Knee replacement

An artificial knee joint is used to replace the damaged joint.

We offer advanced surgical techniques and expert aftercare to replace painful damaged knee joints and help you get back to everyday activities.

Sometimes also called

  • Patellofemoral replacement
  • Partial knee replacement (PKR)
  • Revision knee replacement
  • Total knee replacement (TKR)
  • Unicompartmental knee replacement

At a glance

  • Typical hospital stay
    2–5 days

  • Procedure duration
    1–2 hours

  • Type of anaesthetic
    General, spinal or epidural

  • Available to self-pay?

  • Covered by health insurance?

Why Spire?

  • Fast access to diagnostic tests and scans
  • Consultants who are experts in their field
  • Clear, inclusive pricing
  • 98% of our patients are likely to recommend us to their family and friends

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2021

What is knee replacement?

A knee replacement is a common operation to remove worn or damaged parts of your knee joint and replace them with an artificial joint, to help you move more easily and to reduce pain.

Pain is often caused by wear or damage, usually as a result of osteoarthritis but can also be caused by:

  • Avascular necrosis – death of the knee joint due to a lack of blood supply
  • Bone dysplasia (unusual bone growth)
  • Gout
  • Haemophilia
  • Knee deformity or injury
  • Rheumatoid arthritis

Who needs knee replacement surgery?

Getting older increases your risk of needing knee replacement, but genetics, previous knee injury and lifestyle can play a part, so always seek medical advice if you have symptoms.

Your doctor may recommend knee replacement if:

  • You find it difficult carrying out everyday tasks
  • You have depression due to pain or reduced mobility
  • You’re unable to work or socialise
  • Your mobility is reduced
  • Your quality of life is impacted, including your sleeping

Knee replacement surgery can relieve pain and help you become more active again.

Alternative treatments to knee replacement

Your doctor may suggest an alternative surgical procedure, though the results may not last as long. These treatments are often performed using arthroscopy – a type of keyhole surgery using a thin, flexible, telescopic instrument called an arthroscope.

Alternative surgical treatments include:

  • Arthroscopic washout – flushing the knee joint with fluid using keyhole surgery, often performed with debridement (removal of loose bone or cartilage), although this is less common than it used to be
  • Osteotomy – the shin bone is cut and realigned to reduce the weight carried by the damaged part of your knee
  • Mosaicplasty – transferring healthy cartilage taken from the edge of your joint to the damaged area
  • Microfracture – your surgeon makes small holes in your bones to stimulate cartilage growth
  • Ligament surgery – to reconstruct damaged ligaments

Your doctor will usually only recommend surgery after you’ve tried other non-invasive treatments without success. Other treatments include:

You’ll need an X-ray to show any wear or damage to your joint. Our fast diagnostics means you won’t have to wait long to find out whether knee replacement surgery is right for you. Your consultant will discuss what would be best for you and your lifestyle, so it’s a good time to talk about what you want.

As well as the potential benefits of reducing pain, increasing mobility and improving your quality of life, you should consider:

  • Your new knee joint may eventually need revision surgery after about 20 years
  • As with all major surgery, there are some risks of complications
  • You’ll be less mobile for the first few weeks after the operation so you may need some help around the house and with errands
  • Your new joint won't be able to bend as far as a natural knee

Find your nearest Spire hospital

Almost all our hospitals offer knee replacement surgery and have teams of orthopaedic (bone and muscle) surgeons who specialise in this procedure.

Spire Nottingham Hospital

How knee replacement works

In a healthy knee joint

The ends of your bones and kneecap are covered in smooth cartilage – tissue that helps your bones glide easily across each other.

In an unhealthy knee joint

The cartilage is worn away, causing damage to the ends of your bones at the joint and making it painful and difficult to move.

Knee replacement surgery

Before your operation, you should try stay as active as possible and try strengthening muscles around your knee to help your recovery.

During the operation, your surgeon removes your damaged cartilage and the ends of your bones and replaces them with an artificial joint made of metal and smooth plastic (a prosthesis). The prosthesis is measured to fit your joint beforehand.

