What is knee replacement surgery and how can it help me?

Over 70,000 knee replacements are carried out in England and Wales each year , a procedure that involves replacing the knee joint with an artificial one. Knee replacement surgery is most often carried out to treat pain caused by osteoarthritis though in some cases it may be used to treat a knee injury. If the knee is not put under too much strain, most artificial replacement joints will typically last for at least 20 years.

What happens during knee replacement surgery?

During knee replacement surgery, either the whole of the joint is replaced, known as a total knee replacement (TKR) or, in some cases, only one half, which is known as a unicompartmental knee replacement (UKR).

Is it right for me?

Although knee replacement surgery is often the best treatment for people with advanced osteoarthritis, before you make the decision to go ahead it’s important to:

  • Discuss all your options with your consultant, as well as with your GP and family
  • Discuss your expectations from surgery with your Consultant
  • Ask questions and raise any concerns you may have
  • Weigh up the risks and benefits so that you can make your own informed decision

What is knee osteoarthritis?

Osteoarthritis (OA) of the knee is the most common form of arthritis, causing pain, swelling and stiffness. It’s caused by long term wear to the joint surface cartilage. Thanks to recent research into the causes of knee OA and its treatment, doctors are now able to offer a more effective approach to the management of this condition.

Which areas of the knee are affected?

The most commonly affected areas of the knee are the medial and patellofemoral compartments:

  • The medial compartment is the inner side of the knee, between the thigh and shin bones
  • The patellofemoral compartment is between the kneecap and the thigh
  • The lateral compartment is the outer side of the knee, between the thigh and shin bone

How is it caused?

  • OA is usually a slow, progressive process of wearing of the joint cartilage and is therefore more common in older patients (as joint surface cartilage wears out, raw bone may eventually be exposed)
  • It’s more likely if you have particular inherited traits that put more pressure on the joints, for example bowed legs
  • It can also affect people after they have had an injury either directly to the joint surface or to surrounding ligaments, for example an anterior cruciate ligament (ACL) injury

What are the symptoms?

  • Pain, swelling, stiffness and limited movement of the knee joint
  • Stiffness in the knee(s) first thing in the morning or after sitting for prolonged periods of time
  • Stiffness is often eased with gentle activity such as walking, although in more severe cases even short walks can be painful
  • Sometimes the knees ‘creak’ or ‘crunch’ when you walk or squat. This can be a symptom of knee OA, although this is not always the case as healthy knee joints make these noises too

Some people may have very advanced OA damage and feel very little pain, while others may have severe pain but with very little wear of the joint showing on an X-ray. When knee OA symptoms are very advanced, they can have a major impact on all areas of your life, including gentle exercise such as walking, and it can also affect sleep quality.

How is it diagnosed?

A diagnosis made during a medical consultation is usually backed up by X-rays that will show the extent of the damage. You may also be offered an MRI scan, if the diagnosis is not clear, to differentiate knee OA from other conditions, such as a meniscus tear.

Alternative treatments

We only advise our patients to have knee replacement surgery after other treatments have proved unsuccessful. These include:

  • Painkillers or anti-inflammatory medication
  • Weight loss if necessary
  • Physiotherapy to reduce stiffness and improve muscle strength
  • Arthroscopy (key hole surgery) to clear out any debris inside the knee joint and exercises

How can I help improve the results of surgery?

Research carried out by the World Health Organization (WHO) has shown that patients who have the knowledge, skills and confidence to manage their own condition enjoy better outcomes.

Your experience of having knee replacement surgery is likely to be more positive if you:

  • Make sure you’re well informed so that you understand the procedure and are well prepared
  • Understand what your limitations will be following surgery
  • Make sure you plan in advance so that you have some practical help and support in place
  • Make any necessary adjustments around your home
  • Carry out your rehabilitation exercises as advised – starting before your surgery
  • Follow the advice of your healthcare team to help speed up your recovery

The knee joint

The knee joint consists of the lower end of the thigh bone (femur) and the top of the shin bone (tibia); at the front of the knee is the knee cap (patella). The patella moves up and down in a groove on the front of the femur as the knee bends and straightens. All the surfaces of the bones are covered in articular (chondral) cartilage, which is a smooth, tough and rubbery surface that allows the bones in the knee joint to move easily against each other with minimal friction.

The bones are held together by ligaments and joint capsules; the meniscal cartilages help load-sharing and stability in the medial (inner) and lateral (outer) portions of the joint between the shin bone (tibia) and thigh bone (femur).

What happens during total knee replacement (TKR) surgery?

During total knee replacement surgery, both sides of the knee joint are replaced with artificial parts (prosthesis).

  • The knee joint is opened up to allow the surgeon to smooth off the roughened and worn out ends of the femur and tibia. These include a metal shell on the end of the thigh bone, a metal and plastic spacer on the upper end of the shin bone, and – if necessary – a plastic button on the kneecap
  • If the bones have become more worn on one side or the other (if the inside half of the joint wears away more, your leg will become more bowed and vice versa) then the surgeon can correct this to ensure that your leg is straight by the end of the procedure
  • The ends of the bone are then resurfaced with metal implants, a flat plate on the top of the shin bone, and a contoured cam for the end of the thigh bone
  • A plastic bearing is then fitted between the metal surfaces and this produces a very smooth surface that allows the joint to bend, straighten and twist like a normal knee
  • The surgeon usually, but not always, replaces the back of the knee cap with a plastic button
  • The average stay in hospital after TKR is three nights

What is partial (unicompartmental/unicondylar) knee replacement?

