A total knee replacement is a surgical procedure whereby the diseased knee joint
is replaced with artificial material. The knee is a hinge joint which provides
motion at the point where the thigh meets the lower leg. The thigh bone (or
femur) abuts the large bone of the lower leg (tibia) at the knee joint. During a
total knee replacement, the end of the femur bone is removed and replaced with a
metal shell. The end of the lower leg bone (tibia) is also removed and replaced
with a channeled plastic piece with a metal stem. Depending on the condition of
the kneecap portion of the knee joint, a plastic "button" may also be added
under the kneecap surface.
The posterior cruciate ligament is a tissue that normally stabilizes each side
of the knee joint so that the lower leg cannot slide backward in relation to the
thigh bone. In total knee replacement surgery, this ligament is either retained,
sacrificed, or substituted by a polyethylene post. Each of these various designs
of total knee replacement has its benefits and risks.
What patients should consider a total knee replacement?
Total knee replacement surgery is considered for patients whose knee joints have
been damaged by either progressive arthritis, trauma, or other rare destructive
diseases of the joint. The most common reason for knee replacement in the United
States is severe osteoarthritis of the knees.
What are the risks of undergoing a total knee replacement?
Risks of total knee replacement include blood clots in the legs that can travel
to the lungs (pulmonary embolism). Pulmonary embolism can cause shortness of
breath, chest pain, and even shock. Other risks include urinary tract infection,
nausea and vomiting (usually related to pain medication), chronic knee pain and
stiffness, bleeding into the knee joint, nerve damage, blood vessel injury, and
infection of the knee which can require re-operation. Furthermore, the risks of
anesthesia include potential heart, lung, kidney, and liver damage.
What is involved with the preoperative evaluation for total knee replacement?
Before surgery, joints adjacent to the diseased knee are carefully evaluated.
This is important to ensure optimal outcome from the surgery. Replacing a knee
joint which is adjacent to a severely damaged joint may not yield significant
improvement in function.
Routine blood tests of liver and kidney function, and urine tests are evaluated
for signs of anemia, infection or abnormal metabolism. Chest x-ray and EKG are
performed to exclude significant heart and lung disease which may preclude
surgery or anesthesia. Finally, it is less likely to have good long-term outcome
if the patient's weight is greater than 200 pounds. Excess body weight simply
puts the replaced knee at an increased risk of loosening and/or dislocation.
A similar risk is encountered in younger patients who may tend to be more
active, thereby adding trauma to the replaced joint.
What happens in the postoperative period?
A total knee replacement generally requires between one and one- half to three
hours of operative time. After surgery, patients are taken to a recovery room,
where vital organs are frequently monitored. When stabilized, patients are
returned to their hospital room.
Physical therapy is an extremely important part of rehabilitation and requires
full participation by the patient for optimal outcome. Patients can begin
physical therapy forty-eight hours after surgery. Some degree of pain,
discomfort, and stiffness can be expected during the early days of physical
therapy. Knee immobilizers are used in order to stabilize the knee while
undergoing physical therapy, walking, and sleeping. They may be removed under
the guidance of the therapist for various portions of physical therapy.
A unique device that can help speed recovery is the continuous passive motion (CPM)
machine. The CPM machine is first attached to the operated leg. The machine then
constantly moves the knee through various degrees of range of motion for hours
while the patient relaxes.
Patients will start walking using a walker and crutches. Eventually, patients
will learn to walk up and down stairs and grades. A number of home exercises are
given to strengthen thigh and calf muscles.
How does the patient continue to improve as an outpatient after discharge
from the hospital?
It is important for patients to continue in an outpatient physical therapy
program along with home exercises for optimal outcome of total knee replacement
surgery. Patients will be asked to continue exercising the muscles around the
replaced joint to prevent scarring (contracture) and maintain to muscle strength
for the purposes of joint stability.
The wound will be monitored by the attending physicians and their staff for
healing. Patients also should watch for warning signs of infection including
abnormal redness, increasing warmth, swelling, or unusual pain. It is important
to report any injury to the joint to the doctor immediately.
Future activities are generally limited to those that do not risk injuring the
replaced joint. Sports that involve running or contact are avoided, in favor of
leisure sports, such as golf, and swimming. Swimming is the ideal form of
exercise, since the sport improves muscle strength and endurance without
exerting any pressure or stress on the replaced joint.
Though infrequent, patients with total knee replacements can require a second
operation years later. The second operation can be necessary because of
loosening, fracture or other complications of the replaced joint. Re-operations
are generally not as successful as the original operation and carry higher risks
of complications. Future replacement devices and techniques will improve patient
outcomes and lead to fewer complications.
Web design by Patricia Walter
Copyright Knees For You 12/18/2006
Mission Statement -
Knees for You
is a patient to patient guide to knee replacement. It does not provide medical
advice. It is designed to support, not to replace, the relationship between
patient and clinician.
Advertising - Revenue from this site is derived
from commercial advertising and individual donations. Any
advertisement is distinguished by the word "advertisement"
Privacy - Knees for You does not share email
addresses or personal information with any group or organization.
Content - Knees for You is not controlled or influenced by any
medical companies, doctors or hospitals.
All content is controlled by Patricia Walter -
Joint Health Sites LLC
This site is published by Joint Health Sites
LLC, which is solely responsible for its content. The advertisements on this
site are not intended by the advertisers as an endorsement of the site's
content. The advertisers shall not be liable for any errors or omissions in the
site's content, nor liable for any damages from any person's actions based in
reliance on the site's content.