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Knee replacement surgery

Lesley Dobson / 11 August 2020

Find out what knee replacement surgery involves with our guide.

Consultant talkng to patient about knee pain
What causes knee pain?

Painful knees can make life very uncomfortable, and can even be life-changing. Your doctor may suggest treatments such as painkillers, anti-inflammatory tablets, exercises, physiotherapy and weight-loss to start with.

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However, if your knee is causing a lot of pain, and you have stiffness, feel unstable when standing or walking, or are affected so badly that you can’t do normal every-day activities, your doctor is likely to suggest that you have a replacement knee.

Knee replacement operations are quite common – according to Arthritis Research UK, over 70,000 are carried out in the UK each year.

What causes knee pain?

Osteoarthritis is a very common cause of joint pain - affecting six million people in the UK - and is the most common reason behind knee replacements (also known as arthroplasty).

Knee replacement operations are quite common – over 106,334 knee replacement procedures were carried out in England, Wales and Northern Ireland in 2017. The average age for patients having this operation was 69 years.

About 1 in 5 of adults over 45 in the UK has osteoarthritis of the knee. (1 in 9 adults in the UK have osteoarthritis of the hip). Other causes of joint pain include muscle strains, ligament damage, rheumatoid arthritis, and injuries to the knee.

Read our guide to relieving knee pain

Before your knee replacement surgery

You should have a pre-operative assessment in the weeks leading up to your operation.

This gives you a chance to meet your surgeon and members of their team, so they can talk with you about what to expect on the day of your operation, and how they are going to repair your knee. It also gives you the opportunity to ask any questions, and tell them if there is anything you are particularly concerned about.

Let them know what medicines you’re taking – making a list beforehand is a good idea. You should have a number of tests – blood and urine tests, and an electrocardiogram (ECG). This is to check that you are healthy enough to have surgery.

Ask about whether they have an enhanced recovery programme (ERP). Many hospitals do have this – it’s designed to make sure that patients are healthy before they go into surgery, and have the best care possible during and after their operation. The aim is to help you recover as quickly as possible.

While you’re in hospital you should also see an occupational therapist. They will help you start to get moving again after your operation, and will give you important advice on how to manage over the first few weeks at home.

Ask them about which aids might be useful, and where you can get these. Also ask about help coping at home while you’re recuperating.

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What does knee replacement surgery involve?

You’re likely to have a pre-med – a sedative – before you go to the operating theatre. Knee joint replacements can be carried out with a general anaesthetic, but your surgical team may offer you the choice of having a spinal anaesthetic, or an epidural. Both numb your body from your waist down to your feet, and mean that you are awake for the operation.

Our knees are made up of three bones. The parts involved are the lower end of your thigh bone (the femur), the upper end of your shin bone (the tibia), the small bone that covers the joints, your patella (the knee cap).

The ends of the shin and thigh bones are covered with a layer of hard cartilage. Because of this layer, the ends of these bones can move together without causing pain.

When the cartilage is damaged or worn away, by arthritis or an injury, for example, the bones rub together, and that is what causes the pain.

Depending on the extent of the damage, your surgeon will either suggest a total knee replacement, or a unicompartmental or partial knee replacement, where only one side of your knee joint needs replacing.

Other types of knee surgery:

Kneecap replacement (patellofemoral arthroplasty or replacement) is where the underneath of the kneecap and the trochlea (the groove that runs through it) are replaced.

In some cases, people may need to have a complex or revision knee replacement. This is usually when they have suffered major bone loss because of arthritis or fracture, a serious deformity of the knee, or weakness in the main ligaments.

Your surgeon may discuss carrying out the operation using mini-incision. This is basically the same operation but involves making a cut of 10–12 cm, rather than the conventional 20-30cm long. The advantage is that this reduces the amount of damage to the tissue surrounding the knee.

During the operation your surgeon will remove the damaged parts of the cartilage and the worn ends of your thigh and shin bones. They’ll then fit replacement parts made of metal and plastic, so the ends of the bones can work together again, without causing you pain.

After your knee replacement surgery

The time it takes before you are up and about will depend on how the operation has gone, how healthy you are generally and whether you are on an enhanced recovery programme.

If you are on an enhanced recovery programme, and the operation has gone well, the physiotherapists and nursing staff may help you to start walking on the day you have surgery.

You will need a walking frame or crutches to help you walk for the first couple of days. And you may have a cricket pad splint (a temporary brace), to help support your knee to begin with.

Before you leave the hospital your occupational therapist will give you advice on how to dress, shower and keep moving. They will also talk to you about any equipment you might need at home until you’re back on your feet again.

Want to talk to a GP today? With Saga Health Insurance, you have unlimited access to a qualified GP 24 hours a day, 365 days a year. Find out more about our GP phone service.


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The opinions expressed are those of the author and are not held by Saga unless specifically stated. The material is for general information only and does not constitute investment, tax, legal, medical or other form of advice. You should not rely on this information to make (or refrain from making) any decisions. Always obtain independent, professional advice for your own particular situation.