Bone mineral density and vertebral compression fracture rates in ankylosing spondylitis

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.

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.

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.

Mono-segmental percutaneous screw fixation in the management of AoSpine thoracolumbar type B fracture in patients with ankylosing spondylitis: A new treatment

PURPOSE

To assess the viability and effectiveness of mono-segmental percutaneous screw fixation in the treatment of unstable type B thoracolumbar fracture due to ankylosing spondylitis.

METHODS

We report here all 40 patients treated by mono-segmental screw fixation in this indication, between January 2018 and January 2022, with follow-up at 3 and 9 months. Study variables comprised operating time, length of stay, fusion, stabilization quality, and peri-operative morbidity and mortality.

RESULTS

One patient showed early displacement of rods caused by technical error. None of the others showed secondary displacement of rods or screws. Mean age was 73 years (range 18-93), mean hospital stay 4.8 days (range 2-15), mean operative time 52minutes (range 26-95minutes) and mean estimated blood loss 40ml. There were 2 deaths caused by intensive care unit complications. All patients except those in intensive care were verticalized within 24hours after surgery. Parker score was unchanged for each patient before and after surgery and during follow-up.

CONCLUSION

Mono-segmental percutaneous screw fixation in the treatment of unstable type B thoracolumbar fracture due to ankylosing spondylitis was safe and effective. This study showed that this surgery reduced length of hospital stay, operative time, blood loss and complications compared to open or extended percutaneous surgery, and allowed fast rehabilitation in this vulnerable population.

Rotating Magnetic Field Mitigates Ankylosing Spondylitis Targeting Osteocytes and Chondrocytes via Ameliorating Immune Dysfunctions

Ankylosing spondylitis (AS) is clinically characterized by bone fusion that is induced by the pathological formation of extra bone. Unfortunately, the fundamental mechanism and related therapies remain unclear. The loss of SHP-2 (encoded by Ptpn11) in CD4-Cre;Ptpn11^f/f mice resulted in the induction of AS-like pathological characteristics, including spontaneous cartilage and bone lesions, kyphosis, and arthritis. Hence, this mouse was utilized as an AS model in this study. As one of the basic physical fields, the magnetic field (MF) has been proven to be an effective treatment method for articular cartilage degeneration. In this study, the effects of a rotating magnetic field (RMF; 0.2 T, 4 Hz) on an AS-like mouse model were investigated. The RMF treatment (2 h/d, 0.2 T, 4 Hz) was performed on AS mice from two months after birth until the day before sampling. The murine specimens were subjected to transcriptomics, immunomics, and metabolomics analyses, combined with molecular and pathological experiments. The results demonstrated that the mitigation of inflammatory deterioration resulted in an increase in functional osteogenesis and a decrease in dysfunctional osteolysis due to the maintenance of bone homeostasis via the RANKL/RANK/OPG signaling pathway. Additionally, by regulating the ratio of CD4+ and CD8+ T-cells, RMF treatment rebalanced the immune microenvironment in skeletal tissue. It has been observed that RMF interventions have the potential to alleviate AS, including by decreasing pathogenicity and preventing disease initiation. Consequently, RMF, as a moderately physical therapeutic strategy, could be considered to alleviate the degradation of cartilage and bone tissue in AS and as a potential option to halt the progression of AS.

Reduction and Stabilization of an Extension-Distraction Injury in a Patient with Ankylosing Spondylitis: A Case Report

CASE

The authors reported a case of an 83-year-old man with ankylosing spondylitis throughout the cervical, thoracic, and lumbar spine who sustained a three-column T10 osteoligamentous extension-distraction injury after low-energy trauma. A closed reduction was performed using incremental flexion on a variable flexion-extension table and subsequent stabilization with robotic-assisted percutaneous pedicle screw placement. Postoperative radiographs at 7-month follow-up showed intact implants with adequate alignment with the patient remaining at neurological baseline.

CONCLUSION

A closed reduction method using a variable flexion-extension table with stabilization through percutaneous pedicle screw placement is a safe and appropriate method to achieve spinal realignment in select patients.

Preoperative prediction of sagittal imbalance in kyphosis secondary to ankylosing spondylitis after one-level three-column osteotomy

Background

This study aimed to determine preoperative predictors for sagittal imbalance in kyphosis secondary to ankylosing spondylitis (AS) after one-level three-column osteotomy.

Methods

A total of 55 patients with AS who underwent one-level three-column osteotomy were enrolled. The patients were divided into two groups according to sagittal vertical axis (SVA) value at the final follow-up (group A: SVA > 5 cm; group B: SVA ≤ 5 cm). The radiographic measures included global kyphosis, lumbar lordosis (LL), pelvic tilt (PT), pelvic incidence (PI), sacral slope, T1 pelvic angle (TPA), SVA, osteotomized vertebral angle and PI and LL mismatch (PI − LL). Postoperative clinical outcomes were evaluated using Scoliosis Research Society-22 questionnaire (SRS-22) and Oswestry Disability Index (ODI).

Results

Fifty-five AS patients had an average follow-up of 30.6 ± 10.2 months (range 24–84 months). Group A had larger preoperative and postoperative LL, PT, PI − LL, TPA and SVA values compared with group B (P < 0.05), and no significant differences were found in ODI and SRS-22 scores between the two groups (P > 0.05). Preoperative LL, PT, PI − LL, TPA, and SVA values were positively correlated with the follow-up SVA value (P < 0.05). Among them, TPA > 40.9°, PI − LL > 32.5° and SVA > 13.7 cm were the top three predictors with the best accuracy to predict sagittal imbalance. Immediate postoperative SVA value of ≤ 7.4 cm was a key factor in reducing the risk of sagittal imbalance during follow-up.

Conclusions

Preoperative TPA > 40.9°, PI − LL > 32.5° and SVA > 13.7 cm could predict sagittal imbalance in AS kyphosis after one-level three-column osteotomy, and additional osteotomies were recommended for this condition. Immediate postoperative SVA ≤ 7.4 cm was an optimal indicator for preventing sagittal imbalance.

Level of evidence

IV.

Prevalence and Factors of Osteoporosis and High Risk of Osteoporotic Fracture in Patients with Ankylosing Spondylitis: A Multicenter Comparative Study of Bone Mineral Density and the Fracture Risk Assessment Tool

Background: We investigated the prevalence of and the factors associated with a high risk of osteoporotic fractures in Korean patients with ankylosing spondylitis (AS). Methods: This was a multicenter, retrospective study including 219 AS patients from five university hospitals; the control group was selected by matching age and sex with those of the AS patients. The fracture risk was evaluated based on bone mineral density (BMD) measured by dual-energy X-ray absorptiometry and the fracture risk assessment tool (FRAX) with/without BMD. Results: The mean age of the patients was 47.6 years, and 144 (65.8%) patients were men. According to the WHO criteria and FRAX with/without BMD, the candidates for pharmacological treatment were 44 (20.1%), 20 (13.2%), and 23 (15.1%) patients, respectively, significantly more than those in the healthy control group. Among them, the proportion of patients receiving osteoporosis treatment was 39.1–75%. In logistic regression analysis, menopause was an independent factor for the high risk of fracture according to the WHO criteria and FRAX with/without BMD. C-reactive protein level (odds ratio (OR) 3.8 and OR 6) and glucocorticoid use (OR 1.5 and OR 1.7) were associated with a high risk of osteoporotic fracture based on FRAX without BMD and osteoporosis diagnosed according to the WHO criteria. Conclusions: Our study suggests that both FRAX and WHO criteria may be complementary for treatment decisions to reduce osteoporotic fractures in patients with AS.

