Knee Replacement

Possible Risks And Complications

As with all major surgical procedures, complications can occur. Some of the most common complications following knee replacement are:

Deep Venous Thrombosis (DVT)

This term refers to the formation of blood clots (called thrombosis) in the large veins, usually of the legs or pelvis. It can occur after any operation, but is more likely to occur following surgery on the hip, pelvis, or knee. It results from the slowing of the blood flow in the leg during and after surgery.

A Deep Venous Thrombosis (DVT) may cause the leg to:

  • Swell
  • Become warm to the touch
  • Become painful

Nice to Know:

Surgeons take preventing DVT very seriously.

Some of the commonly used preventative measures include:

  • Moving the leg as soon as possible after surgery
  • Using pressure stockings to keep the blood in the legs moving. They are worn immediately after surgery and continued for several weeks.
  • Prescribing medications that thin the blood and prevent blood clots from forming. They may be started before surgery or immediately after and continued for a period of time following surgery.
  • Using a Continuous Passive Motion Machine that moves the knee throughout it’s range of motion after surgery. This not only helps regain motion but also aids in moving blood throughout the veins.

For further information about deep vein thrombosis, go to Deep Vein Thrombosis.


The chance of getting an infection following artificial knee replacement is less than one percent. Some infections may show up very early, even before discharge from the hospital. Others may not become apparent for months, or even years, after the operation. All patients receive antiobiotics for at least 24 hours after surgery to minimize the risk of infection.

Infection can spread into the artificial joint from other infected areas of the body.

Therefore, your surgeon may want to make sure that you

  • Take antibiotics if ever you have dental work, or undergo a surgical procedure on your bladder and colon to reduce the risk of spreading germs to the knee replacement joint.
  • To minimize the risk of infection, most surgeons will defer doing total knee replacement if there is an open wound anywhere on the body.


To be able to use the knee effectively to rise from a chair, the replaced joint must bend at least to 90 degrees. Most surgeons desire range of motion greater than 110 degrees. In some cases, the ability to bend the knee does not return to normal after an artificial knee replacement. Because of this many surgeons utilize

  • Physical therapy beginning immediately after the surgery to help regain range of motion.
  • Continuous passive motion (CPM): This involves the use of a specialized machine immediately after surgery to increase the range of motion of the operated knee following artificial knee replacement.

Occasionally, excessive scarring after surgery can lead to an increasingly stiff knee. If this occurs, the surgeon may recommend taking the individual back to the operating room after the surgery and simply manipulate ( i.e. bend) the knee under anesthesia to regain motion. This allows the surgeon to breakup and stretch the scar tissue to increase the motion in the knee without injuring the joint.

The most important factor in preventing stiffness is keeping the knee moving in the days and weeks following surgery and actively participating in the physical therapy program.


The major reason artificial joints may eventually fail is because of loosening where the metal or cement meets the bone. There have been great advances in extending how long an artificial joint will last, but loosening is a possibility that may require a revision.

Today one can expect 12-15 years or more of service from an artificial knee. However, in some cases the knee will loosen earlier. A loose artificial implant becomes a problem because of pain and wearing away of the bone. If loosening occurs, another knee replacement may need to be done (this is called a revision total knee replacement). Therefore it is sensible for the individual to have yearly follow up visits with their surgeon that will include an x-ray evaluation of the operated knee.


A complication that can cause the artificial components to loosen or damage the bone is called osteolysis meaning “breakdown of bone”. This may result over the years from tiny particles of worn-out plastic or cement that may potentially migrate into the bone and cause localized damage to the bone. This condition may also result in the need for a total knee revision. That is another reason to have a yearly x-ray evaluation

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