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Frequently Asked Questions

This page provides a brief overview of knee replacement. It can help you make a list of questions to ask your doctor, but it is not meant to provide complete information. Check with your doctor’s office about more comprehensive resources and patient education materials.

About knee replacement surgery

What is knee replacement surgery?
How do I know if I need a knee replacement?
How do I prepare for knee replacement surgery?
What happens during knee replacement surgery?
How is the knee implant attached to the body?

What is knee replacement surgery?

In total knee replacement surgery, the parts of the bones that rub together are resurfaced with metal and plastic implants. Using special, precision instruments, your surgeon will typically remove the damaged surfaces of all three bones—the thighbone (femur), the shinbone (tibia), and the kneecap (patella). The replacement surfaces will then be fixed into place.

The surface of the femur is replaced with a rounded metal component that comes very close to matching the curve of your natural bone. The surface of the tibia is replaced with a smooth plastic component. This flat metal component holds a smooth plastic piece made of ultra-high-molecular-weight polyethylene plastic that serves as the cartilage. The undersurface of the kneecap may also be replaced with an implant made of the same polyethylene plastic.

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How do I know if I need a knee replacement?

If you have difficulty walking or performing everyday activities such as getting dressed, it may be time to consider knee replacement surgery.

People generally try to delay knee replacement for as long as possible, taking pain medications instead. However, for people with severe pain or advanced joint disease, knee replacement is highly successful in relieving pain and restoring joint function. Of course, you should discuss this option with your doctor, as he or she can advise you on the best course of action.

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How do I prepare for knee replacement surgery?

If you and your doctor decide that a knee replacement is right for you, a date will be scheduled for your surgery. You may need to make several preparations for surgery. For example, you may need a physical examination by an internist or your regular doctor, or you may need to donate a unit or two of your own blood. All preparations for surgery should be discussed with your surgeon, but you should also read up on your own. Learn what to expect before, during, and after surgery.

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What happens during knee replacement surgery?

On the day of surgery, a small tube (intravenous line) will be inserted into your arm. This tube will be used to administer antibiotics and other medication during your surgery. You will then be taken to the operating room and given anesthesia. After the anesthesia takes effect, your knee will be scrubbed and sterilized with a special solution.

The surgery will begin with an incision over the knee that will expose the joint. When the bones are fully visible to the surgeon, special precision guides and instruments are used to remove the damaged surfaces and shape the ends of the bones to accept the implants.

The implants are then secured to the bones. It might also be necessary to adjust the ligaments that surround the knee in order to achieve the best possible knee function. When the surgeon is satisfied with the fit and function of the implants, the incision will be closed.

A special drain may be inserted into the wound to drain the fluids that naturally develop at the surgical site. A sterile bandage will then be applied, and you will be taken to the recovery room, where you will be closely monitored. The length of your surgery will depend on your individual circumstances.

Learn more about your specific surgery.

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How is the knee implant attached to the body?

Generally, knee implants are attached to the bones in one of three ways: with bone cement, without bone cement (cementless), or with a combination of the two.

• Bone cement: A special type of acrylic bone cement may be used to secure some or all of the implant components to the bone. Bone cement takes about 15 minutes to set. 
• Cementless: Some implant components have a special porous coating that allows tissue to grow into it for fixation.

The decision to use a cemented or cementless component depends upon many factors, including the intended use of the product, surgeon philosophy, and your condition.

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