ANATOMY

Large ligaments hold the femur and tibia together and provide stability. The long thigh muscles give the knee strength.

All remaining surfaces of the knee are covered by a thin lining called the synovial membrane. This membrane releases a fluid that lubricates the cartilage, reducing 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 reduced function.

COMMON CAUSES OF KNEE PAIN

The most common cause of chronic knee pain and disability is arthritis. Although there are many types of arthritis, most knee pain is caused by just three types: osteoarthritis, rheumatoid arthritis, and post-traumatic arthritis.

Osteoarthritis: this is an age-related “wear and tear” type of arthritis. It usually occurs in people 50 years of age and older, but may occur in younger people, too. 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: this is a disease in which the synovial membrane that surrounds the joint becomes inflamed and thickened. This chronic inflammation can damage the cartilage and eventually cause cartilage loss, pain, and stiffness. Rheumatoid arthritis is the most common form of a group of disorders termed “inflammatory arthritis”.

Post-traumatic arthritis: this can follow a serious knee injury. Fractures of the bones surrounding the knee or tears of the knee ligaments may damage the articular cartilage over time, causing knee pain and limiting knee function.

Osteoarthritis often results in bone rubbing on bone. Bone spurs are a common feature of this form
of arthritis.

DESCRIPTION OF THE PROCEDURE

A knee replacement (also called knee arthroplasty) might be more accurately termed a knee “resurfacing” because only the surface of the bones are actually replaced.

There are four basic steps to a knee replacement procedure:

Prepare the bone: the damaged cartilage surfaces at the ends of the femur and tibia are removed along with a small amount of underlying bone;

Position the metal implants: the removed cartilage and bone is replaced with metal components that recreate the surface of the joint. These metal parts may be cemented or “press-fit” into the bone;

Resurface the patella: the undersurface of the patella (kneecap) is cut and resurfaced with a plastic button. Some surgeons do not resurface the patella, depending upon the case;

Insert a spacer: a medical-grade plastic spacer is inserted between the metal components to create a smooth gliding surface.

(Left) Severe osteoarthritis. (Right) The arthritic cartilage and underlying bone has been removed and resurfaced with metal implants on the femur and tibia. A plastic spacer has been placed in between the implants. The patellar component is not shown for clarity.

IS TOTAL KNEE REPLACEMENT FOR YOU?

The decision to have total knee replacement surgery should be a cooperative one between Orthopaedic evaluation you, your family, your family doctor, and your orthopaedic surgeon. Your doctor may refer you to an orthopaedic surgeon for a thorough evaluation to determine if you might benefit from this surgery.

WHEN SURGERY IS RECOMMEBDED

• Moderate or severe knee pain while resting, either day or night;
• Chronic knee inflammation and swelling that does not improve with rest or medications;
• Knee deformity – a bowing in or out of your knee;
• Failure to substantially improve with other treatments such as anti-inflammatory medications, cortisone injections, lubricating injections, physiotherapy, or other surgeries.

Candidates for surgery

There are no absolute age or weight restrictions for total knee replacement surgery. Recommendations for surgery are based on a patient’s pain and disability, not age. Most patients who undergo total knee replacement are age 50 to 80, but orthopaedic surgeons evaluate patients individually. Total knee replacements have been performed successfully at all ages, from the young teenager with juvenile arthritis to the elderly patient with degenerative arthritis.

Orthopaedic evaluation

An evaluation with an orthopaedic surgeon consists of several components:

Medical history: your orthopaedic surgeon will gather information about your general health and ask you about the extent of your knee pain and your ability to function;

Physical examination: this will assess knee motion, stability, strength, and overall leg alignment;

X-rays: these images help to determine the extent of damage and deformity in your knee;

Other tests: occasionally blood tests, or advanced imaging such as a Magnetic Resonance Imaging (MRI) scan, may be needed to determine the condition of the bone and soft tissues of your knee.

(Left) In this X-ray of a normal knee, the space between the bones indicates healthy cartilage (arrow). (Right) This X-ray of an arthritic knee shows severe loss of joint space and bone spurs (arrows).

Your orthopaedic surgeon will review the results of your evaluation with you and discuss whether total knee replacement is the best method to relieve your pain and improve your function. Other treatment options — including medications, injections, physiotherapy, or other types of surgery — will also be considered and discussed.

In addition, your orthopaedic surgeon 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

DECIDING TO HAVE KNEE REPLACEMENT SURGERY

Realistic expectations

An important factor in deciding whether to have total knee replacement surgery is understanding what the procedure can and cannot do.

More than 90% of people who have total knee replacement surgery 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 will not allow you to do more than you could before you developed arthritis.

