Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate, Inc. and/or its affiliates. All Rights Reserved.

Clinical manifestations of axial spondyloarthritis (ankylosing spondylitis and nonradiographic axial spondyloarthritis) in adults

David T Yu, MD
Astrid van Tubergen, MD, PhD
Section Editor
Joachim Sieper, MD
Deputy Editor
Paul L Romain, MD


Axial spondyloarthritis (axSpA) is a potentially disabling inflammatory arthritis of the spine, usually presenting as chronic back pain, typically before the age of 45. It is often associated with one or more of several articular and periarticular extraspinal features, including synovitis, enthesitis, and dactylitis. It may also be associated with several nonarticular features; these include uveitis, psoriasis, and inflammatory bowel disease (IBD). Patients frequently carry the gene for human leukocyte antigen (HLA)-B27, and patients with active inflammatory disease often have evidence of an elevated acute phase response.

Patients with axSpA can be classified as having either of two subtypes of axSpA: ankylosing spondylitis (AS) or nonradiographic axSpA (nr-axSpA). Patients with AS exhibit radiographic abnormalities consistent with sacroiliitis, but such findings are not evident on plain radiography in nr-axSpA. Instead, in patients with nr-axSpA, the diagnosis is supported by evidence of active inflammation of the sacroiliac (SI) joints on magnetic resonance imaging (MRI), by a combination of other findings, or both. In clinical practice, a distinction between these two forms of axSpA in an individual patient has limited impact on management and may not be relevant, although the classification is of value for epidemiologic and other investigative purposes [1]. (See 'Nomenclature and classification' below.)

The clinical manifestations of axSpA will be reviewed here. The pathogenesis, diagnostic evaluation, and treatment of this disorder in adults are discussed separately, as is spondyloarthritis in children. (See "Pathogenesis of spondyloarthritis" and "Diagnosis and differential diagnosis of axial spondyloarthritis (ankylosing spondylitis and nonradiographic axial spondyloarthritis) in adults" and "Assessment and treatment of ankylosing spondylitis in adults" and "Spondyloarthritis in children".)


There are two subtypes of axial spondyloarthritis (axSpA): ankylosing spondylitis (AS) and nonradiographic axSpA (nr-axSpA). Historically, spondyloarthritis (SpA, formerly termed spondyloarthritides or spondyloarthropathies) has been regarded as a family of arthritis that includes AS; undifferentiated SpA; reactive arthritis; psoriatic arthritis; juvenile SpA; and arthritis and spondylitis associated with inflammatory bowel disease (IBD), including Crohn disease and ulcerative colitis [2]. Traditionally, AS has been regarded as the prototype of SpA, and the majority of publications prior to 2009 on SpA focus on AS. (See "Clinical manifestations and diagnosis of peripheral spondyloarthritis in adults" and "Reactive arthritis" and "Clinical manifestations and diagnosis of psoriatic arthritis" and "Spondyloarthritis in children" and "Clinical manifestations and diagnosis of arthritis associated with inflammatory bowel disease and other gastrointestinal diseases".)

The term "axial spondyloarthritis" (axSpA) became standard nomenclature in 2009, based upon a multinational study of SpA by the Assessment of SpondyloArthritis International Society (ASAS), classifying SpA broadly into two groups [3,4]:

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:

Subscribers log in here

Literature review current through: Nov 2017. | This topic last updated: Aug 10, 2017.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2017 UpToDate, Inc.
  1. Deodhar A, Strand V, Kay J, Braun J. The term 'non-radiographic axial spondyloarthritis' is much more important to classify than to diagnose patients with axial spondyloarthritis. Ann Rheum Dis 2016; 75:791.
  2. Sieper J, Rudwaleit M, Baraliakos X, et al. The Assessment of SpondyloArthritis international Society (ASAS) handbook: a guide to assess spondyloarthritis. Ann Rheum Dis 2009; 68 Suppl 2:ii1.
  3. Rudwaleit M, van der Heijde D, Landewé R, et al. The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis (part II): validation and final selection. Ann Rheum Dis 2009; 68:777.
