Knee replacement surgery replaces parts of injured or worn-out knee joints. The surgery can help ease pain and make the knee work better. During the surgery, damaged bone and cartilage are replaced with parts made of metal and plastic.

To decide whether a knee replacement is right for you, a surgeon checks your knee’s range of motion, stability, and strength. X-rays help show the extent of damage.

The right artificial joints and surgical techniques for you depend on your age, weight, activity level, knee size and shape, and overall health.

Why it’s done

The most common reason for knee replacement surgery is to ease pain caused by arthritis. People who need knee replacement surgery usually have problems walking, climbing stairs and getting up out of chairs.

If only one part of the knee is damaged, surgeons often can replace just that part. If the entire joint needs to be replaced, the ends of the thighbone and shinbone are reshaped and the entire joint resurfaced. These bones are hard tubes that contain a soft center. The ends of the artificial parts are inserted into the softer central part of the bones.

Ligaments are bands of tissue that help hold joints together. If the knee’s ligaments aren’t strong enough to hold the joint together by themselves, the surgeon may choose implants that can be connected so they can’t come apart.

How you prepare

Food and medications

Your health care team might advise you to stop taking certain medications and dietary supplements before your surgery. You’ll likely be instructed not to eat anything after midnight the day of your surgery.

Prepare for your recovery

For several weeks after the procedure, you might need to use crutches or a walker, so arrange for them before your surgery. Make sure you have a ride home from the hospital and help with everyday tasks, such as cooking, bathing and doing laundry.

To make your home safer and easier to navigate during recovery, consider doing the following:

• Create a living space on one floor since climbing stairs can be difficult.
• Install safety bars or a secure handrail in your shower or bath.
• Secure stairway handrails.
• Get a stable chair with a firm seat cushion and back, and a footstool to elevate your leg.
• Arrange for a toilet seat riser with arms if you have a low toilet.
• Get a stable bench or chair for your shower.
• Remove loose rugs and cords.

During the procedure

Knee replacement surgery usually takes 1 to 2 hours. To perform the procedure, the surgeon:

• Makes an incision over the knee.
• Removes diseased and damaged bone and cartilage, leaving healthy bone intact.
• Implants the replacement parts into the thighbone, shinbone and kneecap.