Total Knee Joint Replacement Risks

A knee replacement is one of the most commonly performed orthopaedic surgeries and is usually very successful in treating knee arthritis- relieving pain and restoring knee function. Most people who undergo a total knee joint replacement do not suffer any complications however, it is important to remember that any surgical procedure involves risks. Some of these complications are serious so it is important that you and your surgeon discuss these carefully to ensure that for you, the potential benefits outweigh the risks.

More common complications (affecting 2-5% of patients) include:

  • Pain:
    The knee will be sore after the operation. If you are in pain, it is important to tell staff so that medicines can be given. Pain will improve with time. Rarely, pain will be a chronic problem and may be due to any of the other complications listed below, or, for no obvious reason. Rarely, some replaced knees can remain painful.
  • Bleeding:
    A blood transfusion or iron tablets may occasionally be required.  Rarely, the bleeding may form a blood clot or large bruise within the knee which may become painful and require an operation to remove it.
  • Bruising:
    Bruising is common and expected in knee replacement. The amount varies due to many factors. At times it can be severe and slow down recovery
  • Deep Vein Thrombosis (DVT):
    A DVT is a blood clot in a vein. The risks of developing a DVT are greater after any surgery (and especially bone surgery). DVT can pass in the blood stream and be deposited in the lungs. Your surgeon may give you medication to try and limit the risk of DVTs from forming, may ask you to wear stockings on your legs or to use foot pumps to keep blood circulating around the leg. Starting to walk and moving early is one of the best ways to prevent blood clots from forming
  • Knee Stiffness:
    May occur after the operation, especially if the knee is stiff before the surgery. Manipulation of the joint (under general anaesthetic) may be necessary or even revision knee replacement.
  • Prosthesis Wear:
    With modern operating techniques and new implants, knee replacements last many years. In some cases, they fail earlier. The reason is often unknown. The plastic bearing is the most commonly worn away part.
  • Numbness:
    Nearly all patients will have a small numb patch of skin on the outside of the leg just below the knee. This is because of the incision. It has no functional consequences and after a while is usually forgotten about by most patients.

Less common complications (affecting 1-2% of patients) include:

  • Infection:
    You will be given antibiotics at the time of the operation and the procedure will also be performed in sterile conditions with sterile equipment. Despite this, infections still occur. The wound site may become red, hot and painful. There may also be a discharge of fluid or pus. This is usually treated with antibiotics and an operation to washout the joint may be necessary. In rare cases, the prostheses may be removed and replaced at a later date. The infection can sometimes lead to sepsis (blood infection) and strong antibiotics are required.

Rare complications (affecting less than 1% of patients) include:

  • Pulmonary embolism (PE):
    A PE is the spread of a blood clot to the lungs and can affect your breathing. This can be fatal.
  • Altered wound healing:
    The wound may become red, thickened and painful (keloid scar) especially in patients of certain races.
  • Nerve Damage:
    Damage to the small nerves of the knee is a risk. This may cause temporary or permanent altered sensation around the knee. There may also be damage to the peroneal nerve, this may cause temporary or permanent weakness or altered sensation of the lower leg or foot.
  • Bone Damage:
    Bone may be broken when the prosthesis (false joint) is inserted. This may require fixation, either at time or at a later operation.
  • Blood Vessel Damage:
    The vessels at the back of the knee may be damaged and may require further surgery.
  • Amputation:
    Extremely rarely, events can occur when complications cannot be resolved and the leg requires amputation.