Knee replacement surgery

Knee replacement surgery is an operation to treat knee pain. The procedure involves removing bits of your knee joint that have become damaged and replacing them with artificial elements, also known as implants or a prosthesis. This should remove the source of your pain, helping you to walk more easily and letting you get back to living life as normal. 

Knee replacement surgery (also known as arthroplasty) is a treatment that's usually only recommended if your knee pain is very severe and is seriously reducing your quality of life. It is a major operation, but one that has a good success rate. In the UK, surgeons have been performing knee replacement operations since the 1970s. Approximately 80,000 knee replacements are performed every year in England and Wales.¹

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

This page explains everything you need to know about knee replacement surgery, including the recovery times for knee replacement surgery and the benefits of physiotherapy after knee surgery.

If you're struggling with pain in your knee joint, you're not alone. More than 10 million people in the UK suffer from joint pain. The knee is one of the most common joints to experience pain in, and it can have a significant effect on your life. You might struggle to walk and to do simple things like getting up out of a chair or walking up and down stairs.

Knee pain can make it hard to sleep comfortably and can impact your mental health too. Many people with knee pain find their ability to perform everyday activities is impaired, which can really lower your quality of life.

If you have knee pain, you will see a specialist called an orthopaedic consultant, also known as a consultant orthopaedic surgeon.

What is orthopaedic surgery?

Orthopaedic surgery is focused on the treatment of injuries and disorders of your joints and their associated soft tissues (your ligaments, nerves and muscles). These components make up your musculoskeletal system. Your musculoskeletal system supports and protects your movement and muscular health. It helps support your weight and a range of bodily functions.

There are many factors that can cause damage to your musculoskeletal system, causing pain and swelling in turn. The most common are traumatic injuries (often incurred during contact sport), and degenerative joint conditions such as arthritis, which cause deterioration over time. Joint pain can be experienced as widespread pain throughout your body, but it is more often localised in one or perhaps two joints.

If you are living with pain and stiffness in your knee or knees, a consultant orthopaedic surgeon can help you to locate the cause of your pain and discomfort. They can help you find the best treatment for you, which can help you get back to enjoying your life. 

Surgery is by no means the only treatment option for knee pain. There are various non-surgical treatments available, for example physiotherapy or joint injections. But for some people, the damage to their knee can't be corrected using non-invasive methods, and a knee replacement operation is the best option.

If you suffer from knee pain and are struggling to find a treatment option that works for you, you’re in the right place. We have a network of dedicated consultant orthopaedic surgeons who are ready and waiting to help you. Together we'll find a way to resolve your knee pain.

If you've been told you need knee replacement surgery and want to find out more, this page should tell you everything you need to know.

You might be wondering whether you’re eligible for knee replacement surgery. It certainly won't be the right choice for everyone. Usually, knee replacement surgery is recommended when other, less invasive treatments have failed to manage your knee pain enough to improve your quality of life. 

If you have tried knee replacement alternatives (other forms of treatment available to treat knee pain) and have found these unsuccessful, knee replacement surgery could be the best option for you.

A consultant's view on when to have knee replacement surgery

Mr Winston Kim, one of our highly experienced knee surgeons, explains:

"If you are young - and by that, I mean less than 55 - you want to preserve the native joint for as long as possible because of longevity issues. There are alternatives, such as a partial knee replacement."

So, we won't routinely recommend knee replacement surgery in under 55s. However, for some people it will still be the best option, and the life span of a replacement knee is much longer than people realise.

"Nowadays, research shows that a knee replacement lasts longer than thought previously," notes Mr Kim. "It used to be that after 10 years, patients needed another knee. There's now a one-in-20 lifetime risk of revision until in people 70 and over and a one-in-three chance you will need to have it done again in your life if you have it in your mid-50s.

"The idea is that you want to delay surgery because it's a major operation, but the flipside is that if you delay too long, your fitness deteriorates. The condition is not going to be resolved on its own. So, you want to try conservative means first - non-impact exercise, weight loss, strengthening exercises, tablets, injections, physiotherapy and, if that fails, joint replacement. But it depends on the patient's quality of life, expectations and requirements."

