Knee Replacement Surgery

Learn everything about your treatment

What Is Knee Replacement Surgery

A knee replacement is a commonly performed surgical procedure. The medical name for it is a knee arthroplasty. Both men and women who suffer with severe knee pain often choose to have this surgery. Often, their suffering is due to arthritis of the knee joints. This can cause pain and stiffness and as a result, they may struggle with mobility.

  • Overview

    Procedure time

    1 to 2 hours


    Overnight stay

    3 to 5 nights



    General or local with sedation


    Recovery time

    3-9 months

    A knee replacement involves removing parts of your knee joint and inserting artificial replacements. These artificial knee parts are commonly made up of metal or plastic. This knee replacement overview aims to help you understand the reasons why you may need a knee replacement. Furthermore, it will also educate you on the types of knee replacement you can have.

    The knee joint

    It can be very useful for you to understand the details of what is currently wrong with your knee joint. Often, it helps explain why you may benefit from a knee replacement. Therefore, we would like to start by explaining a bit about the knee joint and how it works.

    The lower end of your thigh bone (femur) and the upper end of your skin bone (tibia) connect to form your knee joint. In a fully functioning, healthy knee joint, a smooth cartilage covers the ends of each bone where they meet. This allows the bones to glide over each other, producing a smooth, easy, pain-free movement of the knee.
    If your cartilage experiences injury or wears away with time, movements of the knee can become stiff and painful. Without the cartilage there to smooth their movement, the two bones of the knee joint now rub together. This can be very painful and can cause the joint to swell.


    What can a knee replacement achieve?

    During a knee replacement, your surgeon will remove the damaged bone and cartilage from your knee joint. They will then replace the them with new, artificial parts. A knee replacement often produces an improvement in a patient’s quality of life. After the surgery, you should experience less pain and notice an improvement in your mobility. As a result, you may also experience an improvement in your mental health. There are two main types of knee replacement available:

    A total knee replacement

    A total knee replacement is the most common type of knee replacement. Your surgeon will remove both the bottom of your thigh bone (femur) and the top of your shin bone (tibia) along with any cartilage that remains. In addition, they may have to replace the surface on the back of your kneecap. However, this is typically not necessary.
    You are more likely to experience medical complications after a total knee replacement. Your incision will also be larger and your hospital stay and recovery time will be longer. However, you are also less likely to require further knee surgery after a total knee replacement. Your surgeon will help you to decide which approach is best for you.

    A partial knee replacement

    Another type of knee replacement is a partial knee replacement. This involves replacing only one side of your knee joint, either the inside (medial) or the outside (lateral). Therefore, if you have a partial knee replacement, your surgeon will only remove part of the bottom of your thigh bone (femur) and part of the top of your shin bone (tibia) on one side of your knee joint.

    Your surgeon may choose to perform this method of knee replacement if your knee has damage only to one side of it. The advantages of this approach is that your surgeon will make a smaller incision therefore there will be less scarring. Furthermore, your hospital stay will be shorter and your recovery will be faster than a total knee replacement. On the other hand, you are more likely to require further knee surgery with this technique. Your surgeon will help you to decide which approach is best for you.

    Who are BOA?

    BOA stands for The British Orthopaedic Association. This is the leading society for Orthopaedic surgeons in the UK. Member surgeons are amongst the most highly-skilled and qualified surgeons in the UK. Choosing to get your hip replacement done by a highly-experienced BOA member surgeon will reduce the risk of complications occurring.

  • Candidates

    Knee replacement candidates

    Why choose to have a knee replacement?

    Knee replacement candidates often suffer with some form of arthritis. Most commonly this is osteoarthritis but may also be rheumatoid or traumatic arthritis. Conditions such as gout and death of the knee bones may also require a knee replacement.

    What is osteoarthritis?

    Osteoarthritis occurs as a result of years of wear and tear on the knee joint as you age. A number of factors may affect your risk of developing this condition. These include:

    • Age – your risk increases as you get older. Most candidates are aged 60-80 but can be any age.
    • Joint injury – overuse of the joint before it fully heals.
    • Obesity – being heavier in weight puts more strain on your joints. (Your knees and hips in particular).
    • Family history – why this is the case is not fully understood yet.

