Knee replacement

Knee replacement surgery involves removing damaged parts of your knee and replacing them with new parts made of metal and plastic.

Key points

  1. Knee joint replacement surgery is carried out if pain from severe arthritis or another injury to your knee stops you from doing your day-to-day activities.
  2. It is only offered when other treatments such as physiotherapy haven’t worked.
  3. People who actively participate in their care before and after surgery are likely to have a better recovery.
  4. There are many things you can do to take part in your care, starting from before your operation, during your stay in hospital and when you get home after discharge.
  5. You can improve the outcome of your surgery by getting yourself as fit and healthy as possible beforehand. This may include stopping smoking, exercising, eating a balanced diet and limiting or avoiding alcohol.

What is knee replacement surgery?

Knee replacement surgery replaces the damaged parts of your knee with new parts. Metal parts replace the ends of your femur (thigh bone) and your tibia (shin bone). A plastic part separates the two metal pieces.

(WebMD, 2019)

When is a knee replacement considered?

Knee replacement surgery is usually recommended if you have severe arthritis or a knee injury that causes disabling pain and other treatments, such as physiotherapy haven't helped reduce pain or improve mobility. The most common reason a knee needs replacing is osteoarthritis of the knee joint. You may be offered knee replacement surgery if:

  • you have severe pain, swelling and stiffness in your knee joint and your mobility is reduced
  • your knee pain is so severe that it interferes with your quality of life and sleep
  • everyday tasks, such as shopping or getting out of the bath, are difficult or impossible
  • you're feeling depressed because of the pain and lack of mobility
  • you can't work or have a normal social life.

You'll also need to be well enough to cope with both a major operation and the rehabilitation afterwards. 

Is a knee replacement right for me?

To decide whether a knee replacement is right for you, talk with your doctor about the risks and benefits of the surgery. Also, find out what you can do if you choose not to have surgery. The following summary is a guide. Also see Is a knee replacement right for you? 

What are the benefits of having knee surgery?

The aim of knee surgery is to relieve pain and decrease stiffness or deformity, and therefore help to improve your independence and quality of life. More than 90% (9 of every 10) patients who have knee replacement surgery experience less pain and greater mobility in their knee after the procedure. 

Are there any risks to having knee surgery?

As with all surgeries, complications sometimes occur with knee replacement surgery. Smoking, obesity or some illnesses may increase your chance of
complications. Complications include the possibility of blood clots or deep venous thrombosis (DVT) of the veins in your legs or pelvis, bleeding, infection, joint stiffness, or loosening and wear of the knee replacement. Though uncommon, when these occur they may delay or limit your full recovery.

Preparing for knee replacement surgery

The better prepared you are for surgery, physically and emotionally, the quicker you will recover from it. Recovery from surgery is not the same for every person. Some people recover faster than others depending upon their age, health status, personal motivation and response to rehabilitation. The following video gives a good explanation about how to prepare for surgery and what to expect during and after the operation.

(Ministry of Health NZ, 2015)

Recovering from knee replacement surgery

Many district health boards (DHBs) have introduced a new way of caring for people who need a hip or knee joint replacement. This is called ERAS –Enhanced Recovery After Surgery. The ERAS pathway of care starts when you and your doctor decide that you need surgery and continues through to your rehabilitation at home or in the community. The approach covers a number of evidence-based interventions that aim to ensure you:

  • are in the best possible condition for surgery
  • have the best possible management during and after your surgery
  • participate in the best possible rehabilitation after surgery.

You are encouraged to be a partner in your own care. The sooner you get out of bed and begin to walk, eat and drink after your operation, the quicker and more comfortable your recovery will be. You return home earlier to your normal life, work and play. All going well, you are likely to return home after 2 to 4 nights in hospital. Read more about ERAS.

How can I be involved in my surgery?

Research has shown that people who actively participate in their own care before and after surgery are likely to have a better recovery. There are many things you can do to take part in your care, starting from before your operation, during your stay in hospital and when you get home after discharge. Your ERAS booklet will give you more details but here is a summary of what to expect and the sorts of things you can do. 

Knee surgery What to expect and things you can do
Before your surgery Things you can do
  • Attend the pre-admission clinic – most people have their first assessment for their fitness for surgery with a nurse in a pre-admission clinic. This clinic typically takes place about 4 to 6 weeks before admission. 
  • Find out as much as you can about what's involved in your operation. Your hospital should provide written information or videos.
  • It's a good idea to take along one key person to your appointments, so they know what is happening and can support you. The more you inform family/whānau and friends about your health, the more helpful they can be.
  • Get yourself as fit and healthy as possible before surgery by stopping smoking, exercising as advised by your doctor, eating a balanced diet and limiting or avoiding alcohol.
  • Your anaesthetist will talk to you about your health, the types of anaesthetic and pain relief that can be used, and their risks and benefits. Consent for your anaesthetic will also be sought at this time.
  • Ask questions about what to expect after surgery.     
While in hospital  What to expect
  • Before your operation, you will see your anaesthetist and surgeon. You may like to ask them questions. It's a good idea to have your questions written down as you may not remember them on the day.
  • Your surgeon or their registrar will review and confirm your operation details and will mark the operation area with a marker pen.
  • Your anaesthetist will also explain the anaesthetic options available to you.
  • You will be fitted with a thrombo-embolic deterrent stocking on the leg that isn’t being operated on. This helps to keep your blood flowing while you are not mobile.
  • Your blood pressure, temperature and heart rate will be taken. You will be washed with a disinfecting solution.
  • After your operation, you will be encouraged to get up and move as soon as it is practical and safe.
  • Research shows that moving early reduces some complications of big operations and starts you on the road to a quicker recovery.
  • You will be shown simple exercises that you can do in bed and you will be assisted to sit in a chair for all your meals.
  • You will be assisted by staff to walk short distances with crutches or a walking frame, once your anaesthetic has worn off and staff have assessed that you are safe to move.
  • Your rehabilitation and mobilisation will be supervised by a physiotherapist.
Things you can do
  • Do your exercises to assist you in your recovery.
  • Give yourself a goal to achieve every day. 
  • Ask questions if you have any concerns.
Discharge What to expect
  • You will be discharged on day 3 after your operation.
  • Usually, this is done in the morning. If you need to wait for transport you may be moved to the discharge lounge.
  • A physiotherapist may visit you to ensure that you can do your exercises independently and walk safely with crutches or a frame.
  • You may also be seen by an occupational therapist, who will ensure you can manage essential everyday tasks, such as getting on and off a bed, chair and toilet.
  • You will be given advice about looking after your knee at home. 
  • Most people can stop using walking aids around 6 weeks after surgery, and start driving after about 8 to 12 weeks.
Things you can do
  • Make sure you understand how to take care of yourself and your knee, eg, how to take care of the operation site, how to take your pain relief, what side effects to expect from the medication and what to do about them, etc.  
  • Getting support from family/whānau and friends is important for your recovery. The more you tell them about your condition and what you need, the more helpful they can be.
  • Give yourself a goal to achieve every day. 
  • Do your exercises to assist you in your recovery.
  • Attend follow-up clinics.
  • If you have any concerns about your health after you are discharged from hospital, seek advice from your GP or an after-hours clinic or the emergency department at your nearest hospital.

Learn more

Total knee replacement: a guide for patients ERAS, Ministry of Health, NZ
A checklist for patients having hip or knee replacement surgery ERAS, Ministry of Health, NZ

Credits: Health Navigator. Reviewed By: Based on Enhanced Recovery After Surgery (ERAS) & Ministry of Health NZ, 2013 Last reviewed: 28 May 2019