Knee replacement, also known as knee arthroplasty, is a surgical procedure to replace the weight-bearing surfaces of the knee joint to relieve pain and disability

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.

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.

Before the procedure

• Your doctor will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
• You will be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully and ask questions if something is not clear.
• In addition to a complete medical history, your doctor may perform a complete physical examination to ensure you are in good health before undergoing the procedure. You may undergo blood tests or other diagnostic tests.
• Notify your doctor if you are sensitive to or are allergic to any medications, latex, tape, and anesthetic agents (local and general).
• Notify your doctor of all medications (prescribed and over-the-counter) and herbal supplements that you are taking.
• Notify your doctor if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting. It may be necessary for you to stop these medications prior to the procedure.
• If you are pregnant or suspect that you are pregnant, you should notify your doctor.
• You will be asked to fast for eight hours before the procedure, generally after midnight.
• You may receive a sedative prior to the procedure to help you relax.
• You may meet with a physical therapist prior to your surgery to discuss rehabilitation.
• Arrange for someone to help around the house for a week or two after you are discharged from the hospital.
• Based on your medical condition, your doctor may request other specific preparation.

During the procedure

Knee replacement requires a stay in a hospital. Procedures may vary depending on your condition and your doctor's practices.

Knee replacement surgery is most often performed while you are asleep under general anesthesia. Your anesthesiologist will discuss this with you in advance.

Generally, knee replacement surgery follows this process:

1. You will be asked to remove clothing and will be given a gown to wear.
2. An intravenous (IV) line may be started in your arm or hand.
3. You will be positioned on the operating table.
4. A urinary catheter may be inserted.
5. If there is excessive hair at the surgical site, it may be clipped off.
6. The anesthesiologist will continuously monitor your heart rate, blood pressure, breathing, and blood oxygen level during the surgery.
7. The skin over the surgical site will be cleansed with an antiseptic solution.
8. The doctor will make an incision in the knee area.
9. The doctor will remove the damaged surfaces of the knee joint and resurface the knee joint with the prosthesis. The knee prosthesis is made up of metal and plastic. The most common type of artificial knee prosthesis is a cemented prosthesis. Uncemented prostheses are not commonly used anymore. A cemented prosthesis attaches to the bone with surgical cement. An uncemented prosthesis attaches to the bone with a porous surface onto which the bone grows to attach to the prosthesis. Sometimes, a combination of the 2 types is used to replace a knee.
The prosthesis is generally comprised of 3 components: the tibial component (to resurface the top of the tibia, or shin bone); the femoral [thigh bone] component (to resurface the end of the thighbone; and the patellar component (to resurface the bottom of the kneecap that rubs against the thighbone).
10. The incision will be closed with stitches or surgical staples.
11. A drain may be placed in the incision site to remove fluid.
12. A sterile bandage or dressing will be applied.

After the procedure

In the hospital

After the surgery you will be taken to the recovery room for observation. Once your blood pressure, pulse, and breathing are stable and you are alert, you will be taken to your hospital room. Knee replacement surgery usually requires an in-hospital stay of several days.

It is important to begin moving the new joint after surgery. A physical therapist will meet with you soon after your surgery and plan an exercise program for you. A continuous passive motion (CPM) machine may be used to begin the physical therapy. This machine moves your new knee joint through its range of motion while you are resting in bed. Your pain will be controlled with medication so that you can participate in the exercise. You will be given an exercise plan to follow both in the hospital and after discharge.

You will be discharged home or to a rehabilitation center. In either case, your doctor will arrange for continuation of physical therapy until you regain muscle strength and good range of motion.

At home

Once you are home, it is important to keep the surgical area clean and dry. Your doctor will give you specific bathing instructions. The stitches or surgical staples will be removed during a follow-up office visit.

To help reduce swelling, you may be asked to elevate your leg or apply ice to the knee.

Take a pain reliever for soreness as recommended by your doctor. Aspirin or certain other pain medications may increase the chance of bleeding. Be sure to take only recommended medications.

Notify your doctor to report any of the following:

• Fever
• Redness, swelling, bleeding, or other drainage from the incision site.
• Increased pain around the incision site.
• You may resume your normal diet unless your doctor advises you differently.

You should not drive until your doctor tells you to. Other activity restrictions may apply. Full recovery from the surgery may take several months.

It is important that you avoid falls after your knee replacement surgery, because a fall can result in damage to the new joint. Your therapist may recommend an assistive device (cane or walker) to help you walk until your strength and balance improve.

Making certain modifications to your home may help you during your recovery. These modifications include, but are not limited to, the following:

• Proper handrails along all stairs
• Safety handrails in the shower or bath
• Shower bench or chair
• Raised toilet seat
• Long-handled sponge and shower hose
• Dressing stick
• Sock aid
• Long-handled shoe horn
• Reaching stick to grab objects
• Removing loose carpets and electrical cords that may cause you to trip
• Avoiding stair-climbing until recommended by your doctor

Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.