    The main symptoms of this condition are joint pain and stiffness. As a result, moving around becomes harder and simple daily tasks like walking become more difficult.
    Some patients may only have mild symptoms and may try other types of treatments first. These treatments may include: weight loss, regular exercise and the use of walking aids. In patients with moderate symptoms, using pain-killers and anti-inflammatory medications may help. If these do not work, steroid injections into the knee joint may also be helpful.

    Sometimes however, none of these treatments work to relieve symptoms. Therefore, surgical replacement of the knee may be the next, best option.

    Who are the ideal candidates for a knee replacement?

    Nearly all candidates suffer with knee pain and stiffness. These may be due to a form of arthritis or another cause. If they are considering surgery as a treatment option, candidates are usually struggling with movement like bending and walking around. This can make life very difficult for them and can often have a negative impact on their mental health.

    Below is a list of what an ideal candidate may be like. This is just a general guide, however. Your surgeon will be able to tell you if you are a good candidate or not.
    Ideal knee replacement candidates:

    • Have X-rays to show evidence of their condition.
    • Are fit and well aside from their knee issues.
    • Have no serious medical conditions.
    • Have a healthy BMI.
    • Are non-smokers or are prepared to quit for at least 6 weeks before and after the surgery.
    • Have realistic expectations for the surgery.
    • Have sufficient support from family and/or friends.
    • Are willing to follow specific aftercare instructions which may include physical therapy.

  • Procedure

    Knee replacement procedure

    How is a knee replacement procedure performed?

    A knee replacement generally takes from 1 to 2 hours to perform. Your surgeon will make a cut on your knee and remove the damaged surfaces of the two bones in your knee joint. They will remove any remaining cartilage and will use a plastic part to resurface your kneecap, if necessary. They will then use surgical cement to insert and stabilise your new artificial knee joint. This should relieve any pain or disability that you suffered because of your knee. More details on a knee replacement procedure can be found below.

    1. Consent

    On the day of your surgery, you will meet with your surgeon. They will go over what the procedure involves, the possible risks and complications that could occur and your expectations for the surgery. If you would still like to go ahead with the surgery, you will need to sign your consent. It is important that you make a fully informed and carefully considered decision. Therefore, we recommend that you read the consent form thoroughly and ask any questions you may have before you sign your consent.

    2. Anaesthesia

    You will meet with your anaesthetist before your operation. There are two anaesthetic agents your anaesthetist may use for your knee replacement.

    Firstly, they may decide to use a local anaesthetic. This involves injecting a local anaesthetic agent into your spine so that you cannot feel anything from the waist down. If they use this approach you will be awake for the duration of the surgery but will not feel any pain. If you would prefer, your anaesthetist can also give you a sedative agent to make you a little drowsy and less aware of what is happening. Both the local anaesthetic and the sedative will take a few hours to wear off.

    The other option your anaesthetist may use is a general anaesthetic agent. If they use this, you will be asleep for the duration of the procedure. You will awaken gradually when the surgery is over and may feel groggy for a few hours. This will wear off with time. You may notice a change in your concentration and memory too but this will resolve within 1 or 2 days.

    3. Incisions

    Your surgeon will make a vertical cut on your knee. The size of this incision will depend on what sort of knee replacement you are having done. A total knee replacement involves a larger incision while a partial knee replacement involves a smaller incision.

    4. Closing of incisions

    Your surgeon will use staples or stitches to close your wounds. They may also insert drains into the wound to help reduce any swelling.

    5. Return to the ward

    After the surgery is complete, you will be taken back to the ward. If your anaesthetist chose a local anaesthetic agent, you will be awake for this. You may still be drowsy if you have had a sedative. The numbness from your anaesthetic and the drowsiness will wear off within a few hours.

    If you have had a general anaesthetic, you will wake up slowly. You may feel groggy for a few hours but this will wear off.

  • Your consultation

    Knee replacement consultation

    What should I expect from my knee replacement consultation?

    Your initial knee replacement consultation will usually last between 15 minutes to 1 hour. During this time your surgeon will explain the procedure and tell you about the potential risks and complications that could occur. Your surgeon may need to see a referral letter from your GP. You will need to check if you need to bring this with you on the day. In addition if you have any X-Ray images of your knee, bring these along too.

    Your surgeon will ask you a few questions during the consultation which may include:

    • What is your health like currently?
    • Do you suffer from any serious medical conditions?
    • Have you had any major surgeries in the past?
    • Do you take any medications? (This includes prescribed, over-the-counter and herbal remedies.)
    • Do you smoke/drink alcohol/use recreational drugs?
    • Do you have any X-ray images that show evidence of your arthritis?
    • What other treatments have you tried?
    • How are your symptoms currently?
    • What do you expect to achieve from this procedure?

