If medications, changing your activity level, and using walking supports are no longer helpful, you may want to consider total knee replacement surgery. By resurfacing your knee's damaged and worn surfaces, total knee replacement surgery can relieve your pain, correct your leg deformity, and help you resume your normal activities.

One of the most important orthopaedic surgical advances of this century, knee replacement was first performed in 1968. Improvements in surgical materials and techniques since then have greatly increased its effectiveness. About 267,000 total knee replacements are performed each year in the United States. Whether you have just begun exploring treatment options or have already decided with your orthopaedic surgeon to have total knee replacement surgery, this booklet will help you understand more about this valuable procedure.

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The knee is the largest joint in the body. Nearly normal knee function is needed to perform routine everyday activities. The knee is made up of the lower end of the thigh bone (femur), which rotates on the upper end of the shin bone (tibia), and the knee cap (patella), which slides in a groove on the end of the femur. Large ligaments attach to the femur and tibia to provide stability. The long thigh muscles give the knee strength.

The joint surfaces where these three bones touch are covered with articular cartilage, a smooth substance that cushions the bones and enables them to move easily.

All remaining surfaces of the knee are covered by a thin, smooth tissue liner called the synovial membrane. This membrane releases a special fluid that lubricates the knee which reduces friction to nearly zero in a healthy knee.

Normally, all of these components work in harmony. But disease or injury can disrupt this harmony, resulting in pain, muscle weakness, and less function.

The most common cause of chronic knee pain and disability is arthritis. Osteoarthritis, rheumatoid arthritis, and traumatic arthritis are the most common forms.

Osteoarthritis usually occurs after the age of 50 and often in an individual with a family history of arthritis. The cartilage that cushions the bones of the knee softens and wears away. The bones then rub against one another causing knee pain and stiffness.

Rheumatoid Arthritis is a disease in which the synovial membrane becomes thickened and inflamed, producing too much synovial fluid which over-fills the joint space. This chronic inflammation can damage the cartilage and eventually cause cartilage loss, pain and stiffness.

Post Traumatic Arthritis can follow a serious knee injury. A knee fracture or severe tears of the knee's ligaments may damage the articular cartilage over time, causing knee pain and limiting knee function.

Your physician may refer you to an orthopaedic surgeon for a thorough evaluation to determine if you could benefit from this surgery.

Reasons that you may benefit from total knee replacement commonly include:

• Severe knee pain that limits your everyday activities, including walking, going up and down stairs, and getting in and out of chairs. You may find it hard to walk more than a few blocks without significant pain and you may need to use a cane or walker.
• Moderate or severe knee pain while resting, either day or night.
• Chronic knee inflammation and swelling that doesn't improve with rest or medications.
• Knee deformity-a bowing in or out of your knee.
• Knee stiffness-inability to bend and straighten your knee.
• Failure to obtain pain relief from non-steroidal anti-inflammatory drugs. These medications, including aspirin and ibuprofen, often are most effective in the early stages of arthritis. Their effectiveness in controlling knee pain varies greatly from person to person. These drugs may become less effective for patients with severe arthritis.
• Inability to tolerate or complications from pain medications.
• Failure to substantially improve with other treatments such as cortisone injections, physical therapy, or other surgeries.
• Most patients who undergo total knee replacement are age 60 to 80, but orthopaedic surgeons evaluate patients individually. Recommendations for surgery are based on a patient's pain and disability, not age. Patients as young as age 16 and older than 90 have undergone successful total knee replacement.

• A medical history, in which your orthopaedic surgeon gathers information about your general health and asks you about the extent of your knee pain and your ability to function.
• A physical examination to assess your knee motion, stability, and strength and overall leg alignment.
• X-rays to determine the extent of damage and deformity in your knee.
• Occasionally blood tests, an MRI (Magnetic Resonance Imaging) or a bone scan may be needed to determine the condition of the bone and soft tissues of your knee.

Your orthopaedic surgeon will review the results of your evaluation with you and discuss whether total knee replacement would be the best method to relieve your pain and improve your function. Other treatment options including medications, injections, physical therapy, or other types of surgery also will be discussed and considered. Your orthopaedic surgeon also will explain the potential risks and complications of total knee replacement, including those related to the surgery itself and those that can occur over time after your surgery.

More than 90 percent of individuals who undergo total knee replacement experience a dramatic reduction of knee pain and a significant improvement in the ability to perform common activities of daily living. But total knee replacement won't make you a super-athlete or allow you to do more than you could before you developed arthritis.

