Fast Five Quiz: Ankylosing Spondylitis Signs and Symptoms

Herbert S. Diamond, MD; Marina Magrey, MD


March 16, 2023

Peripheral musculoskeletal involvement occurs in 30%-50% of patients with AS. Peripheral arthritis predominantly involves the lower extremity joints like knees and ankles but other joints can also get involved. Enthesitis, which is inflammation at the site of insertion of ligaments and tendons onto bone, is a common clinical feature. The most frequently involved sites include:

  • Insertion of the plantar fascia on the calcaneus or the metatarsal heads

  • Achilles tendon insertion

  • Base of the fifth metatarsal head

  • Tibial tuberosity

  • Superior and inferior poles of the patella

  • Iliac crest

Other sites of involvement include:

  • Greater trochanter

  • Ischial tuberosity

  • Costochondral junctions

  • Distal scapula

  • Lateral epicondyle

  • Distal ulna

Involvement of the temporomandibular joint occurs in approximately 10% of patients and involvement of the costovertebral and costotransverse joints can occur, leading to decreased range of motion and restriction in respiration.

Learn more about the clinical presentation of AS.


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