Knee Replacement Surgery
When a knee is so severely damaged by disease or injury, an artificial knee replacement
may be considered. During knee replacement surgery, joint surfaces are replaced by
prostheses. The most common age for knee replacement is between 50 and 80 years old.
Who might be a candidate for knee replacement?
The most common condition that results in the need for knee replacement surgery is
osteoarthritis. This is a degenerative joint disease that affects mostly middle-aged
and older adults. Osteoarthritis is characterized by the breakdown of joint cartilage
and bone in the knees. Other forms of arthritis, such as rheumatoid arthritis and
arthritis that results from a knee injury can also lead to degeneration of the knee
joint. In addition, fractures, torn cartilage, or torn ligaments also can lead to
irreversible damage to the knee joint over the years.
The decision to replace the painful knee with an artificial one is a joint decision
between you and your doctor. Other alternative treatments may first be used, including
assistive walking devices, anti-inflammatory medicines, injections, and bracing.
What happens before the surgery?
In addition to a complete medical history, your doctor may do a complete physical
exam, including X-rays, to ensure you are in good health before undergoing surgery.
In addition, you may also meet with a physical therapist to discuss rehabilitation
after the surgery and undergo blood tests (or other tests).
How is a knee replaced with an artificial knee?
Although each procedure varies, generally, surgery to replace a knee usually lasts
about 2 hours. After the damaged bone and cartilage of the knee is removed, the orthopedic
surgeon will place the new artificial knee in its place.
The most common type of knee prostheses used in replacement surgery is a cemented
prosthesis. Uncemented prosthesis is not commonly used. Sometimes, a combination of
the 2 types is used to replace a knee. A knee prosthesis is made up of metal with
ceramic or plastic. A cemented prosthesis is attached to the bone with a type of epoxy.
An uncemented prosthesis attaches to the bone with a fine mesh of holes on the surface.
The bone grows into the mesh and attaches naturally to the prosthesis.
The prosthesis (artificial knee) is usually made up of these 3 components:
Tibial component (to replace the top of the tibia, or shin bone)
Femoral component (to replace the two femoral [thighbone] condyles and the patella
Patellar component (to replace the bottom surface of the kneecap that rubs against
While undergoing surgery, you may be under general anesthesia or awake with spinal
or epidural anesthesia.
Knee replacement surgeries usually require an in-hospital stay of a few days. Even
while in the hospital, you usually start physical therapy exercises to begin regaining
range of motion in the knee. Physical therapy will continue at home. Pain medicine
also will be given to keep you comfortable.
The incision will have stitches or staples that will be removed after a few weeks.