Knee joint replacement

Alternative Names: Total knee replacement; Knee arthroplasty; Knee replacement - total; Tricompartmental knee replacement; Subvastus knee replacement; Knee replacement - minimally invasive; Knee arthroplasty - minimally invasive

Knee joint replacement is surgery to replace a knee joint with a man-made (artificial) joint. The artificial joint is called a prosthesis.

See also: Unicompartmental knee arthroplasty

Description of Procedure

During knee joint replacement surgery, damaged cartilage and bone are removed from the knee joint. Man-made (artificial) pieces, called prostheses, are then placed in the knee. These pieces may be placed in up to three surfaces in the knee joint:

• Lower end of the thigh bone. This bone is called the femur. The replacement part is usually made of metal.
• Upper end of the shin bone--the large bone in your lower leg. This bone is called the tibia. The replacement part is usually made from metal and a strong plastic.
• Back side of your kneecap. Your kneecap is called the patella. The replacement part is usually made from a strong plastic.

You will not feel any pain during the surgery because you will have one of these two types of anesthesia:

• General anesthesia. This means you will be asleep and unable to feel pain.
• Regional (spinal or epidural) anesthesia. Medicine is put into your back to make you numb below your waist. You will also get medicine to make you sleepy. And you may get medicine that will make you forget about the procedure, even though you are not fully asleep.

After you receive anesthesia, your surgeon will make a cut over your knee to open it up. This cut is often 8 to 10 inches long. Then your surgeon will:

• Move your kneecap (patella) out of the way, then cut the ends of your thigh bone and shin (lower leg) bone to fit the replacement part.
• Cut the underside of your kneecap to prepare it for the new pieces that will be attached there.
• Fasten the two parts of the prosthesis to your bones. One part will be attached to the end of your thigh bone and the other part will be attached to your shin bone.
• Attach both parts to the underside of your kneecap. A special bone cement is used to attach these parts.
• Repair your muscles and tendons around the new joint and close the surgical cut.

The surgery usually takes around 2 hours.

Usually, artificial knees have both metal and plastic parts. Some surgeons now use different materials, including metal on metal, ceramic on ceramic, or ceramic on plastic.

Risks of Knee joint replacement

Risks of any surgery are:

• Bleeding
• Blood clots that may travel from your legs to your lungs
• Breathing problems
• Heart attack or stroke during surgery
• Infection, including in the lungs, urinary tract, and chest

For more information about joint replacement, see also: Risks of hip and knee replacement.

Knee joint replacement prosthesis	Knee joint replacement - series

Review Date: 9/22/2011
Reviewed By: C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Dept of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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