  4. Rudwaleit M, van der Heijde D, Landewé R, et al. The Assessment of SpondyloArthritis International Society classification criteria for peripheral spondyloarthritis and for spondyloarthritis in general. Ann Rheum Dis 2011; 70:25.
  5. Kiltz U, Baraliakos X, Karakostas P, et al. Do patients with non-radiographic axial spondylarthritis differ from patients with ankylosing spondylitis? Arthritis Care Res (Hoboken) 2012; 64:1415.
  6. Costantino F, Zeboulon N, Said-Nahal R, Breban M. Radiographic sacroiliitis develops predictably over time in a cohort of familial spondyloarthritis followed longitudinally. Rheumatology (Oxford) 2017.
  7. van Tubergen A, Weber U. Diagnosis and classification in spondyloarthritis: identifying a chameleon. Nat Rev Rheumatol 2012; 8:253.
  8. Strand V, Rao SA, Shillington AC, et al. Prevalence of axial spondyloarthritis in United States rheumatology practices: Assessment of SpondyloArthritis International Society criteria versus rheumatology expert clinical diagnosis. Arthritis Care Res (Hoboken) 2013; 65:1299.
  9. Rudwaleit M, Khan MA, Sieper J. The challenge of diagnosis and classification in early ankylosing spondylitis: do we need new criteria? Arthritis Rheum 2005; 52:1000.
  10. Reveille JD, Weisman MH. The epidemiology of back pain, axial spondyloarthritis and HLA-B27 in the United States. Am J Med Sci 2013; 345:431.
  11. Reveille JD, Hirsch R, Dillon CF, et al. The prevalence of HLA-B27 in the US: data from the US National Health and Nutrition Examination Survey, 2009. Arthritis Rheum 2012; 64:1407.
  12. Reveille JD. Epidemiology of spondyloarthritis in North America. Am J Med Sci 2011; 341:284.
  13. Dean LE, Jones GT, MacDonald AG, et al. Global prevalence of ankylosing spondylitis. Rheumatology (Oxford) 2014; 53:650.
  14. Brown MA, Laval SH, Brophy S, Calin A. Recurrence risk modelling of the genetic susceptibility to ankylosing spondylitis. Ann Rheum Dis 2000; 59:883.
  15. Carter N, Williamson L, Kennedy LG, et al. Susceptibility to ankylosing spondylitis. Rheumatology (Oxford) 2000; 39:445.
  16. de Winter JJ, van Mens LJ, van der Heijde D, et al. Prevalence of peripheral and extra-articular disease in ankylosing spondylitis versus non-radiographic axial spondyloarthritis: a meta-analysis. Arthritis Res Ther 2016; 18:196.
  17. Calin A, Garrett S, Whitelock H, et al. A new approach to defining functional ability in ankylosing spondylitis: the development of the Bath Ankylosing Spondylitis Functional Index. J Rheumatol 1994; 21:2281.
  18. Underwood MR, Dawes P. Inflammatory back pain in primary care. Br J Rheumatol 1995; 34:1074.
  19. Sieper J, van der Heijde D, Landewé R, et al. New criteria for inflammatory back pain in patients with chronic back pain: a real patient exercise by experts from the Assessment of SpondyloArthritis international Society (ASAS). Ann Rheum Dis 2009; 68:784.
  20. Weisman MH. Inflammatory back pain: the United States perspective. Rheum Dis Clin North Am 2012; 38:501.
  21. Roussou E, Sultana S. Spondyloarthritis in women: differences in disease onset, clinical presentation, and Bath Ankylosing Spondylitis Disease Activity and Functional indices (BASDAI and BASFI) between men and women with spondyloarthritides. Clin Rheumatol 2011; 30:121.
  22. Carette S, Graham D, Little H, et al. The natural disease course of ankylosing spondylitis. Arthritis Rheum 1983; 26:186.
  23. Vosse D, van der Heijde D, Landewé R, et al. Determinants of hyperkyphosis in patients with ankylosing spondylitis. Ann Rheum Dis 2006; 65:770.
