What is knee arthroplasty?

NewsGuard 100/100 Score

Knee arthroplasty or knee replacement surgery has developed to its present advanced stage over the last few decades. This is mainly due to technical advances and better understanding of knee pathophysiology and functions.

Knee arthroplasty involves removal of the damaged, worn or diseased knee joint with an artificial joint or a prosthetic implant.

Why is knee arthroplasty needed?

The most common reason for performing a knee arthroplasty is joint arthritis.

The number of total knee replacements is on the rise with more than 70,000 knee replacements being carried out in England and Wales each year.

The majority of patients who need and undergo such operations are over 65 years of age.

Once replaced, the new knee will last for at least 15 to 20 years, especially if taken good care of. (1-5)

Types of knee replacement

There are 3 types of knee replacement –

  • Unicompartmental knee replacement or Partial knee replacement – This means a replacement of a single compartment of the knee. This can be either the inner part of the knee (medial) or the outer part (lateral).

    It is preferred in patients with osteoarthritis who have one part of the knee damaged by disease. It is not suitable for patients with rheumatoid arthritis (RA) which usually affects the whole joint.

  • Unconstrained bicompartmental knee replacement or Total knee replacement – This is the commonest method of total knee replacement. The lower end of the thigh bone is replaced by a prosthetic made up of metal (titanium or cobalt/chromium-based alloys) that is similar to the bone it replaces.

    The top part of the shin bone that forms the lower end of the knee joint is made of a plastic (polyethylene) cushion and a stem that joins with the shin bone or tibia below. The artificial joint functions like a normal knee joint.

  • Constrained bicompartmental knee replacement – This surgery is performed in bone tumors and is rare. Here the artificial joint is fixed and so does not move or bend like a normal joint.

Choice of prosthetic device

There are over a hundred different knee replacement designs the surgeons may choose from. A complete prosthesis now weighs about 15 to 20 ounces.

Some factors that determine choice of the prosthetic device include age and weight of the patient. Desire for a certain level of activity, quality of life, health and cost of the prosthesis are other determinants.

Reasons for knee replacement surgery

Reasons to opt for knee replacement surgery include:

  • osteoarthritis (commonest indication)
  • rheumatoid arthritis
  • haemophilia or bleeding disorder
  • other types of arthritis
  • gout
  • bone cancers and tumors

Prior to surgery

Before surgery the knee is examined and imaging studies like X rays, MRI and arthroscopic studies of the knee joint are advised.

The choice of the prosthetic and extent of surgery is based on the results of these studies. In case of a joint infection, blood vessel disease knee arthroscopy cannot be performed.

How is knee replacement surgery performed?

Knee replacement surgery is performed under regional anethesia.

Commonly epidural anesthesia is employed where the anethetic injection is made in the spine over the lower back and this renders the patient numb to pain below the waist.

A cuff like tourniquet is placed over the thighs just before the incision. When inflated this aids in reducing the blood flow to the operative site and reduces the risk of bleeding.

An eight to twelve inch incision is made in the front or side of the knee. The muscles are cut open and the joint cavity is exposed.

The damaged parts of the joint including the lower part of the femur, upper part of the tibia are removed or sawed off.

The new implants are sealed on the sawed off edges with the help of bone cement.

Some implants are uncemented. These can be set over the edges of the sawed off bones in a press fit system.

Prosthetic cartilage is placed between the prosthetic ends of the femur and tibia to aid normal movement of the knee.

Minimally invasive surgery

Minimally invasive surgery as the name suggests involves a smaller incision of three to five inches.

Here the surgeon works the implant through a smaller opening. This leads to less pain and more rapid recovery.

After surgery

After the surgery the tourniquet is removed or deflated. The incision and the operative site is checked for any bleeding points.

The surrounding muscles and ligaments are sewn back together and these provide stability to the joint and assist it in movement.

A small drainage tube is placed within the incision to drain of blood or excess fluids and the incision is sutured or stapled.

The wound is dressed and the knee is cast in a splint to aid recovery.

Returning mobility

Patients are encouraged to walk on the second postoperative day. Early movement and physiotherapy is recommended for rapid recovery. Early discharge is encouraged at between 5 days and 2 weeks.

Complications of knee arthroplasty

Common complications of knee arthroplasty include infection, blood loss, pain, thromboembolism or formation of clots that may travel up to the lungs and brain causing life threatening consequences.

Other complications include nerve damage, damage to blood vessels, fractures, loosening of prosthesis etc.

Further Reading

Last Updated: Jun 10, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Mandal, Ananya. (2023, June 10). What is knee arthroplasty?. News-Medical. Retrieved on April 13, 2024 from https://www.news-medical.net/health/What-is-knee-arthroplasty.aspx.

  • MLA

    Mandal, Ananya. "What is knee arthroplasty?". News-Medical. 13 April 2024. <https://www.news-medical.net/health/What-is-knee-arthroplasty.aspx>.

  • Chicago

    Mandal, Ananya. "What is knee arthroplasty?". News-Medical. https://www.news-medical.net/health/What-is-knee-arthroplasty.aspx. (accessed April 13, 2024).

  • Harvard

    Mandal, Ananya. 2023. What is knee arthroplasty?. News-Medical, viewed 13 April 2024, https://www.news-medical.net/health/What-is-knee-arthroplasty.aspx.


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
Gender concordance between patient and surgeon may not affect mortality rates, study finds