Enthesitis is
inflammation of the
entheses, the sites where tendons or ligaments insert into the bone.[1][2] It is an enthesopathy, a
pathologic condition of the entheses. Early clinical manifestations are an aching sensation akin to "working out too much", and it gets better with activity. It is worse in the morning (after sleeping and not moving). The muscle insertion hurts very focally as it joins into the bone, but there is little to no pain at all with passive motion. There are some cases of isolated, primary enthesitis which are very poorly studied and understood. It is known to be associated with other
autoimmune diseases, like spondyloarthropathies and psoriasis (thought to often precede psoriatic arthritis). A common autoimmune enthesitis is at the
heel, where the
Achilles tendon attaches to the
calcaneus.
^Hendrix CL (2005). "Calcaneal apophysitis (Sever disease)". Clinics in Podiatric Medicine and Surgery. 22 (1): 55–62, vi.
doi:
10.1016/j.cpm.2004.08.011.
PMID15555843.
^"Tendinitis". National Institute of Arthritis and Musculoskeletal and Skin Diseases. 12 April 2017. Retrieved 18 November 2018.