With normal use and activity, every knee replacement implant begins to wear in its plastic spacer. Excessive activity or weight may speed up this normal wear and may cause the knee replacement to loosen and become painful. Therefore, most surgeons advise against high-impact activities such as running, jogging, jumping, or other high-impact sports for the rest of your life after surgery.

Realistic activities following total knee replacement include unlimited walking, swimming, golf, driving, light hiking, biking, ballroom dancing, and other low-impact sports.

With appropriate activity modification, knee replacements can last for many years (15-20 years).

Possible complications of surgery

The complication rate following total knee replacement is low. Serious complications, such as a knee joint infection, occur in fewer than 2% 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 full recovery.

Discuss your concerns thoroughly with your orthopaedic surgeon prior to surgery.

Infection

Infection may occur in the wound or deep around the prosthesis. It may happen while in the hospital or after you go home. It may even occur years later.

Minor infections in the wound area are generally treated with antibiotics. Major or deep infections may require more surgery and removal of the prosthesis. Any infection in your body can spread to your joint replacement.

Implant problems

Although implant designs and materials, as well as surgical techniques, continue to advance, implant surfaces may wear down and the components may loosen. Additionally, although an average of 115° of motion is generally anticipated after surgery, scarring of the knee can occasionally occur, and motion may be more limited, particularly in patients with limited motion before surgery.

Continued pain

A small number of patients continue to have pain after a knee replacement. This complication is rare, however, and the vast majority of patients experience excellent pain relief following knee replacement.

Neurovascular injury

While rare, injury to the nerves or blood vessels around the knee can occur during surgery.

PREPARING FOR SURGERY

Medical evaluation

If you decide to have total knee replacement surgery, your orthopaedic surgeon may ask you to schedule a complete physical examination with your family doctor several weeks before the operation. This is needed to make sure you are healthy enough to have the surgery and complete the recovery process. Many patients with chronic medical conditions, like heart disease, may also be evaluated by a specialist, such as a cardiologist, before the surgery.

Tests

Several tests, such as blood and urine samples, and an electrocardiogram, may be needed to help your orthopaedic surgeon plan 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. To reduce the risk of infection, major dental procedures (such as tooth extractions and periodontal work) should be completed before your total knee replacement surgery.

Urinary evaluations

People with a history of recent or frequent urinary infections should have a urological evaluation before surgery. Older men with prostate disease should consider completing required treatment before undertaking knee replacement surgery.

Physical ability evaluation

Your physiotherapist will evaluate your physical ability included joint motion, strength and cardio pulmonary function to develop a pre-operative programme optimising your surgery and your recovery

Social planning

Although you will be able to walk with walking aids soon after surgery, you will need help for several weeks with such tasks as cooking, shopping, bathing, and doing laundry

Safety precaution for home environment

Several modifications can make your home easier to navigate during your recovery. The following items may help with daily activities:

• 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 (and a height of 45 to 50 cm), 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.

YOUR SURGERY

You will most likely be admitted to the hospital the day before your surgery

Anaesthesia

After admission, you will be evaluated by a member of the anaesthesia team. The most common types of anaesthesia are general anaesthesia (you are put to sleep) or spinal, epidural, or regional nerve block anaesthesia (you are awake but your body is numb from the waist down). The anaesthesia team, with your input, will determine which type of anaesthesia will be best for you.

Procedure

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

Different types of knee implants are used to meet each patient’s individual needs.

(Left) An X-ray of a severely arthritic knee. (Right) The X-ray appearance of a total knee replacement. Note that the plastic spacer between the bones does not show up in an X-ray.

After surgery, you will be moved to the recovery room, where you will remain for several hours while your recovery from anaesthesia is monitored. After you wake up, you will be taken to your hospital room.

Your stay in the hospital

You will most likely stay in the hospital for 7-8 days.

Pain management

After surgery, your surgeon will prescribe medication to relieve your pain. This is very important to talk with your health caregiver such as doctors, nurses or physiotherapists when you experience pain to help you to be as much as possible comfortable and pain free. Your surgeon will also prescribe physiotherapy to manage your pain with free medication techniques. Well-adjusted exercise programme and walking will help you to reduce your pain along with RICE programme (Rest, Ice, Compression and Elevation), an ice compressive therapy. Talk with your surgeon if postoperative pain becomes a problem.

Blood clot prevention

Your orthopaedic surgeon may prescribe one or more measures to prevent blood clots and decrease leg swelling. These may include special support hose and blood thinners.

Foot and ankle movement also is encouraged immediately following surgery to increase blood flow in your leg muscles to help prevent leg swelling and blood clots.

