Total knee arthroplasty (TKA)
The knee joint is made up of the lower end of the femur (the thigh bone) and the upper end of the shin bone (tibia) as well as the back of the kneecap (patella). In normal knees, smooth cartilage lining the joint along with support of the surrounding tissues (muscles, ligaments and tendons) these bones can slide over one another allowing movement to occur painlessly. If the joint is injured or there is wear and tear over time (arthritis), the cartilage can be worn away and the uncovered bone ends come into contact (figure 1). As a result they rub and grind on each other leading to pain and a reduction in movement (stiffness).
Figure 1: Arthritic right knee.
A knee replacement operation replaces the worn away bone ends with an artificial joint and the new prosthetic metal components also smoothly slide over one another using a plastic spacer, relieving pain and restoring mobility. These are put in through a cut (incision) at the front of the knee. The outcomes are very good for the majority and newer technologies mean that they can now last 20years for most patients.
The operation is usually done with a spinal or general anaesthetic (so that the patient has the option of being awake or asleep) although in some cases. Typically the procedure takes around an hour for a primary knee replacement but longer for complex or revision cases where previous surgery has taken place.
The operation is performed through a cut on the front of the knee.
The bone ends are prepared by cutting away the worn cartilage and reshaping the ends of the bone using special cutting blocks so that the new knee can be applied to the bone bones.
The new joint is inserted and tested to ensure that the new joint moves well and is stable (figure 2). The wound is then closed with stitches and a dressing is applied. Dissolvable stitches are used which will not need to be removed.
Figure 2: Right sided knee replacement.
Potential risks of the procedure
Total knee arthroplasty is a successful procedure but (as with any surgical procedure) there are risks involved. These include:
Bleeding, Infection, Thrombosis and embolism (blood clots), Pain, Stiffness, Numbness along the front of the knee and loosening.
The overall risk of complications is relatively low after TKA but these will be discussed. I base my consenting process on the use the Orthoconsent pre populated forms which are approved by the British Orthopaedic Association (BOA) and are available at orthoconsent.com.
You will be followed up in the long term with clinic visits at 3,6 and 12 months initially post surgery and will also be contacted via post or email with questionnaires as well as xray studies to determine how well your knee is functioning and how it is affecting your lifestyle.