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DanNordström

Axial Spondyloarthritis and Ankylosing Spondylitis

Essentials

  • An integral feature of the disease is inflammation involving ligament insertion sites and facet joints of the spine as well as the sacroiliac (SI) joints.
  • The condition often affects HLA-B27 positive individuals and belongs to the group of spondyloarthritides together with
  • Several of the above conditions may be encountered in members of the same family, and they may all lead to ankylosing spondylitis.
  • The condition is termed ankylosing spondylitis when it has become chronic and no causative agent has been detected, unlike in reactive arthritis.
  • Axial spondyloarthritis and ankylosing spondylitis are considered to be a continuum of the same disease, even if not all patients with axial spondyloarthritis end up having ankylosing spondylitis.

Definition and incidence

  • Axial spondyloarthritis and ankylosing spondylitis are part of the same spectrum of disease; in axial (non-radiographic) spondyloarthritis inflammatory changes can be visualised at the SI joints and also at the spine by magnetic resonance imaging (MRI), but if radiographic changes are present the condition has already evolved into ankylosing spondylitis.
  • Some (about one third) cases of axial spondyloarthritis will progress to ankylosing spondylitis, and these patients should receive active treatment sufficiently early. At risk are HLA-B27-positive smoking patients who also have an elevated CRP concentration.
  • Ankylosing spondylitis is nearly as common as rheumatoid arthritis, but less than one third of patients are diagnosed with the clinical disease. Axial spondyloarthropathy is almost as frequent in women as in men, but severe ankylosing spondylitis requiring hospital treatment is mainly encountered in men.
  • The incidence peaks at around the age of 25 years, but the diagnosis is often delayed. The newer definition, axial spondyloarthritis, reduces the diagnostic delay because MRI is used in the diagnostics.

Clinical picture

  • It is most important that inflammatory back pain is identified, the criteria for which are fulfilled when a patient with back pain for HASH(0x2ed5390) 3 months presents with at least 4 of the following 5 criteria:
    • age at symptom onset less than 40 years
    • insidious onset of back pain
    • pain at night that eases after getting up
    • symptoms improve with exercise
    • symptoms do not improve with rest.
  • Sacroiliitis: lumbosacral and gluteal pain that wakes the patient during the second half of the night
  • Stiffness after rest and sitting down
  • Stiffness and pain in the spine, tender spots at the cartilages of the thorax
  • Peripheral arthritis mainly affecting the large joints of the lower limbs
  • Enthesitis is common in the lower limbs (pain under the heel)
  • Dactylitis (sausage finger or toe 1)
  • Acute uveitis in 20% of patients (uveitis may be the first manifestation of the disease)
  • Sometimes chronic inflammatory bowel disease (Crohn's disease or ulcerative colitis)
  • Psoriasis and palmoplantar pustulosis
  • Conduction defects of the heart and aortitis may occasionally occur (auscultation, ECG if in doubt)

Diagnosis

  • Clinical picture (see above)
  • Clinical findings
    • Tenderness elicited in the SI joints by compression, palpation and manipulative stress tests (Patrick's test picture 3)
    • Fingertip to floor distance while bending forward
    • Schober test (normal: at least 4 cm difference in the distance of lines originally 10 cm apart)
    • Lumbar lateral flexion (sidebending, normal 20 cm)
      1. The patient stands with their back against a wall, with shoulder blades and buttocks in contact with the wall, lower limbs straight and feet 15 cm apart, arms hanging naturally by their sides.
      2. A mark is placed on the lateral side of the patient's thigh at the level of their middle finger.
      3. The patient bends sideways, keeping the contact with the wall and their heels on the ground, while sliding their hand along the side of their thigh.
      4. At the point of maximal bending, a second mark is placed on the thigh in line with the first mark, indicating the new position of the middle finger.
      5. The distance between the two marks is measured with a tape measure.
      6. The test is repeated on both sides.
    • Occiput to wall distance (normal 0 cmhttp://www.physio-pedia.com/Occiput_to_Wall_Distance_OWD)
    • Chest expansion (the normal difference in the chest circumference between maximal expiration and maximal inspiration is HASH(0x2ed5390) 4 cm at the nipple level)
  • ESR and CRP levels may be elevated in about half of patients. Rheumatoid factor or citrullinated peptide antibody tests are not useful in the diagnostics.
  • MRI scan of the SI joints is recommended as the primary imaging study in patients less than 35 years of age in order to detect early changes; in patients older than this, plain x-rays are suitable as the primary investigation.
  • X-rays are taken of the lumbar spine (the first changes often appear at the boundary between the thoracic and lumbar spine) and the SI joints. It takes 2-8 years for radiographic sacroiliitis to evolve.
  • MRI can be used to verify sacroiliitis before radiological changes are visible in plain x-rays thus allowing the assessment of the degree of the inflammation.
    • MRI is recommended to be carried out if the clinical picture fulfils the criteria for inflammatory back pain (see above) while the x-rays of the SI joints are still normal.
    • Oedematous changes in the spine (Romanus- and Andersson-type lesions) also support the diagnosis.
    • Abnormal MRI findings are usually present as soon as 2 months after symptom onset.
    • Sources of error include e.g. postpartum period and endurance sports.
    • When considering the need for imaging studies, it should be kept in mind that the symptom onset of spondyloarthritis does not occur after the age of 45 years.
    • Use in the diagnostic workup should be restricted to patients with a history that fulfils the criteria of inflammatory back pain and with symptom onset before the age of 40-45 years.
  • Classification criteria for axial spondyloarthritis by ASAS (The Assessment of SpondyloArthritis international Society), see table T1.

