Enthesitis is inflammation of soft tissue (muscle, ligament or tendon) right where it inserts into the bone. It is associated with arthritis and is one of the main signs of spondyloarthritis. Enthesitis is also associated with DISH, a disease in which some of your spinal ligaments harden.
Enthesitis often causes the affected area of the soft tissue to become ropey (called fibrosis) and/or solid (called calcification or ossification). It can be quite painful; the pain occurs mainly when you use your muscles and they pull on your bones.
Medications given for enthesitis are aimed at either reducing inflammation or suppressing the immune system. They include NSAIDs, prednisone (a corticosteroid), methotrexate, (a cancer drug) and sulfasalazine (a drug often given for rheumatoid arthritis). TNF blockers are a relatively new type of medication used to treat enthesitis. TNF blockers are also called biologics.
Enthesitis is often found at the sacroiliac joints when you have an inflammatory arthritis disease such as spondylitis. It is considered to be an active inflammatory lesion. For people with spondylitis, an MRI using one of several specialized techniques is used to find evidence of enthesitis and other active inflammatory lesions. Enthesitis is most often diagnosed by history and physical exam alone.