The surgery is carried out under a general anaesthetic or a spinal or epidural anaesthetic where you’re awake but can’t feel anything below your waist.

There are two main kinds of knee replacements: total knee replacement surgery and partial knee replacement surgery.

Total knee replacement

Your surgeon will make an incision below your knee and replace both sides of your joint, and sometimes your kneecap. The procedure takes up to three hours. Your surgeon replaces the end of your thigh bone with a curved piece of metal and your shin bone with a flat metal plate. A plastic spacer is positioned between the two metal parts to reduce friction as you bend your knee.

Partial knee replacement

If you have less damage, your surgeon may only need to replace just one side of your joint using a partial knee replacement. Recovery will usually be faster and you may have more mobility improvements than with a total knee replacement.

For partial knee replacement, your surgeon may perform mini-incision surgery using smaller cuts and instruments to improve recovery time.

As well as total and partial knee replacement, there are other procedures that may be suitable.

Kneecap replacement

Also called a patellofemoral replacement or patellofemoral joint arthroplasty, this is a less complex surgery than a knee replacement if only your kneecap is damaged.

Complex or revision knee replacement

If you have major bone loss, a deformity or ligament weakness, you might need a complex knee replacement. The artificial joint has a longer stem that fixes into your bones, and additional components that can give you more stability. This type of surgery is also sometimes used if you need to have a knee replacement redone.

Advances in surgery

Exciting recent advances mean that surgeons can often operate using smaller incisions, so there’s less impact on your surrounding muscles and tendons and you’ll recover more quickly. Artificial joints (prostheses) can even be created using MRI scans and 3D printing to tailor the size and shape to your knee.

Some of our hospitals also use computer assisted (image-guided) surgery to enable the surgeon to position the replacement more precisely. Some hospitals also use pre-programmable robotic arms to help fit your joint.

Knee replacement surgery

Watch how a knee replacement surgery takes place

Play video
View transcript of this video Hide video transcript

This video explains what happens during a hip replacement surgery. A hip replacement is a common operation to remove worn or damaged parts of your hip joint and replace them with an artificial joint. It is often recommended if other treatments such as physiotherapy or steroid injections haven't helped reduce pain or improve mobility.

Your hip is the joint between the thigh bone or femur and the pelvis. The pelvis contains three bones called ilium, ischium, and pubis. 

The hip joint is a ball-and-socket joint. The round head of the femur rests in a cavity, the acetabulum, that allows the rotation of the limb. The surface of these bones is coated with smooth, slippery cartilage also called articular cartilage which protects and cushions your bones allowing them to move easily next to each other.

When the cartilage is worn or damaged, the bones rub against each other causing pain and lack of mobility. Under an aesthetic, the surgeon will remove both the socket and the top of your thigh bone. The replacement components are the metal head and a plastic cup which are then inserted back into the socket of your pelvis.

A replacement ball on a stem will be inserted into your thigh bone. The ball is then placed into the socket putting your hip joint back together. 

The surgery usually takes around 90 minutes. You should be able to leave the hospital after three to five days.

For the first weeks after the surgery, you'll need a walking aid such as crutches to help support you. Physiotherapy will help strengthen your muscles and ensure your new hip works at its best. For more information, contact your local Spire hospital or visit the Spire Healthcare website.

Your operation: what to expect

Who will be involved?

As well as your chosen surgeon, your care team will include:

  • A physiotherapist – before and after surgery
  • A consultant radiologist – an expert in assessing images taken during scans (such as X-ray or MRI)
  • An anaesthetist – to administer anaesthetic during the operation

A physician is also available to see you if you have any medical issues or complications after surgery.

Preparing for your knee replacement operation

Your consultant or physiotherapist will recommend exercises you can do to strengthen the muscles around your knee before surgery to improve your recovery time. It’s also a good idea to prepare your home for after your operation to make it easier for you to get around safely and more easily – remove anything you can trip over and make sure important items are easy to reach. Research what’s involved with a knee replacement surgery so you can ask your care team any questions and know what to expect on the day and during your recovery.