  24. Sawacha Z, Carraro E, Del Din S, et al. Biomechanical assessment of balance and posture in subjects with ankylosing spondylitis. J Neuroeng Rehabil 2012; 9:63.
  25. Rudwaleit M, Metter A, Listing J, et al. Inflammatory back pain in ankylosing spondylitis: a reassessment of the clinical history for application as classification and diagnostic criteria. Arthritis Rheum 2006; 54:569.
  26. Braun A, Gnann H, Saracbasi E, et al. Optimizing the identification of patients with axial spondyloarthritis in primary care--the case for a two-step strategy combining the most relevant clinical items with HLA B27. Rheumatology (Oxford) 2013; 52:1418.
  27. Vander Cruyssen B, Muñoz-Gomariz E, Font P, et al. Hip involvement in ankylosing spondylitis: epidemiology and risk factors associated with hip replacement surgery. Rheumatology (Oxford) 2010; 49:73.
  28. Sampaio-Barros PD, Bertolo MB, Kraemer MH, et al. Primary ankylosing spondylitis: patterns of disease in a Brazilian population of 147 patients. J Rheumatol 2001; 28:560.
  29. Ramos-Remus C, Major P, Gomez-Vargas A, et al. Temporomandibular joint osseous morphology in a consecutive sample of ankylosing spondylitis patients. Ann Rheum Dis 1997; 56:103.
  30. Rudwaleit M, Haibel H, Baraliakos X, et al. The early disease stage in axial spondylarthritis: results from the German Spondyloarthritis Inception Cohort. Arthritis Rheum 2009; 60:717.
  31. Ciurea A, Scherer A, Exer P, et al. Tumor necrosis factor α inhibition in radiographic and nonradiographic axial spondyloarthritis: results from a large observational cohort. Arthritis Rheum 2013; 65:3096.
  32. Mielants H, Van den Bosch F. Extra-articular manifestations. Clin Exp Rheumatol 2009; 27:S56.
  33. Maksymowych WP, Chou CT, Russell AS. Matching prevalence of peripheral arthritis and acute anterior uveitis in individuals with ankylosing spondylitis. Ann Rheum Dis 1995; 54:128.
  34. Zeboulon N, Dougados M, Gossec L. Prevalence and characteristics of uveitis in the spondyloarthropathies: a systematic literature review. Ann Rheum Dis 2008; 67:955.
  35. Stolwijk C, van Tubergen A, Castillo-Ortiz JD, Boonen A. Prevalence of extra-articular manifestations in patients with ankylosing spondylitis: a systematic review and meta-analysis. Ann Rheum Dis 2015; 74:65.
  36. Stolwijk C, Essers I, van Tubergen A, et al. The epidemiology of extra-articular manifestations in ankylosing spondylitis: a population-based matched cohort study. Ann Rheum Dis 2015; 74:1373.
  37. Rosenbaum JT. Uveitis in spondyloarthritis including psoriatic arthritis, ankylosing spondylitis, and inflammatory bowel disease. Clin Rheumatol 2015; 34:999.
  38. Muñoz-Fernández S, Martín-Mola E. Uveitis. Best Pract Res Clin Rheumatol 2006; 20:487.
  39. Tay-Kearney ML, Schwam BL, Lowder C, et al. Clinical features and associated systemic diseases of HLA-B27 uveitis. Am J Ophthalmol 1996; 121:47.
  40. Leirisalo-Repo M, Turunen U, Stenman S, et al. High frequency of silent inflammatory bowel disease in spondylarthropathy. Arthritis Rheum 1994; 37:23.
  41. De Keyser F, Mielants H. The gut in ankylosing spondylitis and other spondyloarthropathies: inflammation beneath the surface. J Rheumatol 2003; 30:2306.
  42. Van Praet L, Van den Bosch FE, Jacques P, et al. Microscopic gut inflammation in axial spondyloarthritis: a multiparametric predictive model. Ann Rheum Dis 2013; 72:414.
