Knee Replacement Overview

Knee replacement is a surgery to relieve knee pain and improve mobility of the knee, most often in people with arthritis of the knee. Most knee pain is caused by one of the following types of arthritis:

  • Osteoarthritis – Cartilage covering the bone surfaces in the knee wears out over time.
  • Rheumatoid arthritis – The membrane that surrounds the knee joint becomes inflamed and thickened, which leads to damage to the cartilage in the knee.
  • Post-traumatic arthritis – Arthritis develops in the knee after a knee injury.

The knee joint is made up of three bones: the lower end of the thighbone, the upper end of the shinbone, and the kneecap. The bone surfaces where these three bones touch are covered with smooth cartilage that protects the bones and enables them to move easily in the joint.

Knee replacement surgery does not actually involve replacing any structures of the knee. It is a “resurfacing” procedure, in which only the surface of the bones is replaced with metal, plastic, and/or ceramic.

Types of knee replacement surgery

  • Total knee replacement – All of the knee joint surfaces are replaced.
  • Partial knee replacement – Only the surface on one side of the knee joint is replaced.

Total knee replacement surgery typically involves the following steps listed in this patient education guide. The materials used may vary.

  1. Damaged cartilage surfaces at the ends of the thighbone and shinbone are removed along with a small amount of bone underneath the cartilage.
  2. Metal components replace the cartilage and bone that were removed. This recreates the smooth surfaces of the knee joint.
  3. The surface on the underside of the kneecap is cut and resurfaced with a plastic button. (Note: In some cases, the patella is not resurfaced.)
  4. A plastic spacer is inserted between the metal components to create a smooth gliding surface.

Risks and potential complications after knee replacement surgery include:

  • Infection at the incision site
  • Infection deep around the resurfacing materials
  • Blood clots in the leg veins or pelvis
  • Nerve and blood vessel injury
  • Continued knee pain
  • Continued stiffness due to scar tissue in the knee
  • Loosening of the resurfacing materials


Written by Laurie LaRusso, MS, ELS

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