According to the American Academy of Orthopedic Surgeons, over 250,000 knee replacement surgeries, or arthroplasties, are performed in the United States each year. Most of these surgeries are for individuals over the age of 65. However, more and more surgeries are being performed on younger patients. The first knee replacement was performed in 1968. Since then, advances in surgical technique as well as replacement knees have changed the field of knee replacement surgeries.

The complexity of knee replacement surgery depends on whether one knee or both knees are being replaced. In cases of those afflicted with arthritis (who usually have pain in both knees) both knees are often replaced at one time, rather than having two separate surgeries. In other cases, doctors recommend operating on one knee at a time so that the unaffected leg can aid movement while the leg that was operated on heals itself. Replacing both knees is known as bilateral total knee replacement, or bilateral knee arthroplasty.

During knee surgery, the damage part of the joint is removed and the surface of the bone is replaced so that an artificial joint can be attached. A period of four to five months of physical therapy is required after knee surgery, a process which begins when the patient is still in the hospital after surgery. Individuals who have had surgery can engage in low-impact physical activity, such as swimming or waling, and can eventually select high-impact sports.