What are the physical findings of peripheral entheses in ankylosing spondylitis (AS)?

Updated: Feb 02, 2021
  • Author: Lawrence H Brent, MD; Chief Editor: Herbert S Diamond, MD  more...
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Peripheral enthesitis occurs in approximately 33% of patients. These lesions are painful and tender to palpation and may be associated with swelling of the tendon or ligament insertion.

The most common and characteristic peripheral sites of enthesitis are the insertion of the Achilles tendon on the calcaneus and the insertion of the plantar fascia on the calcaneus. Certain anatomic areas may be more prone to enthesitis because of biomechanical stress. Carefully examine patients for tenderness upon palpation.

Enthesitis and synovitis account for some of the peripheral joint involvement. Peripheral joint disease occurs in 33% of patients, most commonly in the hips. Hip involvement usually occurs in the first 10 years of the disease course and is typically bilateral.

Other joints may be involved, including the following:

  • Shoulder girdle (glenohumeral, acromioclavicular, and sternoclavicular joints)
  • Costovertebral joints
  • Costosternal junctions
  • Manubriosternal joints
  • Symphysis pubis
  • Temporomandibular joint

Peripheral joints are uncommonly involved. When they are involved it is in an asymmetric oligoarticular pattern.

Dactylitis (sausage digit) is very uncommon in patients with AS. Isolated small-joint involvement of the hands, feet, or dactylitis strongly suggests reactive arthritis (ReA), psoriatic arthritis (PsA), or undifferentiated spondyloarthropathy (USpA).

Destructive arthritis may affect the hips or shoulder girdle, which may result in limited range of motion and flexion deformities.

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