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All topics
  1. What it is
  2. Who it helps
  3. Timing
  4. The procedure
  5. Patient journey
  6. Recovery supplies
  7. Implant designs
  8. Side-by-side
  9. Robotics and alignment
  10. US manufacturers
  11. What the evidence says
  12. Value analysis
  13. Questions to ask
  14. Resources
  15. Glossary
  16. References

Overview

What is total knee replacement?

Total knee replacement, also called total knee arthroplasty (TKA), is surgery that resurfaces a damaged knee joint. The surgeon removes the worn cartilage and a thin layer of bone from the ends of the thighbone (femur) and shinbone (tibia), and covers them with an implant. It is one of the most common operations in the US: the American Academy of Orthopaedic Surgeons says more than 700,000 are done each year.45

Despite the name, the whole knee isn't removed. A knee replacement usually has three or four parts:

  • Femoral component: a curved metal piece that caps the end of the thighbone.
  • Tibial component: a flat metal tray fixed to the top of the shinbone.
  • Plastic spacer: a medical-grade polyethylene insert that sits on the tray and acts as the new gliding surface.
  • Patellar button (sometimes): a plastic dome that resurfaces the back of the kneecap. Not every surgeon or patient needs one.

The main reason for knee replacement is painful osteoarthritis that limits daily life.1 Other causes include rheumatoid arthritis and arthritis after an injury.

When arthritis affects only one part of the knee, some people can have a partial (unicompartmental) knee replacement instead, which resurfaces just that part. See partial vs total knee replacement.

Clinical detail
  • In Medicare alone there were 480,958 primary TKAs in 2019, a 156% increase since 2000. One model projects about 1.22 million Medicare TKAs a year by 2040.2
  • Revision TKA in Medicare is projected to rise from 53,217 in 2019 to 115,147 by 2040.42
Value analysis

Volume growth, a shift toward outpatient surgery and bundled payment programs all shape implant purchasing. See value analysis considerations.

Sources for this page

  1. Price AJ, et al. Knee replacement. Lancet. 2018;392(10158):1672-1682. doi:10.1016/S0140-6736(18)32344-4
  2. Shichman I, et al. Projections and epidemiology of primary hip and knee arthroplasty in Medicare patients to 2040-2060. JB JS Open Access. 2023;8(1):e22.00112. doi:10.2106/JBJS.OA.22.00112
  3. Shichman I, et al. Projections and epidemiology of revision hip and knee arthroplasty in the United States to 2040-2060. Arthroplast Today. 2023;21:101152. doi:10.1016/j.artd.2023.101152
  4. American Academy of Orthopaedic Surgeons, OrthoInfo. Total knee replacement. orthoinfo.org/treatment/total-knee-replacement

All references