Following surgery, you will be advised to avoid some types of activity for the rest of your life, including jogging and high impact sports.

With normal use and activity, every knee replacement develops some wear in its plastic cushion. Excessive activity or weight may accelerate this normal wear and cause the knee replacement to loosen and become painful. With appropriate activity modification, knee replacements can last for many years.

Medical Evaluation If you decide to have total knee replacement surgery, you may be asked to have a complete physical by your family physician several weeks before surgery to assess your health and to rule out any conditions that could interfere with your surgery.

Tests Several tests, such as blood samples, a cardiogram, and a urine sample may be needed to help your orthopaedic surgeon plan your surgery.

Preparing Your Skin and Leg Your knee and leg should not have any skin infections or irritation.Your lower leg should not have any chronic swelling. Contact your orthopaedic surgeon prior to surgery if either is present for a program to best prepare your skin for surgery.

Blood Donation It is unlikely that you will be advised to donate your own blood prior to the surgery. In the event that you are, it will be stored for use if you need blood after your surgery.

Medications Tell your orthopaedic surgeon about the medications you are taking. He or she will tell you which medications you should stop taking and which you should continue to take before surgery.

Dental Evaluation Although the incidence of infection after knee replacement is very low, an infection can occur if bacteria enter your bloodstream. Treatment of significant dental diseases (including tooth extractions and periodontal work) should be considered before your total knee replacement surgery.

Urinary Evaluations A preoperative urological evaluation should be considered for individuals with a history of recent or frequent urinary infections. For older men with prostate disease, required treatment should be considered prior to knee replacement surgery.

Social Planning Though you will be able to walk on crutches or a walker soon after surgery, you will need help for several weeks with such tasks as cooking, shopping, bathing, and doing laundry. If you live alone, your surgeon's office and a social worker or a discharge planner at the hospital can help you make advance arrangements to have someone assist you at home. They also can help you arrange for a short stay in an extended care facility during your recovery, if this option works best for you.

Home Planning Several suggestions can make your home easier to navigate during your recovery. Consider:

• Safety bars or a secure handrail in your shower or bath.
• Secure handrails along your stairways.
• A stable chair for your early recovery with a firm seat cushion (height of 18-20 inches), a firm back, two arms, and a footstool for intermittent leg elevation.
• A toilet seat riser with arms, if you have a low toilet.
• A stable shower bench or chair for bathing.
• Removing all loose carpets and cords.
• A temporary living space on the same floor, because walking up or down stairs will be more difficult during your early recovery.

The procedure itself takes about two hours. Your orthopaedic surgeon will remove the damaged cartilage and bone and then position the new metal and plastic joint surfaces to restore the alignment and function of your knee.

Many different types of designs and materials are currently used in total knee replacement surgery. Nearly all of them consist of three components: the femoral component (made of a highly polished strong metal), the tibial component (made of a durable plastic often held in a metal tray), and the patellar component (also plastic).

After surgery, you will be moved to the recovery room, where you will remain for one to two hours while your recovery from anesthesia is monitored. After you awaken, you will be taken to your hospital room.

You will most likely stay in the hospital for several days. After surgery, you will feel some pain, but medication will be given to you to make you feel as comfortable as possible. Walking and knee movement are important to your recovery and will begin immediately after your surgery.

To avoid lung congestion after surgery, you should breathe deeply and cough frequently to clear your lungs.

Your orthopaedic surgeon may prescribe one or more measures to prevent blood clots and decrease leg swelling, such as special support hose, inflatable leg coverings (compression boots), and blood thinners.

To restore movement in your knee and leg, your surgeon may use a knee support that slowly moves your knee while you are in bed. The device, called a continuous passive motion (CPM) machine, decreases leg swelling by elevating your leg and improves your venous circulation by moving the muscles of your leg.

Foot and ankle movement is encouraged immediately following surgery to also increase blood flow in your leg muscles to help prevent leg swelling and blood clots. Most patients begin exercising their knee the day after surgery. A physical therapist will teach you specific exercises to strengthen your leg and restore knee movement to allow walking and other normal daily activities soon after your surgery.

Possible Complications After Surgery

The complication rate following total knee replacement is low. Serious complications, such as a knee joint infection, occur in less than 2 percent of patients. Major medical complications, such as heart attack or stroke occur even less frequently. Chronic illnesses may increase the potential for complications. Although uncommon, when these complications occur they can prolong or limit your full recovery.