This type of surgery involves replacing only the worn part of the knee. Your consultant will be able to advise whether this is a better option for you than total knee replacement surgery. In this surgery:

  • If the wear in the knee is only present in one half of the knee then most surgeons will suggest only replacing this half of the knee, leaving the remaining normal knee surfaces untouched
  • This has some advantages over TKR in that patients tend to recover slightly more quickly and are more likely to feel as if it’s their own knee rather than a replacement
  • The average stay in hospital after partial knee replacement surgery is three nights

What are the risks of knee replacement surgery?

All surgery carries risks and these will be discussed with you in detail. Complications following knee replacement surgery are rare. However, it’s important you understand these before you decide to go ahead. You’re more likely to have complications if you smoke, are obese or have other health problems.

The risks of knee replacement surgery are outlined below.

The chance of infection is less than 1% and can usually be treated effectively with antibiotics. Usually only the skin is affected, but if bacteria get into the knee itself then it may be necessary to have a further operation to wash it out with saline solution and give stronger antibiotics via a drip. On very rare occasions it may be necessary to remove the knee replacement completely to allow the bacteria to be treated. It’s then replaced, either during the same procedure, or after four – six weeks.
You can help prevent infection by keeping the wound clean and dry. You’ll be advised how to care for the wound before you leave hospital.

Blood clots
Blood clots can occur after any operation but are more likely to occur following lower limb orthopaedic operations. To reduce the risk of blood clots, you’ll be encouraged get up and walk around as soon after your operation as possible, often on the same day. We will also assess your risk of developing a blood clot and, in some cases, you’ll be prescribed blood thinning medication. You’ll also be given some foot and ankle exercises immediately after surgery and will also be advised to wear special socks for six weeks after surgery.

Deep vein thrombosis (DVT)
This is when a blood clot develops in the deep veins in the back of your lower leg; however, some swelling in the leg after surgery is very common. If you’re worried you have DVT, you should see a doctor as soon as possible. The risk of DVT is less than 1% and treatment includes blood thinning medication

Pulmonary embolism (PE)
This is when part of a blood clot that forms in the leg breaks away and is carried to the lung. The risk of this is extremely low (1 in 1000) and treatment is the same as for DVT (see above)

Nerve damage
Small nerves that supply sensation to the skin near the operation site can be damaged, although the risk of this is small (less than 2%).

Loosening of the prosthesis
In most cases artificial replacements last at least 20 years.2 However, being overweight or overusing the joint will result in increased wear and tear. Loose or painful artificial joints can normally be replaced but, in some cases, the results of a second procedure aren’t as good as the first and the risks of the operation can also be higher.

Medical problems
There is a small risk of developing a medical problem following surgery. These include heart attacks, strokes and pneumonia. There is also a small risk of dying associated with this type of operation (nationally this figure is 0.4%). These risks will be discussed with you at the time of consultation with your surgeon.

How we reduce the risks of surgery

You will be screened for bacteria and MRSA before your surgery to reduce the chance of an infection, and during your operation you’ll also be given intravenous antibiotics. If you’re concerned about the risks of surgery, please discuss this with your consultant and/or anaesthetist before you give consent for the operation.
Research has shown that patients who engage more with improving their own health and are well informed have better outcomes. There is more information about preparing for surgery in the next section.

What improvement can I expect after my surgery?

The benefits of surgery include:

  • Reduced pain: most patients who have a total knee replacement have significant pain relief, enabling them to return to their everyday activities. This includes going up or down stairs, getting in and out of chairs, and walking longer distances. It’s normal to have some discomfort following your operation; however, our techniques aim to make the surgery as comfortable as possible, in most cases allowing you to walk on the same day. You will also be given a personalised exercise plan to help you to return to normal as quickly as possible
  • Reduced stiffness: the new joint has highly engineered metal and plastic surfaces designed to allow it to move smoothly and freely
  • Increased mobility: with a combination of reduced pain and improvement in stiffness, your overall mobility is likely to be improved enabling you to return to a more active lifestyle
  • How long does it take to recover?
    You’ll be in hospital for up to four days and will be shown how to walk using crutches (which you’ll need to use for up to six weeks).
    After surgery, you will be given a rehabilitation programme of gentle exercises to build up your strength and range of movement and, in most cases, you should be able to return to light everyday activities within three to six weeks.

How long will I need to have off work?

Depending on the kind of work you do, you may need up to six weeks off work. However, your consultant will be able to advise you about this as everyone is different and your rate of recovery may be different from other people’s. We normally recommend that you don’t work at all for the first two weeks, gradually returning to normal after four to six weeks (if your job mainly involves sitting down). Manual workers may need up to three months to return to normal.

Which activities could I do?

The aim of surgery is to help you to return to your normal everyday activities without being in pain. This includes going up and down stairs, walking and non-competitive sports including:

  • Swimming
  • Golf
  • Driving
  • Cycling
  • Ballroom dancing

Which activities should I avoid?

An artificial knee isn’t the same as a normal knee and you should avoid overloading the joint. It’s also important not to take part in activities that will wear the joint or result in an injury so it’s best to avoid:

  • Jogging or running
  • Contact sports
  • Sports that involve jumping
  • High impact aerobics
  • You may not be able to do work that involves heavy labour

Fortius Joint Replacement Centre
at Bupa Cromwell Hospital

164 -178 Cromwell Road

E: info@fortiusclinic.com

Appointments: +44 (0)203 693 2119

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