    This may seem like a lot of information to share about yourself. However, it is important to remember that your surgeon is a professional health care worker and that they need to know this information in order to decide how best to help you. Therefore, you must be as open and honest as you possibly can when answering these questions.

    What questions should I ask during my knee replacement consultation?

    While your surgeon will ask you many questions about yourself, this consultation is also an opportunity for you to also ask questions. It is vital that you fully understand all that a knee replacement involves, including the procedure, the risks and complications and the recovery process. Some patients find it useful to write their questions down and take a list with them to their consultation. This makes them less likely to forget to ask something which is important to them. To help you, we have created a list of questions you may like to ask your surgeon at your knee replacement consultation. Additionally, feel free to add any of your own!

    • What have the results of your previous knee replacements been like?
    • Do you think a total or partial knee replacement would be better for me?
    • Am I a good candidate for this procedure?
    • Do you think my expectations for this surgery are realistic?
    • How long is the recovery period?
    • Will I be in pain after the surgery?

  • Risk & complications

    Knee replacement risks and complications

    What are the main knee replacement risks and complications?

    Every surgery comes with possible risks and complications. Before you agree to have surgery you should educate yourself on what these are and take some time to think about the information. To help you do this, we have compiled a list of the main knee replacement risks and complications. These include, but are not limited to, the following:


    As surgery is an invasive procedure, it introduces the risk of infection to your body. Infections are not common however, as your surgeon and their team will take every precaution possible to prevent them from occurring. If you were to get an infection, you would become aware when things are not settling down as you had been told they would in the first 1-3 weeks. It is important you aware of what signs to look out for so that you know when to seek medical assistance:

    • A temperature of 38° C or over.
    • Fever, chills, night sweats.
    • Redness of the wound which spreads away from the wound after the first 48 hours.
    • Pain or discomfort that your pain medication does not resolve.
    • A foul-smelling pus/discharge from the wound.

    If infections do occur, they are generally minor and can be treated using a short course of antibiotics with success. On the rare occasion that an infection were to become serious, further surgery may be necessary.

    Bleeding & bruising

    A little bleeding from the wound after surgery can be normal. Consequently, you should also expect bruising around the area of your knee. Sometimes, a collection of blood can form beneath the skin – the medical name for this is a haematoma. This is not normal and your surgeon will need to remove it. These usually form within 24 hours of the surgery and you will fell a lot of pain and tightness in the treatment area. Haematoma’s generally require medical treatment but this should not affect the results of your knee replacement.

    Damage to surrounding structures

    There is always a small risk that your surgeon may damage surrounding ligaments, arteries or nerves during your knee replacement. While this risk is small, it is important that you choose a surgeon that you trust to minimise risks as much as possible. Take the time to consider your options before you choose the right surgeon for you. If any of this damage were to occur, further surgery may be necessary to fix the issue.

    Loosening or wearing out of the artificial joint

    Over time, your new knee joint may become loose. This may be because the cement holding the joint together loosens or the bone may dissolve a little. The artificial parts of the joint may also wear away as time progresses. Both loosening and wearing away of the joint can be painful and may require further surgery to fix. A second surgery rarely has as good of an outcome as the first, and comes with a higher risk of complications.


    Fractures of the bones of your knee joint or the artificial knee joint itself can occur during or after surgery. If this were to happen, revision surgery would be necessary.


    You will have a vertical scar on the front of your knee after surgery. This may range from 10-18cm long depending on if you have a total or partial knee replacement. Your scars will be lumpy and pink initially. However, with a good scar care regimen, their appearance should fade over time. This may include regular massage with scar gel once the wound has healed and using SPF when out in the sun to prevent discolouration. Ask your surgeon for more advice on how best to look after your scars.
    The formation of scar tissue within your knee joint can cause stiffness of joint movement. Physiotherapy and following your surgeon’s advice can generally prevent this occurring.

    General surgical risks

    There are some standard risks that apply to all surgeries. These include, but are not limited to:

    • Blood clot formation
    • Anaesthetic complications
    • Nausea and vomiting
    • Post-operative pain

    Your anaesthetist and surgeon will be prepared to manage these knee replacement risks and complications if any of them were to occur.