Blood clots in the leg veins are the most common complication of knee replacement surgery. Your orthopaedic surgeon will outline a prevention program, which may include periodic elevation of your legs, lower leg exercises to increase circulation, support stockings, and medication to thin your blood.

Discuss your concerns thoroughly with your orthopaedic surgeon prior to surgery. Your Recovery at Home

The success of your surgery also will depend on how well you follow your orthopaedic surgeon's instructions at home during the first few weeks after surgery. Wound Care You will have stitches or staples running along your wound or a suture beneath your skin on the front of your knee. The stitches or staples will be removed several weeks after surgery. A suture beneath your skin will not require removal.

Avoid soaking the wound in water until the wound has thoroughly sealed and dried. A bandage may be placed over the wound to prevent irritation from clothing or support stockings.

Diet Some loss of appetite is common for several weeks after surgery. A balanced diet, often with an iron supplement, is important to promote proper tissue healing and restore muscle strength.

Activity Exercise is a critical component of home care, particularly during the first few weeks after surgery. You should be able to resume most normal activities of daily living within three to six weeks following surgery. Some pain with activity and at night is common for several weeks after surgery. Your activity program should include:

• A graduated walking program to slowly increase your mobility, initially in your home and later outside.
• Resuming other normal household activities, such as sitting and standing and walking up and down stairs.
• Specific exercises several times a day to restore movement and strengthen your knee. You probably will be able to perform the exercises without help, but you may have a physical therapist help you at home or in a therapy center the first few weeks after surgery.

Driving usually begins when your knee bends sufficiently so you can enter and sit comfortably in your car and when your muscle control provides adequate reaction time for braking and acceleration. Most individuals resume driving about four to six weeks after surgery.

Avoiding Problems After Surgery

Blood Clot Prevention Follow your orthopaedic surgeon's instructions carefully to minimize the potential of blood clots which can occur during the first several weeks of your recovery.

Warning signs of possible blood clots in your leg include:

• Increasing pain in your calf.
• Tenderness or redness above or below your knee.
• Increasing swelling in your calf, ankle, and foot.

Warning signs that a blood clot has travelled to your lung include:

• Sudden increased shortness of breath.
• Sudden onset of chest pain.
• Localized chest pain with coughing.

Notify your doctor immediately if you develop any of these signs.

Preventing Infection

Following your surgery, you should take antibiotics prior to dental work or any surgical procedure that could allow bacteria to enter your bloodstream. Warning signs of a possible knee replacement infection are:

• Persistent fever (higher than 100 degrees orally).
• Shaking chills.
• Increasing redness, tenderness, or swelling of the knee wound.
• Drainage from the knee wound.
• Increasing knee pain with both activity and rest.

Notify your doctor immediately if you develop any of these signs.

Avoiding Falls A fall during the first few weeks after surgery can damage your new knee and may result in a need for further surgery. Stairs are a particular hazard until your knee is strong and mobile. You should use a cane, crutches, a walker, hand rails, or someone to help you until you have improved your balance, flexibility, and strength.

Your surgeon and physical therapist will help you decide what assistive aides will be required following surgery and when those aides can safely be discontinued.

Most patients can expect to nearly fully straighten the replaced knee and to bend the knee sufficiently to go up and down stairs and get in and out of a car. Kneeling is usually uncomfortable, but it is not harmful. Occasionally, you may feel some soft clicking of the metal and plastic with knee bending or walking. These differences often diminish with time and most patients find these are minor, compared to the pain and limited function they experienced prior to surgery. Your new knee may activate metal detectors required for security in airports and some buildings. Tell the security agent about your knee replacement if the alarm is activated.

After surgery, make sure you also do the following:

• Participate in regular light exercise programs to maintain proper strength and mobility of your new knee.
• Take special precautions to avoid falls and injuries. Individuals who have undergone total knee replacement surgery and suffer a fracture may require more surgery.
• Notify your dentist that you had a knee replacement. You should be given antibiotics before all dental surgery for the rest of your life.
• See your orthopaedic surgeon periodically for a routine follow-up examination and X-rays, usually once a year.

The largest, strongest and heaviest joints in the body, knees provide support and mobility and carry almost half the body's weight. Functioning like a hinge where the lower end of the femur (thighbone) rotates on the upper end of the tibia (shinbone) and patella (kneecap), a healthy knee lets you move your lower leg forward and backward, and swivel slightly to point the toes in or out. Ligaments and cartilage stabilize and support the joint, preventing it from moving too far from side to side. If osteoarthritis wears away a knee joint's articular cartilage, your doctor may recommend total knee arthroplasty (replacement), a common and successful procedure that improves knee motion and lets you resume relatively normal activities without pain. An orthopaedic surgeon resurfaces the knee joint, replacing damaged and worn weight-bearing surfaces with a prosthesis (implant) made of metal alloys, ceramic material or high-density plastic parts which may be joined to bone by acrylic cement.