  44. Bandinelli F, Terenzi R, Giovannini L, et al. Occult radiological sacroiliac abnormalities in patients with inflammatory bowel disease who do not present signs or symptoms of axial spondylitis. Clin Exp Rheumatol 2014; 32:949.
  45. Cantini F, Niccoli L, Nannini C, et al. Case-control Study on Dactylitis, Enthesitis, and Anterior Uveitis in Spondyloarthritis Associated with Inflammatory Bowel Diseases: Role of Coexistent Psoriasis. J Rheumatol 2017; 44:1341.
  46. Stolwijk C, Pierik M, Landewé R, et al. Prevalence of self-reported spondyloarthritis features in a cohort of patients with inflammatory bowel disease. Can J Gastroenterol 2013; 27:199.
  47. van Erp SJ, Brakenhoff LK, van Gaalen FA, et al. Classifying Back Pain and Peripheral Joint Complaints in Inflammatory Bowel Disease Patients: A Prospective Longitudinal Follow-up Study. J Crohns Colitis 2016; 10:166.
  48. Rudwaleit M, Baeten D. Ankylosing spondylitis and bowel disease. Best Pract Res Clin Rheumatol 2006; 20:451.
  49. El Maghraoui A. Extra-articular manifestations of ankylosing spondylitis: prevalence, characteristics and therapeutic implications. Eur J Intern Med 2011; 22:554.
  50. Pérez Alamino R, Maldonado Cocco JA, Citera G, et al. Differential features between primary ankylosing spondylitis and spondylitis associated with psoriasis and inflammatory bowel disease. J Rheumatol 2011; 38:1656.
  51. Edmunds L, Elswood J, Kennedy LG, Calin A. Primary ankylosing spondylitis, psoriatic and enteropathic spondyloarthropathy: a controlled analysis. J Rheumatol 1991; 18:696.
  52. Li Y, Zhang S, Zhu J, et al. Sleep disturbances are associated with increased pain, disease activity, depression, and anxiety in ankylosing spondylitis: a case-control study. Arthritis Res Ther 2012; 14:R215.
  53. Ward MM, Reveille JD, Learch TJ, et al. Impact of ankylosing spondylitis on work and family life: comparisons with the US population. Arthritis Rheum 2008; 59:497.
  54. Brionez TF, Assassi S, Reveille JD, et al. Psychological correlates of self-reported disease activity in ankylosing spondylitis. J Rheumatol 2010; 37:829.
  55. Sieper J, Hu X, Black CM, et al. Systematic review of clinical, humanistic, and economic outcome comparisons between radiographic and non-radiographic axial spondyloarthritis. Semin Arthritis Rheum 2017; 46:746.
  56. Jang JH, Green CE, Assassi S, et al. The contribution of disease activity on functional limitations over time through psychological mediators: a 12-month longitudinal study in patients with ankylosing spondylitis. Rheumatology (Oxford) 2011; 50:2087.
  57. Baysal O, Durmuş B, Ersoy Y, et al. Relationship between psychological status and disease activity and quality of life in ankylosing spondylitis. Rheumatol Int 2011; 31:795.
  58. Gordeev VS, Maksymowych WP, Evers SM, et al. Role of contextual factors in health-related quality of life in ankylosing spondylitis. Ann Rheum Dis 2010; 69:108.
  59. Wu Q, Inman RD, Davis KD. Fatigue in ankylosing spondylitis is associated with the brain networks of sensory salience and attention. Arthritis Rheumatol 2014; 66:295.
  60. Hemington KS, Wu Q, Kucyi A, et al. Abnormal cross-network functional connectivity in chronic pain and its association with clinical symptoms. Brain Struct Funct 2016; 221:4203.
  61. Bidad K, Gracey E, Hemington KS, et al. Pain in ankylosing spondylitis: a neuro-immune collaboration. Nat Rev Rheumatol 2017; 13:410.
  62. Wendling D, Prati C. Spondyloarthritis and fibromyalgia: interfering association or differential diagnosis? Clin Rheumatol 2016; 35:2141.
  63. Essers I, Stolwijk C, Boonen A, et al. Ankylosing spondylitis and risk of ischaemic heart disease: a population-based cohort study. Ann Rheum Dis 2016; 75:203.
