Knee replacement: Surgery can relieve pain

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Knee replacement: Surgery can relieve pain

Knee replacement — Comprehensive overview of total knee replacement surgery and recovery.

Knee replacement surgery — also known as total 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 (prosthesis) made of metal alloys, high-grade plastics and polymers.

In the 1950s, the first artificial knees were little more than crude hinges. Now that more than 300,000 knee replacement surgeries are performed each year, 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.

Who is knee replacement for?

Knee replacement can improve knee problems associated with osteoarthritis, rheumatoid arthritis and other degenerative conditions, such as avascular necrosis — a condition in which obstructed blood flow causes your bone tissue to die.

Knee replacement may help you if:

  • You have pain that limits activities such as walking, climbing stairs and getting in and out of chairs, or you experience moderate or severe knee pain at rest.
  • You have limited function or mobility, such as chronic knee stiffness and swelling that prevent you from bending and straightening your knee.
  • You've tried other methods to improve symptoms, for example resting, weight loss, physical therapy, medications, braces and surgery, but they've failed.
  • You have a knee deformity, such as a joint that bows in or out.
  • You're age 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 knee prematurely. For those people, a doctor may recommend a nonsurgical treatment program or suggest an alternative surgery such as arthroscopy, leg straightening (osteotomy), or a partial knee replacement, which replaces fewer components than total knee replacement.
  • You're generally healthy. Good candidates for knee replacement are typically healthy, without conditions such as restricted blood flow, diabetes, or infections that can complicate surgery and recovery. Obesity alone won't disqualify you from surgery, but it may slow healing and increase your risk of infection after surgery.

How do you prepare for knee replacement?

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.

Ask your doctor to explain precisely what the surgery can accomplish. Discuss what you can realistically expect from surgery. For example, although the procedure usually relieves pain and improves everyday mobility, you won't be able to run marathons.

Because the procedure requires anesthesia, your doctor or anesthesiologist advises you on taking your usual medications and dietary supplements. You'll likely be instructed not to eat anything after midnight before your 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

How is knee replacement done?

During the procedure, your knee is in a bent position so that all surfaces of the joint are fully exposed. After making an incision between 6 and 12 inches in length, your surgeon moves aside your muscles, kneecap and connective tissues and cuts away the damaged joint surface. He or she takes measurements to ensure a good fit for your new prosthesis and smoothens your bones' rough edges.

The surgeon then inserts the prosthesis. Before closing the incision, he or she bends and rotates your knee, testing and balancing it to ensure that it functions properly.

Some people choose to have both knees replaced at the same time. Whether this improves the outcome of surgery or whether surgery on both knees is more risky is controversial among surgeons. Discuss your concerns with your surgeon.

Knee replacement surgery

Images of knee, before and after knee replacement surgery

Knee replacement surgery can repair damage from osteoarthritis and other inflammatory conditions. The artificial joint has metal alloy caps for your thighbone and shinbone, and high-density plastic to replace eroded cartilage within the joint and on your kneecap.

Artificial knee joint

Image of artificial knee joint

An artificial knee joint includes, among other components, metal alloy caps for your thighbone (top piece) and shinbone (bottom piece). High-density plastic on the shin component replaces lost cartilage.

What can you expect during knee replacement?

On the day of surgery, the anesthesia team evaluates you. 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.

Your doctor places several monitors on your body to help make sure that your heart rate, blood pressure and blood oxygen levels stay at safe levels throughout the procedure. These monitors may include a blood pressure cuff on your arm and sticky heart-monitor leads stuck to your chest.

Expect the procedure to last about two hours. 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 several days before going home. You may feel some pain, but nerve blocks and medications prescribed by your doctor will help control it.

Knee replacement results

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. To help regain movement, you may use a device called a continuous passive motion machine, which slowly moves your knee while you're in bed.

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

More than 95 percent of people who have a total knee replacement experience significant pain relief, improved mobility and a better overall quality of life.

Three to six weeks after the procedure, 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.

Knee X-rays

Knee X-rays

X-rays of an osteoarthritic knee before and after knee replacement surgery.

Risks of knee replacement

As with any surgery, knee replacement surgery carries the risk of potentially life-threatening infection, heart attack and stroke. Blood clots in the leg vein (thrombophlebitis) or in the lungs (pulmonary embolism) are a major concern, so blood thinners are commonly used to help prevent them.

Other risks include knee-joint infection, nerve damage, and the possibility that your new knee could break or become dislocated. Although the risks of such serious complications are rare, 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 such warning signs as a fever greater than 100 F, shaking chills, drainage from the surgical site, and increasing redness, tenderness, swelling and pain in the knee. If antibiotics fail to clear up the infection, you usually need one surgery to remove the infected joint and another surgery to install a new one. Your chances of a good-to-excellent outcome that reduces pain and improves function decline with each additional surgery.

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.

Looking ahead

Since the late 1990s, some surgeons have offered a minimally invasive total knee replacement procedure. This procedure involves a somewhat smaller skin incision. However, more research into the long-term effects is necessary to know whether this newer procedure is as safe and effective as standard total knee replacement.

    Last Updated: 05/19/2006
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