Fixed- vs. mobile-bearing

Most people get a fixed-bearing prosthesis that reduces knee pain dramatically and may last for many years. Knee prostheses consist of three component parts that function together as a system:

• Femoral: a polished, strong metal shell on the lower end of the thighbone.
• Tibial: a high-density polyethylene piece on top of a metal tray.
• Patellar: a high-density polyethylene piece replacing the underside of the kneecap in the center of the knee.

If you are younger, more active and/or overweight, sometimes a doctor may recommend a rotating platform/mobile-bearing knee replacement designed for potentially longer performance with less wear. Doctors also consider gender, occupation, disability level, pain intensity, interference with lifestyle and other medical conditions in selecting the appropriate prosthesis.

Difference is bearing surface

Like fixed-bearing replacements, mobile-bearing knees use three components to provide a relatively natural and even interface. The difference is the bearing surface. In a mobile-bearing knee replacement, both the metallic femoral component and metallic tibial tray move across a polyethylene insert to create a dual-surface articulation. The insert absorbs forces across a larger contact surface, helping reduce the amount of wear to the bearing and loosening in places where the prosthesis attaches to bone.

Advantages:

Mobile-bearing knee replacements can reduce early wear failure caused by high contact stress and early loosening failure caused by over-constraint. The insert's mobility ensures congruent contact between the femoral and tibial components and conformity of the surfaces that move together when you bend and rotate your knee during activity. The mobile-bearing insert lets you move the knee from both the thighbone and shinbone. You can also rotate the shinbone slightly.

Disadvantages:

Compared with fixed-bearing designs, mobile-bearing knee implants are less forgiving of imbalance in soft tissues. They may increase the chance of dislocation and may cost more than fixed-bearing implants.

Description

Total knee arthroplasty (or replacement) is a surgery that is performed for severe degeneration of the knee joint. More than 300,000 people a year undergo the procedure. Minimally invasive total knee arthroplasty is a method of performing a knee replacement through a smaller incision.

Knees wear out for a variety of reasons, including inflammation from arthritis, injury or simply wear and tear. A knee replacement is the resurfacing of the worn out surfaces of the knee, replacing the cartilage that has been lost with metal and plastic. This is typically done through an incision down the center of the knee that averages 8" to 10" long. Minimally invasive total knee arthroplasty is a way of performing the surgery through a incision that is only 4" to 6" long, with potentially less damage to the tissue around the knee.

Risk Factors/Prevention

Although arthritis can run in families, most arthritis is due to a lifetime of wear and tear on the knees. The reasons that some people get severe arthritis and others don't, or even why one of a person's knees gets arthritis while the other does not aren't known. Some known causes are previous injuries or obesity. Symptoms

Knee arthritis leads to pain that is often associated with activity but can occur at rest. Patients often find it difficult to go up or down stairs, walk distances, get up from low seats. There can be associated swelling, stiffness or a feeling of instability.

Nonsurgical Treatment Options

The first step in treating knee arthritis is activity modification and a program of regular exercise and weight loss. The muscles around the knee protect it during activity and every step puts several times your body weight through your knee. Soft knee braces and modifications of your shoe can sometimes help. Anti-inflammatories (NSAIDs) are usually the first medications recommended for arthritis. Some dietary supplements also might be helpful. The use of a cane or walker may also help to assist walking and improve mobility.

The next step is injections of either steroids (to decrease inflammation) or a lubricant (to improve the function of the knee). These can offer some relief and be repeated intermittently if helpful.

Surgical Treatment Options

Surgery is the final step in the treatment of knee arthritis. A knee replacement can help to eliminate most of the pain from arthritis and is indicated if the steps above have failed and the pain from the arthritis is limiting your lifestyle and activities.

Surgical options include knee arthroscopy (although this is rarely indicated just for arthritis), partial knee replacement and total knee replacement.

Total knee replacement can be performed in the traditional way, through an 8"- to 10"- incision or by using newer techniques, through a 4"- to 6"-incision. The goal of knee replacement is to provide a pain-free knee that allows relatively normal activities and lasts as long as possible. In order to achieve these goals it is extremely important that the knee replacement be inserted in the best possible position and with the bone and ligaments prepared very carefully to allow it to be functional and durable. Using the current techniques, 90 percent to 95 percent of knee replacements should last 15 years or longer.

