As with all major surgical procedures, complications can occur. Some of the
most common complications following knee replacement are:
- Thrombophlebitis
- Infection
- Stiffness
- Loosening
This is not intended to be a complete list of the
possible complications, but these are the most common complications.
Thrombophlebitis
Thrombophlebitis, sometimes called Deep Venous Thrombosis (DVT), can occur
after any operation, but is more likely to occur following surgery on the hip,
pelvis, or knee. DVT occurs when the blood in the large veins of the leg forms
blood clots within the veins. This may cause the leg to swell and become warm to
the touch and painful. If the blood clots in the veins break apart, they can
travel to the lung, where they get lodged in the capillaries of the lung and cut
off the blood supply to a portion of the lung. This is called a pulmonary
embolism. (Pulmonary = lung, embolism = fragment of something traveling through
the vascular system). Most surgeons take preventing DVT very seriously. There
are many ways to reduce the risk of DVT, but probably the most effective is
getting you moving as soon as possible! Some of the commonly used preventative
measures include pressure stockings to keep the blood in the legs moving and
taking medications that thin the blood and prevent blood clots from forming.
Infection
Infection can be a very serious complication following an artificial joint
replacement surgery. The chance of getting an infection following artificial
knee replacement is probably somewhere around 1%. Some infections may show up
very early - before you leave the hospital. Others may not become apparent for
months, or even years, after the operation. Infection can spread into the
artificial joint from other infected areas. Your surgeon may want to make sure
that you take antibiotics when you have dental work or surgical procedures on
your bladder and colon to reduce the risk of spreading germs to the joint.
Stiffness
In some cases, the ability to bend the knee does not return to normal after
an artificial knee replacement. Many orthopaedic surgeons are now using a
machine known as a CPM machine (continuous passive motion) immediately after
surgery to try and increase the range of motion following artificial knee
replacement. Other orthopaedic surgeons rely on physical therapy beginning
immediately after the surgery to regain the motion. It is not clear which is the
best approach. Both approaches have benefits and risks, and the choice is
usually made by the surgeon based on his experience and preferences. To be able
to use the leg effectively to rise from a chair, the knee must bend at least to
90 degrees. A desirable range of motion should be greater than 110 degrees.
Balancing the ligaments and soft tissues (during surgery) is the most important
determining factor in regaining an adequate range of motion following knee
replacement, but sometimes increasing scarring after surgery can lead to an
increasingly stiff knee. If this occurs, your surgeon may recommend taking you
back to the operating room, placing you under anesthesia once again, and
forcefully manipulating the knee to regain motion. Basically, this allows the
surgeon to breakup and stretch the scar tissue without you feeling it. The goal
is to increase the motion in the knee without injuring the joint.
Loosening
The major reason that artificial joints eventually fail continues to be a
process 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 all will
eventually loosen and require a revision. A loose prosthesis is a problem
because it causes pain. Once the pain becomes unbearable, another operation will
probably be required to revise the knee replacement.
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