knee replacement adverse outcomes

This operation involves resurfacing the knee joint.  The most common reason for performing this operation is to relieve pain.  There are two broad categories of knee replacement: cemented and uncemented.  In addition a variety of materials are used in the components of a knee replacement.  Your surgeon will discuss which is considered the most suitable for you.

 The following list covers most of the common and/or serious risks of total knee replacement.  However, you need to remember that the vast majority of patients have a good or excellent outcome from this operation and you need to keep in perspective the small chance of any of these events below occurring against the likely benefits of this operation.

INFECTION: Infections can either be close to the skin surface (superficial) or deep in the wound (deep).  The risk of a superficial wound infection is approximately 5 in 100 (5%) and usually can be treated with antibiotics alone.  The risk of a deep infection is less than1 in 100 (1%) and if this occurs further surgery and time in hospital may be required.

 BLEEDING/HAEMATOMA:  Occasionally excessive bleeding may occur.  The blood may then accumulate and form a clot (haematoma).  The risk of developing an haematoma is less than 5%.  Infrequently the haematoma may need to be surgically drained.

 DVT or PE: DVT (Deep Vein Thrombosis) refers to clots forming in the deep veins of the legs.  DVT’s which cause symptoms, occur in less than 5% (5 in 100) patients.  Clots may travel from the deep veins in the legs and lodge in the blood vessels in the lungs (PE or Pulmonary Embolus).  When this happens it may cause no symptoms at all but occasionally it can cause breathlessness and chest pain.  Extremely rarely ie, less than 1 in 10000 (0.001%) it can cause sudden death.

 SWOLLEN LEG:  After knee replacement generalised swelling (oedema)  of your legs may be present for many months  The leg on the side of the knee replacement is usually worse affected..  The swelling will gradually subside over time.

 KNEE STIFFNESS:  Most knee replacements will bend from straight (extension) to 110º of bend (flexion).  Approx 8% of knees will not bend beyond 90º and 5% will not fully straighten.  Manipulation of the knee under general anaesthetic may be tried to improve this movement but occasionally the stiffness is permanent.  Rarely the patella mechanism may not function after surgery resulting in weakness and inability to fully straighten the knee.

 PERSISTING PAIN:  Pain to some extent can be experienced for up to 1 year after surgery.  In 1% of cases pain can persist indefinitely with no obvious cause.

 PREMATURE FAILURE OF IMPLANTS:  We expect that you should get at least 10 years from the artificial joint before it needs further replacement.  Sometimes for unexplained reasons knee replacements fail earlier and need to be revised (re-done).

 NERVE OR VESSEL DAMAGE:  This is a very rare event.  The popliteal artery at the back of the knee can be potentially damaged resulting in a loss of blood flow to the leg.  The peroneal nerve can be "stretched" particularly if the knee is very deformed before surgery.  This may result in a foot drop and numbness.

 DISLOCATION:  Again this is a very rare event.  The patella (kneecap) can slide excessively (sublux) or dislocate.  Even less often the knee replacement itself can dislocate.  Further surgery may be required to "re-align" the components.

 OTHER:  It is unlikely that you will be able to kneel or squat comfortably after knee replacement.  It is usual to have an area on the outside of the knee which is numb.  This will gradually improve with time.  There is a reported incidence of 0.1% risk of needing an above knee amputation as a result of a serious complication of knee joint replacement.

 NOTE:  A good outcome from knee replacement surgery is very dependent on your commitment to rehabilitate your new knee replacement.

 Please also note that it has been shown that smoking significantly increases the risks and complications of surgery and reduces the chance of a successful outcome.