Spinal cord injury and spinal fracture in patients with ankylosing spondylitis

Background

Spinal cord injury (SCI) and spinal fracture are major complications in patients with ankylosing spondylitis (AS) who sustain spinal trauma. The purpose of this study was to investigate the incidence, predictors, and sequelae of spinal trauma in patients with AS.

Methods

This retrospective study included patients with AS who were admitted for spinal trauma between January 1, 2006, and June 30, 2016. The study compared clinical outcomes of patients between group 1: SCI alone, group 2: spinal fracture alone (no SCI), and group 3: both SCI and spinal fracture.

Results

Of the 6285 patients with AS admitted during the retrospective study period, only 105 suffered from spinal trauma and were enrolled in the study. Case number in group 1, 2, and 3 was 11(10.48%), 45(42.85%), and 49(46.67%), respectively. Among the patients with spinal fractures, 52.1% had SCI. Bamboo spine was significantly more prevalent in the fracture group than in the nonfracture group (78.7% vs. 36.4%; P = 0.006). Patients with SCI had more instances of subluxation or dislocation (48.3% vs. 8.9%; P < 0.001) and more cases of spinal epidural hematoma (SEH; 21.7% vs. 2.2%; P = 0.003) than patients without SCI. The rate of delayed diagnosis for spinal fracture was 31.4%, with one-third of patients developing delayed SCI. Among the patients with incomplete SCI, 58.3% achieved neurological improvement after treatment (P = 0.004).

Conclusions

Patients with AS and bamboo spine at radiograph had a higher rate of spinal fracture, which may be an important factor in SCI in patients with AS. Spinal fractures involving the C3–C7 region, subluxation or dislocation, severe spinal fracture, and SEH were found to be predictive of SCI, and SCI in patients with AS resulted in higher mortality and complication rates.

Bone Involvement in Patients with Spondyloarthropathies

Spondyloarthropathies (SpA) are common systemic inflammatory rheumatic diseases, in which, as in other rheumatic diseases, levels of markers of bone resorption are elevated, leading to bone loss and elevated risk of vertebral fractures. However, the diseases are also associated with new bone formation in the spine, the so-called syndesmophytes. We tried to unravel the pathogenesis of formation and growth of syndesmophytes and evaluated new diagnostic and treatment options. After a successful meeting of the Working Group on Rheumatic Diseases at the ECTS 2020, we (WL and CR) were excited about the quality of the speakers (CM, JH, AG, and GL) and their complimentary lectures. Given the relative lack of reviews on spondyloarthropathies and bone, we decided to work together on a comprehensive review that might be interesting for basic scientists and clinically relevant for clinicians. Radiographic progression in axSpA is linked to several risk factors, like male sex, smoking, HLA-B-27, increased levels of CRP, presence of syndesmophytes, and marked inflammation on MRI. The potential role of mechanical stress in the context of physically demanding jobs has been also suggested to promote structural damages. Different treatment options from NSAIDs to biologic agents like TNF inhibitors (TNFi) or IL-17inhibitors (IL-17i) result in a reduction of inflammation and symptoms. However, all these different treatment options failed to show clear and reproducible results on inhibition on syndesmophyte formation. The majority of data are available on TNFi, and some studies suggested an effect in subgroups of patients with ankylosing spondylitis. Less information is available on NSAIDs and IL-17i. Since IL-17i have been introduced quite recently, more studies are expected. IL-17 inhibitors (Il-17i) potently reduce signs and symptoms, but serum level of IL-17 is not elevated, therefore, IL-17 probably has mainly a local effect. The failure of anti-IL-23 in axSpA suggests that IL-17A production could be independent from IL-23. It may be upregulated by TNFα, resulting in lower expression of DKK1 and RANKL and an increase in osteogenesis. In active AS markers of bone resorption are increased, while bone formation markers can be increased or decreased. Bone Turnover markers and additional markers related to Wnt such as DKK1, sclerostin, and RANKL are valuable for elucidating bone metabolism on a group level and they are not (yet) able to predict individual patient outcomes. The gold standard for detection of structural lesions in clinical practice is the use of conventional radiographics. However, the resolution is low compared to the change over time and the interval for detecting changes are 2 years or more. Modern techniques offer substantial advantages such as the early detection of bone marrow edema with MRI, the fivefold increased detection rate of new or growing syndesmophytes with low-dose CT, and the decrease in 18F-fluoride uptake during treatment with TNFα-inhibitors (TNFi) in a pilot study in 12 AS patients. Detection of bone involvement by new techniques, such as low-dose CT, MRI and 18-Fluoride PET-scans, and bone turnover markers, in combination with focusing on high-risk groups such as patients with early disease, elevated CRP, syndesmophytes at baseline, male patients and patients with HLA-B27 + are promising options for the near future. However, for optimal prevention of formation of syndesmophytes we need more detailed insight in the pathogenesis of bone formation in axSpA and probably more targeted therapies.

Prediction of Vertebral Fractures by Trabecular Bone Score in Patients With Ankylosing Spondylitis

Ankylosing spondylarthritis (AS) is associated falsely increased lumbar spine bone mineral density (BMD). New tool for discrimination of subjects at fracture risk is needed. Vertebral fracture (VF) prediction of routine methods for osteoporosis assessment, BMD and trabecular bone score (TBS), in patients with AS. Cross-sectional study of all AS patients regularly followed at the rheumatology outpatient clinics of two centers. All subjects undergone BMD measurement at lumbar spine (LS), total hip (TH) and femoral neck (FN) using Hologic® Horizon device. TBS at L1-4 in all subjects by TBS InSight® software were assessed. Vertebral fracture assessment (VFA) was performed using the lateral spine imaging IVA™ and graded using Genant semi-quantitative approach. 119 AS subjects (90 males/29 females), mean age 47.6 years were included in the study. In 20 patients 34 VFs were detected, from whom 7 patients had multiple fractures. Subjects with VF were older and had lower FN BMD, TBS in comparison to non-VF subjects. No differences in LS BMD, FN BMD or BASDAI between groups were observed. Among patients with VF only 3 had T-score less than -2.5 but 7 has TBS less than 1.23 which means highly degraded microarchitecture. AS patients with VF have lower TBS and FN BMD in comparison to non-VF subjects. In addition, TBS was able to detect 20 % more VFs than BMD. Therefore, TBS seems promising in VF discrimination among patients with AS.

Targeting chondrocytes for arresting bony fusion in ankylosing spondylitis

Bony fusion caused by pathological new bone formation manifests the clinical feature of ankylosing spondylitis (AS). However, the underlying mechanism remains elusive. Here we discovered spontaneous kyphosis, arthritis and bony fusion in mature CD4-Cre;Ptpn11^f/f mice, which present the pathophysiological features of AS. A population of CD4-Cre-expressing proliferating chondrocytes was SHP2 deficient, which could differentiate into pre-hypertrophic and hypertrophic chondrocytes. Functionally, SHP2 deficiency in chondrocytes impeded the fusion of epiphyseal plate and promoted chondrogenesis in joint cavity and enthesis. Mechanistically, aberrant chondrocytes promoted ectopic new bone formation through BMP6/pSmad1/5 signaling. It is worth emphasizing that such pathological thickness of growth plates was evident in adolescent humans with enthesitis-related arthritis, which could progress to AS in adulthood. Targeting dysfunctional chondrogenesis with Smo inhibitor sonidegib significantly alleviated the AS-like bone disease in mice. These findings suggest that blockade of chondrogenesis by sonidegib would be a drug repurposing strategy for AS treatment.

Current treatments cannot significantly alleviate the radiographic progression in ankylosing spondylitis (AS), which results in joints stiffness and bony fusion of AS. Smo inhibitor sonidegib retards the pathological new bone formation in AS through targeting dysfunctional chondrogenesis.