  • Preparing for your treatment

    Knee replacement preparation

    How can I prepare for a knee replacement?

    As part of your knee replacement preparation, you may like to make some minor lifestyle adjustments when preparing for your surgery. For example, you should stop smoking for at least 6 weeks before and after your operation. You should maintain a healthy diet and do some form of regular exercise if possible. Swimming may be a good form of exercise as it doesn’t put pressure on your knee joints, and strengthens the leg muscles around the knee.

    Knee surgery is a serious procedure and it will take some time before you fully recover from it. During your recovery time you should be as stress-free as possible and make sure to get plenty of rest. The best way to ensure you get the relaxed, speedy recovery that you want is through good preparation. And the good news is that knee replacement preparation doesn’t involve doing anything too difficult. We have put together a list of things you might like to get out off the way before you come into hospital.

    Household chores

    Household chores can require a lot of energy. After your knee replacement, you should not be over-exerting yourself. Therefore, it is a good idea to get some jobs out of the way while you are still fit to do so. For example, you may like to take out the bins, do the laundry and do a general house clean. You may like to move things that you may need to a level that you can reach to avoid climbing or bending, e.g. crockery and food items.


    It is likely you will not feel up to going shopping in the first few days after your surgery. Therefore, it is useful to do a big food shop before you come into hospital to stock up on everything you will need. Some patients like to cook meals and freeze them so that they don’t have to cook during their recovery. You may like to try this if you think it is a good idea. Another service you may find useful during your recovery is online food shopping!

    Children and pets

    If you have any children or pets, you will need to organise for someone to help you look after them. Both children and pets require a lot of energy and it is likely you will be too tired after your surgery to be able to look after either. Ask family or friends if they can lend a helping hand!


    You will be unable to drive home after your knee replacement. Therefore you should arrange for friends or family to pick you up from the hospital.

    You may not be able to drive from 4 to 8 weeks after your surgery. Your surgeon will be able to give you more specific advice when you return to the hospital 10 to 14 days after your procedure for a check-up. It is so important to follow your surgeon’s advice. Driving when you have been told not to could result in prosecution or the harm of you and/or somebody else. You should check with your insurer what their policy is on driving after a knee replacement.


    As part of your knee replacement preparation, ensure you eat a healthy, balanced diet. This will allow your body to prepare itself for the operation. Your surgeon will advise you on when to stop eating and drinking before surgery and what medications to take or stop.

    A healthy diet is also important to help with your recovery and healing process. Make sure you eat plenty of green vegetables and fresh fruits. Eat high protein foods like chicken and fish. Try to avoid sugary and salty foods. Stay hydrated by ensuring that you drink plenty of water and try to limit your caffeine intake.


    Prepare for your knee replacement recovery by buying baggy trousers or shorts that are not tight on your leg. This will make them easy to put on and take off and will not restrict movement of your knee. Bear in mind that your knee may be quite swollen after the surgery and will be dressed in bandages. You may like to wear slip on shoes to avoid bending where possible.


    Making sure that you have extra pillows or cushions around the house will be useful. You can use these to prop your leg up while you rest or sleep. This will be more comfortable for you and will also help to reduce any swelling in your knee. Your knee will likely be painful after surgery. Your surgeon will advise you on what pain medication to use to ensure that you get enough rest and sleep.

    It is vital that you follow any specific preparatory instructions that your surgeon gives you.

  • Aftercare

    Knee replacement aftercare

    What can I expect after my knee replacement?

    It is helpful to know what to expect from knee replacement aftercare. This can often help with any nerves or anxiety you may have before your operation. When you meet with your surgeon for your consultation, they will discuss the procedure and the more specific aftercare details with you. They will address any concerns you have about your recovery and answer any questions you may have.

    After your surgery, you will be given an appointment to return for a follow-up. This is generally 10-14 days after your surgery. During this appointment your surgeon will review your progress and check that you are recovering as you should be. They will examine your knee and remove any drains or stitches if necessary.

    How will I feel after my knee replacement?

    This will depend on what anaesthetic agent your anaesthetist uses for your surgery. If they use a local anaesthetic agent you will be awake for the duration of the surgery. You will feel numb from the waist down for a few hours but this will begin to wear off with time. Pain relief will be available for when this happens. If you choose to have a sedative in addition to your local anaesthetic, you will feel drowsy for a few hours after surgery but again, this will wear off with time.

