Knee Replacement Surgery: Overview

In This Article

Knee replacement surgery—also called knee arthroplasty—involves removing a patient's damaged joint surface and replacing it with a metal and plastic implant. This surgery is performed on patients with severe arthritis (most commonly, osteoarthritis). While knee replacement surgery is considered a safe and effective operation, it's important to gain knowledge about the potential risks involved, as well as the recovery process, which may take up to a year in some patients.

A doctor holding a knee replacement unit
Peter Dazeley / Peter Dazeley Owner / Getty Images

What Is Knee Replacement Surgery?

A knee replacement surgery is typically performed by an orthopedic surgeon in a hospital. Less commonly, the surgery may be performed in an outpatient surgical center. This one to two-hour surgery is most commonly done on adults and rarely, in children.

Your surgical team will help you decide what type of anesthesia is best for you:

During a knee replacement surgery, the bone and cartilage at the end of the thigh bone and shinbone are removed. An implant that is made up of metal and plastic is then placed on the knee to create a new joint surface. This implant functions similar to a normal knee

Various Surgical Techniques

Traditionally, the patient's implant is fixed into the bone with cement. Now though, a novel cement-less technique may be used. This means that the implant is press-fit onto the bone, allowing the bone to grow and permanently bond to the implant without any cement.

There is still debate within the medical community about whether a cemented or cement-less fixation is better. Early research has found that in young patients, cement-less fixation may provide better outcomes in terms of pain relief and restoring knee function.


Absolute contraindications to undergoing knee replacement surgery include patients who:

Relative contraindications include patients with:

  • A neuropathic arthropathy (called a Charcot knee)
  • A skin condition over the knee joint
  • Morbid obesity
  • Certain psychiatric illnesses, especially a history of substance abuse
  • Insufficient bone stock for prosthesis implantation
  • Unrealistic expectations with regards to the potential surgical outcome
  • Severe peripheral vascular disease

Potential Risks

Knee replacement surgery has become quite common, but there are still risks. Fortunately, well over 90% of patients who undergo knee replacement surgery have good results.

Besides general surgical risks like blood clots, pneumonia, and bleeding, other potential complications that may occur after a knee replacement surgery include: 

Purpose of Knee Replacement Surgery

The purpose of knee replacement surgery is to restore knee function and alleviate symptoms, like knee pain and stiffness, in patients with arthritis who cannot obtain relief from nonsurgical therapies.

The word arthritis means inflammation of the joint. Over time, the inflammation can lead to cartilage loss and exposed bone, instead of a normal, smooth joint surface.

Nonsurgical therapies for arthritis often include a combination of the following:

Most commonly, knee replacement surgery is performed in older individuals with osteoarthritis.

However, surgery may also be performed in people with one or more damaged knee joints from post-traumatic arthritis, or in people with inflammatory arthritis like rheumatoid arthritis or psoriatic arthritis. Rarely, children with juvenile idiopathic arthritis may undergo knee replacement surgery.

How to Prepare

After scheduling your knee replacement surgery, you will be provided with instructions on how to prepare for the operation.

These instructions may suggest the following:

  • Wear loose-fitting clothing on the day of your surgery.
  • Stop eating after midnight on the eve of your surgery.
  • Stop certain medications for a period of time before your surgery (for example, nonsteroidal anti-inflammatory drugs, or NSAIDs like ibuprofen).
  • Pack personal items for your hospital stay, such as your toothbrush, comb, and phone charger, as well as anything that will make your hospital stay more comfortable (e.g., a sleep mask or earplugs)
  • Arrange to have someone help you at home for a week or two after being discharged from the hospital.

You may also meet with a physical therapist prior to surgery to help prepare you for your knee rehabilitation program after the operation.

What to Expect on the Day of Surgery

On the day of your knee replacement surgery, you will first go to a pre-operative room where you will change into a hospital gown. A nurse will then record your vital signs and place a peripheral IV in your hand or arm.

After briefly meeting with members of the surgical and anesthesia team, you will be taken into the operating room. If undergoing general anesthesia, you will be given medications to put you to sleep.

Knee replacement surgery with then typically proceed with the following steps:

  • The surgeon will make a six to eight-inch incision (cut) over your knee.
  • The damaged parts of your knee joint will be removed, and the surgeon will attach a prosthesis to the bone, most commonly with cement.
  • Once the prosthesis is placed, the incision site will be closed with staples or stitches. A drain may be placed at the surgical site, which will be removed later.
  • A sterile bandage will then be placed over the knee wound.


After knee replacement surgery, you can expect to stay in the hospital for approximately one to three days. While many patients experience significant pain relief and a rapid improvement in knee functioning within weeks of the surgery, full recovery can take anywhere from six months to a year.

As you recover in the hospital, you can expect the following:

Once discharged home, it's important to follow your surgeon's post-operative instructions, which may include the following:

  • Wearing a compression sock, and elevating/icing your knee to reduce swelling.
  • Taking your medication as directed, which may include pain medications, stool softeners, an anticoagulant, and anti-nausea drugs.
  • Resuming your normal diet and maintaining a normal weight.
  • Avoiding alcohol and drinking plenty of fluids.
  • Keeping your wound clean and dry and changing the knee bandage as instructed.
  • Resuming normal activities within three to six weeks after surgery.

Long-Term Care

The success of knee replacement surgery depends partially on the rehabilitation period that follows the operation.

With rehabilitation, patients can generally expect the following after surgery:

  • Patients should be able to almost fully straighten out their replaced knee.
  • Patients should be able to climb stairs and bend their knee enough to get in and out of a car.
  • Patients may still experience some knee discomfort and stiffness after surgery, especially when bending the knee excessively.
  • Patients may hear a clicking sound when walking or bending—this usually decreases over time.

Besides attending physical therapy appointments and engaging in various exercises at home, it's important to follow-up with your surgeon as advised. Your surgeon will want to ensure that your knee is maintaining good strength, stability, and mobility.

Keep in mind too—knee implants can also loosen or wear out over time. Therefore, it's important to follow your surgeon's instructions when it comes to your knee and overall health.

A Word From Verywell

No doubt, many people have knee arthritis, but it can be difficult to know when the right time is to have knee replacement surgery. To make the best decision, be sure to meet with and engage in thoughtful discussions with your primary care physician, rheumatologist, and/or orthopedic surgeon. Do not hesitate to ask questions, voice your concerns, and seek out second opinions.

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Article Sources
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