Osteoarthritis, or “wear and tear” arthritis, is a common degenerative disease often seen in older people. It can affect any of the body’s joints, but is most common in load-bearing joints like the knees and hips. Osteoarthritis of the hip happens when the cartilage that cushions the bones that form the hip joint wears down, causing pain and stiffness. While aging is the main cause, previous injury can lead to it as well.