Knee replacement

Knee replacement surgery — also known as knee arthroplasty (ARTH-ro-plas-tee) — can help relieve pain and restore function in severely diseased knee joints. During knee replacement, a surgeon cuts away damaged bone and cartilage from your thighbone, shinbone and kneecap and replaces it with an artificial joint made of metal alloys, high-grade plastics and polymers.


Medical X-rays, Knee joint


English: Typical locations of arthroscopic sur...
English: Typical locations of arthroscopic surgery incisions in a knee joint following surgery for a tear in the meniscus. (Photo credit: Wikipedia)

Knee replacement surgery — also known as knee arthroplasty (ARTH-ro-plas-tee) — can help relieve pain and restore function in severely diseased knee joints. During knee replacement, a surgeon cuts away damaged bone and cartilage from your thighbone, shinbone and kneecap and replaces it with an artificial joint made of metal alloys, high-grade plastics and polymers.

The first artificial knees were little more than crude hinges. Now, you and your doctor can choose from a wide variety of designs that take into account your age, weight, activity level and overall health. Most knee replacement joints attempt to replicate your knee’s natural ability to roll and glide as it bends.

Why it’s done

The most common reason for knee replacement surgery is to repair joint damage caused by osteoarthritis and rheumatoid arthritis.

You may be a candidate for knee replacement if:

  • Your pain is disabling.People who need knee replacement surgery usually have problems walking, climbing stairs, and getting in and out of chairs. They also may experience moderate or severe knee pain at rest.
  • Other treatments haven’t helped.More conservative treatments include weight loss, physical therapy, a cane or other walking aid, medications, and braces.
  • You have a knee deformity.Knee replacement can be especially helpful for people who have a knee that bows in or out.
  • You’re 55 or older.Knee replacement is typically performed in older adults, but it may be considered for adults of all ages. Young, physically active people are more likely to wear out their new knees prematurely.
  • Your general health is good. Conditions such as restricted blood flow, diabetes or infections can complicate surgery and recovery.


As with any surgery, knee replacement surgery carries risks, including:

Risks of serious complications are rare. According to the American Association of Orthopaedic Surgeons, fewer than 2 percent of people undergoing knee replacement surgery experience serious complications. Put another way, for every 100 knee replacement procedures, one or two people will experience serious complications.

Infection can occur years after surgery
Infection is an ongoing concern. Even years after surgery, bacteria can travel through your bloodstream and infect the surgical site.

Notify your doctor immediately if you notice:

  • Fever greater than 100 F (37.8 C)
  • Shaking chills
  • Drainage from the surgical site
  • Increasing redness, tenderness, swelling and pain in the knee

An infected knee replacement usually requires surgery to remove the artificial parts and antibiotics are necessary to kill the bacteria. After the infection is cleared, another surgery is performed to install a new knee. Your chances of a good or excellent outcome that reduces pain and improves function decline with each additional surgery.

Artificial knees can wear out
Another risk of knee replacement surgery is failure of the new knee joint. Subjected to daily stress, even the strongest metal and plastic parts eventually wear out. You’re at a greater risk of joint failure if you’re a young, obese male or you have complicating conditions.

How you prepare

An orthopedic surgeon — a doctor who treats muscle and bone problems — performs knee replacement procedures. Before the procedure, the surgeon takes your medical history and performs a physical examination to assess your knee’s range of motion, stability and strength. He or she also orders an X-ray exam to determine the extent of knee damage. You’ll undergo a full medical exam, including blood tests, an electrocardiogram and a urine test, before surgery.

Knee replacement surgery requires anesthesia to make you comfortable during surgery. Your input and personal preference helps the team decide whether to use general anesthesia, which renders you unconscious during the operation, or spinal or epidural anesthesia, during which you are awake but can’t feel any pain from your waist down.

Your doctor or anesthesiologist may advise you to stop taking certain medications and dietary supplements before your surgery. You’ll likely be instructed not to eat anything after midnight before your surgery.

Plan ahead for your recovery after surgery
For several weeks after the procedure, you may need the assistance of crutches or a walker. Make advance arrangements for transportation home from the hospital and help with everyday tasks such as cooking, bathing and doing laundry. If you live alone, your surgeon’s staff can suggest a temporary caretaker.

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

  • Create a total living space on one floor since climbing stairs can be difficult.
  • Install safety bars or a secure handrail in your shower or bath.
  • Secure handrails along your stairways.
  • Obtain 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.
  • Try a stable bench or chair for your shower.
  • Remove all loose carpets and cords.

What you can expect


Illustration showing a healthy knee, a knee with osteoarthritis and knee that has undergone knee replacement surgery 
Knee replacement

During knee replacement surgery
During the procedure, your knee is in a bent position so that all surfaces of the joint are fully exposed. After making an incision about 8 to 10 inches (20 to 25 centimeters) in length, your surgeon moves aside your kneecap and cuts away the damaged joint surfaces. Minimally invasive procedures use much smaller incisions, usually less than 4 inches (10 centimeters) long.

After the joint surfaces are prepared, the surgeon inserts and attaches the pieces of the artificial joint. Before closing the incision, he or she bends and rotates your knee, testing and balancing it to ensure that it functions properly. Expect knee replacement surgery to last about two hours.

After knee replacement surgery
After surgery, you’re wheeled to a recovery room for one to two hours. You’re then moved to your hospital room, where you typically stay for a couple of days before going home. You may feel some pain, but nerve blocks and medications prescribed by your doctor will help control it.

During the hospital stay, you’re encouraged to move your foot and ankle, which increases blood flow to your leg muscles and helps prevent swelling and blood clots. You may need to receive blood thinners and wear support hose or compression boots to further protect against swelling and clotting.

The day after surgery, a physical therapist shows you how to exercise your new knee. During the first few weeks after surgery, you’re more likely to experience a good recovery if you follow all of your surgeon’s instructions concerning wound care, diet and exercise. Your physical activity program needs to include:

  • A graduated walking program — first indoors, then outdoors — to gradually increase your mobility
  • Slowly resuming other normal household activities, including walking up and down stairs
  • Knee-strengthening exercises you learned from the hospital physical therapist, performed several times a day



X-rays of a knee before and after knee replacement surgery
Knee X-rays

Most people who have a knee replacement experience significant pain relief, improved mobility and a better overall quality of life. Talk with your doctor about what you can expect from knee replacement surgery.

Three to six weeks after knee replacement surgery, you generally can resume most normal daily activities such as shopping and light housekeeping. Driving is possible in four to six weeks if you can bend your knee far enough to sit in a car and you have enough muscle control to properly operate the brakes and accelerator.

After you’ve recovered, you can enjoy a variety of low-impact activities, such as walking, swimming, playing golf or biking. But higher impact activities, such as jogging, skiing, tennis, and sports that involve contact or jumping, may be out. Talk to your doctor about your limitations.



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  5. Billante MJ, et al. Knee replacement in aging athletes. In: DeLee JC, et al. DeLee and Drez’s Orthopaedic Sports Medicine. 3rd ed. Philadelphia, Pa.: Saunders Elsevier; 2009.–s1630_3895. Accessed March 5, 2010.
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  9. Joint surgery. American College of Rheumatology. Accessed March 5, 2010.

MY00091 May 15, 2010

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Knee Replacement wound which has been stapled ...
Knee Replacement wound which has been stapled closed (Photo credit: Wikipedia)

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