Knee arthroplasty
Knee arthroplasty is performed under general anesthesia. The orthopedic surgeon
makes an incision over the affected knee. The patella (knee cap) is moved out of the way,
and the ends of the femur and tibia are cut to eliminate any rough parts and to permit a
better adhesion of the prosthesis.
The two parts of the prosthesis are implanted into the thigh bone (femur) and the tibia
bone, using a special bone cement. Usually, metal is used on the end of the femur, and
plastic is used on the tibia, for the new knee surface. However, newer surfaces including
metal on both sides or ceramic on both sides are now being used. The patella is also
resurfaced with plastic in some cases.
You will return from surgery with a large dressing to the knee area. A small drainage tube
will be placed during surgery to help drain excess fluids from the joint area.
Your leg will be placed in a continuous passive motion (CPM) device. This is a mechanical
device that flexes (bends) and extends (straightens) the knee to keep the knee from
getting stiff.
Gradually, the rate and amount of flexion will be increased as tolerated. The leg should
always be in this device when in bed. The CPM device helps speed recovery, decreases
post-operative pain, bleeding and infection.
You will experience moderate pain after surgery. However, you may receive
patient-controlled analgesia (PCA), or epidural analgesics (spinal) to control your pain
for the first 3 days after surgery.
The pain should gradually decrease, and by the third day after surgery, oral analgesic
medications may be sufficient to control your pain. Try to schedule your pain medications
about one half hour before walking or position changes.
You will also return from surgery with several IV lines in place to provide fluid and
nutrition. The IV will remain in place until you are taking adequate amounts of fluids by
mouth.
Prophylactic (preventive) antibiotics may be given to reduce the risk of developing an
infection, necessitating removal of the artificial joint.
You will also return from surgery wearing anti-embolism stockings or inflatable pneumatic
compression stockings. These devices are used to reduce your risk of developing blood
clots, which are more common after lower extremity surgery.
Additionally, you will be encouraged to start moving and walking early after surgery. You
will be assisted out of bed to a chair on the first day after surgery. When in bed, bend
and straighten your ankles frequently to prevent development of blood clots.
You may be instructed on how to use an incentive spirometry device (a plastic device to
encourage deep breathing), and cough and deep breathing exercises to gradually increase
the depth of your respirations in order to prevent pneumonia.
A foley catheter may be inserted during surgery to monitor the function of your kidneys
and hydration level. This will be removed on the second or third day after surgery. You
will be encouraged to try to walk to the bathroom with assistance.
Reasons for Knee arthroplasty
- Knee joint replacement may be recommended for:
- knee pain that has failed to respond to conservative therapy (including medication,
injections and physical therapy for 6 months or more)
- knee pain that limits or prevents activities of importance to the patient
- arthritis of the knee
- decreased knee function caused by arthritis
- inability to sleep through the night because of knee pain
- some tumors involving the knee
Knee arthroplasty t is usually not recommended for partients with
- current knee infection
- poor skin coverage around knee
- paralysis of the quadriceps muscles
- severe peripheral vascular disease or neuropathy affecting knee
- severe limiting mental dysfunction
- terminal disease (metastatic disease)
- morbid obesity (over 300 lb.)
Risks of Knee arthroplasty
- blood clots in the legs (deep vein thrombosis or DVT)
- DVT that breaks loose and goes to the lungs (embolus)
- pneumonia
- infection necessitating removal of the joint
- loosening of the prosthesis
- dislocation of the prosthesis
Knee arthroplasty - specieal precaution
People who have a prosthetic device (such as an artificial joint) need to take special
precautions against infection. You should carry a medical identification card indicating
that you have a prosthetic device. Also, always inform your health care provider of your
prosthetic knee joint. You should receive prophylactic antibiotics prior to dental work or
any invasive procedure.
Expectations after Knee arthroplasty
Results with a total Knee arthroplasty have been excellent. The operation relieves pain
in over 90% of patients, and most need no assistance walking after recovery. Most
prostheses last 10 to 15 years, some as long as 20 years, before loosening and requiring
revision surgery.
Recovery from Knee arthroplasty
The hospital stay generally lasts 4 or 5 days, but the total recovery period varies
from 2-3 months to a year. Walking and range of motion exercises will be started
immediately after surgery. Some surgeons recommend the use of a machine that will bend the
knee for the patient in bed.
Some patients require a short stay in a rehabilitation hospital to become safely
independent in their activities of daily living. The use crutches or a walker for a few
weeks or even months after surgery may be necessary.
The physical therapy initiated in the hospital will continue after discharge until
strength and motion return. Skiing and contact sports are generally to be avoided, but
activities like swimming, tennis and golf are usually possible after full recovery from
surgery.
Information base on Medline
Update Date: 7/17/2001
Updated by: Benjamin D. Roye, M.D., M.P.H., Department of
Orthopaedics, New York-Presbyterian Hospital, New York, NY. Review provided by VeriMed
Healthcare Network.
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