The minimally invasive knee replacement technique attempts to accomplish all of this through a smaller incision. With the smaller incision come the potential benefits of a shorter hospital stay, a shorter recovery and a more cosmetic scar. There is no reason to believe that the knee will function any better. In fact, although there is no question that a knee can be put in through a smaller incision, it is still unknown whether it can be done as well.

One recent very early study of 70 minimally invasive total knees found that patients may have less blood loss, shorter hospital stays and better motion. Unfortunately, we won't know if these new techniques affect the long-term function and durability of the knee replacement for 10 to 15 years. Long-term durability is much more important than whether you were in the hospital for 2 days or 4 days after surgery.

Research on the Horizon

To address concerns about accurate positioning of the knee replacement, advocates of minimally invasive knee replacement are working on combining the small incision with computer-guided instruments. The potential benefits, risks and costs of this have yet to be established.

Severe degenerative joint disease (DJD) of the knee results in pain, limited function, and a poorer quality of life. Total knee arthroplasty (TKA) is a safe and effective treatment of severe DJD of the knee. Patient satisfaction rates after TKA range from 90% to 95%.[1,2] The high satisfaction rate is dependent on the following factors:

• patient selection;
• implant design;
• surgical technique; and
• postoperative rehabilitation and compliance.

However, TKA can fail, requiring that the patient undergo revision surgery. Annually, 35,000 TKAs are revised worldwide.[3] The published literature finds the following as the causes for failure of TKA:

• Infection;
• Loosening;
• Instability;
• Patellofemoral complications;
• Prosthesis fracture; and
• Polyethylene wear.[4-6]

At The American Academy of Orthopaedic Surgeons 69th Annual Meeting, held in Dallas, Texas in February 2002, Dr. Peter F. Sharkey, from Philadelphia, Pennsylvania, and his colleagues[3] presented data describing the mechanisms of failure in a series of revision TKAs performed between September 1997 and October 2000. These investigators conducted a retrospective review of 212 consecutive TKAs in 203 patients who underwent total knee revision at the Rothman Institute in Philadelphia, Pennsylvania. The average age was 68 years for both males and females.

The causes for failure were determined based on preoperative history, physical examination, and radiographic and intraoperative findings. Dr. Sharkey divided the failures into early (less than 2 years from primary surgery) and late (greater than 2 years). Early revision made up 56% of the cases, and 46% were late. The need for revision in this series is summarized in the following table.

*More than 1 cause may exist for each revision.

The most prevalent overall mechanism of failure was polyethylene wear; significant wear was noted in 25.1% of all revisions. However, there was a difference between early and late revisions. Polyethylene wear was found in the early revision group, but significant wear was found only in 11.8% of the patients. The primary mode of failure requiring revision for patients in the early failure group was instability or malalignment due to infection. Infection was responsible for 25.4% of all early revisions. In the late failure group, infection occurred in only 7.8% of the cases. Component loosening was a common cause of both early and late knee arthroplasty failure: 16.9% and 34.4%, respectively. Instability was noted in 21.2% of early and 22.2% of late revision knees.

Significant stiffness associated with arthrofibrosis after total knee arthroplasty was found in 16.9% of patients in the early revision group and in 12.2% of patients who had late revision surgery.

A total of 11.9% of early and 12.2% of late revision knee arthroplasties had component malalignment or malposition resulting in an overall percentage of 11.8%. Revision after periprosthetic fracture accounted for 2.8% of all revisions.

The following figure was presented by Dr. Sharkey and lists the different types of failure mechanism and the affected percentage in each group (early vs late).

The authors concluded that:

• While knee replacement is one of the most successful procedures in reconstructive orthopaedic surgery, failure does occur, and when it happens, the impact is significant.
• Improvements on the manufacturing side, such as improved polyethylene or alternative-bearing surfaces, could diminish the rate of failure after total knee arthroplasty.
• In this series, polyethylene failure was the most common cause of failure, especially noteworthy in the late revision surgery group.
• Early failure after TKA is related to infection, instability, malalignment, or malposition of the knee components.
• Knowledge of the current mechanisms by which total knee arthroplasties fail would allow investigators to focus their efforts on pertinent problematic issues.
• Research efforts should be focused on determining the mechanisms for knee replacement failure and attention should be directed toward correcting these causes.