Percutaneous instrumentation with cement augmentation for traumatic hyperextension thoracic and lumbar fractures in ankylosing spondylitis: a single-institution experience

OBJECTIVE

The typical traumatic thoracolumbar (TL) fracture in patients with ankylosing spondylitis (AS) is a hyperextension injury involving all three spinal columns, which is associated with unfavorable outcomes. Although a consensus on the management of these highly unstable injuries is missing, minimally invasive surgery (MIS) has been progressively accepted as a treatment option, since it is related to lower morbidity and mortality rates. This study aimed to evaluate clinical and radiological outcomes after percutaneous instrumentation with cement augmentation for hyperextension TL fractures in patients with AS at a single institution.

METHODS

This cohort study was completed retrospectively. Back pain was assessed at preoperative, postoperative, and final follow-up visits using the visual analog scale (VAS). Patient-reported outcomes via the Oswestry Disability Index (ODI) and the new mobility score (NMS) were obtained to assess disability and mobility during follow-up. Radiological outcomes included the Cobb angle, sagittal index (SI), union rate, and implant failure. Intra- and postoperative complications were recorded.

RESULTS

A total of 22 patients met inclusion criteria. The mean patient age was 74.2 ± 7.3 years with a mean follow-up of 39.2 ± 17.4 months. The VAS score for back pain significantly improved over the follow-up period (from 8.4 ± 1.1 to 2.8 ± 0.8, p < 0.001). At the last follow-up, all patients had minor disability (mean ODI score 24.4 ± 6.1, p = 0.003) and self-sufficiency of mobility (mean NMS 7.5 ± 1.6, p = 0.02). The Cobb angle (5.2° ± 2.9° preoperatively to 4.4° ± 3.3° at follow-up) and SI (7.9° ± 4.2° to 8.8° ± 5.1°) were maintained at follow-up, showing no loss of segmental kyphosis. Bone union was observed in all patients. The overall complication rate was 9.1%, while the reoperation rate for implant failure was 4.5%.

CONCLUSIONS

Percutaneous instrumentation with cement augmentation for traumatic hyperextension TL fractures in AS demonstrated good clinical and radiological outcomes, along with a high bone union level and low reoperation rate. Accordingly, MIS reduced the complication rate in the management of these injuries of the ankylosed spine.

Trends in hospitalizations for vertebral compression fracture in ankylosing spondylitis: data from the National Inpatient Sample 2000-2014

Ankylosing spondylitis (AS) patients are at increased risk of vertebral compression fractures (VCF). Our objective was to examine the yearly trend of VCF hospitalizations in AS patients as compared to rheumatoid arthritis (RA) and the general population. National Inpatient Sample (NIS) database (2000-2014) was used to identify adult (≥ 18 years) hospitalizations, based on validated ICD-9 diagnosis codes. The rate of VCF hospitalizations, as a primary diagnosis, was assessed in three mutually exclusive groups: AS, RA, and the general population. The prevalence of VCF hospitalization was highest in AS (2.70%), compared to 0.77% in RA and 0.35% in the general population. Over the 15-year period, VCF hospitalization in AS was noted to have an increasing trend (Annual Percent Change (APC) = 4.73, p < 0.05) in contrast to the stable trend in the general population (APC = 0.34, p = NS) and a declining trend in RA (APC -3.61, p < 0.05). VCF related to AS was also associated with a longer hospital stay as compared to the general population (8.1 days vs. 5.1 days, p < 0.05) and higher inpatient mortality (3.4% vs. 1.0%, p < 0.05). A higher rate of VCF hospitalization along with an increasing trend was noted in AS as compared to RA and compared to the general population. Better screening approaches and treatment strategies for AS patients with VCF risk are urgently needed to reduce hospitalizations and related complications. Key Points • An increasing trend of VCF hospitalization was noted in AS, in contrast to a declining trend in RA and a stable trend in the general population. • VCF in AS was associated with longer hospital stay and higher inpatient mortality than in RA and the general population.

Preliminary analysis of interaction of the fat fraction in the sacroiliac joint among sex, age, and body mass index in a normal Chinese population

Objective

Iterative decomposition of water and fat with echo asymmetry and least-squares estimation-iron quantification (IDEAL-IQ) is a noninvasive and objective method used to quantitatively measure fat content. Although this technique has been used in the entire abdomen, IDEAL-IQ findings in the sacroiliac joint (SIJ) have rarely been reported. This preclinical study was performed to quantify the amount of fat in the SIJ in healthy volunteers by IDEAL-IQ.

Methods

From April to November 2017, 60 healthy volunteers with low back pain were included in this retrospective study. The participants were allocated into groups by age (15–30, 31–50, and ≥51 years), sex (male and female), and body mass index (BMI) (<18.5, 18.5–23.9, and ≥24.0 kg/m²). The iliac-side (Fi) and sacral-side (Fs) fat fractions were obtained in all groups. Two- and three-factor multivariate analyses were performed to analyze the effects of sex, age, and BMI on the Fi and Fs.

Results

The interaction among sex, age, and BMI had no statistically significant effect on the dependent variable. Both Fi and Fs were significantly influenced by age. Fs was significantly influenced by sex.

Conclusion

The IDEAL-IQ sequence can be used to quantitatively assess the SIJ fat content in healthy volunteers.

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.

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.

Chin on Chest Deformity Caused by Upper Cervical Kyphosis Associated With Ankylosing Spondylitis: A Case Report

Chin on chest deformity caused by upper cervical kyphosis associated with ankylosing spondylitis is rare. A 66-year-old woman presented at our institute with chief complaints of difficulty in horizontal gaze and opening her mouth. Cervical radiographs showed a C0–2 angle of 1° on flexion and 7° on extension, and her chin-brow vertical angle was 49°. We planned fixation surgery at C0–5 posteriorly to prevent the progression of kyphosis, with slight correction of the kyphosis at C0–2. The correction was performed by pushing down the over lordotically contoured titanium rods connected to an occipital plate onto the C3–5 lateral mass screws, just like cantilever technique. No palpable cracking or loss of resistance was noticed during the correction. However, intraoperative radiographs revealed apparent anterior separation of the vertebral bodies between C3 and C4. Postoperative computed tomography images at the C3/4 level suggested hemorrhage from the fracture site. Tracheostomy was performed because of massive edema around the pharynx. To secure solid bone fusion, staged surgery to extend the fusion to T3 and to graft an additional iliac bone was performed. Fortunately, the C2–7 angle was corrected to 40°, and her chin-brow vertical angle was restored to 17° without any catastrophic complications. Although the patient finally obtained an ideal sagittal alignment, the surgeon should be aware that the technique had a higher perioperative risk for iatrogenic fracture, resulting in neurological and vascular injuries.

Trabecular Bone Score (TBS) Predicts Fracture in Ankylosing Spondylitis: The Manitoba BMD Registry

INTRODUCTION

Ankylosing spondylitis (AS) is a chronic inflammatory disease of the spine characterized among other features by spinal boney proliferation, back pain, loss of flexibility, and increased fracture risk. Overlying bone limits the utility of bone mineral density (BMD) by dual X-ray absorptiometry (DXA) in the spine. Trabecular bone score (TBS) is a bone texture measurement derived from the spine DXA image that indicates bone quality and fracture risk independent of BMD.

METHODOLOGY

Using the Manitoba Bone Density Program database, patients with diagnosis codes for ankylosing spondylitis, baseline DXA and lumbar spine TBS were identified. Incident nontraumatic fractures (major osteoporotic [MOF], clinical spine, hip, and all fracture) were identified from population based databases. Cox-proportional hazard models are presented.

