What is Knee Replacement Surgery?

What is Knee Replacement Surgery?

Knee replacement surgery, also called arthroplasty, involves surgically removing damaged bone and cartilage from the knee joint and replacing it with either metal or plastic joints (prosthesis). This helps restore mobility and reduce pain from severe knee joint disease. 

The most common causes for knee replacement surgery are:

  • Osteoarthritis 
  • Rheumatoid arthritis
  • Traumatic arthritis

As arthritis more often affects older people, the most common age for knee replacement surgery is between 60 and 80 years old. In some cases, younger people can also be affected by diseases of the knee joints, making them candidates for surgery.

Types of Knee Replacement Surgery


Knee replacement surgery becomes an alternative when injections, medication, and physical therapy have failed. The two primary knee replacement surgeries performed are total knee replacement and partial knee replacement.

  • Total knee replacement surgery requires the removal of the entire damaged joint. This joint is replaced with an artificial joint composed of metal/ceramic and plastic. Total knee replacement surgery may sometimes be done as a same-day procedure. At times, it may require an in-patient hospital stay for a couple of days should any complications arise. 

    Diagram of knee joint replacement

  • Partial knee replacement surgery is the most viable alternative when only one out of the three knee sections has sustained damage from arthritis or injury. It is a smaller procedure than a total knee replacement and typically has a faster recovery. Only 10-15% of patients with knee arthritis patients are candidates for partial knee replacement.

How is Knee Replacement Surgery Performed?


Prior to knee replacement surgery, a patient is given anesthesia. The patient can choose to receive general anesthesia, which puts you to sleep during the procedure. Another option is spinal or epidural anesthesia, which blocks the nerves below the waist allowing the patient to remain awake yet feel no pain (though conscious sedation is typically given to keep patients more comfortable). An antibiotic will also be given intravenously to help prevent any post-operative infections.

During knee replacement surgery, the surgeon will make an incision along the knee about 6-10 inches long (15 to 25 centimeters). At this point, the surgeon can manipulate the kneecap to remove any damaged joint tissue. The damaged material is then replaced with a new artificial joint. This operation usually lasts one to two hours. 

A partial knee replacement surgery takes approximately 45 minutes to an hour. Patients are then transferred to the recovery room for about an hour. Afterward, patients undergo physical therapy to regain their optimum flexibility and strength. Sometimes partial knee replacements are referred to as “half knee replacements.” However, this is incorrect since partial knee replacements involve only one of the three major compartments of the knee.

Risks to Consider


As with any surgery, there are possible risks involved with knee replacements. Common risks include:

  • Infection
  • Blood clots in the legs or lungs
  • Stroke or heart attack
  • Possible nerve damage
  • Stiffness or scar tissue if the patient does not actively engage in post-op physical therapy

Preparing for Knee Replacement Surgery


Before knee replacement surgery, patients will be advised to stop taking medications that can cause bleeding, such as blood thinners, aspirin, or ibuprofen. Patients are also instructed to refrain from eating or drinking after midnight the night before surgery. 

Arriving early to your scheduled surgery appointment may help you ease any anxiety and prepare for any last-minute changes to the operating schedule.

What to Expect After Knee Replacement Surgery

After the Surgery

Recovery time in the hospital depends on the individual needs of each patient. Immediately following knee replacement surgery, patients will spend a few hours in the recovery unit. After that, you will be transferred to a hospital room for about 1-2 days. In some cases, you can go home the same day. You’ll be prescribed several medications after surgery, including a few different types of pain medication.

A physical therapist will instruct you on how to exercise your new knee and practice breathing exercises to relieve pain. You will be told to walk and move your ankle and foot to prevent blood clots from forming. In addition, compression boots or a support hose will be used to avoid blood clots and swelling. Instructions regarding exercise, diet, and wound care at home will be provided at discharge.



Some measures can be taken to avoid knee replacement surgery, such as weight control and exercise to strengthen your muscles and increase flexibility.

Your surgeon will determine if your condition and symptoms warrant knee replacement surgery.

Most people who have a total knee replacement can expect the implants to last between 15 to 20 years. Patients who had knee replacements at a younger age may eventually need a second operation to change the implants.

Patients often need a walker for 1 to 2 weeks after their operation. Then you might use a cane for a few weeks. Generally, patients walk on their own in about 2-4 weeks.

Get Care

Trust NewYork-Presbyterian for Your Knee Replacement Surgery

Suffering from knee pain and swelling can make everyday chores and activities unbearable. Our healthcare professionals are knowledgeable and sensitive to the symptoms of knee pain, injury, and diseases. Start your journey to feeling better by scheduling a consultation appointment with one of our world-renowned orthopedic surgeons at NewYork-Presbyterian and Columbia Orthopedics.