Total Knee Replacement Surgery

Total knee replacement and the related resurfacing (partial) replacement surgery are procedures in which the orthopedic surgeon removes damaged bone and cartilage from the knee joint and implants an artificial joint surface that is designed to mimic the rolling, gliding motion of the human knee. The prosthesis is customized to the patient's joint, taking into consideration the patient's age, weight, general health and activity level. Knee replacement, followed by rehabilitative therapy, alleviates pain and restores function in the damaged knee joint.

As cartilage wears away over time and bone becomes exposed, bone surfaces rubbing against each other cause pain, resulting in a diagnosis of arthritis. A person with advanced arthritis of the knee joint resulting in severe pain that interferes with daily activity is typically a candidate for total knee replacement or a related form of resurfacing.

What Is Knee Replacement Surgery?

In knee replacement surgery, the surgeon removes the damaged surfaces of the bones and then fits replacement components into place. The prosthetic knee implanted in a total knee replacement consists of three pieces made of rugged polyethylene (high density plastic) and alloy metals. These pieces resurface the three bones that comprise the knee joint. The surface of the femur is replaced with a rounded metal component that comes very close to matching the curve of the natural bone. The surface of the tibia is replaced with a flat metal component that holds a smooth plastic piece made of polyethylene that serves as the cartilage. The undersurface of the patella may also be replaced with an implant made of polyethylene. The knee replacement appears and functions much like a normal knee. After knee replacement surgery, the patient will recover most of the normal range of motion of the knee, from extension (straight leg) to flexion (bent leg).

The knee is the largest joint in the body.

A healthy knee moves easily, allowing walking, turning, and squatting without pain, as a complex network of bones, cartilage, ligaments, muscles, and tendons work together to make a knee flexible. The knee joint is made up of three bones: the femur (thighbone), tibia (shinbone) and patella (kneecap). When someone bends or straightens the knee, the rounded end of the femur rolls and glides across the relatively flat upper surface of the tibia. The ends of the femur and tibia are covered with a thin, smooth layer of cartilage lubricated by a few drops of synovial fluid to lubricate the joint, further reducing friction and making movement easier. The patella is attached to the muscles that allow straightening of the knee and provides leverage that reduces strain on these muscles.

Ligaments (another type of soft tissue) lie along the sides and back of the knee, holding the bones of the knee joint in place. These ligaments work with the muscles that control the bones, and the tendons that connect the muscles to the bones, so you can bend and straighten your knee. Bursae (fluid-filled sacs) cushion the area where skin or tendons glide across bone.

The Orthopedics Institute in the News

Health Check: Knee Replacement Improves Quality of Life for RI Man ( 

Dealing with Arthritis: Do You Need Joint Replacement? ( 
(Featuring John A. Froehlich, MD, MBA, program director of the Total Joint Center)