Why might I need a knee replacement?

Knee replacement (also known as knee arthroplasty) procedures are primarily performed on someone who is suffering from severe and debilitating osteoarthritis. As such, it is performed only after all possible non-surgical avenues have been explored. This is because a knee replacement surgery is considered a major surgery, requiring a 4-6 night hospital stay. Nonetheless, knee replacements performed at the appropriate time-point have excellent patient outcomes.


A knee replacement essentially involves replacing the diseased joint with a prosthesis. There are several different implants available, so your surgeon will decide on the best option for you, depending on a multitude of factors.


The knee can be functionally split into three compartments; the medial, lateral and patellofemoral compartments. As such, the entire knee, or a portion of it only, can be replaced. Knee replacements will typically involve 4 steps:

  1. Preparing the bone: damaged cartilages at the ends of the femur or tibia are removed, along with a small amount of underlying bone.
  2. Positioning the prosthesis: metal components that recreate the removed parts of the joint are cemented into the remaining joint.
  3. Resurfacing the kneecap (patella): if required, the surface under the kneecap is cut and resurfaced.
  4. Inserting a spacer: a plastic spacer is inserted between any of the metal components, to ensure that the joint can move smoothly.


What is a total knee replacement?

A total knee replacement (TKR) or total knee arthroplasty (TKA) involves replacing the medial and lateral compartments of the diseased knee. The patella may also need to be resurfaced in some cases.

What is a patellofemoral replacement?

A patellofemoral replacement or arthroplasty (PFA) involves the resurfacing of only the patellofemoral compartment. This procedure typically treats cartilage damage on the underside of the kneecap (i.e. the patella). A PFA is a type of ‘partial’ knee replacement and as such is a less invasive procedure, with a faster recovery time (in comparison to TKAs). It also allows for the preservation of healthy parts of the knee.

patellofemoral replacement tka

What is a Unicompartmental knee replacement?

Much like PFAs, a unicompartmental knee replacement or arthroplasty (UKA) is a type of ‘partial’ knee replacement. It is performed on patients with degeneration to a limited area of their knee. This degeneration can be in any of the three compartments of the knee. Although it also allows for the preservation of healthy parts of the knee, UKA’s have the potential to require a revision to a TKA in the future, should healthy areas degenerate.


Bayliss, J. (2019). Knee Replacement Surgery: Are There Alternative Treatments?. [online] Arthritis Queensland. Available at: [Accessed 10 Sep. 2019]. (2019). Knee replacement surgery. [online] Available at: [Accessed 10 Sep. 2019]. (2019). Patellofemoral Replacement. [online] Available at: [Accessed 10 Sep. 2019]. (2019). Total Knee Replacement - OrthoInfo - AAOS. [online] Available at: [Accessed 10 Sep. 2019]. (2019). Unicompartmental Knee Replacement - OrthoInfo - AAOS. [online] Available at: [Accessed 10 Sep. 2019].