RESULTS

We identified 188 patients with diagnosed AS. TBS was lower in those with incident MOF (1.278 ± 0.126, compared to 1.178 ± 0.136, p < 0.001). Unadjusted TBS and FRAX-MOF-BMD adjusted predicted major osteoporotic fracture (N = 19) (hazard ratio [HR] 2.04, 95% confidence interval [CI]: 1.28-2.26, p = 0.003; HR 1.81, 95% CI: 1.11-2.96, p = 0.018). TBS unadjusted and FRAX-MOF-BMD adjusted also predicted clinical spine fracture (N = 7) (HR 2.50, 95% CI: 1.17-5.37; p = 0.019; HR 2.40 95% CI: 1.1-5.25; p = 0.028). Higher HRs were observed for prediction of hip fracture (N = 6), but these did not achieve statistical significance (FRAX-adjusted HR 1.74, 95% 0.73-4.17; p = 0.211). Unadjusted models show TBS was predictive of all fracture (N = 27) (HR 1.60, 95% CI: 1.08-2.39; p = 0.020), which was borderline significant after adjustment for FRAX-MOF-BMD (HR 1.51, 95% CI: 1.00-2.29; p = 0.052).

CONCLUSION

We report the first analysis of TBS for fracture prediction as an incident event in AS. TBS independently predicted major osteoporotic and clinical spine fracture in AS independent of FRAX.

Can fusion to S1 maintain favorable surgical outcomes following one-level pedicle subtraction osteotomy in patients with thoracolumbar kyphosis secondary to ankylosing spondylitis?

PURPOSE

To compare the surgical outcomes between ankylosing spondylitis (AS)-related thoracolumbar kyphosis patients with the lowest instrumented vertebra (LIV) at S1 or above following one-level pedicle subtraction osteotomy (PSO).

METHODS

One hundred and two AS patients undergoing one-level PSO with a minimum of 2-year follow-up were included. Twenty-two patients were in group S1 (LIV at S1), and eighty were in group non-S1 (LIV above S1). Radiographic parameters including lumbar lordosis (LL), sacral slope (SS), pelvic incidence (PI), and sagittal vertical axis (SVA) were measured. Oswestry Disability Index (ODI) and visual analog scale (VAS) were applied for clinical assessment.

RESULTS

In both S1 and non-S1 groups, the radiographic parameters and clinical outcomes were significantly improved after surgery (P  < 0.05). Patients undergoing distal fusion to S1 had significantly larger preoperative PI-LL mismatch, SVA, and smaller preoperative LL and SS compared to those in group non-S1 (P  < 0.05). No significant difference was found between the two groups regarding preoperative and final follow-up ODI and VAS (P  > 0.05), as well as the improvement in ODI and VAS (P  > 0.05). The incidence of overall complications and each type of complication including the implant failure was similar between group S1 and non-S1 (P  > 0.05).

CONCLUSION

Selecting S1 as the LIV without pelvic fixation following one-level PSO in thoracolumbar kyphosis caused by AS could achieve satisfactory surgical outcomes and might not increase the complications. Patients with relatively severe sagittal imbalance, loss of LL, PI-LL mismatch, and small SS might be the potential candidates for distal fusion to S1 following one-level PSO.

Pharmacological treatment for managing bone health in axial spondyloarthropathy: systematic review and meta-analysis

Axial spondyloarthropathy (axSpA) is associated with an increased prevalence of osteoporosis, but no recommendations exist to guide management. This systematic review and meta-analysis aim to assess the efficacy of pharmacological and non-pharmacological interventions on bone mineral density (BMD) in axSpA. Electronic databases were searched from inception to June 2019 for randomised controlled trials (RCTs) and quasi (q)-RCTs with pharmacological and non-pharmacological interventions. Independent reviewers undertook screening, and risk of bias and quality assessments. Primary outcomes of interest were BMD at spine and hip. Eight studies (two RCTs and six qRCTs) were included (602 participants). Moderate level evidence favoured alendronate over placebo at femoral neck [mean difference (MD) 2.01, 95% CI 0.67 to 3.35], but there was low-level evidence showing no effect at the spine. There was moderate level evidence showing no effect of tumour necrosis factor inhibitors (TNFi) on BMD at total hip (MD - 0.01, 95% CI - 0.06 to 0.04). Very low-level evidence demonstrated no effect of TNFi on spine or femoral neck. Moderate level evidence favoured neridronate over infliximab at the spine (MD 3.26, 95% CI 1.14 to 5.38), but low-level evidence showed no effect at the total hip (MD 2.75, 95% CI - 0.21 to 5.71). There were no eligible studies investigating the efficacy of non-pharmacological interventions. We conditionally recommend alendronate for management of low BMD in axSpA. The balance of evidence does not recommend the use of TNF-inhibitors for treating low BMD. There is a lack of high-quality evidence guiding clinicians treating osteoporosis in axSpA.

Role of HLA-B27 in the comorbidities observed in Axial Spondyloarthritis: Data from COMOSPA

OBJECTIVE

To analyze the potential association between the presence of HLA-B27 and the different comorbidities observed in Axial Spondyloarthritis patients.

METHODS

A comparative cross-sectional study including Axial Spondyloarthritis patients from COMOSPA registry. COMOSPA is a worldwide registry that includes a wide set of anthropometric and clinical variables from 3984 patients with Spondyloarthritis. The registry also includes the most frequent comorbidities observed in Spondyloarthitis such as obesity, hypertension, diabetes, hyperlipidemia, heart ischemic disease, stroke, renal failure, neoplasms, peptic ulcer, diverticulitis, chronic obstructive pulmonary disease, and the presence of osteoporosis. A descriptive analysis and a multiple logistic regression model was performed including all variables assessed.

RESULTS

2370 patients fulfilled ASAS criteria of Axial Spondyloarthritis patients and were included in the study. 1858 (78.4%) of them were HLA-B27 positive. HLA-B27 positive Axial Spondyloarthritis patients presented significantly higher percentage of male sex, longer disease duration, higher percentage of definite Ankylosing Spondylitis, higher CRP levels, and were also more frequent tobacco consumers and excessive alcohol intakers compared to the negatives. However, disease activity measured by BASDAI, BASFI and ASDAS-CRP were all significantly higher in the HLA-B27 negative patients compared to the positive ones. The only association observed between any comorbidity and presence of HLA-B27 genotype was the presence of osteoporosis, even after adjusting in the multivariate analysis for all variables assessed.

CONCLUSION

The association observed between the HLA-B27 genotype and the presence of osteoporosis in Axial Spondyloarthritis patients could be of great relevance given the impact of osteoporosis in the phenotypical frame of these patients.

Gut microbiota alterations associated with reduced bone mineral density in older adults

Objective

To investigate compositional differences in the gut microbiota associated with bone homeostasis and fractures in a cohort of older adults.

Methods

Faecal microbiota profiles were determined from 181 individuals with osteopenia (n = 61) or osteoporosis (n = 60), and an age- and gender-matched group with normal BMD (n = 60). Analysis of the 16S (V3-V4 region) amplicon dataset classified to the genus level was used to identify significantly differentially abundant taxa. Adjustments were made for potential confounding variables identified from the literature using several statistical models.

Results

We identified six genera that were significantly altered in abundance in the osteoporosis or osteopenic groups compared with age- and gender-matched controls. A detailed study of microbiota associations with meta-data variables that included BMI, health status, diet and medication revealed that these meta-data explained 15–17% of the variance within the microbiota dataset. BMD measurements were significantly associated with alterations in the microbiota. After controlling for known biological confounders, five of the six taxa remained significant. Overall microbiota alpha diversity did not correlate to BMD in this study.

