What Is Knee Replacement Surgery? What Is Knee Arthroplasty?

Editor's Choice
Main Category: Bones / Orthopedics
Also Included In: Arthritis / Rheumatology
Article Date: 05 Jul 2012 - 12:00 PST


Knee replacement surgery, also known as knee arthroplasty, is regarded as a modern surgical procedure that can accurately be described as "knee resurfacing". This procedure entails restoring the weight bearing facade of the knee joint that is damaged, worn out, or diseased to relieve pain and movement disability. It is performed through the implant of an orthopedic metal and plastic component shaped as a joint so that the knee can move properly.

Arthroplasty is a field of medicine which deals with the surgical reconstruction and total replacement of degenerated joints. Arthroplasty uses artificial body parts (prosthetics). Arthroplasty literally means "the surgical repair of a joint".

When the articular cartilage of the knee becomes damaged or worn out, it becomes painful - the patient finds it extremely hard to move the knee. The bones, rather than sliding over each other with the minimum of friction, rub and crush together.

If an artificial prosthesis is surgically implanted, the patient will feel much less pain, possibly none, and his knee will move properly.

Replacement surgery in a damaged knee joint by placing an artificial prosthesis will alleviate pain and help better movement of the knee.

Today, every year, over 600,000 knee replacement surgeries are carried out in the United States and more than 70,000 in England and Wales. Most patients are seniors - aged over 65 years.

For most patients, a replacement knee surgical procedure will last for at least 15 to 20 years, especially if cared for properly and not put under too much strain. More than 90% of people who have total knee replacement surgery experience a dramatic decrease in knee pain and a significant improvement in their ability to perform common activities of daily living.

However, total knee replacement will not let you do more than you could before you developed, for example, arthritis.

Women tend to have more severe symptoms and worse knee function before surgery, but recover faster after surgery, compared to men. Although men take longer to recover, within twelve months they have caught up, researchers from Hassenpflug University of the Schleswig-Holstein Medical Center in Germany, reported in Clinical Orthopaedics and Related Research. (Link to article)

Reasons to perform knee replacement surgery

Today, a knee replacement surgery is considered a routine operation. Below are the three most common reasons for the procedure:

• Osteoarthritis - This type of arthritis is age related - caused by the normal long wear and tear of the knee joint. The majority of patients are over 50; however, younger people may be affected.
  
  This is a type of arthritis caused by inflammation, breakdown, and the gradual and eventual loss of cartilage in the joints - over time, the cartilage wears down.
  
  When the bones rub against each other for a few years, they may compensate by growing thicker, but this will result in more friction and more pain.
  
  
  
  X-ray image of a human hip with severe osteoarthritis


• Rheumatoid arthritis - also called inflammatory arthritis, occurs when the membrane surrounding the knee joint is inflamated and thick. This inflammation becomes chronic and will damage the cartilage causing soreness and stiffness.


• Post-traumatic arthritis - this type of arthritis is due to a severe knee injury. When the bones around the knee break or the ligaments tear, this will affect the knee cartilage. Sometimes, surgery is the best option.

Male smokers less likely to need surgery - researchers from the University of Adelaide in Australia, reported in the journal Arthritis & Rheumatism that men who regularly smoke have a lower risk of undergoing total joint replacement surgery compared to those who never smoked. They described their findings as "surprising". (Link to article)

When is knee replacement surgery recommended?

Knee surgery is recommended for older people, although adults or teenagers of any age can be candidates for the procedure, since they are physically active and will more rapidly wear the joint out. The weight, gender, or age of the person is never a factor when considering knee replacement surgery. Whether or not to perform surgery is nearly always based on the severity of pain and degree of disability of the patient.

If should be noted that knee replacement surgery that occurs earlier in life usually means further surgery later on. However, several studies have proven that knee replacement surgery performed before severe stiffness and pain set in is associated with better outcomes.

When considering the option of knee replacement surgery, doctors take into account a number of symptoms:

• Severe knee pain or stiffness: Do symptoms seriously undermine the patient's ability to carry out everyday tasks and activities, such as walking, going upstairs, getting in and out of cars, getting up from a chair, etc?