Physiotherapy

Please refer to our brochure “Knee replacement rehabilitation”.

Most patients begin exercising their knee the day after surgery. A physiotherapist 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.

The day of surgery, you will meet your physiotherapist who will optimise your installation at bed for more independency, wil implement the ice compressive programme to limit pain and swelling, advise you ankle pump to reduce blood clot risk, and place your leg elevated.

The day following your surgery, you will perform the first stand with your physiotherapist and walk your first steps with walking aids. Then daily, your physiotherapist will help you to develop confidence and autonomy in walking, using your leg and for daily activities. The ice compressive programme will be continued daily until discharge. You may also use a machine called knee continuous passive motion. This machine will support your leg while bending and extending. This activity pain free will reduce your knee pain and swelling while recovering your knee motion

Preventing pneumonia

It is common for patients to have shallow breathing in the early postoperative period. This is usually due to the effects of anaesthesia, pain medications, and increased time spent in bed. This shallow breathing can lead to a partial collapse of the lungs (termed “atelectasis”) which can make patients susceptible to pneumonia. To help prevent this, it is important to take frequent deep breaths. Your nurse may provide a simple breathing apparatus called a spirometer to encourage you to take deep breaths.

YOUR RECOVERY AT HOME

The success of your surgery will depend largely on how well you follow your orthopaedic surgeon and your physiotherapist 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 12 days after surgery. A suture beneath your skin will not require removal.

Avoid soaking the wound in water until it has thoroughly sealed and dried. You may continue to bandage the wound to prevent irritation from clothing or support stockings.

Physiotherapy programme

After discharge, your surgeon may recommend to continue physiotherapy on an outpatient basis along with your home programme.

Please refer to our brochure “Knee replacement rehabilitation”.

Diet

Some loss of appetite is common for several weeks after surgery. A balanced diet, often with an iron supplement, is important to help your wound heal and to 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, standing, and climbing stairs;
• Specific exercisesseveraltimes 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 physiotherapist help you at home or in a therapy centre the first few weeks after surgery.

You will most likely be able to resume driving when your knee bends enough that you can enter and sit comfortably in your car, and when your muscle control provides adequate reaction time for braking and acceleration. Most people resume driving approximately four to six weeks after surgery.

AVOIDING PROBLEMS AFTER SURGERY

Blood clot prevention

Follow your orthopaedic surgeon’s instructions carefully to reduce the risk of blood clots developing during the first several weeks of your recovery. He or she may recommend that you continue taking the blood thinning medication you started in the hospital. Notify your doctor immediately if you develop any of the following warning signs.

Warning signs of blood clots

The 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 of pulmonary embolism

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

• Sudden shortness of breath
• Sudden onset of chest pain
• Localised chest pain with coughing.

Preventing infection

A common cause of infection following total knee replacement surgery is from bacteria that enter the bloodstream during dental procedures, urinary tract infections, or skin infections. These bacteria can lodge around your knee replacement and cause an infection.

After your knee replacement, you must take preventive antibiotics before dental or surgical procedures that could allow bacteria to enter your bloodstream.

Warning signs of infection

Notify your doctor immediately if you develop any of the following signs of a possible knee replacement infection:

• Persistent fever (higher than 38 °C 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.

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 have someone to help you until you have improved your balance, flexibility, and strength.

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

OUTCOMES

How your new knee is different

Improvement of knee motion is a goal of total knee replacement, but restoration of full motion is uncommon. The motion of your knee replacement after surgery can be predicted by the range of motion you have in your knee before surgery. Most patients can expect to be able to almost fully straighten the replaced knee and to bend the knee sufficiently to climb stairs and get in and out of a car. Kneeling is sometimes uncomfortable, but it is not harmful.

Most people feel some numbness in the skin around your incision. You also may feel some stiffness, particularly with excessive bending activities

Most people also feel or hear some clicking of the metal and plastic with knee bending or walking. This is a normal. These differences often diminish with time and most patients find them to be tolerable when compared with 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.

Protecting your knee replacement

After surgery, make sure you also do the following:

• Participate in regular light exercise programsto maintain properstrength and mobility of your new knee;
• Take special precautions to avoid falls and injuries. If you break a bone in your leg, you may require more surgery;
• Make sure your dentist knows that you have 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

Extending the life of your knee implant

Currently, more than 90% of modern total knee replacements are still functioning well 15 years after the surgery. Following your orthopaedic surgeon’s instructions after surgery and taking care to protect your knee replacement and your general health are important ways you can contribute to the final success of your surgery.

Sources – “the American Academy of Orthopaedics Surgeons”