  64. Haroon NN, Paterson JM, Li P, et al. Patients With Ankylosing Spondylitis Have Increased Cardiovascular and Cerebrovascular Mortality: A Population-Based Study. Ann Intern Med 2015; 163:409.
  65. Eriksson JK, Jacobsson L, Bengtsson K, Askling J. Is ankylosing spondylitis a risk factor for cardiovascular disease, and how do these risks compare with those in rheumatoid arthritis? Ann Rheum Dis 2017; 76:364.
  66. Moltó A, Etcheto A, van der Heijde D, et al. Prevalence of comorbidities and evaluation of their screening in spondyloarthritis: results of the international cross-sectional ASAS-COMOSPA study. Ann Rheum Dis 2016; 75:1016.
  67. Eder L, Sadek M, McDonald-Blumer H, Gladman DD. Aortitis and spondyloarthritis--an unusual presentation: case report and review of the literature. Semin Arthritis Rheum 2010; 39:510.
  68. Slobodin G, Naschitz JE, Zuckerman E, et al. Aortic involvement in rheumatic diseases. Clin Exp Rheumatol 2006; 24:S41.
  69. Vinsonneau U, Brondex A, Mansourati J, et al. Cardiovascular disease in patients with spondyloarthropathies. Joint Bone Spine 2008; 75:18.
  70. Brunner F, Kunz A, Weber U, Kissling R. Ankylosing spondylitis and heart abnormalities: do cardiac conduction disorders, valve regurgitation and diastolic dysfunction occur more often in male patients with diagnosed ankylosing spondylitis for over 15 years than in the normal population? Clin Rheumatol 2006; 25:24.
  71. Ozkan Y. Cardiac Involvement in Ankylosing Spondylitis. J Clin Med Res 2016; 8:427.
  72. Moyssakis I, Gialafos E, Vassiliou VA, et al. Myocardial performance and aortic elasticity are impaired in patients with ankylosing spondylitis. Scand J Rheumatol 2009; 38:216.
  73. Kim DY, Lee SJ, Ryu YJ, et al. Progressive Pulmonary Fibrocystic Changes of Both Upper Lungs in a Patient with Ankylosing Spondylitis. Tuberc Respir Dis (Seoul) 2015; 78:459.
  74. Berdal G, Halvorsen S, van der Heijde D, et al. Restrictive pulmonary function is more prevalent in patients with ankylosing spondylitis than in matched population controls and is associated with impaired spinal mobility: a comparative study. Arthritis Res Ther 2012; 14:R19.
  75. Boushea DK, Sundstrom WR. The pleuropulmonary manifestations of ankylosing spondylitis. Semin Arthritis Rheum 1989; 18:277.
  76. Kchir MM, Mtimet S, Kochbati S, et al. Bronchoalveolar lavage and transbronchial biopsy in spondyloarthropathies. J Rheumatol 1992; 19:913.
  77. Quismorio FP Jr. Pulmonary involvement in ankylosing spondylitis. Curr Opin Pulm Med 2006; 12:342.
  78. Kiris A, Ozgocmen S, Kocakoc E, et al. Lung findings on high resolution CT in early ankylosing spondylitis. Eur J Radiol 2003; 47:71.
  79. Lee CC, Lee SH, Chang IJ, et al. Spontaneous pneumothorax associated with ankylosing spondylitis. Rheumatology (Oxford) 2005; 44:1538.
  80. van der Weijden MA, Claushuis TA, Nazari T, et al. High prevalence of low bone mineral density in patients within 10 years of onset of ankylosing spondylitis: a systematic review. Clin Rheumatol 2012; 31:1529.
  81. Geusens P, Lems WF. Osteoimmunology and osteoporosis. Arthritis Res Ther 2011; 13:242.
  82. Roux C. Osteoporosis in inflammatory joint diseases. Osteoporos Int 2011; 22:421.
  83. Gratacós J, Collado A, Pons F, et al. Significant loss of bone mass in patients with early, active ankylosing spondylitis: a followup study. Arthritis Rheum 1999; 42:2319.