Conclusion

Reduced BMD in osteopenia and osteoporosis is associated with an altered microbiota. These alterations may be useful as biomarkers or therapeutic targets in individuals at high risk of reductions in BMD. These observations will lead to a better understanding of the relationship between the microbiota and bone homeostasis.

The Risk and Consequences of Vertebral Fracture in Patients with Ankylosing Spondylitis: A Population-based Data Linkage Study

OBJECTIVE

To compare the long-term prevalence, incidence, and outcomes of vertebral fracture (VF) between ankylosing spondylitis (AS) patients and matched controls, including the role of extraarticular manifestations (EAM) and osteoporosis.

METHODS

This was a statewide observational study using linked health data for 2321 patients with AS and 22,976 controls presenting to hospital from 1980 to 2015. Data were analyzed using incidence rates (per 1000 person-yrs) and ratios (IRR), multivariable Cox proportional hazards regression, and Kaplan-Meier survival curves.

RESULTS

Over a median 13.92 (interquartile range 7.58-21.67) years of follow-up, patients with AS had a greater VF prevalence and greater incidence of developing a new VF compared to controls (9.3% vs 2.5%, 6.8% vs 1.9%, respectively, all P < 0.001). Patients with AS had an increased risk of developing a VF after adjustments for age, sex, and osteoporosis (HR 2.55, 95% CI 2.11-3.09) compared to controls; this risk remained throughout the study period. Patients with AS were 5 years younger at time of first VF (P = 0.008) and had a greater likelihood of a recurrent VF (IRR 4.64; 95% CI 4.54-4.75) compared to respective controls. Mortality overall was comparable between patients with AS and controls after adjustment for age, sex, osteoporosis, and VF status (HR 0.90; 95% CI 0.80-1.01).

CONCLUSION

The significantly increased risk of VF in patients with AS has not altered following the introduction of tumor necrosis factor inhibitor treatment. Although patients with AS experience a first VF at a younger age than controls, this does not lead to an increased risk of death.

Measuring bone density in axial spondyloarthropathy: Time to turn things on their side?

AIM

Osteoporosis in axial spondyloarthropathy (axSpA) is difficult to accurately diagnose due to osteoproliferation of the spine interfering with conventional (anteroposterior, AP) dual-energy X-ray absorptiometry (DXA). This study compares AP and lateral projections of DXA when assessing bone mineral density (BMD) of the spine and investigates the impact of osteoproliferation on AP DXA.

METHOD

In this cross-sectional study, structured standardized assessments collected demographic, clinical, laboratory and radiographic data. DXA assessed BMD of the spine using PA and lateral projections. Hip BMD was assessed in the usual manner. World Health Organization (WHO) criteria assessed prevalence of low BMD. Incorporating lateral DXA in the bone health assessment of axSpA was investigated. SPSS was used for statistical analysis.

RESULTS

A total of 100 patients had paired AP and lateral DXA studies: 78% were male, mean (SD) age 52 (12) years. BMD of the spine measured by AP projection was significantly higher than BMD measured by lateral projection (mean difference 0.34 g/cm² , 95% CI 0.30-0.37). More patients had low BMD with lateral compared to AP projection (47% vs 16%, P = .01). At the hip, 34% of patients had low BMD. Disease duration, body mass index and radiographic severity independently predicted a difference between AP and lateral measurements of the spine.

CONCLUSION

Lateral DXA of the spine is unaffected by osteoproliferation of the spine in axSpA and detects significantly more cases of low BMD than conventional AP DXA. Lateral DXA should be included in BMD assessment of patients with axSpA.

Long-Term Treatment With TNF-Alpha Inhibitors Improves Bone Mineral Density But Not Vertebral Fracture Progression in Ankylosing Spondylitis

The aim of this cohort study was to evaluate the long-term effects of TNF inhibitors (TNFis) on BMD and the incidence of vertebral fractures (VFxs) in patients with ankylosing spondylitis (AS). Consecutive patients with active AS with TNFi treatment duration up to 4 years with available DXA scans and spine X-rays were included. BMD (classified according to the WHO criteria for osteoporosis) of the hip and lumbar spine, the VFx (classified as a Genant score >1/>20% height loss), and radiological progression (modified stoke ankylosing spondylitis spinal score [mSASSS]) scores were obtained at baseline and at 4 years of TNFi treatment. Overall, 135 AS patients were included. At baseline, 40.1% of patients had low BMD of the hip and 40.2% of the lumbar spine. This decreased to 38.1% (p = 0.03) with low hip BMD and 25.3% (p < 0.001) of the lumbar spine BMD after 4 years of TNFi treatment. VFxs were present at baseline in 11.1% of the 131 patients, which increased to 19.6% after 4 years of TNFi treatment. A Genant score ≥2, was found at baseline in 3 out of 14 VFx (21.4%) patients, which increased to 7 out of 27 VFx (25.9%) patients after 4 years. All disease activity parameters-the ankylosing spondylitis disease activity scale, the C-reactive protein, the erythrocyte sedimentation rate, and the bath ankylosing spondylitis disease activity index-decreased significantly (p < 0.001). The mean radiological progression (n = 80) increased significantly from a median mSASSS of 4.0 (1.5 to 16.0) at baseline to 6.5 (2.1 to 22.9) after 4 years of TNFi treatment (p < 0.001). Despite the improvement in BMD and the decrease in disease activity, we still found new VFxs, an increase in severity in the number and grade of VFxs, and radiographic progression during 4 years of treatment with TNFis in AS patients with long disease duration. © 2019 American Society for Bone and Mineral Research.

Does solid fusion eliminate rod fracture after pedicle subtraction osteotomy in ankylosing spondylitis-related thoracolumbar kyphosis?

BACKGROUND CONTEXT

Rod fracture (RF) has a negative impact on the surgical outcome of patients with ankylosing spondylitis (AS) after lumbar pedicle subtraction osteotomy (PSO). However, there is a paucity of published studies analyzing the risk factors for RF in PSO-treated patients with AS with thoracolumbar kyphosis.

PURPOSE

The objective of this study was to investigate the risk factors for RF after PSO for thoracolumbar kyphosis secondary to AS.

STUDY DESIGN/SETTING

This is a retrospective single-center study.

PATIENT SAMPLE

Patients with AS who underwent PSO for thoracolumbar kyphosis between January 2002 and December 2016 were included.

OUTCOME MEASURES

Demographic data, including age, sex, body mass index, and smoking status, were summarized. The surgical data analyzed included the levels of osteotomy, the fusion levels, the upper instrumented vertebra, the lower instrumented vertebra, the osteotomy site, the rod material, the rod diameter, and the rod contour angle (RCA). Radiographic parameters included the sagittal vertical axis, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. Radiographic parameters were measured at baseline, immediately after the operation, and at the final follow-up. Adequate ossification of the anterior longitudinal ligament (ALL) at the PSO level was defined by a total bony bridge. Adequate ossification of the ALL was also measured at baseline, immediately after the operation, and at the final follow-up.

METHODS

Patients with a minimum of 2 years' follow-up or patients who developed RF were enrolled in the study. Recruited patients were divided into the RF group and the no-RF group based on whether they developed RF. Patient demographics, operative data, radiographic parameters, and adequate ossification of the ALL were analyzed to determine the risk factors for RF. For patients with RF, the fusion status at the PSO level, the time course to the development of RF, the site of RF, and the corresponding solution were also recorded.