Differential diagnosis

  • Osteitis condensans ilii on x-rays
  • Degenerative spine diseases
  • Diffuse idiopathic skeletal hyperostosis (DISH) on x-rays
  • Sciatica
  • Other spondyloarthritis
    • Reactive arthritis
    • Psoriatic arthropathy
    • Arthritis associated with inflammatory bowel disease

ASAS criteria for classification of axial spondyloarthritis (SpA) in patients with back pain for HASH(0x2ed5390) 3 months and age at onset < 45 years

Sacroiliitis (on MRI or plain x-rays) + HASH(0x2ed5390) 1 SpA feature

or

HLA-B27 + HASH(0x2ed5390) 2 other SpA features		SpA features
  • Inflammatory back pain
  • Arthritis
  • Enthesitis (in the heel)
  • Uveitis
  • Dactylitis
  • Psoriasis
  • Crohn's disease / ulcerative colitis
  • Good response to NSAIDs
  • Family history of SpA
  • HLA-B27 positive
  • Elevated CRP concentration
Source: 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(6):777-83. [PubMed]
Treatment and organization of care Tnf-Alpha Inhibitors for Ankylosing Spondylitis, Physiotherapy Interventions for Ankylosing Spondylitis, Sulfasalazine for Ankylosing Spondylitis, Methotrexate for Ankylosing Spondylitis, Nsaids for Axial Spondyloarthritis, Exercise Programmes for Ankylosing Spondylitis
  • Physiotherapy is the cornerstone of treatment in order to prevent structural damage to the spine. It is most important to encourage regular spinal stretching exercises and the patient should be given a safe exercise programme (note the fracture risk in a completely rigid osteoporotic spine).
  • NSAID medication prescribed in primary care (preferably with a regularly used COX-2-selective drug) relieves symptoms markedly better than in degenerative diseases of the back, and a therapeutic trial is useful in differential diagnosis. Treatment courses may last even for a month, and they are also thought to slow down the radiological progression of the disease. As necessary, at least two medicines are tried one after the other in combination with physiotherapy.
  • If treatment in primary care is not sufficient, the patient is referred to specialized care to confirm the diagnosis and start antirheumatic medication (e.g. MRI).
  • Sulfasalazine is most probably useful at the early stage of the disease especially if ESR and/or CRP are elevated or if the patient has peripheral joint involvement.
  • The efficacy of methotrexate is more disputable, but some benefit can be expected in peripheral disease.
  • Local corticosteroid injections are useful for peripheral arthritis, sacroiliitis and enthesitis.
  • Biological agents(a TNF inhibitor, IL-17 inhibitor or JAK inhibitor)
    • Biological or JAK inhibitor medication only if the following criteria are fulfilled: moderate pain and severe spinal stiffness in the morning suggesting active spinal disease, as demonstrated by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI, calculator http://basdai.com/) score HASH(0x2ed5390) 4, elevated CRP or active sacroiliitis on MRI as well as an unsuccessful therapeutic trial with a maximum dose of an NSAID and sulfasalazine or methotrexate.

Response assessment

  • The effectiveness of the treatment is assessed after 3 months. The assessment is based on both the doctor's and the patient's own assessment, and it includes the use of disease activity measures (e.g. CRP and BASDAI http://basdai.com/ or ASDAS [Ankylosing Spondylitis Disease Activity Score http://www.asas-group.org/instruments/asdas-calculator/]).
  • If the BASDAI score has not decreased by HASH(0x2ed5390) 2 units or the ASDAS by HASH(0x2ed5390) 1.1 units at 6 months at the latest, treatment is inadequate and requires intensification and often a change of medication.

    References

    • Ramiro S, Nikiphorou E, Sepriano A, et al. ASAS-EULAR recommendations for the management of axial spondyloarthritis: 2022 update. Ann Rheum Dis 2023;82(1):19-34 [PubMed]
    • 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(6):784-8[PubMed]
    • 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(6):777-83. [PubMed]