  84. Dos Santos FP, Constantin A, Laroche M, et al. Whole body and regional bone mineral density in ankylosing spondylitis. J Rheumatol 2001; 28:547.
  85. El Maghraoui A, Borderie D, Cherruau B, et al. Osteoporosis, body composition, and bone turnover in ankylosing spondylitis. J Rheumatol 1999; 26:2205.
  86. Karberg K, Zochling J, Sieper J, et al. Bone loss is detected more frequently in patients with ankylosing spondylitis with syndesmophytes. J Rheumatol 2005; 32:1290.
  87. Vosse D, Landewé R, van der Heijde D, et al. Ankylosing spondylitis and the risk of fracture: results from a large primary care-based nested case-control study. Ann Rheum Dis 2009; 68:1839.
  88. Pray C, Feroz NI, Nigil Haroon N. Bone Mineral Density and Fracture Risk in Ankylosing Spondylitis: A Meta-Analysis. Calcif Tissue Int 2017; 101:182.
  89. Mundwiler ML, Siddique K, Dym JM, et al. Complications of the spine in ankylosing spondylitis with a focus on deformity correction. Neurosurg Focus 2008; 24:E6.
  90. Vosse D, Feldtkeller E, Erlendsson J, et al. Clinical vertebral fractures in patients with ankylosing spondylitis. J Rheumatol 2004; 31:1981.
  91. Geusens P, De Winter L, Quaden D, et al. The prevalence of vertebral fractures in spondyloarthritis: relation to disease characteristics, bone mineral density, syndesmophytes and history of back pain and trauma. Arthritis Res Ther 2015; 17:294.
  92. Westerveld LA, Verlaan JJ, Oner FC. Spinal fractures in patients with ankylosing spinal disorders: a systematic review of the literature on treatment, neurological status and complications. Eur Spine J 2009; 18:145.
  93. Leone A, Marino M, Dell'Atti C, et al. Spinal fractures in patients with ankylosing spondylitis. Rheumatol Int 2016; 36:1335.
  94. Liu H, Qian BP, Qiu Y, et al. Vertebral body or intervertebral disc wedging: which contributes more to thoracolumbar kyphosis in ankylosing spondylitis patients?: A retrospective study. Medicine (Baltimore) 2016; 95:e4855.
  95. Nugent M, Berney MJ, Morris S. Clinical outcomes following spinal fracture in patients with ankylosing spondylitis. Ir J Med Sci 2017; 186:677.
  96. Khedr EM, Rashad SM, Hamed SA, et al. Neurological complications of ankylosing spondylitis: neurophysiological assessment. Rheumatol Int 2009; 29:1031.
  97. Chaudhary SB, Hullinger H, Vives MJ. Management of acute spinal fractures in ankylosing spondylitis. ISRN Rheumatol 2011; 2011:150484.
  98. Thumbikat P, Hariharan RP, Ravichandran G, et al. Spinal cord injury in patients with ankylosing spondylitis: a 10-year review. Spine (Phila Pa 1976) 2007; 32:2989.
  99. Ramos-Remus C, Gomez-Vargas A, Guzman-Guzman JL, et al. Frequency of atlantoaxial subluxation and neurologic involvement in patients with ankylosing spondylitis. J Rheumatol 1995; 22:2120.
  100. Lee JS, Lee S, Bang SY, et al. Prevalence and risk factors of anterior atlantoaxial subluxation in ankylosing spondylitis. J Rheumatol 2012; 39:2321.
  101. Bartleson JD, Cohen MD, Harrington TM, et al. Cauda equina syndrome secondary to long-standing ankylosing spondylitis. Ann Neurol 1983; 14:662.
  102. Sant SM, O'Connell D. Cauda equina syndrome in ankylosing spondylitis: a case report and review of the literature. Clin Rheumatol 1995; 14:224.
  103. Lee SH, Lee EJ, Chung SW, et al. Renal involvement in ankylosing spondylitis: prevalence, pathology, response to TNF-a blocker. Rheumatol Int 2013; 33:1689.
