What is Knee Joint Replacement?

Knee joint replacement is surgery to replace a painful damaged or diseased knee joint with an artificial joint (prosthesis).

Who should have knee replacement surgery?

Knee joint replacement may be recommended for:

  • Knee pain that has failed to respond to conservative therapy (including medication, injections, and physical therapy for six 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 joint replacement is usually not recommended for:

  • Current knee infection
  • Poor skin coverage around the knee
  • Paralysis of the quadriceps muscles
  • Severe limiting mental dysfunction
  • Morbid obesity (over 300 lbs)

What is involved in surgery?

The operation 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 fit the prosthesis and to provide better adhesion of the prosthesis. Similarly, the undersurface of the knee cap is cut to allow for placement of an artificial component.

The two parts of the prosthesis are implanted onto the ends of the thighbone (tibia), and the undersurface of the knee cap (patella) using a special bone cement. Usually, metal is used on the end of the femur, and plastic is used on the tibia and patella, for the new knee surface. However, newer surfaces including metal on metal, ceramic on ceramic, or ceramic on plastic are now being used.

You will return from surgery with a large dressing around the knee area. A small drainage tube will be placed into the knee during surgery to help drain excess fluids from the joint area.

Your leg may be placed in a continuous passive motion (CPM) device after surgery. 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.

How much pain is involved with this surgery?

You will experience moderate pain after surgery. However, you may receive injections of narcotics medications, patient-controlled analgesia (PCA) or epidural analgesics (spinal) to control your pain for the first three days after surgery.

The pain should gradually decrease, and by the third day after surgery, oral 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 will 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.

Antibiotics may be given to reduce the risk of developing an infection, necessitating removal of the artificial joint.

You will be 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.

When can I begin to walk after this surgery?

You will be encouraged to start moving and walking as early as the first day 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.

What are the risks of this surgery?

  • The risks of this surgery include:
  • 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
  • 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.

Will I need physical therapy?

The physical therapy initiated in the hospital will continue after discharge until your strength, motion, functional mobility and balance return. Contact sports should generally be avoided, but low impact activities, such as swimming and golfing, are usually possible after full recovery from surgery.

What is the expected outcome following knee replacement surgery?

The results of total knee replacement are often 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.

To consult with one of our doctors at Orthopedic Associates of Port Huron, please call (810) 985-4900 or schedule an appointment online.