Knee replacement surgery

This is a popular form of surgery which is performed on cases of osteoarthritis. But it is sometimes carried out on rheumatoid arthritis and/or other inflammatory joint disorders.

Knee replacement surgery along with replacement surgery for hips, shoulders, elbows, ankles and wrists are very common operations for arthritis.

Most people who undergo knee replacement surgery are 65 and over. Slightly more women than men have this surgery.

If you require a hip replacement as well as a new knee joint then you will be advised to undergo hip surgery first. The reason for this is that you will need a strong and flexible hip to support your new knee.

Knee replacement surgery is discussed as follows:

  • Why knee replacement surgery?
  • Criteria for knee replacement surgery
  • Not suitable for knee replacement surgery?
  • Benefits of knee replacement surgery
  • Disadvantages of knee replacement surgery
  • Knee replacement procedures
  • Complications of knee replacement surgery
  • Recovery from knee replacement surgery
  • Alternatives to knee replacement surgery

Why knee replacement surgery?

This is usually recommended if other forms of treatment have failed such as medication, e.g. painkillers or the condition has worsened. It is often seen as the best course of treatment for severe forms of arthritis such as osteoarthritis or if you are experiencing problems with mobility.

Criteria for knee replacement surgery

Your age, state of health and lifestyle will be taken into account. The surgeon will use these to determine if you are suitable for an operation and when.

There are arguments for and against surgery which also includes whether to delay this and if so, for how long.

It is argued that having surgery at an early stage in your arthritis means that you will need revision surgery later on. This joint may have loosened or become dislocated during this time and will need correcting.

Much of this depends upon you and your lifestyle. For example, if you play a great deal of sport or undertake intense exercise then this joint will wear out much quicker than someone who is less active.

Conversely, some experts argue that it is better to proceed with surgery rather than leaving it until the joint has become very stiff and shows sign of severe deterioration.

This will be decided by your orthopaedic surgeon.

Not suitable for knee replacement surgery?

You may not be suitable for surgery if you have extremely weak thigh muscles or have chronic ulcers beneath the knee.

Having weak thigh muscles means that they will not be able to support your new knee joint.

Deep sores or ulcers underneath, or around the knee increases the risk of infection which may rule out surgery. Infection is one of several side effects of all forms of surgery so this is likely to worsen that risk.

If you are unable to have a knee replacement then the surgeon will suggest alternative forms of treatment.

Benefits of knee replacement surgery

The main benefit is no more pain from your arthritis. Another benefit is being able to move around as well as regaining your independence.

Other benefits include:

  • Able to undertake your normal daily activities
  • Able to participate in exercise
  • Able to socialise and participate in society

Many people who have undergone surgery state that they have a new lease of life. They are able to resume many of the activities they previously undertook and feel like a valued member of society.

You will notice a difference is you had to change jobs, were forced to give up work or unable to work in any capacity as a result of arthritis. You should be able to resume your old job or undertake a type of employment that was previously denied to you.

The majority of people are happy with their knee replacement.

Disadvantages of knee replacement surgery

It is only fair to mention about the drawbacks as well as the benefits.

What you must remember is that a replacement knee joint is never totally effective as a natural joint. They are a good alternative and have enabled many people to live a normal life.

But they do have their limitations. A replacement joint does not last forever and may need correction at some point in the future. Plus this new joint can become dislocated or start ‘clicking’after a while.

A replacement joint does not have the full range of movement as a natural joint. They do not allow full extension which is important especially if you play competitive sport.

It is not uncommon for people to undergo more than one revision surgery. But each revision is less successful than the previous one.

Knee replacement procedures

Knee replacement surgery involves the removal of the ends of bone worn down by fraying cartilage and the remains of this cartilage. This is then replaced by a metal joint and plastic ‘cartilage’which enables the joint to move in the same way as a natural joint.

Find out more about the structure of the joints in your joints section.

Your ageing joint is removed and replaced by a prosthesis (artificial joint) which is made from metal, ceramic or plastic. This is fixed in place with a special type of cement (acrylic): alternately this may be inserted into place without any cement and the surface scraped or ‘roughened’ to encourage bone to grow onto it.

