A normal joint is lined with tissue and enclosed in a capsule with cartilage (a rubbery cushion which keeps the bones from rubbing together) covering the ends of the bones. Degeneration of the cartilage leads to: Pain Swelling Limited motion joint replacement kneeWhen a joint is limited and not exercised, surrounding muscles may shrink and become weaker, and eventually, unable to bear weight. Common causes of joint pain and cartilage degeneration which can result in the need for total joint replacement include: Severe arthritis Trauma, such as serious fracture Injury that doesn’t heal properly Avascular neurosis (hip joint degeneration) Congenital deformities or abnormalities