Arthritis and surgery: knee replacement

How does arthritis affect the knee?

According to Arthritis Australia, arthritis is the major cause of disability and chronic pain in Australia today. The most common form of arthritis is osteoarthritis (OA). This results from the breakdown of cartilage (a smooth, cushioning substance) on the end of bones where they meet to form a joint, making the normally smooth surface rough or uneven. Although the frequency of symptoms and severity of OA can vary among people, OA of the knee may lead to stiffness and pain around the knee joint, clicking, locking, unsteadiness, muscle weakness and pain when walking or standing.

Other possible causes of pain and loss of function in the knee include:

  • rheumatoid arthritis (RA), which occurs when the synovial membrane (thin, smooth tissue in the knee) becomes inflamed and overproduces synovial fluid which then increases the pressure within the joint, which may lead to cartilage damage; and
  • knee injury. Arthritis of the knee can develop following a severe injury to the knee. Knee fractures, torn ligaments or meniscal tears can lead to cartilage damage.

For some people affected by OA of the knee, replacement surgery (also known as a knee arthroplasty) may offer an improvement in their quality of life through reduced pain and increased mobility.

Who may require a knee replacement?

If you suffer from severe arthritis of the knee that remains painful despite medication, exercise, rest and supports to assist your mobility, you may benefit from a total knee replacement. The main indication for knee replacement is unrelieved pain — if you are adequately mobile and your pain is manageable, you probably do not need a knee replacement.

Your suitability for knee replacement surgery will be assessed based on your medical history and physical and X-ray examinations.

What does a knee reconstruction involve?

A knee replacement operation will usually take between one and 2 hours. After evaluation by an anaesthetist, you will be given either a general anaesthetic (which will cause you to fall asleep for the operation) or a spinal anaesthetic (where you remain awake but are anaesthetised from the waist down).

A knee reconstruction involves surgery to replace your knee joint with a prosthesis—an artificial knee joint. Mostly, these prostheses are made of plastic and metal, and consist of 3 main components:

  • femoral (thigh bone) component;
  • tibial (shin bone) component; and
  • patellar (knee) component.

The metal shafts of the femoral and tibial components are inserted to replace the end of the femur (thigh bone) and the top of the tibia (shin bone). On the end of the metal shafts is a polyethylene (plastic) coating which acts as replacement cartilage.

How long will my knee replacement last?

More than 90 per cent of knee replacements will last for more than 10 years, depending on your level of activity and weight. The heavier and more active you are, the more quickly they will wear out. Knee replacements can be replaced if they wear out, although revision surgery is generally more difficult than the initial replacement.

After the operation: recovery

Most people spend about 5 to 7 days in hospital, depending on their progress and rehabilitation. Your surgeon may provide you with a programme designed to prevent blood clots in the legs — a complication which can happen after knee replacement surgery. Some warning signs include:

  • an increase in swelling of the calf, foot or ankle;
  • the presence of a tender or red area above or below the knee;
  • pain in the calf muscle; and
  • shortness of breath, chest pain or collapse (if clots break off and travel to your lungs).

Although infection of the knee joint can occur, this is quite rare.

It is important to plan ahead for your recovery from knee replacement surgery. Here are some tips to help make your home accessible after surgery and to promote a fast recovery.

  • Install safety bars and handrails in your bathroom and on stairs.
  • Remove any loose floor coverings or electrical cords that could lead to a fall.
  • You may wish to use a raised toilet seat if you have a low toilet that is difficult to access.
  • A stable, firm chair and a footstool may help you during your initial recovery period.
  • You may need to use a cane, crutches or a walking frame for a few weeks following your surgery as your new knee may be sore.
  • You should be able to resume driving approximately 6 weeks after your surgery, although this can vary from person to person.
  • An appropriate exercise programme is essential following knee surgery to ensure strength and mobility are maintained. Suitable activities, which you can maintain for the rest of your life, include walking, swimming and golf. It is recommended you avoid sports that involve running, jumping or high impact. Talk to your doctor or surgeon about what activities are right for you.

Physiotherapists can help greatly with rehabilitation, while occupational therapists are helpful in making sure your home is safe and advising on any modifications or appliances that may be needed.

Talk to your family as well as your doctor

The decision to have knee replacement surgery should be discussed with family members who may be responsible for assisting you following the operation.

Knee replacement can be a successful option for many people experiencing pain related to arthritis of the knee: more than 90 per cent of people who have a total knee replacement improve their ability to perform everyday tasks and have reduced levels of knee pain.

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