Enthesitis-related juvenile idiopathic arthritis, also known as enthesitis-related arthritis (ERA), usually combines joint pain and inflammation (arthritis) with tenderness where the ligaments or tendons attach to bones (enthesitis). The enthesitis is commonly around the kneecaps and the heels, and joints-usually spine, hips, knees, and ankles-are stiff and painful.
ERA is more common in boys. Some children go on to develop a spondyloarthropathy such as adult ankylosing spondylitis.
Many children who have ERA also have inflammatory eye disease, called uveitis. Uveitis sometimes has no symptoms before vision loss occurs, so frequent eye exams with an ophthalmologist are needed.
WebMD Medical Reference from Healthwise