Revision Knee Replacement

The Knee is essentially made up of four bones. The femur or thighbone is the bone connecting the hip to the knee. The tibia or shinebone connects the knee to the ankle. The Patella (Kneecap) is the small bone in the front of the knee and rides on the knee joint as the knee bends. The fibula is a shorter and the thinner bone running parallel to the tibia on its outside. The Joint acts like a hinge but with some rotation.

The Knee is a synovial joint, which means it is lined by synovium. The Synovium produces fluid lubricating and nourishing the inside of the joint.

Articular cartilage is the smooth surfaces at the end of the femur and tibia. It is the damage to this surface which causes arthritis.

Why does a Knee need to be revised?



  • Pain is the primary reason for revision. Usually the cause is clear but not always. Those knees without an obvious cause for pain, in general, do not do as well after surgery.

  • Plastic (polyethylene) wear .This is one of the easier revisions where only the plastic insert is changed.

  • Instability which means the knee is not stable and may be giving way or not feel safe when you walk.

  • Loosening of either the femoral, tibial or patella component. This usually presents as pain but may be asymptomatic. It is for this reason why you must have your joint followed up for life as there can be changes on X-ray that indicate that the knee should be revised despite having any symptoms.

  • Infection-usually presents as pain but may present as swelling or an acute fever.

  • Osteolysis (bone loss). This can occur due to particles being released into the knee joint which result in bone being destroyed.

  • Stiffness-this is difficult to improve with revision but can be helped with the right indications.

     
     

Risks and complications



  • As with any major surgery there are potential risks involved. The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages.


  • It is important that you are informed of these risks before the surgery takes place.


Complications can be medical (general) or local complications specific to the knee.

Medical complications include those of the anesthetic and your general well being. Almost any medical condition can occur so this list is not complete.
Complications include:

  •    > Allergic reactions to medications

  •    > Blood loss requiring transfusion with its low risk of disease transmission

  •    > Heart attacks, strokes, kidney failure, pneumonia, bladder infections

  •    > Complications from nerve blocks such as infection or nerve damage

  •    > Serious medical problems can lead to ongoing health concerns, prolonged hospitalization or rarely death.


Local complications

Stiffness in the knee Ideally your knee should bend beyond 100 degrees but on occasion the knee may not bend as well as expected. Sometimes manipulations are required; this means going to theatre and under anesthetic the knee is bent for you.

Wound irritation or breakdown

The operation will always cut some skin nerves so you will inevitably have some numbness around the wound. This does not affect the function of your joint. You can also get some aching around the scar. Vitamin E cream and massaging can help reduce this.

Occasionally you can get reactions to the sutures or a wound breakdown which may require antibiotics or rarely further surgery.

Infection

Infection can occur with any operation. In the knee this can be superficial or deep. Infection rates are approximately 1%. If it occurs, it can be treated with antibiotics but may require further surgery. Very rarely your knee prosthesis may need to be removed to eradicate the infection.

Blood clots (Deep Venous Thrombosis)

These can form in the calf muscles and can travel to the lung (Pulmonary embolism). These can occasionally be serious and even life threatening. If you get calf pain or shortness of breath at any stage you should notify your surgeon.

Damage to nerves or blood vessels

Also rare but can lead to weakness and loss of sensation in part of the leg. Damage to blood vessels may require further surgery if bleeding is ongoing.

Wear

The plastic liner eventually wears out over time, usually 10 to 15 years, and may need to be changed.

Cosmetic Appearance

The knee may look different than it was because it is put into the correct alignment to allow proper function.

Dislocation

An extremely rare condition where the ends of the knee joint lose contact with each other or the plastic insert can lose contact with the tibia(shinbone) or the femur (thigh bone).

Patella problems

Patella (knee cap) can dislocate. That is, it moves out of place and it can break or loosen.

Ligament injuries

There are a number of ligaments surrounding the knee. These ligaments can be torn during surgery or break or stretch out any time afterwards. Surgery may be required to correct this problem.

Fracture or breaks in the bone can occur during surgery or afterwards if you fall. To fix these you may require surgery.

Although every effort has been made to explain the complications there will be complications that may not have been specifically mentioned. A good knowledge of this operation will make the stress of undertaking the operation easier for you to bear.

The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages. It is important that you are informed of these risks before the surgery.

You must not proceed until you are confident that you understand this procedure, particularly the complications.



Conclusion


We hope that you have found this information helpful.

Surgery exists as a method of correcting a problem and improving a patient's condition which is everyone's goal.