Enthesitis is inflammation of an enthesis — the point where a tendon, ligament or joint capsule attaches to bone. Common sites include the Achilles tendon, plantar fascia, elbow and around the pelvis. Painful, tender entheses that don't settle are a hallmark of the spondyloarthritis family (ankylosing, psoriatic and reactive arthritis) and help distinguish it from rheumatoid arthritis, which mostly targets the joint lining (synovium).
What is enthesitis?
Enthesitis: Enthesitis is inflammation at the entheses — where tendons or ligaments attach to bone. Characteristic of spondyloarthropathies (AS, PsA) and often the first symptom (e.g. Achilles tendon pain, plantar fasciitis).
Last updated 2026-07-04. This is general information, not a substitute for personalised medical advice.