Before your operation, you’ll have a pre-operative assessment appointment with a nurse to check your general health before surgery and discuss any medications you’re currently taking that you may need to stop or adjust before surgery.

Most knee replacement surgery is carried out using general anaesthetic. Typically, you must not eat for about six hours or drink for two hours before general anaesthesia. However, you will be told to avoid certain fluids (milk) and water or black tea or black coffee is usually recommended. You’ll also need to wear compression stockings during and after surgery to avoid blood clots in your leg while you’re immobile.

How long does knee replacement surgery take?

Usually between one and three hours, depending on whether you’re having a total knee replacement or a partial knee replacement.

Anaesthetic choices

Your consultant will help you decide what anaesthetic is best for you. You'll have either a general, spinal or epidural anaesthetic, so you’ll be fully unconscious or awake but unable to feel anything from the waist down. If you have the spinal or epidural options, you may have a sedative to help you feel more relaxed.

Pain after knee replacement

Everyone experiences pain differently and you’re likely to feel discomfort for some time afterwards. But don’t worry, you’ll be given painkillers after the operation and we can help you to manage any pain in the following days and weeks.

Your hospital stay

The average hospital stay is two to five days, with total knee replacements requiring longer than partial knee replacements.

Q & A

Winston Kim, Consultant Orthopaedic Surgeon

Talking about knee replacement surgery

Your recovery: what to expect

Recovery can take several months and you’ll need to do knee replacement exercises and have physiotherapy regularly to improve your mobility.

Short term side effects

There’ll be some pain in your knee after the operation so you’ll be given painkillers and you can continue to take over-the-counter painkillers when you’re home. Your knee, legs and feet may be swollen – you can try keeping your leg raised or using an ice pack in a tea towel for 20 minutes every three to four hours to help.

You’ll need someone to take you home and help with errands around the house for the first few days as you regain some mobility. The stitches in your knee will need to be removed around 10 to 12 days after your operation or they’ll gradually disappear if they’re dissolvable stitches.

Physiotherapy and ongoing treatment

Soon after surgery, our physiotherapist will take you through a series of exercises designed to strengthen the muscles around your new knee and improve and optimise movement of the joint. It’s important you carry on doing them after you’ve left hospital. This will help speed up your recovery so you can enjoy normal activities again.

Your lifestyle after treatment

Many people enjoy a full and active life after knee replacement surgery. You can take part in most low-impact sports, although your consultant will tell you if you need to wear a leg brace.

Our team will support you all the way to get the most from your surgery.

How long does a knee replacement last?

Most knee joint replacements last for 20 years or more.

Risks and complications

Most people have knee replacement surgery without complications, but all surgery carries risks and your consultant will explain them to you before you go ahead.

Short term side-effects include:

  • Pain
  • Swelling
  • Weakness

You’ll have some scarring, which will gradually fade with time.

Complications can include:

  • Abnormal bone growth
  • Blood clot – this is a medical emergency and symptoms include chest pains and breathlessness
  • Excess scare tissue
  • Failure of artificial knee joint
  • Fracture
  • Infection of the knee joint
  • Joint stiffness and instability
  • Limited relief of pain
  • Nerve damage
  • Numbness
  • Unexpected bleeding into your knee joint

Risks of general anaesthetic

Serious complications associated with general anaesthetic do occur, but they're extremely rare. For most people, the benefits in terms of controlled unconsciousness and removal of pain are much greater than the disadvantages. It’s estimated that serious complications result in approximately four deaths for every million anaesthetics given. The pre-operative assessment is carried out to limit the risk of any complications occurring.

At Spire hospitals, your safety is our top priority. We have high standards of quality control, equipment and cleanliness and an ongoing system of review and training for our medical teams.