Alternative treatments for knee pain and problems

Common knee replacement alternatives include:

Knee injection therapy

Also known as steroid injection therapy, this treatment involves injecting steroid medication into your painful knee joint. It can be effective at reducing swelling and inflammation and lowering your pain levels.

Oral anti-inflammatories

These will be prescribed by your GP or consultant and can be available on repeat prescription if needed. For our Joint Pain Matters 2020 Report, we surveyed thousands of people in the UK who were living with joint pain. We found that medication was the most common treatment option used by our respondents, with 69.76% of respondents using it to manage their pain effectively. 

Heat therapy

Your doctor might recommend using heat therapy (in the form of icepacks or heat pads) to manage your pain. This can be an effective way of reducing swelling or numbing pain, if needed.

Physiotherapy for joint pain

A physiotherapist will work with you to build a tailored exercise plan to help strengthen your knee muscles and relieve any tension or pain around the joint.

Physiotherapy can be an alternative to knee replacement surgery, and it is also used to help people recover faster from a knee replacement operation. If you have knee surgery with Circle, you'll be seen by a specialist physiotherapist who will guide you through a set of knee replacement exercises to perform throughout your recovery. These can help you to get better more quickly and should give you the best chance of a full recovery.

There are many reasons why you might suffer from knee pain and need knee replacement surgery. These include:

Osteoarthritis

Osteoarthritis is when the smooth cartilage that protects your joint surface deteriorates over time. As well as pain, it can also cause swelling and tenderness in your knee joint.

It is important to remember that knee arthritis symptoms affect everyone differently. Some people suffer severe pain as a result of osteoarthritis and struggle to perform everyday activities, making life challenging. Other people find that their symptoms are less severe and do not occur as regularly.

Rheumatoid arthritis

Rheumatoid arthritis (RA) affects more than 400,000 people in the UK. It is an inflammatory joint condition caused by an autoimmune process that makes your body mistakenly attack its healthy cells. This often causes chronic joint pain and deterioration. Joints affected by RA are usually surrounded by inflamed tissue.

Post-traumatic knee arthritis (kneecap traumatic arthritis)

A broken kneecap (which is also known as a patellar fracture) happens when the small bone at the front of your knee breaks. It is usually caused by a traumatic knee injury during sport and can lead to kneecap arthritis.

Septic arthritis

This is a much less common form of arthritis. It's a severe joint infection that can be caused by a traumatic injury to your joint, including a bite or wound. It can also happen as the result of an infection following surgery. Septic arthritis requires immediate medical attention. The damage caused by septic arthritis can lead to the need for knee replacement surgery.

Not everyone with knee pain needs a knee replacement operation, but there are some common symptoms that indicate you might need a knee joint replacement, including:  

• Persistent knee pain that limits your movement
• A change in the appearance of your knee
• Knee pain when bending down
• Knee pain while exercising
• Knee pain during sex
• Severe knee stiffness
• Knee pain when walking
• Knee pain at night
• An inability to support your body weight on one leg
• Limited relief from other forms of treatment you've tried

Living with persistent knee pain can dramatically impact your quality of life. If you're living with any of the above symptoms, it’s important to find out more about the possibility of knee replacement surgery. 

You can usually see a consultant orthopaedic surgeon for your first appointment within 48 hours of booking your appointment with us.   

What will your consultant ask you?

Your initial consultation is a chance for your specialist to find out as much as they can about you and your knee. They will ask you lots of questions about your health, and they'll examine your medical history in detail. they want to know about both previous and existing medical conditions, whether you are taking any medications or currently undergoing any treatments for your knee pain, and whether anything has helped to ease your knee problems in the past. 

They will ask you personal questions too, perhaps about your hobbies and interests and how your pain has affected your ability to enjoy these. This is because they want to understand what's important to you and why you are seeking treatment for knee pain. They want to know how long you've been in pain, how and when the pain began, and how it impacts your daily life.

