Spondyloarthritis, Spondyloarthropathies, SpA 4.5/5 (8)

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Spondyloarthritis is a group of rheumatic autoimmune (inflammatory) diseases that attack joints (arthritis) and back (spondylitis). Other characteristics are that some people get one or more swollen fingers or toes in the form of dactylitis, tendon attachment inflammation (enthesitis) and eye inflammation (uveitis/iridocyclitis). In the blood, an increased occurrence of the hereditary tissue type HLAB-27 is seen in some of the SpA subgroups: -Ankylosing spondylitis (Bekhterev's disease) rsuitable as the prototype of spondyloarthritis. Inflammation in the pelvic joint (iliosacral joint) and HLA-B27 in the blood is seen in almost everyone. Psoriatic arthritis, SpA-related to inflammatory bowel disease UC or CD, reactive arthritis (after infections) og enthesitis related arthritis (in children). Udifferentiated spondyloarthritis exists when the medical history and examinations show that SpA is clearly present, but the condition does not fit into the other diagnoses (reference: Dougados M, 2011). The term spondyloarthritis has existed since 1974 when Moll and colleagues defined the condition (reference: Moll JM, 1974).


It is estimated that 0,5-1,6% of the population has spondyloarthritis (prevalence), of which Bekhterev's disease and psoriatic arthritis make up the majority of cases. The part of the incidence due to Bekhterev's is highest in the far north (1,6% in Arctic regions) where the hereditary factor HLA-B27 is most common (reference: Stolwijk C, 2016). In comparison, the incidence in southern parts of the globe is only 0,2% in South-East Asia. In southern Sweden, the incidence of SpA in a population study is estimated at 0,45% (reference: Haglund E, 2011). Illustration: Back pain, including in the iliosacral joint, is typical of spondyloarthritis.


  • The most common symptom is arthritis (arthritis) in the knee, ankle or hip joint.
  • Many also experience back pain and stiffness lasting more than three months (Inflammatory back pain) as the first symptom, often at a young age (the teens - at the latest at the age of 40).
Swollen and warm knee occurs with spondyloarthritis
  • Morning stiffness in the back for at least 30 minutes.
  • Improvement of physical activity, not of being at rest.
  • Waking up in the early hours of the morning or at night due to pain.
  • Alternating pain in the pelvis (gluteal).


Medical history typically ask for symptoms such as signs of joint inflammation, back pain/stiffness, symptoms from the eyes, urinary tract, skin or bowels. Family with SpA (first or second degree relatives).

Clinical examination includes general assessment of skin, eyes, internal organs, but also joints, tendon attachments (Achilles tendons and plantar fascia) and back

Blood tests may show elevated inflammation tests (CRP, blood lowering reaction (SR)). HLA B27 positive (25-95%, against 8-16% in the population).

Imaging with MRI, CT or X-ray examinations often show signs of inflammation in sacroiliac joints (between pelvis and spine) and binflammatory changes in the spine. In early or uncertain cases, MRI images can be easily misinterpreted (please see below).


Made based on symptoms and examination findings

  • The tissue type HLA-B27 occurs in approx. 8% in the population of Southern Norway and twice as often the furthest north in Norway and alone is not a criterion for the diagnosis
  • MRI examination of iliosacral joints may show changes earlier than CT and X-ray examination
    • "Usures" in the joints are inflammatory changes in the cartilage and bone substance that usually persist
    • MRI changes that show "edema" is an uncertain finding that can go back and is not necessarily caused by rheumatic inflammation.
    • When different specialists interpret the same MRI images of the iliosacral joint at «non-radiographic SpA», they disagree / come to a different conclusion in about one in three cases

Differences in different spondyloarthritisr (reference: Richlin CT, 2018)

CharacteristicsPsoriatic arthritisAnkylosing spondylitisReactive arthritisIBD-associated arthritis
Age at onset (years)36203030
Male/female ratio1:13:13:12:1
Peripheral arthritis96%30%90%30%
Axial arthritis50%100%-30%
Nail lesions87%UnusualUnusualUnusual
HLA B2740-50%90%70%30%

ICD-10 codes

The ASAS criteria. Inflammation of the back/spondylitis is sometimes defined according to the ASAS criteria (reference: Rudwaleit M, 2009) which originally intended to catch patients early after the onset of the disease. Diagnosing early, however, entails such an increased risk of someone being misdiagnosed that the criteria are not used in normal clinical practice. One must be especially aware that only 30% of people with inflammatory back pain develop spondyloarthritis (reference: Wang R, 2018), in some studies even fewer, and that physical exercise and among a number of others who are healthy, MRI images show changes that can be misinterpreted as inflammation (reference: the winter J, 2018).

Similar conditions, differential diagnoses


The treatment options have improved a lot in recent years. Before the treatment starts, it is important to be informed about the disease, what the treatment goal is, and about side effects that may occur. Treatment goals are often to reduce symptoms (pain and stiffness), maintain physical function, minimize complications from the back, joints, eyes, internal organs and the mental burden, but there is no treatment that cures the diseases. The treatment must be adapted to the individual and have a clear goal within a specific period of time.

Physical therapy, self training and symptomatic medications like NSAIDs (for example Voltaren / diclofenac) is basis. NSAIDs reduce pain and improve physical mobility. It is debated whether the development of the disease (on radiological images) is also reduced. Some need disease-reducing additional treatment which can also include Biological treatment with TNF inhibitors. TNF inhibitors reduce symptoms and improve mobility. There is also evidence that the development of the disease (on radiological images) is also being slowed down.

Guidelines and recommendations


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