Treatment and recovery timeline

Although everyone's different, here’s a rough guide to total knee replacement recovery time:

View interactive timeline View full timeline

Day 1

You should be able to stand using a walking aid

2–5 days

You’ll be able to leave hospital

1 week

Able to walk independently with crutches

4–6 weeks

May be able to drive (check with your car insurance company)

6 weeks

Able to walk without crutches

3 months–1 year

Usually free from pain and swelling

2 years

Full recovery as scar tissue is healed and muscles restored by exercise

  • Day 1

    You should be able to stand using a walking aid

  • 2–5 days

    You’ll be able to leave hospital

  • 1 week

    Able to walk independently with crutches

  • 4–6 weeks

    May be able to drive (check with your car insurance company)

  • 6 weeks

    Able to walk without crutches

  • 3 months–1 year

    Usually free from pain and swelling

  • 2 years

    Full recovery as scar tissue is healed and muscles restored by exercise

Frequently asked questions

How soon will I be up and about?

You’ll be helped out of bed to stand around 12 to 24 hours after your operation. You can then walk with a frame or crutches and should be able to do so independently after a week. If you’ve had keyhole surgery or are on an enhanced recovery programme, it may be sooner.

A physiotherapist will show you some exercises you can do to help strengthen your knee that you can start the day after surgery.

How long will it be before I feel normal?

It can take up to two years for your knee to recover, however, you should be able to resume normal daily activities within six weeks and any pain and swelling should settle within three months. Your leg may be swollen for up to a year.

When can I drive again?

You shouldn’t drive until it’s safe for you to do so – this means you should be able to comfortably make an emergency stop and be free from the sedative side effects of any painkillers. This is usually four to six weeks after your operation. Many insurance companies don’t insure you for a number of weeks after an operation, so make sure you check before you drive.

When can I go back to work?

Working can help your recovery by keeping you active. If you have a desk job, you can usually return to work around eight weeks after your operation, but it can be up to 12 weeks if you have a more physically active job.

When can I do housework?

You should be able to get back to most daily activities including light chores after six weeks. Avoid standing for too long to avoid ankle swelling and don’t stretch or bend down. You should avoid any heavy lifting or strenuous activity for three months after your operation.

How will it affect my sex life?

There’s no set time when it’s safe to have sex. You should treat it like any other physical activity during your recovery and gradually build up to it and only if it feels comfortable. Make sure you follow your physiotherapists advice about what movements to avoid.

Will I have to go back to the hospital?

You’ll return to hospital a few weeks after your operation for a follow-up appointment to check your recovery progress.

Will I need another new knee?

For most people, their new knee lasts around 20 years or even longer for total knee replacement. Partial knee replacements tend to need to be replaced sooner – after around 10 years. The chances of needing a repeat operation is higher if you’re overweight, you run, play vigorous sports or you conduct heavy manual work.

Are there any sports or activities I shouldn't do after my knee replacement?

You should gradually build up any activity, and should be able to manage walking or swimming around six to eight weeks after surgery, depending how fit you were before surgery. You should avoid high impact sports such as running, contact sports or weight lifting. Your consultant or physiotherapist will be able to advise which sports you can do, they may recommend avoiding tennis, squash and skiing, but cycling, dancing and golf may be fine.

How can I make my recovery easier?

Preparing for your surgery by being as fit as possible and strengthening your knee muscles will help improve your recovery time. Before your operation, it’s also a good idea to prepare your home to make it easier for you to get around safely and more easily. Remove anything you can trip over and make sure important items are easy to reach.

For the first few days or weeks at home, you may need someone to help you with errands and household chores.

When can I fly after knee replacement surgery?

Speak to your consultant or GP before flying to find out what’s right for you. It’s important to note that your chance of deep vein thrombosis (DVT) increases if you fly after recent surgery.

Airlines have their own regulations about passengers flying after surgery, so make sure you check beforehand.

What are knee implants made from?

Knee implants are made from high-grade plastics, polymers and metal alloys.

The treatment described on this page may be adapted to meet your individual needs, so it's important to follow your healthcare professional's advice and raise any questions that you may have with them.

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