• Moderate but continuous knee pain: Is pain present while sleeping or resting?


• Chronic knee inflammation and swelling: Does the swelling not improve after taking medications or resting? Do drugs cause unpleasant side effects?


• Knee deformity: Is there is a noticeable arch in the inside or outside of the knee?


• Nothing else worked: The doctor has prescribed medications and physical therapy without any substantial improvement.


• Depression: Depression can be a serious, debilitating and devastating illness. Chronic pain and problems with mobility can eventually lead to depression, especially if the patient cannot do normal daily or social activities properly. Replacement knee surgery may prevent depression from occurring, or help get rid of it.

Preparing for a knee replacement surgery procedure

Since knee arthroplasty is major surgery, pre-operative preparation, medical consultations, and physical evaluations usually begin one month before the set date of the operation.

The patient will have to undergo a series of preparatory and diagnostic tests, which include checking blood count, how the blood clots, electrocardiograms, and checking urine.

Surgery is usually performed either under general, spinal or epidural anesthetic. The surgeon, together with the anesthesiologist will usually determine on the day of the operation what type of anesthetic will be used.

The procedure itself takes approximately 1 to 2 hours. The orthopedic surgeon will remove the damaged cartilage and bone, and then position the new metal and (or) plastic implant to restore the alignment and function of the knee.

Two major types of knee replacement surgeries

TKR (Total knee replacement)

The surgery involves the replacement of both sides of the knee joint. It is the most common procedure.

Surgery lasts between one and three hours.

Experts say that the implant will last from 15 to 20 years.

Despite having much less pain and better mobility, there will be scar tissue, which means there will always be some difficulty in moving and bending the knees.

Most surgeons believe that TKR is a more reliable long term procedure.

PKR (Partial knee replacement)

This surgery is done when only one side of the knee joint is replaced. Hence, it does not last as long as a total replacement. Less bone is removed, so the incision is smaller.

PKR is suitable for around one in four people with osteoarthritis. Post-operative rehabilitation is simpler, there is less blood loss, lower risk of infection and blood clots. PKR in general includes a shorter hospital stay and recovery period.

PKR often results in more natural movement in the knee. Most PKR patients are able to get up and about after their their operation more rapidly than TKR ones.

Surgical alternatives to knee replacement surgery, and other procedures

In some cases, a number of surgical alternatives or procedures can be considered, depending on the severity of the wear and tear. However, knee replacement surgery tends to have better long-term results.

• Kneecap replacement - Patellofemora joint arthroplasty can be performed when only the kneecap is damaged. It is a short surgical procedure with a fast recovery time.


• Mini-incision surgery (MIS) - Still considered a new surgical technique, it is most commonly used in PKR. The difference is that the orthopedic surgeon performs a very small cut in front of the knee rather than the standard large opening. New specialized instruments are inserted in the small opening to maneuver around the tissue rather than cutting through it. Since the procedure is less harmful to the joint, the recovery time is much quicker and less painful.


• Image-guided surgery - Although considered as a very accurate alternative in positioning the new knee joint, it is still not a common surgery. As a matter of fact, only 1% of all operations are done through image-guided surgery. With the aid of computerized images, and infrared beacons, the surgeon performs the surgery from a second room (operating theater).


• Arthroscopic washout and debridement - An arthroscope (tiny telescope) is inserted through small incisions in the knee. The knee is then washed out with saline solution which clears away any tiny bits of bone. This procedure is not advisable if the patient has severe arthritis.


• Osteotomy - This is an open operation. The shin bone is cut and re-aligned so that the patient's body weight no longer bears down on one part of the knee.
  
  This procedure is sometimes used for younger people with limited arthritis, where it may enable a knee replacement to be postponed. Patients should be told they will probaly need a knee replacement surgery procedure at a later date.


• Autologous chondrocyte implantation (ACI) - This procedure is when new cartilage from the patient´s own cells matures artificially in a test tube and is later introduced into the damaged area. It is a common procedure used when the patient has injured his knee in an accident. A more common procedure for patients with accidental injuries, rather than those with arthritis.

What are the risks of surgery?