In order to assess your symptoms properly and make an accurate diagnosis of your knee pain, your consultant will gently carry out a physical examination of your knee joint(s). They want to evaluate how you move your knee joint and in which positions it causes you the most pain. Sometimes your consultant will request an X-ray to help confirm their diagnosis. If so, this will be performed by one of our radiographers. Other diagnostic testing that could be used includes CT scanning and blood tests.

What should you ask your consultant?

After your consultant has confirmed the cause of your knee pain, they will share more information about knee replacement surgery and whether it might be the right treatment option for you. They will also discuss other potential treatments for your knee pain to ensure you have a comprehensive understanding of your options. 

Your consultant is there to answer any questions you might have about knee replacement surgery and to alleviate any concerns you might  have about undergoing surgery, knee replacement recovery times, or any other treatment. Please don't hesitate to ask any and every question that comes into your head. No question is silly, no question is too small. We want you to feel as informed and involved as possible. 

How long will I wait for knee replacement surgery?

The exact timeframe will differ from person to person, but in general you will have fast access to treatment, without a waiting list. There shouldn't be any delays, and you can pick a time and date that are convenient for you.

Your knee joint consists of three equally important bones – your femur (upper leg bone), tibia (thigh bone), and patella (kneecap). These form the inner, outer, and kneecap compartments (three in total). In a healthy knee, these bones are covered with smooth and healthy cartilage. In a painful knee, these components are often covered by deteriorated and damaged cartilage.

There are several types of knee replacement surgery. Which one is best for you will depend on the location and the extent of the damage inside your knee joint. Your consultant orthopaedic surgeon will be able to determine which type you need. The two main types of knee replacement surgery are:

Total knee replacement surgery

Also known as total knee arthroplasty, this procedure involves replacing two or three compartments of your knee joint.

During a total knee replacement operation, your orthopaedic surgeon will remove and replace both sides of your knee joint and replace each with a prosthesis. The back of your kneecap might also be replaced, though only if necessary.

Partial knee replacement surgery (also known as a half knee replacement)

During partial knee replacement surgery, your orthopaedic surgeon will only remove and replace one compartment of your knee, replacing this with a prosthesis. This procedure is generally performed with smaller incisions and has a more minimally invasive approach. If you only have damage to one compartment of your knee, this could be the best option for you, however that won't always be the case.

Robotics-assisted knee surgery

Many of our hospitals now offer knee surgery using robotic tools that can help our surgeons be more precise and accurate when operating. This can mean less pain during your recovery and may even lead to better long-term results.

MAKO and NAVIO are two of the robotic arm tools we use to perform knee replacement surgery (both partial and total).

Your consultant will encourage you to do certain things or change certain aspects of your lifestyle before you have surgery on your knee. This is to get you in better health before the operation and give you the best chance of a good recovery afterwards. They might suggest that you do things such as:

Lose excess weight

Your consultant might ask that you lose any excess weight before surgery. Losing weight can reduce the risk of complications happening during surgery and may speed up your recovery process.

Stay active

Many people question how far to walk after a knee replacement operation. Your activity levels should be relatively high both before and after surgery (low-impact, gentle walking is best). You should not perform high-impact exercise after surgery as this could actually put your recovery at risk.

Avoid drinking alcohol

You should avoid drinking alcohol for at least 48 hours before having knee replacement surgery. Please speak with your consultant about this.

Eat a balanced diet

You will be given advice about the sort of food you should eat before surgery, as well as whether there are any you should avoid consuming beforehand. Please discuss this with your consultant in more detail.

Assess your medications

Your consultant will also share detailed information about whether you should avoid taking your usual medication before hospital, or the kind of medication you might need to take after.

Eliminate tripping hazards at home

Remember to eliminate any tripping hazards before your surgery, so that you do not trip and fall when you return home from surgery (your  mobility will be limited at first).

