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Why do I need a hip or knee joint replacement?

The most common cause of deterioration of the hip or knee joint is osteoarthritis; other conditions that can cause damage to a joint are rheumatoid arthritis and fractures (broken bones). Osteoarthritis is a common disease affecting the joints in the body, most commonly the knees and hip. The joint surfaces, which are covered in smooth cartilage, become damaged, gradually get thinner and roughen  and this produces pain. Eventually, there may be no cartilage left in some areas of the joint.

Healthy Hip

Healthy hip

Osteoarthritic Hip

Osteoarthritic hip

 Healthy Knee

Healthy knee

 04 Osteoarthritic Knee

Osteoarthritic knee

What is a total hip replacement?

A total hip replacement is a surgical procedure for replacing the hip joint. The hip joint is made up of two parts, the hip socket (acetabulum, a cup shaped bone in the pelvis) and the "ball" or head of the thigh bone (femur). During the operation, these two parts are removed and replaced with smooth artificial surfaces. These artificial pieces (the prosthesis) are implanted into healthy portions of the pelvis and thigh bone. The total hip replacement operation is designed to relieve pain, reduce stiffness and improve your ability to walk.

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What is a total knee replacement?

A total knee replacement is a surgical procedure for replacing the knee joint. The knee joint 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. During the operation, these parts are removed and replaced with smooth artificial surfaces.

If required, a plastic button is put on the knee cap. A partial knee replacement only replaces the worn part of the knee. The total and partial knee replacement operations are designed to relieve pain, reduce stiffness and improve your ability to walk.

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What can be expected after a total knee or total hip replacement?

A total knee or hip replacement will provide a large reduction in pain in 90% of patients and allow patients to carry out normal daily activities. Most total joint replacements last over 10 years (95%). The artificial joint may or may not allow you to return to active sports or heavy labour and you must be guided by your surgeon. Taking part in high impact activities and being overweight may speed up the wear and tear process, which could result in the artificial joint loosening and becoming painful. Your surgeon will advise you on what level of activity you can do.

The aim of surgery is for you to be able to resume your normal everyday activities without pain, including climbing stairs and walking. It is also possible to participate in recreational walking, swimming, golf, driving, light hiking, cycling and ballroom dancing.

Activities not suitable include jogging or running, contact sports, jumping sports and high impact aerobics. The reasons for this are that the knee or hip replacement will wear out more quickly or an injury involving the replacement may be difficult to treat.

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What complications (risks) can occur?

This section is not meant to frighten you, but help you to make an informed decision on whether to have a total hip or knee replacement, and to help you cope better with any complications that may occur. It is important that you understand that there are possible risks linked with any major operation. Total hip or knee replacements are no exception.

Total hip or knee replacement surgery is usually very successful but a small percentage of patients may develop complications. Illness, smoking and obesity may increase the chance for complications.

Though uncommon, when these complications occur, they may delay or limit your full recovery.

Total hip or knee replacement surgery is usually very successful but a small percentage of patients may develop complications. Illness, smoking and obesity may increase the chance for complications.

Though uncommon, when these complications occur, they may delay or limit your full recovery.

Infection
An infection can occur in the wound or deep tissue around the prosthesis. This could happen while you are in hospital, after you go home and can even occur years later as any infection in your body can spread to your joint replacement. Minor infections are usually treated with antibiotics but major infections can sometimes require surgery and removal of the prosthesis.

Dislocation
Occasionally after a total hip joint replacement the head of the prosthesis can become dislodged from the socket. In most cases the hip can be relocated without surgery. The period that you are most at risk for dislocation is the first six weeks following surgery.

Blood clots, deep vein thrombosis (DVT)
This is the term used when a blood clot develops in the deep veins in the back of your lower leg. When detected the treatment may involve blood thinning injections followed by a course of tablets. There is about a 4% risk of developing a DVT following surgery.

Foot Drop
It is unusual to damage any major nerves or blood vessels. However, a nerve maybe stretched or damaged during surgery (this is called nerve palsy). This can result in a weakened lower leg or
a foot that drops down, over time nerve injuries may improve. This
complication is rare; occurring in less than 1:1000 patients.

Loosening of the prosthesis
Hip replacements do wear and some will require replacing. Wear or loosening of the components may occur between 10-15 years after surgery; this can be accelerated in excessive activity or obesity. Revision operations can usually be performed; however the results may not be as good as the initial operation and the risks or complications are greater.

Difference in leg length
Your surgeon will do their best to ensure that your leg length is equal, however sometimes this is not always possible as arthritis or wear and tear may have destroyed some of your bone, which could cause your operated leg to become shorter. This may result in you needing to wear a raised shoe or insole.

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Reference Material

Ease your arthritis with - physical activity
With arthritis, everyday tasks can be challenging, and the idea of becoming more physically active could be daunting. Experiencing ongoing pain, joint stiffness and fatigue can be extremely discouraging. However studies show that regular and appropriate physical activity help improve pain tolerance, mood and quality of life for people with arthritis.
A good physical activity programme is possible for people of all abilities, sizes, ages and attitudes; for more information please read this information from www.arthritis.org.nz.

Educational videos for hip and knee replacement can be viewed on the Ministry Of Health (MOH) website. The videos are designed to provide you with information on how you can prepare for your operation, what to expect when you go into hospital and your recovery.
Follow this link for Knee/hip replacement - Patient education videos

You may also find the information contained in this internet link useful.
View Youtube - DrMikeEvans - hip and knee surgery

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Last updated: February 27, 2017