Skip to main content

What is knee replacement?

Knee replacement is a surgical treatment that replaces a severely damaged knee joint with a prosthesis or implant. This type of surgery is often recommended to people with painful conditions of the knee that have not responded to more conservative nonsurgical treatments.

The American Academy of Orthopaedic Surgeons (AAOS) reports that more than 650,000 people undergo total knee replacement surgery each year. The surgery involves placing implants on the end of the distal femur (thigh bone), upper end of the tibia (shin bone) and back surface of the patella (kneecap).

Why it's done

Knee replacement is done to decrease knee pain and improve function—making it easier to walk, exercise and enjoy other activities without soreness or discomfort.

Types of knee replacement

  • Partial knee replacement surgery—In some patients, arthritis is limited to just one part of the knee. When this is the case, partial knee replacement may be an option. Also known as uni-compartmental knee replacement, this surgical treatment replaces the damaged knee compartment with an implant, while the healthy cartilage and bone in the rest of the knee is retained. The benefits of partial knee replacement include a smaller incision, less blood loss, faster recovery time, and quicker return to normal activities.
  • Total knee replacement—During total knee replacement, the knee joint is resurfaced by removing the diseased bone and cartilage. These surfaces are replaced with a metal and plastic implant that can help alleviate the pain of arthritis while increasing mobility and function. Because there are subtle differences in the anatomy of men and women, knee implants are designed specifically to accommodate for the different size of the bones between genders. This increases functionality and durability of the implant.
  • Knee revision surgery—Over time, a knee implant can begin to fail because of normal wear and tear. With decreased joint functionality and increasing pain symptoms, knee revision surgery may be necessary. During this surgery, the damaged components of the existing implant are removed and a new prosthesis is inserted. 


Complications of knee replacement are rare but do happen. Your surgeon will talk to you about these and any other possible complications of the surgery, and your surgeon and the operating room staff will take special care to reduce your risks. You may be given certain medicine(s) such as antibiotics and blood thinners to decrease your chances of getting an infection or blood clot.

What to expect

You will receive general or regional anesthesia during your surgery. General anesthesia puts you into a deep sleep, whereas regional anesthesia provides numbness to certain areas of the body and may be combined with other medicines to help you relax. Your surgeon will talk with your anesthesiologist or nurse anesthetist to decide which type of anesthesia is best for you.

The usual timeframe for this type of surgery varies depending on the complexity of the case, but is typically one to three hours. Your surgeon will determine a more precise time based on your individual needs. The amount of time often depends on how much time it will take to prepare you and the type of equipment and anesthesia used.

How to prepare

  • You will need a complete physical examination by your primary care doctor or healthcare provider within four to six weeks of your surgery. This time frame allows the surgical team enough time to review your medical report before your procedure.
  • By exercising to strengthen the area around your knee prior to surgery, you can help decrease the time needed to recover. Your doctor can provide instructions on the best exercises for you to start two to three months before your surgery to optimize your results.


After knee replacement surgery, you need to protect your new knee and understand how it will influence the way you perform your daily activities. Your occupational therapist (OT) will assist you in regaining your independence in activities of daily living. Your physical therapist (PT) will educate and train you to move safely with an assistive device, navigate obstacles and avoid falls.

Most surgeons recommend you apply as much weight as you can tolerate through your operated leg. However, there are certain instances where more restrictions may apply. Your physician will specify your weight-bearing status. Your surgeon will let you know when you can resume certain movements and activities. No matter how small the task, always ask for help when you need it. 

Before leaving the hospital, your surgeon and healthcare team will discuss your rehabilitation options with you and your family.

dear doctor
How to make a decision and when to know it's time.

Our joint replacement orthopedists have the training, expertise and skill to help improve your quality of life.

Browse doctors
Go to top