There is more than one type of prosthesis and the type you have will depend upon your surgeon’s preferences, your body shape and age.

These types of surgery are now performed using a spinal anaesthetic which means that you will be unable to feel anything from the waist downwards. But you will be awake for the entire procedure.

You can have a general anaesthetic instead if you prefer not to view your procedure.

Types of procedures include:

  • Complete (total) knee replacement
  • Partial knee replacement (with or without keyhole surgery)
  • Complete knee cap replacement
  • Complex knee replacement
  • Knee revision surgery
  • Robotic knee surgery

As you can see there are a range of different techniques for knee replacement surgery. The technique you have will depend upon your surgeon.

Complete knee replacement

This involves replacing the end of the joint of the femur (thigh bone) and the top of the joint of the shin bone (tibia). The end of the femur joins the top of the tibia which comprises the knee joint.

The original kneecap (patella) is left in place as this provides a strong support for these replacements. But if this has severely deteriorated then it will be replaced with a synthetic variety.

These new parts are cemented in place, left unfixed to encourage bone to attach or fixed with a plastic fitting.

Partial knee replacement

This is often performed if only one side of the knee has arthritis. It can be performed via a small incision which means less scarring or bruising as with a full knee replacement.

This is only suitable for people who have strong ligaments within their knees. This is only realised at the time of surgery which may mean that the patient requires a full replacement instead.

This is an ideal procedure for younger people but older people can benefit from this surgery.

This surgery can be performed as minimally invasive surgery which means small incisions, i.e. keyhole surgery. This technique is not usually performed for a full replacement due to the risk of complications.

Complete knee cap replacement

The knee cap or patella can be replaced if this is the only part of the knee with arthritis. This is also known as a ‘patellofemoral replacement’.

The replacement knee cap is made of a strong, smooth substance and resembles a plastic dome in appearance.

This surgery is less successful than a full knee replacement due to the risk of this arthritis spreading to other areas of the knee. As a result of this surgeons tend to advise people to undergo the full replacement.

But this does have the advantage of a quicker recovery period and is effective if arthritis has not spread to other areas.

Complex knee replacement

This is a complicated form of surgery –hence the name –which is performed in cases of severe bone deterioration, weak knee ligaments or the knee has become grossly deformed.

The replacement parts are attached more securely to prevent any dislocation. Additional parts are used to replace any missing bits of bone.

This is often carried out as a form of revision surgery.

Knee revision surgery

This surgery is carried out to repair or replace a faulty artificial joint. An artificial joint lasts for around 15 years before wearing out which means a further replacement will be needed.

Second, third or more replacements are not unknown.

Robotic knee surgery

The use of robotics in surgery is a relatively new development and one that is proving to be very successful. Surgical tools are attached to the robotic device and using computer imagery, are guided by the surgeon during the procedure.

This is a minimally invasive procedure which means fewer traumas for the patient.

Complications of knee replacement surgery

Most forms of surgery are carried out without any problems. But there is always a small risk of complications with any surgery which includes knee replacements.

But many of these complications are minor and easily treated.

They include:

  • Infection
  • Blood clot (thrombosis)
  • Nerve damage
  • Tissue damage
  • Ligament damage
  • Artery damage
  • Adverse reaction to anaesthesia (very rare)

The surgeon will discuss these complications with you. The risk of them happening is small and depends upon your age and current state of health.

Recovery from knee replacement surgery

This can be a long process and frustrating at times but the results are usually worth it.


Expect to be tired, bruised, and sore and in some discomfort a day or two after your surgery. This is normal and can be controlled with painkillers.

You will be on a drip and painkillers plus a catheter whilst in hospital. A special brace may have been fitted which provides additional support to weak muscles/ligaments surrounding the affected joint.

Thin tubes called ‘drains’ will have been inserted into the surgical wound to allow excess fluids and blood to drain away from the wound and prevent excessive bruising.

You will remain in hospital for a week or so after surgery although this depends upon the type of surgery you have had and how well you are healing.