    If your anaesthetist uses a general anaesthetic, you will wake up gradually after your surgery. You may feel a little groggy but this will wear off within a few hours. Pain relief will be available for when you need it. Your concentration and memory may be affected and will take 1 or 2 days to return to normal.

    When will I be able to go home after my knee replacement?

    You will usually stay in hospital for 3 to 5 days after your surgery. This will depend on how well you are recovering. If your surgeon has any concerns about your recovery, you may have to stay a little longer. They will be able to give you a more specific time-frame when they assess you after your operation.

    Will I be able to drive after my surgery?

    No. You will be unable to drive for a period of time after your surgery. Generally this is for 4 to 8 weeks, but can extend to 12 weeks if your surgeon has concerns about how you are recovering. Your surgeon will be able to give you a more specific time-frame regarding driving again when they examine you after your surgery. It is important to follow your surgeon’s advice carefully to protect both yourself and others on the road. We advise that you check with your insurer what their policy is for driving after a knee replacement.

    When will I be able to return to work?

    This will depend entirely on what sort of work you do and how you recover after surgery. If you have a sedentary job where you sit down a lot, you should be able to return to work from 2 to 6 weeks after your surgery. You should elevate your leg when possible and take regular, short walks to keep your knee joint active.

    If your job involves light activities, then you can probably return to work around 6 to 12 weeks after surgery or when you can walk without a limp. For more physically demanding jobs, you will probably have to wait around 12 weeks before you can return to work.

    This is general information we provide to all patients. Your surgeon will be able to give you more specific information which is tailored to you and your circumstances. Make sure that you follow their knee replacement aftercare instructions carefully.

    When will I be able to exercise again?

    Active recovery from a knee replacement is vital to keeping mobile and regaining strength. You will probably begin moving your knee from 1 day after surgery. A physiotherapist will help you with walking and moving around after your knee replacement. You may have to use a crutch or a walking stick for the first few weeks.
    Your physiotherapist and surgeon will give you more specific advice on when you can start to re-introduce certain activities back into your routine.

    Although it is important for you to rest after your surgery, it is equally important that you do not remain in bed all day. Taking regular short walks is vital to helping reduce the risk of blood clots formation.

    How can I look after my scars?

    When your surgeon removes your stitches and your wounds are fully healed, your surgeon may recommend a particular scar care regimen. This may involve daily scar massage using a scar gel or a moisturiser. As your scar becomes less tender, you may be able to increase the pressure of your massage to smooth out any lumpiness in the scar tissue. When out in the sun, it is important to cover up your scar or use a high-SPF sun screen to avoid discolouration. You can ask your surgeon for more scar care tips during your follow-up appointment.

    The above information we have provided is generalised to all patients. It is absolutely vital that you follow your surgeon’s specific knee replacement aftercare advice to ensure that you get best results possible.

  • FAQs

    Knee replacement FAQs

    What are some common knee replacement FAQs?

    We have made a list of the most common knee replacement FAQs. We hope that they may answer some of the questions that you may have.

    How long will my knee replacement last?

    Artificial joints are made to last for a long time. The materials used should be able to withstand the routines of active people. Most knee replacements last 10 to 15 years, however there is research being done to see how we can make these artificial joints last even longer.

    Total knee replacements tend to last longer than partial knee replacements. You are more likely to need another knee replacement if you are overweight or do regular heavy, manual work. It is important to have regular X-rays of your knee to review how your new joint is doing. Your surgeon will advise you on how often you should have an X-ray – it may be every 5 years or so. If you have any complications like loosening or wearing away of your new knee joint, you may require revision surgery to fix this.

    Will I be able to partake in all my normal activities after my knee replacement?

    While it is really important to be active after your knee replacement, you will need to build up your activities gradually. You will eventually be able to partake in light activities like jogging, cycling or dancing. However, high-impact activities like running, jumping and heavy lifting will not be possible. Doing these sorts of activities against your surgeon’s advice may risk causing damage to your new knee joint.

    Your physiotherapist will show you some exercises you can do to build up the muscle strength in your legs. It is important to follow this advice if you want to make a full recovery.

    Will I be able to climb stairs after my knee replacement?

    Yes. Your physiotherapist will work with you while you are still in hospital to achieve this goal. This is particularly important if you live in a house with stairs. We want you to be able to leave hospital feeling confident that you can manoeuvre around your house safely.