Stock up on food and supplies at home

In the weeks after your surgery, your mobility might be limited as you regain your strength. You might not be able to just pop to the shops as usual. It's important that you or a member of your support network stock your house with food and supplies so that you don't have to worry about going out during your knee operation recovery period. Alternatively, arrange for a friend or family member to do your shopping for you for the first few weeks after your surgery.

Your orthopaedic surgeon and healthcare team will give you all the information you need to feel prepared before coming to hospital. This will include travel arrangements, what to bring to the hospital, any pre-operative testing required, as well as how best to manage any lifestyle changes recommended in preparation for surgery.

Anaesthetic for knee replacement surgery

Knee replacement surgery is usually performed either under general anaesthetic, spinal anaesthetic, or epidural. Under general anesthetic, you will not be awake. When under spinal anaesthetic or epidural, you will be awake but numb from the waist down. If this is the case, you will probably be given a sedative too, so you are unlikely to remember the procedure.

What happens during surgery

During a total knee replacement operation, your orthopaedic surgeon will first create an incision in your knee to access your patella (kneecap). This is moved aside to provide access to your joint. Your surgeon will then remove the damaged ends of your femur (thighbone) and tibia (shinbone). The ends of these bones are measured and shaped to fit your prosthesis. But before this is fitted, your orthopaedic surgeon will test your joint with a trial prosthesis.

Once the prosthesis is ready to be fitted, your surgeon will replace the end of your femur with a curved metal piece, while a metal plate will replace the end of your tibia. They will position a plastic spacer between these two metal parts to minimise friction. Total knee replacement surgery could also include replacing the back of your patella (kneecap), but this will depend on the extent of damage to your knee.

If you are having partial knee replacement surgery to remove and replace a specific damaged part, surgery can be performed using a smaller incision.

After your partial or total knee replacement surgery, your incision will be closed with stitches or clips and covered with a dressing.

Knee replacement surgery time

The surgery typically lasts for one to two hours, but this depends on the type of surgery your consultant is performing.

Can you damage a knee replacement?

A traumatic fall or injury can damage your knee replacement, just as it would damage your real knee. Weakness in your knee joint can lead to a loss of balance after your knee replacement, which is why it is important to follow specialist knee replacement exercises set by your physiotherapist. We talk about these in more detail below.

What is a knee implant made of?

Usually, a prosthesis is made of a metal alloy with a plastic insert. In some cases, implants are made from ceramics, or a ceramic and metal composite.

Knee replacement operations have been performed since the 1970s. The implants and surgical techniques have developed significantly since then, but the general objective behind the procedure remains the same: to remove your damaged knee joint and replace it with a prosthesis, helping you live a more active and fulfilled life as a result.  

In England and Wales there are approximately 80,000 knee replacement procedures performed each year.¹ This large volume reflects positive surgery outcomes, which can last for over 20 years.

In fact, according to The National Institute for Health Research, more than 80% of total knee replacements last for 25 years or more.

Every individual’s knee replacement recovery time looks slightly different depending on their individual circumstances and recovery goals. Research has shown that the time of your stay in hospital following surgery can impact your recovery time. Most people can leave hospital within two days, but more and more people are going home within the same day or 24 hours of having surgery. Your consultant will tell you how long your time in hospital will be, because they understand your individual circumstances. It will be affected by factors including:

• Your usual everyday activities
• How active you were before having knee replacement surgery
• The nature of your job (i.e. whether you have an active job or a desk job)
• Your age

A total knee replacement recovery timeline will look slightly different to a partial knee replacement recovery timeline. Your orthopaedic surgeon will understand your personal circumstances and health better and be able to advise what your personal knee surgery recovery timeline looks like.

