Ankylosing spondylitis, other spondyloarthritides, and related conditions

The spondyloarthritides are a group of inflammatory rheumatic diseases with predominant involvement of axial and peripheral joints and entheses, together with other characteristic clinical features, including inflammatory back pain, sacroiliitis, peripheral arthritis (mainly in the legs), enthesitis, dactylitis, preceding infection of the urogenital/gastrointestinal tract, psoriatic skin lesions, Crohn-like gut lesions, anterior uveitis, and a family history of Spondyloarthritis. They are the second most frequent inflammatory rheumatic diseases after rheumatoid arthritis.

Five subsets can be distinguished on clinical grounds: (1) ankylosing spondylitis; (2) reactive (spondylo)arthritis/Reiter’s syndrome (see Chapter 19.8); (3) psoriatic (spondylo)arthritis; (4) (spondylo)arthritis associated with inflammatory bowel diseases; and (5) undifferentiated spondyloarthritis. Prevalence in any population correlates roughly with that of HLA B27, but the relevance of this to pathogenesis is not known. Another more recent approach is to differentiate the SpA on the basis of the predominant clinical manifestation: predominant axial and/or peripheral SpA.

Ankylosing spondylitis

Diagnosis requires one of three clinical criteria—(1) inflammatory back pain; (2) limitation of spinal movement in three planes; or (3) deterioration of chest expansion—and radiological sacroiliac joint changes (bilateral grade 2 or unilateral grade 3/4). Sacroiliac radiographs may be normal in early disease when dynamic MRI of the sacroiliac joints can be helpful in providing objective evidence of sacroiliitis in clinically suspicious cases.

Age of onset is commonly in the twenties, with male:female ratio of 2:1. Early in the course of disease there may be no limitation of spinal movement or chest expansion, but as it progresses there is restriction of lateral flexion, forward flexion, and extension.

Treatment options include acute anti-inflammatory therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) and local corticosteroids, disease-modifying drugs (DMARDs: sulfasalazine and methotrexate) and biologicals (anti-tumour necrosis factor), together with physiotherapy. There is no cure.

Psoriatic arthritis

Psoriasis precedes joint disease in most cases, but there is poor correlation between onset, severity and activity of psoriatic skin lesions and arthritis. More than 80% of patients with psoriatic arthritis have nail dystrophy.

The most characteristic features are dactylitis and osteoproliferative changes in radiographs of peripheral joints. The CASPAR criteria, which are both sensitive and specific, require established inflammatory articular disease with at least three points from the following features: (1) current psoriasis (score 2); (2) a history of psoriasis (unless current psoriasis); (3) a family history of psoriasis (unless current psoriasis or history of psoriasis); (4) dactylitis; (5) juxta-articular new bone formation; (6) rheumatoid factor negativity; and (7) nail dystrophy.

Many patients improve with the use of NSAIDs and intra-articular steroids, especially in the case of large joint involvement or flexor tenosynovitis. Those who do not improve need to be treated with DMARDs (sulfasalazine, methotrexate).

Arthritis associated with inflammatory bowel disease

Similar to the other spondyloarthritides, the arthritis is mostly asymmetric and predominantly affects the legs. Flaring of gut symptoms is often associated with arthritis. Treatment with NSAIDs may be effective for arthritis and spondylitis but can exacerbate bowel disease: there are few data on the use of DMARDs.

Undifferentiated spondyloarthritis

Diagnosis requires inflammatory back pain and/or peripheral arthritis of the legs (usually asymmetrical) and at least one other of the following characteristic features in addition: (1) enthesitis; (2) a positive family history for spondyloarthritis; (3) psoriasis; or (4) inflammatory bowel disease. Dactylitis, anterior uveitis, and HLA B27 may also be used for making a diagnosis of undifferentiated spondyloarthritis. Nonspecific therapy is as for other arthritides. Sulfasalazine may be useful for peripheral and axial symptoms, but very few therapeutic trials with DMARDs have been performed.

SAPHO syndrome

There are no evaluated diagnostic criteria for SAPHO syndrome (synovitis, acne, pustulosis palmaris et plantaris, hyperostosis, and osteitis): most convincing clinically is the combination of a classical skin symptom—such as pustolosis or significant acne—with a characteristic joint or bone lesion—such as arthritis of the sternoclavicular joint, osteitis, or hyperostosis in the anterior chest wall. Analgesics, NSAIDs, and intra-articular steroids are usually effective.