RESULTS

Rod fracture occurred in 11 (8.9%) of the 123 recruited patients. Solid fusion at the PSO level was found in all patients in the RF group. The average duration to the onset of RF was 31.4 months (range, 12-68 months). All RFs occurred at or immediately adjacent to the PSO level. The RCA was greater in the RF group than in the no-RF group (27.8° vs 22.9°, p=.031). A greater proportion of patients with a rod diameter of 5.50 mm were found in the RF group than in the no-RF group (100.0% vs 68.8%, p=.033). There was a larger proportion of patients with adequate ossification of the ALL at the final follow-up visit in the no-RF group than in the RF group (67.0% vs 27.3%, p=.018). Multivariate analyses demonstrated that the RCA (odds ratio, 1.174; 95% confidence interval, 1.018-1.354; p=.028) and adequate ossification of the ALL at the final follow-up visit (odds ratio, 0.079; 95% confidence interval, 0.014-0.465; p=.005) were independent factors for RF. Notably, revision surgery was performed among six patients, whereas conservative treatment was used for the remaining five patients.

CONCLUSIONS

In patients with AS after PSO for thoracolumbar kyphosis with solid fusion at the PSO level, the incidence of RF was 8.9%. Rod diameter was identified as a risk factor for RF. Furthermore, the RCA was identified as an independent risk factor for RF. In contrast, adequate ossification of the ALL around the PSO level at the final follow-up visit was identified as an independent protective factor for RF.

Management of Andersson Lesion in Ankylosing Spondylitis Using the Posterior-Only Approach: A Case Series of 18 Patients

Study Design

This retrospective study was conducted including 18 patients who underwent posterior-only stabilization and fusion procedure for pseudoarthrosis in the ankylosed spine from October 2007 to May 2015.

Purpose

This study aimed to describe the treatment outcomes in 18 patients with Andersson lesion (AL) who were managed using the posterior-only approach.

Literature Review

AL is an unstable, localized, vertebral, or discovertebral lesion of the spine. It is observed in patients with ankylosing spondylitis. The exact etiology of this disorder remains unclear, and the treatment guidelines are not clearly described.

Methods

We analyzed 18 patients with AL who were treated with posterior long segment spinal fusion without any anterior interbody grafting or posterior osteotomy. Pre- and postoperative radiography, computed tomography, and recent follow-up images were examined. The pre- and postoperative Visual Analog Scale score and the Oswestry Disability Index score were evaluated for all patients. Whiteclouds’ outcome analysis criteria were applied at the follow-up. Moreover, at study completion, patient feedback was collected; all the patients were asked to provide their opinion regarding the surgery and were asked whether they would recommend this procedure to other patients and them self undergo the same procedure again if required.

Results

The most common site was the thoracolumbar junction. The symptom duration ranged from 1 month to 10 years preoperatively. Most patients experienced fusion by the end of 1 year, and the fusion mass could be observed as early as 4 months. Pseudoarthrosis void of up to 2.5 cm was noted to be healed in subsequent imaging. In addition, clinically, the patients reported good symptomatic relief. No patient required revision surgery. Whiteclouds’ outcome analysis score at the latest follow-up revealed good-to-excellent outcomes in all patients.

Conclusions

ALs can be treated using the posterior-only approach with long segment fixation and posterior spinal fusion. This is a safe, simple, and quick procedure that prevents the morbidity of anterior surgery.

Vitamin D levels in patients with ankylosing spondylitis: Is it related to disease activity?

Objective:

Ankylosing Spondylitis (AS) is an inflammatory rheumatic disease that mainly affects the axial spine. Osteopenia and osteoporosis are the main complications of AS. Vitamin D has functions on the immune system. In this study, we aimed to compare vitamin D levels and Bone Mineral Density (BMD) values between AS patients and controls.

Methods:

A total of 68 patients with axial AS and 34 healthy controls were enrolled in this study conducted between March 2018 and May 2018. Vitamin D concentrations, BMD values, disease activity, back mobility, functionality and radiologic damage were evaluated.

Results:

Vitamin D concentrations, the total BMD-femur and BMD-femur neck values were significantly lower in AS patients (p = 0.001, p = 0.011 and p = 0.003). No significant correlations were detected between vitamin D levels and BMD-femur total, BMD-femur neck values, disease activity, back mobility, functionality and radiologic damage scores (p > 0.05). Disease activity parameters were significantly and negatively correlated with total BMD-femur and BMD-femur neck values (p < 0.05).

Conclusion:

Our study demonstrates that AS patients have lower vitamin D levels, total BMD-femur and BMD-femur neck values. Higher disease activity increases bone loss in AS. Regular measurement of BMD and vitamin D should be kept in mind when planning a treatment in AS.

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.

Trabecular bone score as an assessment tool to identify the risk of osteoporosis in axial spondyloarthritis: a case-control study

Objectives

To compare the trabecular bone score (TBS) between patients with axial spondyloarthritis (axSpA) and matched normal controls and identify risk factors associated with a low TBS.

Methods

TBS and BMD were assessed in the two groups (axSpA and control) using DXA. Osteoporosis risk factors and inflammatory markers were also assessed. Disease activity and radiographic progression in the sacroiliac joint and spine were evaluated in the axSpA group. Multivariate linear regression analysis was performed to identify risk factors associated with TBS.

Results

In the axSpA group, 248 subjects were enrolled; an equal number of age- and sex-matched subjects comprised the control group. The mean TBS was 1.43 (0.08) and 1.38 (0.12) in the control and axSpA groups, respectively (P < 0.001); BMD at the lumbar spine did not differ between the two groups. The TBS was negatively correlated with ESR and CRP levels in the axSpA group only (P < 0.001 and P = 0.007, respectively). Syndesmophytes in the axSpA group was associated with lower TBS (P < 0.001) but higher lumbar BMD (P = 0.021) vs controls. In the multivariate analyses, ESR, CRP and spinal radiographic progression were significantly associated with TBS.

Conclusion

TBS assessments revealed poor bone quality in patients with axSpA compared with the matched controls. In axSpA, systemic inflammatory markers were negatively correlated with TBS and spinal radiographic progression and inflammatory markers were independently correlated with low TBS. TBS may, therefore, be a useful clinical tool to identify the risk of osteoporosis in patients with axSpA.

The Role of Autoantibodies in Bone Metabolism and Bone Loss

Many autoimmune diseases are associated with deranged bone metabolism. The resulting localized or systemic bone loss can compromise the quality of life of patients by causing local bone deformities or fragility fractures. There is emerging evidence that antibodies have a direct impact on key players of bone homeostasis, in particular osteoclasts. Clinical and pre-clinical studies provide insight into the function of autoantibodies related to Rheumatoid Arthritis (rheumatoid factor, anti-citrullinated protein antibodies, and anti-carbamylated protein antibodies) and their inflammation-independent interaction with bone cells. Furthermore, we summarize the current knowledge about neutralizing antibodies to the antiresorptive protein osteoprotegerin, which have been described in patients with Coeliac Disease, Rheumatoid Arthritis, and Spondyloarthritis.

Evaluation of bone quality with trabecular bone score in active spondyloarthritis

OBJECTIVE

Many patients with spondyloarthritis (SpA) are at risk of fracture due to bone fragility, whereas their bone mineral density (BMD) is not significantly diminished. Other tools, such as trabecular bone score (TBS), evaluating other characteristics of bone tissue are therefore necessary in order to evaluate bone changes in these patients. Therefore we evaluated TBS as a bone quality marker, in a cohort of patients with SpA and investigated which clinical and biological factors were correlated with TBS values.

METHODS

Patients fulfilling ASAS criteria of SpA with a BMD assessment and visiting our department for initiation or switch of a biologic treatment were selected. The clinical and biological data were collected at the time of BMD measurement.