Knee operation recovery in hospital

Depending on your location and your preference, you might choose to stay in hospital for longer to take part in a more advanced rehabilitation programme, supervised by your physiotherapy team. If this is something you're interested in, you should ask your consultant when you first discuss surgery. Some common goals you’ll be set to make before being discharged in hospital include:

• Able to manage stairs/steps (if required)
• Walking safely with your walking aid
• Able to get in/out of bed independently
• Wash and dress independently
• Understand and completed your exercises
• Your wound is satisfactory (some oozing/bleeding is normal)
• Your pain is controlled to allow you to do your exercises/walking
• One to two days after surgery

Just 12 to 24 hours after surgery, most people can get out of bed and walk using aids such as crutches or a walker. Your physiotherapist will help you get out of bed and take your first steps following the procedure.

Two to six weeks after surgery

After two to six weeks, you can start incorporating gentle exercises such as long walks into your everyday routine. You can usually return to work at this stage too, depending on the type of work you do (if you have an office job, you can return to the office).

Twelve weeks after surgery

Six to 12 weeks after knee replacement surgery, you should be well on the way to a full recovery and able to carry out everyday activities with ease.

Physiotherapy after knee replacement surgery

Your physiotherapist will work with you to build a specialist exercise plan tailored to your needs following surgery. These exercises will strengthen your knee muscles and improve your mobility. We know that getting mobile quickly reduces complications and speeds up your recovery.

You will be able to put your full weight onto your new knee after surgery, but, as your muscles will be weaker, you will need to walk with the help of a walking aid (usually elbow crutches) until your pain reduces and your strength returns. Your physiotherapist will show you how to do this safely.

Before you get up for the first time you can start your bed exercises as soon as you come back from your surgery.

Your physiotherapist will advise how regularly you should perform these exercises outside of your sessions, as well as any equipment you might need to get to help you do them. (If you do need equipment, we'll help you source it.)

Specialist exercises after knee replacement

While you're in hospital, you'll have physiotherapy sessions to kickstart your knee operation rehabilitation. These sessions will be led by a chartered physiotherapist. Initial rehabilitation aims to reduce knee pain and stiffness and restore full extension (straightening) and at least 90 degrees of flexion (bend) of the knee. Under normal circumstances, your physiotherapist will aim for your knee to have full extension and at least 90 degrees flexion six weeks after the operation.

How much walking after knee replacement surgery is advised?

You will likely be advised to begin walking on your knee soon after surgery. Your physiotherapist will help you take your first steps to ensure you do not put too much strain on your new knee. Usually, you are helped to stand within 12 to 24 hours of your operation. Your consultant will encourage you to walk with a frame or crutches to initially to avoid putting pressure on your knee.

Walking after knee replacement surgery is recommended, but please be gentle with yourself as you recover. You don’t need to walk extreme distances to reap the benefits of walking.

How long does pain last after knee replacement?

It is usual to have initial discomfort after knee replacement surgery, especially when walking or exercising. This should decrease over time, and will be eased by the specialist knee replacement exercises that your physiotherapist recommends.

If you continue to have pain in your knee beyond what you were told to expect, you should speak with your consultant orthopaedic surgeon about why this might be. They will be able to investigate this further and provide a solution.

What not to do after knee replacement surgery

It is best to avoid heavy lifting and strenuous exercises during your recovery period. It is also best to avoid sports that pose a high risk of falling at the time, such as skiing or mountain biking. Your physiotherapist will provide you with a list of movements to avoid as you heal, including bending your knees at certain angles. You should follow these, and the strengthening and conditioning exercises set by your physiotherapist, until advised otherwise.

Your healthcare team are here to answer any questions you have about your recovery process, including information on driving after knee replacement surgery, the best position to sleep after knee replacement surgery, and any other concerns or queries you might have.

Complications can occur during any surgery. Potential complication during any surgical procedure include:  

• Pain
• Infection in the surgical wound
• Excessive bleeding
• Scarrin
• Blood clotting
• Chest infection
• Heart attack
• Stroke

Specific complications that can occur during a knee replacement surgery include:  

• Pain
• Swelling
• Stiffness
• Fracture
• Damage to your nerves
• Damage to blood vessels
• Infection in your knee