Experts say that total knee replacements have extremely low complication rates - and occur in fewer than 2% of patients. Complications may include stroke, DVT (deep vein thrombosis), infection in the knee joint, or heart attack. Nerve damage occurs in 1 to 2% of patients.

Persistent pain or stiffness occurs in 8-23% of patients.

About 1 in every 50 patients will experience prosthesis failure within five years of their operation.

Other complications occur in about 1 in 20 surgeries, but most of these are minor and can be successfully treated. Some of the most common complications are listed below:

• Allergic reaction to the bone cement.
• Continuous pain long after knee replacement.
• Excess bone forming around the artificial knee joint restricting movement of the knee.
• Excess scar tissue resulting in restricted movement of the knee.
• Fracture in the bone around the artificial joint during or after surgery.
• Infection of the healing wound.
• Instability of the knee cap resulting in painful dislocation to the outer side of the knee.
• Ligament, artery or nerve damage in the area around the knee joint.
• Loss of motion and stiffness.
• Numbness in the area around the wound scar.
• The kneecap becoming dislocated.
• Unforeseen bleeding in the knee joint.
• Wearing down of implant surfaces - components may loosen.

Obesity and complications - obese patients are much more likely to experience post-operative complications than people of normal weight. Dutch researchers explained that in a study, they found that obese individuals had a 3.3 times greater risk of infection and a 1.5 times greater chance of aseptic loosening. (Link to article)

Replace both knees at the same time? - John P. Meehan, MD, study author and orthopedic surgeon from the University of California, Davis, explained at the 2011 Annual Meeting of the American Academy of Orthopedic Surgeons (AAOS), 2011, that considerably fewer prosthetic joint infections as well as other knee complications occurred twelve months after surgery if the patient had both knees replaced simultaneously, rather than stretching out the operations over time. (Link to article)

Recovering in the hospital after knee replacement surgery

Patients will feel pain after the operation. It is important that physical rehabilitation is adhered to strictly.

Possibly a day after the procedure medical staff will try to encourage patients to get up and try to walk about, usually with some kind of walking aid.

Physical therapy session are aimed at strengthening the knee. They may hurt at first. However, the sessions are crucial, because they significantly reduce the risk of future complications.

The patient will utilize a passive motion machine to restore movement in the knee and leg.

In general, a patient having knee replacement surgery will be hospitalized from five to ten days. Hospital stay duration depends on how well the patient responds to rehabilitation. Patients with very little help at home may be advised to stay in hospital for longer.

Recovering at home

Patients can take up to three months to recover completely from a knee replacement surgical procedure.

It is important that patients comply with the instructions given by doctors, nurses and the physical therapist.

The patient may be asked to:

• Take iron supplements to aid wound healing and muscle strength
• Do everything possible to avoid a fall, which might mean further surgery
• Not bend down and lift heavy things, at least during the first few weeks
• Not to soak the wound until the scar is completely healed, otherwise there is a serious risk of infection
• Not to stay standing still for long periods. The ankles might swell
• Follow all the instructions carefully for all medications
• Follow the medical team's advice on exercises to ensure rapid and proper mobility
• Have a footstool so that the affected leg may be elevated
• Make sure the shower has a secure handrail
• Make sure there are no loose carpet and wrinkly mats around the house, to prevent falls
• Look out for any signs and symptoms of infections, blood clots or pulmonary embolism
• If possible, have the bedroom downstairs
• When showering, use a stable, non-slippery bench or chair
• Use crutches, a walking stick, or a walker until the knee is strong enough to take your body weight

In general six weeks after the operation, the person can resume normal day to day activities, but some pain and swelling will remain for up to 3 months.

The patient must also be aware that during the following two years, scar tissues and muscles will still be healing.

Patients who have undergone knee replacement surgery should avoid extreme sports.

Lower expectations among those with rheumatoid arthritis - rheumatoid arthritis patients who undergo total knee replacement surgery generally have lower expectations than patients with osteoarthritis - this might undermine their enthusiasm for post-surgical rehabilitations, which sadly worsens their outcomes, said researcher at the Hospital for Special Surgery, New York City. (Link to article)

Written by Christian Nordvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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