What is an enthesis? How does it relate to the disease process in Axial Spondyloarthritis?
An enthesis is a site of insertion of a ligament, tendon, or articular capsule into the bone. In axSpA, the initial inflammatory process involves the enthesis, followed by a process that results in new bone formation or fibrosis and occasionally erosion.
Sites of enthesopathy in axSpA include the sacroiliac joints, ligamentous structures of the intervertebral discs, manubriosternal joints, symphysis pubis, attachments in the spinous processes, iliac crests (whiskering), trochanters, patellae, clavicles, and calcanei (Achilles enthesitis or plantar fasciitis).