An inflammation of the entheses, the sites where tendons or ligaments insert into the bone.
Also called enthesopathy, or any pathologic condition involving the entheses.
Enthesitis, the inflammation at the site where ligaments, tendons, and joint capsules attach to the bone, is the prominent pathologic lesion in psoriatic arthritis in contrast to synovitis in rheumatoid arthritis.
The entheses are any point of attachment of skeletal muscles to the bone, where recurring stress or inflammatory autoimmune disease can cause inflammation or occasionally fibrosis and calcification.
The Achilles tendon is one of the primary entheses involved in inflammatory autoimmune disease and it is associated with HLA B27 arthropathies like ankylosing spondylitis, psoriatic arthritis, and reactive arthritis (Reiter’s syndrome).