  104. Strobel ES, Fritschka E. Renal diseases in ankylosing spondylitis: review of the literature illustrated by case reports. Clin Rheumatol 1998; 17:524.
  105. Levy AR, Szabo SM, Rao SR, et al. Estimating the occurrence of renal complications among persons with ankylosing spondylitis. Arthritis Care Res (Hoboken) 2014; 66:440.
  106. Gratacós J, Collado A, Sanmartí R, et al. Coincidental amyloid nephropathy and IgA glomerulonephritis in a patient with ankylosing spondylitis. J Rheumatol 1993; 20:1613.
  107. Lance NJ, Curran JJ. Amyloidosis in a case of ankylosing spondylitis with a review of the literature. J Rheumatol 1991; 18:100.
  108. Ostensen M, Ostensen H. Ankylosing spondylitis--the female aspect. J Rheumatol 1998; 25:120.
  109. Sieper J, Braun J, Rudwaleit M, et al. Ankylosing spondylitis: an overview. Ann Rheum Dis 2002; 61 Suppl 3:iii8.
  110. Niccoli L, Nannini C, Cassarà E, et al. Frequency of anemia of inflammation in patients with ankylosing spondylitis requiring anti-TNFα drugs and therapy-induced changes. Int J Rheum Dis 2012; 15:56.
  111. Maksymowych WP. What do biomarkers tell us about the pathogenesis of ankylosing spondylitis? Arthritis Res Ther 2009; 11:101.
  112. Kang KY, Hong YS, Park SH, Ju JH. Increased serum alkaline phosphatase levels correlate with high disease activity and low bone mineral density in patients with axial spondyloarthritis. Semin Arthritis Rheum 2015; 45:202.
  113. Laurent MR, Panayi GS. Acute-phase proteins and serum immunoglobulins in ankylosing spondylitis. Ann Rheum Dis 1983; 42:524.
  114. Franssen MJ, van de Putte LB, Gribnau FW. IgA serum levels and disease activity in ankylosing spondylitis: a prospective study. Ann Rheum Dis 1985; 44:766.
  115. Jang JH, Ward MM, Rucker AN, et al. Ankylosing spondylitis: patterns of radiographic involvement--a re-examination of accepted principles in a cohort of 769 patients. Radiology 2011; 258:192.
  116. Poddubnyy D, Brandt H, Vahldiek J, et al. The frequency of non-radiographic axial spondyloarthritis in relation to symptom duration in patients referred because of chronic back pain: results from the Berlin early spondyloarthritis clinic. Ann Rheum Dis 2012; 71:1998.
  117. van der Linden S, Valkenburg HA, Cats A. Evaluation of diagnostic criteria for ankylosing spondylitis. A proposal for modification of the New York criteria. Arthritis Rheum 1984; 27:361.
  118. Bennett PH, Burch TA. Population Studies of the Rheumatic Diseases, Excerpta Medica Foundation, Amsterdam 1968. p.456-457.
  119. van den Berg R, Lenczner G, Feydy A, et al. Agreement between clinical practice and trained central reading in reading of sacroiliac joints on plain pelvic radiographs. Results from the DESIR cohort. Arthritis Rheumatol 2014; 66:2403.
  120. Baraliakos X, Braun J. Hip involvement in ankylosing spondylitis: what is the verdict? Rheumatology (Oxford) 2010; 49:3.
  121. Weber U, Jurik AG, Lambert RG, Maksymowych WP. Imaging in Spondyloarthritis: Controversies in Recognition of Early Disease. Curr Rheumatol Rep 2016; 18:58.
  122. Rudwaleit M, Jurik AG, Hermann KG, et al. Defining active sacroiliitis on magnetic resonance imaging (MRI) for classification of axial spondyloarthritis: a consensual approach by the ASAS/OMERACT MRI group. Ann Rheum Dis 2009; 68:1520.
  123. Lambert RG, Bakker PA, van der Heijde D, et al. Defining active sacroiliitis on MRI for classification of axial spondyloarthritis: update by the ASAS MRI working group. Ann Rheum Dis 2016; 75:1958.