Getting up and moving around

If you have undergone a minimally invasive procedure then you will be encouraged to get up and move around on the same day. The reason for doing this is to restore movement to the joint. Plus it is prevents the risk of blood clot forming which is a problem if you are immobile for a long period of time.

This will be left for a couple of days if you have undergone surgery under a general anaesthetic or a complex joint replacement.

A physiotherapist will provide you with a series of exercises to do with the aim of restoring mobility and getting you used to your new joint. This will take place each day you are in hospital.

Hydrotherapy is another option. This involves gentle exercises in a swimming pool which does not put any undue pressure or strain on the joints.

Once the surgeon and his/her staff are happy with your progress and your wound shows signs of healing nicely then you will be discharged.


If you have stitches then you will be asked to return to the hospital to have these removed unless they are the dissolvable ones. The dissolvable stitches are reabsorbed into the wound.

Stitches are removed usually 10 days after surgery.

Follow up appointment

This will take place after 6 to 12 weeks and will also include a review of your current condition. Further appointments will be arranged each year, every two years etc to monitor your progress.

Back at home

Once you arrive back at home it is important to have some sort of plan for how you will manage on a day to day basis until you are fully recovered. Ask your partner or someone in your family to help and make sure that you get plenty of rest.

You should be able to return to work 6 to 12 weeks following your surgery although this will depend upon your job. You will be able to return sooner if you have a desk job compared to a manual job.

Do not overdo things. Whilst it is important that you are up and about as soon as you are able it is important that your new knee has time to heal. Exercise will help to strengthen the muscles and provide support for the joint.

Avoid twisting and turning actions with your knee until it is healed. This also applies to bending up and down or squatting. Try not to stand for long periods of time as this causes the ankles to swell.

Look after your new knee. Your knee will continue to heal and improve for a couple of years after surgery. But it is important that you are aware of potential issues such as infection, pain and stiffness.

If you experience any of these then speak to your GP.

The surgeon/physiotherapist/occupational therapist at the hospital will advise you about getting back to normal after surgery.

Further information about this can be found in our living with arthritis section.

Potential danger/warning signs

If you notice any hard, red and sore areas on your legs then contact your GP or consultant. It may be bruising but there is also the possibility that a blood clot has developed which needs treating.

If you experience pain and/or difficulty breathing after your surgery then seek urgent medical advice. This may a sign of a ‘pulmonary embolism’in which a blood clot has formed in your lungs.

This is very rare but does happen so it is important that you are aware of this risk.

Alternatives to knee replacement surgery

In most cases, conventional treatment is recommended before any type of surgery. But if you are not suitable for a knee replacement then there are few other procedures which are surgical operations but do not involve removal of the damaged joint.

These include:

    • Osteotomy
    • Microfracture
    • Arthroscopy
    • Autologous chondrocyte therapy (ACT)


This involves the surgeon making an incision across the shin bone before fixing this so that it prevents any weight being placed on the damaged joint. Any weight or pressure is evenly distributed to stop any further damage.

This was performed instead of a knee replacement but is rarely done nowadays.


This is a form of keyhole surgery in which tiny holes are drilled into the surface of the bone with the aim of encouraging new cartilage to grow.

This is not advised for cases of advanced arthritis.


This is another minimally invasive surgery which is often performed on younger people. Small incisions are made either side of the knee through which a camera mounted tube is inserted to help guide the surgeon during the procedure.

Slim tools are inserted to remove bits of torn cartilage which have caused the knee to ‘lock’or to smooth down rough edges.

This is not usually performed in cases of severe arthritis.

Autologous chondrocyte therapy (ACT)

This is a new technique in which new cartilage is grown via a test tube before being implanted into the damaged knee. It is designed to treat parts of the knee which have been damaged by an injury, e.g. sports injury.

Further research is needed to prove the effectiveness of this treatment for arthritis.

Most people are satisfied with the results of their surgery but if you experience any problems or find that your mobility has not improved to the extent you hoped then speak to your surgeon.

You need to have realistic expectations before this surgery but new advances mean that treatments are improving all the time. It may help you to think about the countless numbers of people who have regained their independence and their life as a result of this surgery.

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