A total knee replacement (TKR) is a replacement of the femoral and tibial surfaces of the knee joint, , and generally also part of the patella, with metal and plastic.

 

x-ray of total knee replacement

The most common indication for total knee replacement is significant pain related to arthritis in the mature or older patient where medications and physiotherapy not longer offer effective relief.

The articulating surfaces of the joint are removed, so there is no going back after a total knee replacement.

 

 

Components of a total knee replacement

components of a total knee replacement

Total knee replacement usually implies replacing all three of the articulating areas in the knee with implants comprised of metal and plastic. A femoral and a tibial implant replace the two joint surfaces between femur and tibia, and a patellar implant replaces the joint surface between femur and patella.

Between the two larger implants is a plastic spacer, which effectively replaces the two menisci.

 

tibial and femoral components from back

If you look at the implant from the back, you can better appreciate that each rounded condyle of the joint is really a separate articulation (or contact point).  In a partial knee replacement the surgeon can replace just one of these articulations. In fact, even in a so-called total knee replacement it is quite common for the surgeon to avoid replacing the patellar implant if the joint cartilage there is still good.

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Steps of total knee replacement surgery

The surgeon will walk through the following stages during surgery:

  1. Shaping the end of the femur
  2. Shaping the top of the tibia
  3. Cementing the femoral component into place
  4. Cementing the tibial tray into place
  5. Attaching the plastic spacer
  6. Shaping the back of the patella
  7. Cementing the patellar button into place
  8. Closing the wound in layers

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Watching out for complications

Rehabilitation is commonly started some time before the surgery, to optimise range of motion and muscle strength and give the patient the best chance of early mobilisation. It is critical to prevent clotting (deep vein thrombosis) and infection as a result of surgery, and blood thinners (eg heparin) and antibiotics are administered for a period before surgery. The most dreaded complication is infection which may result in months of treatment, and even temporary removal of the implant until the joint is clear of the infection.

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Synonyms: 
Total knee arthroplasty
TKR
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