  124. Marzo-Ortega H, McGonagle D, O'Connor P, et al. Baseline and 1-year magnetic resonance imaging of the sacroiliac joint and lumbar spine in very early inflammatory back pain. Relationship between symptoms, HLA-B27 and disease extent and persistence. Ann Rheum Dis 2009; 68:1721.
  125. Weber U, Lambert RG, Østergaard M, et al. The diagnostic utility of magnetic resonance imaging in spondylarthritis: an international multicenter evaluation of one hundred eighty-seven subjects. Arthritis Rheum 2010; 62:3048.
  126. Arnbak B, Grethe Jurik A, Hørslev-Petersen K, et al. Associations Between Spondyloarthritis Features and Magnetic Resonance Imaging Findings: A Cross-Sectional Analysis of 1,020 Patients With Persistent Low Back Pain. Arthritis Rheumatol 2016; 68:892.
  127. de Hooge M, van den Berg R, Navarro-Compán V, et al. Patients with chronic back pain of short duration from the SPACE cohort: which MRI structural lesions in the sacroiliac joints and inflammatory and structural lesions in the spine are most specific for axial spondyloarthritis? Ann Rheum Dis 2016; 75:1308.
  128. Weber U, Pedersen SJ, Østergaard M, et al. Can erosions on MRI of the sacroiliac joints be reliably detected in patients with ankylosing spondylitis? - A cross-sectional study. Arthritis Res Ther 2012; 14:R124.
  129. Baraliakos X, Maksymowych WP. Imaging in the diagnosis and management of axial spondyloarthritis. Best Pract Res Clin Rheumatol 2016; 30:608.
  130. Jeong H, Yoon JY, Park EJ, et al. Clinical characteristics of nonradiographic axial spondyloarthritis in Korea: a comparison with ankylosing spondylitis. Int J Rheum Dis 2015; 18:661.
  131. van der Heijde D, Landewé R. Imaging in spondylitis. Curr Opin Rheumatol 2005; 17:413.
  132. van der Heijde D, Sieper J, Maksymowych WP, et al. Spinal inflammation in the absence of sacroiliac joint inflammation on magnetic resonance imaging in patients with active nonradiographic axial spondyloarthritis. Arthritis Rheumatol 2014; 66:667.
  133. Hermann KG, Baraliakos X, van der Heijde DM, et al. Descriptions of spinal MRI lesions and definition of a positive MRI of the spine in axial spondyloarthritis: a consensual approach by the ASAS/OMERACT MRI study group. Ann Rheum Dis 2012; 71:1278.
  134. Ramiro S, van Tubergen A, van der Heijde D, et al. Brief report: erosions and sclerosis on radiographs precede the subsequent development of syndesmophytes at the same site: a twelve-year prospective followup of patients with ankylosing spondylitis. Arthritis Rheumatol 2014; 66:2773.
  135. Ramiro S, Stolwijk C, van Tubergen A, et al. Evolution of radiographic damage in ankylosing spondylitis: a 12 year prospective follow-up of the OASIS study. Ann Rheum Dis 2015; 74:52.
  136. Ward MM, Learch TJ, Gensler LS, et al. Regional radiographic damage and functional limitations in patients with ankylosing spondylitis: differences in early and late disease. Arthritis Care Res (Hoboken) 2013; 65:257.
  137. Terslev L, Naredo E, Iagnocco A, et al. Defining enthesitis in spondyloarthritis by ultrasound: results of a Delphi process and of a reliability reading exercise. Arthritis Care Res (Hoboken) 2014; 66:741.
  138. D'Agostino MA, Aegerter P, Bechara K, et al. How to diagnose spondyloarthritis early? Accuracy of peripheral enthesitis detection by power Doppler ultrasonography. Ann Rheum Dis 2011; 70:1433.
  139. Mandl P, Navarro-Compan V, Terslev L, et al. EULAR recommendations for the use of imaging in spondyloarthritis in clinical practice. Ann Rheum Dis 2014; 73 (Suppl 2):abstract FRI0127.
Topic Outline