RESULTS

Ninety-five patients were included in the study, with a mean age of 40.2 and a mean disease duration of 8.2 years. Lumbar BMD T-score was <-1 and <-2.5 in 17% and 3% of patients, respectively. On average, TBS value was 1.34±0.12. Lumbar BMD was positively correlated with TBS (r=0.61), while disease duration, disease activity score and serum PTH levels were negatively correlated with TBS (r=-0.24, r=-0.33, and r=-0.27, respectively). These correlations persisted in a multivariate analysis. Furthermore, more than half of the patients with a BMD level above -2.5 T-score had a low TBS value.

CONCLUSION

Our results show that TBS provides information additional to BMD on the bone status of patients with SpA. They suggest that TBS may help in identifying those patients at risk of fracture.

Which measuring site in ankylosing spondylitis is best to detect bone loss and what predicts the decline: results from a 5-year prospective study

BACKGROUND

Studies have shown increased prevalence of osteoporosis and increased risk for vertebral fractures in patients with ankylosing spondylitis (AS). Measurements of bone mineral density (BMD) in the lumbar spine anterior-posterior (AP) projection may be difficult to interpret due to the ligamentous calcifications, and the lateral projection might be a better measuring site. Our objectives were to investigate BMD changes after 5 years at different measuring sites in patients with AS and to evaluate disease-related variables and medications as predictors for BMD changes.

METHODS

In a longitudinal study, BMD in Swedish AS patients, 50 ± 13 years old, was measured with dual-energy x-ray absorptiometry (DXA) at the hip, the lumbar spine AP and lateral projections, and the total radius at baseline and after 5 years. Patients were assessed with questionnaires, blood samples, and spinal radiographs for grading of AS-related alterations in the spine with the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) and assessment of vertebral fractures by the Genant score. Multiple linear regression analyses were used to investigate predictors for BMD changes.

RESULTS

Of 204 patients included at baseline, 168 (82%) were re-examined after 5 years (92 men and 76 women). BMD decreased significantly at the femoral neck and radius and increased significantly at the lumbar spine, both for AP and lateral projections. Mean C-reactive protein during follow-up predicted a decrease in the femoral neck BMD (change in %, β = -0.15, p = 0.046). Use of bisphosphonates predicted an increase in BMD at all measuring sites (p < 0.001 to 0.013), except for the total radius. Use of tumor necrosis factor inhibitors (TNFi) predicted an increase in AP spinal BMD (β = 3.15, p = 0.012).

CONCLUSION

The current study (which has a long follow-up, many measuring sites, and is the first to longitudinally assess the lateral projection of the spine in AS patients) surprisingly showed that lateral projection spinal BMD increased. This study suggests that the best site to assess bone loss in AS patients is the femoral neck and that inflammation has an adverse effect, and the use of bisphosphonates and TNFi has a positive effect, on BMD in AS patients.

Autoantibodies to Osteoprotegerin are Associated with Low Hip Bone Mineral Density and History of Fractures in Axial Spondyloarthritis: A Cross-Sectional Observational Study

Osteoporosis is a recognised complication of axial spondyloarthritis (axSpA) and is thought to be due to functional impairment and the osteoclast-activating effects of proinflammatory cytokines. The development of autoantibodies to OPG (OPG-Ab) has been associated with severe osteoporosis and increased bone resorption in rheumatoid arthritis. In this study, we screened for the presence of OPG-Ab in axSpA and reviewed their clinical significance. We studied 134 patients, recruited from two centres in the United Kingdom. Their mean age was 47.5 years and 75% were male. Concentrations of OPG-Ab were related to bone mineral density (BMD) and fracture history using linear and logistic regression models adjusting for age, gender, disease duration and activity, body mass index and bisphosphonate use. We detected OPG-Ab in 11/134 patients (8.2%). Femoral neck and total hip BMD were significantly reduced in OPG-Ab positive patients (0.827 vs. 0.967 g/cm², p = 0.008 and 0.868 vs. 1.028 g/cm², p = 0.002, respectively). Regression analysis showed that the presence of OPG-Ab was independently associated with total hip osteopenia (OR_adj 24.2; 95% CI 2.57, 228) and history of fractures (OR_adj 10.5; 95% CI 2.07, 53.3). OPG-Ab concentration was associated with total hip BMD in g/cm² (ß = -1.15; 95% CI -0.25, -0.04). There were no associations between OPG-Ab concentration and bone turnover markers, but free sRANKL concentrations were lower in OPG-Ab-positive patients (median 0.04 vs. 0.11 pmol/L, p = 0.050). We conclude that OPG-Ab are associated with hip BMD and fractures in axSpA suggesting that they may contribute to the pathogenesis of bone loss in some patients with this condition.

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.

Serum bone-turnover biomarkers are associated with the occurrence of peripheral and axial arthritis in psoriatic disease: a prospective cross-sectional comparative study

Background

A recent systematic review identified four candidate serum-soluble bone-turnover biomarkers (dickkopf-1, Dkk-1; macrophage-colony stimulating factor, M-CSF; matrix metalloproteinase-3, MMP-3; osteoprotegerin, OPG) showing possible association with psoriatic arthritis (PsA). We aimed to: (i) confirm and determine if these four biomarkers are associated with PsA; (ii) differentiate psoriasis cases with and without arthritis; and (iii) differentiate PsA cases with and without axial arthritis.

Methods

A prospective cross-sectional comparative two-centre study recruited 200 patients with psoriasis without arthritis (PsC), 127 with PsA without axial arthritis (pPsA), 117 with PsA with axial arthritis (psoriatic spondyloarthritis, PsSpA), 157 with ankylosing spondylitis (AS) without psoriasis, and 50 matched healthy controls (HC). Serum biomarker concentrations were measured using ELISA. Multivariable regression and receiver operating characteristic analyses were performed.

Results

MMP-3 concentrations were significantly higher and M-CSF significantly lower in each arthritis disease group compared with HC (p ≤ 0.02). MMP-3 concentrations were significantly higher (adjusted odds ratio, OR_adj 1.02 per ng/ml increase in concentration; p = 0.0004) and M-CSF significantly lower (OR_adj 0.44 per ng/ml increase; p = 0.01) in PsA (pPsA and PsSpA combined) compared with PsC. Dkk-1 concentrations were significantly higher (OR_adj 1.22 per ng/mL increase; p = 0.01), and OPG concentrations significantly lower (OR_adj 0.20 per ng/mL increase; p = 0.02) in patients with axial arthritis (PsSpA and AS combined) than in those without (pPsA). Furthermore, Dkk-1 concentrations were significantly higher along a spectrum of increasing axial arthritis; Dkk-1 concentrations were higher in AS compared with PsSpA (OR_adj 1.18 per ng/mL increase; p = 0.02). Receiver operating characteristic analysis showed MMP-3 to be the best single biomarker for differentiating PsA from PsC (AUC 0.70 for a cut-off of 14.51 ng/mL; sensitivity 0.76, specificity 0.60).

Conclusions

MMP-3 and M-CSF are biomarkers for the presence of arthritis in psoriatic disease, and could therefore be used to screen for PsA in psoriasis cohorts. Dkk-1 and OPG are biomarkers of axial arthritis; they could therefore be used to screen for the presence of axial disease in PsA cases, and help differentiate PsSpA from AS. High concentrations of Dkk-1 in AS and PsSpA compared with HC, support previous reports that Dkk-1 is dysfunctional in the spondyloarthritides.

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.

Complications after Fusion for Thoracolumbar Fractures in Patients with Ankylosing Spondylitis

STUDY DESIGN

Retrospective analysis of a Medicare database (2005 to 2012).

OBJECTIVE

To study postoperative complication rates following thoracolumbar fusion for traumatic thoracolumbar fracture in patients with ankylosing spondylitis (AS) compared with patients without AS.

