What is tendinitis? Tendinitis is swelling and pain in a tendon, which is tissue that connects muscles to bones. It is a common condition, usually caused by repeated injuries to a tendon.
What is psoriatic arthritis? Psoriatic arthritis is a condition that causes swelling and pain in joints and the places where tendons and ligaments attach to bones. Most people who develop psoriatic arthritis already have psoriasis (a skin disease), but a small number have joint pain before the skin rash.