Knee arthroplasty has two primary purposes: pain relief and improved functioning of the knee joint. Because of the importance of the knee to a person's ability to stand upright, improved joint functioning includes greater stability in the knee.

Disorders and conditions that may lead to the need for knee replacement surgery include:

Osteoarthritis (OA). 

Rheumatoid arthritis (RA).

Trauma. Damage to the knee from a fall, automobile accident, or workplace or athletic injury may trigger the process of cartilage breakdown inside the joint. Trauma is a common cause of damage to the knee joint.