METHODS

The PearlDiver database (2005 to 2012) was queried to examine postoperative complication rates in patients with AS undergoing posterior thoracolumbar fusion for thoracolumbar fracture (n  =  968). Complication rates were compared with proportion-matched controls without AS undergoing the same procedure (n  =  1,979). We examined and compared the incidence of death, postoperative infection, transfusion, venous thromboembolism, respiratory failure, pneumonia, myocardial infarction, urinary tract infection, and acute renal failure in each cohort within 90 days postoperatively.

RESULTS

Patients with AS had significantly higher rates of surgical site infection (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.2 to 2.2, p  =  0.002), day-of-surgery transfusion rates (OR 1.5, 95% CI 1.3 to 1.8, p < 0.0001), respiratory failure (OR 1.8, 95% CI 1.3 to 2.5, p  =  0.0006), pneumonia (OR 1.8, 95% CI 1.3 to 2.5, p  =  0.0002), acute renal failure (OR 1.6, 95% CI 1.2 to 2.3, p  =  0.005), and total medical complications (OR 1.5, 95% CI 1.2 to 1.9, p < 0.0001). Ninety-day mortality was not different between the two cohorts (p  =  0.18).

CONCLUSIONS

Thoracolumbar fusion for thoracolumbar fracture in patients with AS is associated with increased rates of surgical site infection, transfusion, respiratory failure, pneumonia, and acute renal failure postoperatively compared with patients without AS. The level of evidence in this study was III.

Clinical outcomes following spinal fracture in patients with ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis is a seronegative rheumatoid condition mainly affecting the axial skeleton. It leads to progressive deformity and stiffening of the spine with an increased risk of vertebral fractures and significant neurological deficits compared to the general population.

AIM

This study aimed to evaluate the outcomes of patients with ankylosing spondylitis who sustained acute vertebral fractures over a 10-year period.

METHODS

A retrospective review of patient records and radiographic images was performed. Mechanism of injury, fracture type, timing of diagnosis, neurological deficit, management and complications were assessed.

RESULTS

Twenty-four patients were included. Most (23) sustained low energy injuries. Five (20%) patients had a delayed diagnosis over 24 h after the time of injury. Twelve (50%) of patients had a neurological deficit at the time of admission and most did not recover. Eighteen (75%) patients underwent surgical stabilisation. There were 19 complications (in 15 patients) following surgery.

CONCLUSION

Patients with ankylosing spondylitis are at risk of spinal fracture and associated spinal cord injury after relatively minor trauma. Delayed diagnosis places the patient at risk of neurological compromise, and thus a high index of suspicion is needed when assessing this patient group.

Ankylosing Spondylitis Patients Have Impaired Osteoclast Gene Expression in Circulating Osteoclast Precursors

INTRODUCTION

Ankylosing spondylitis (AS) is typically characterized by focal bone overgrowth and also by systemic bone loss. We hypothesize that the increased osteoproliferation found in AS might be partially due to reduced ability of osteoclast precursors (OCPs) to differentiate into osteoclasts (OCs). Therefore, our aim was to characterize bone remodeling and pro-osteoclastogenesis inflammatory environment, monocytes' phenotype, and in vitro osteoclast differentiation in AS patients.

METHODS

Patients with active AS without any ongoing therapy and age- and gender-matched healthy donors were recruited. Receptor activator of nuclear factor-κβ (RANKL) surface expression on circulating leukocytes and frequency and phenotype of monocyte subpopulations were assessed. Quantification of serum levels of bone turnover markers and cytokines, in vitro OC differentiation assay and quantitative reverse transcription real-time PCR for OC-specific genes were performed.

RESULTS

Pro- and anti-inflammatory cytokine serum levels were higher in AS patients than in controls. RANKL neutrophil expression was higher in AS patients when compared to healthy donors, but CD51/CD61 expression was lower in the classical monocyte subpopulation. Concerning osteoclastogenesis, we found no differences in the in vitro osteoclast differentiating potential of these cells when compared to healthy donors. However, we observed low expression of CSF1R, RANK, and NFATc1 in AS OCPs.

CONCLUSION

Despite the high levels of pro-inflammatory cytokines present in AS patients, no differences in the number of OC or resorbed area were found between AS patients and healthy donors. Moreover, we observed that OCPs have low OC-specific gene expression. These findings support our hypothesis of an impaired response of OCPs to pro-osteoclastogenic stimuli in vivo in AS patients.

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.

Spinal fractures in patients with ankylosing spondylitis

The ankylosed spine is prone to fracture even after minor trauma due to its changed biomechanical properties. The two central features of ankylosing spondylitis (AS) that promote the pathological remodeling of the spine are inflammation and new bone formation. AS is also associated with osteoporosis that is attributed to an uncoupling of the bone formation and bone resorption processes. Therefore, bone resorption occurs and promotes weakening of the spine as well as increased risk of vertebral fractures which can be hugely different in terms of clinical relevance. Even in the presence of symptomatic clinical vertebral fractures, the diagnosis can be overruled by attributing the pain to disease activity. Furthermore, given the highly abnormal structure of the spine, vertebral fracture diagnosis can be difficult on the basis of radiography alone. CT can show the fractures in detail. Magnetic resonance imaging is considered the method of choice for the imaging of spinal cord injuries, and a reasonable option for exclusion of occult fractures undetected by CT. Since it is equally important for radiologists and clinicians to have a common knowledge base rather than a compartmentalized view, the aim of this review article was to provide the required clinical knowledge that radiologists need to know and the relevant radiological semiotics that clinicians require in diagnosing clinically significant injury to the ankylosed spine.

The vitamin D status in ankylosing spondylitis in relation to intestinal inflammation, disease activity, and bone health: a cross-sectional study

We assessed the vitamin D status in ankylosing spondylitis (AS) patients and healthy controls in the late winter when no vitamin D is produced by the sunlight. The vitamin D status was often poor, but not lower in AS and not associated with disease activity or signs of gut inflammation.

INTRODUCTION

The aims of the study were to investigate the vitamin D levels attained mainly by dietary intake in ankylosing spondylitis (AS) in comparison with healthy controls and in relation to gut inflammation, measured indirectly by fecal calprotectin, disease activity, osteoproliferation, bone mineral density (BMD), and vertebral fractures.

METHODS

Serum 25-hydroxy vitamin D (25(OH)D) was measured in 203 AS patients and 120 healthy controls at the end of "the vitamin D winter," when the out-door UVB irradiation is too low to allow synthesis of vitamin D3 in the skin at the latitude of Gothenburg, Sweden. Fecal calprotectin was measured in stool samples. Disease activity was assessed with CRP, ESR, ASDASCRP, BASDAI, BAS-G, BASFI, and BASMI. Lateral spine radiographs were scored for osteoproliferation and vertebral fractures using the mSASSS and Genant scores. BMD was measured in the lumbar spine and femoral neck.

RESULTS

Vitamin D insufficiency (a serum 25(OH)D <50 nmol/L) was found in approximately 50 % of the AS patients, but serum 25(OH)D was not different from healthy controls and not significantly correlated with fecal calprotectin, gastrointestinal symptoms, disease activity parameters, mSASSS, BMD, or vertebral fractures.

CONCLUSIONS

The vitamin D status was often poor in the late winter in AS but not different from the healthy controls. No evidence for a connection between subclinical gut inflammation, malabsorption, and hypovitaminosis D was found. Serum 25(OH)D was not associated with disease activity, osteoproliferation, BMD, or vertebral fractures. We suggest that the lower vitamin D levels in AS, previously found by others, may be caused by reduced out-door UVB exposure.