual energy X-ray absorptiometry (DEXA). Laboratory and clinical disease activity parameters were documented, and anteroposterior sacroiliac radiographs were taken to determine the radiologic progression.

RESULTS

The urine deoxypyridinoline levels of the patients with AS were statistically significantly higher (P = 0.02) and the serum osteocalcin levels were significantly lower with respect to controls (P = 0.03). The femoral neck and femur BMD values and T scores were significantly lower in patients with AS compared with the controls (P = 0.019, 0.003, 0.01, and 0.01, respectively). The differences in BMD values and T scores of the distal 1/3 radius between 2 groups were not statistically significant. The relation between BMD and disease activity, and radiologic progression in patients with AS could not detected.

CONCLUSION

Sparing of distal regions such as the as radius suggests that osteoporosis might be due to localized effects of inflammatory activity or immobility rather than a systemic effect. Both increased resorption and decreased formation might be involved in the pathogenesis of osteoporosis. Radius BMD may not be appropriate to evaluate bone loss in patients with AS.

Epidemiology of Osteoporosis in Rheumatic Diseases

Much work has been directed at establishing the impact of osteoporosis and related fragility fractures in rheumatic diseases. Several cross-sectional studies reported that disability and reduced motility that are due to functional impairment are among the most important determinants of bone loss in different rheumatic diseases. At the same time, longitudinal studies have confirmed the detrimental effect of uncontrolled disease activity on bone density. In this perspective, the suppression of inflammation probably remains the main concern when considering treatment options. Besides these variables, pharmacologic agents that are used commonly in the treatment of these conditions probably have an adjunctive effect on bone loss in rheumatic patients. Large epidemiologic studies have demonstrated clearly that patients who have RA, SLE, or AS are at an increased risk for fragility fractures. Further studies are required to investigate the effective impact of osteoporosis and fragility fractures in other rheumatic diseases, and to define the relationship between OA and osteoporosis. A better appreciation of the impact and mechanisms of osteoporosis in rheumatic diseases by rheumatologists represents a clinical challenge; however, a greater understanding of this frequent complication will improve the quality of health care and the lives of patients who have rheumatic diseases.

Methoden der Bildgebung und der Knochendichtemessung bei der Osteoporose im Rahmen entzündlich-rheumatischer Erkrankungen

Besides clinical history and clinical findings conventional X-ray is important in the evaluation of osteoporosis as the third diagnostic tool. Its purpose is mainly excluding other diseases and proof of fractures as well as their follow up. Also X-ray is able to demonstrate complications of osteoporosis such as insuffiency fractures and effects of therapy as for example fluorosis. For very early diagnosis bone densitometry is used. Today the improved methods deliver fracture prediction percentages of high value. As a planar measurement method DXA of the spine and of the femoral neck can be used. Volumetric tools, which can measure trabecular bone, without overlying cortical bone, are computed tomography of the spine and of the distal radius. Quantitative ultrasound is an interesting approach, but which does not really measure bone densitometry and which is net yet suited for clinical follow up. Quantitative Magnetic Resonance is far from routine clinical application.