Consultant talking to female patient about knee replacement

What Is A Knee Replacement?

  • What’s the difference between a total or partial knee replacement?
  • How long will it last?
  • And what are the risks?

What Is A Total Knee Replacement?

Many people believe that a knee replacement involves ‘swapping’ a damaged knee for a new and improved model, but the word ‘replacement’ is rather misleading and you’ll rarely hear knee surgeons use it.

The treatment is actually a resurfacing, which involves adding metal components to the damaged ends of the femur and tibia (thighbone and shinbone) and placing a plastic bearing in between.

Total knee replacement x-ray
Total knee replacement
Partial knee replacement x-ray

What Is A Partial Knee Replacement?

As we explore here, your knee has three major compartments.

Where only one of those components is affected by arthritis you may be suitable for a uni-compartmental (sometimes called a half knee or partial) replacement.

The most usual site for this is the medial (inner) compartment of the knee.


Partial knee replacement x-ray

How Does A Knee Replacement Stop Pain?

Knee replacement surgery relieves pain by removing its source.

With the surfaces of the bone capped by the metal components, the bone can no longer grind against bone – which is what causes the pain of osteoarthritis.

Knee replacement benefits

Benefits Of A Knee Replacement

Whether yours is a partial or total knee replacement, you should notice the following benefits: 

  • A dramatic reduction in pain. Within weeks of treatment, many of our patients say they are completely pain free. This can have a dramatic effect on quality of life, sleep and even relationships
  • A return to normal or near-normal function, enabling you not only to walk or work without pain, but also to enjoy sports including running, cycling, golf and skiing
  • If you are suffering deformity of the knee because of the arthritis (e.g. bow legs) you should see an improvement

Partial Or Total Knee Replacement – Which Is Better?

Depending on the level of damage to your knee this can be a rather academic question. If you have damage to multiple compartments of your knee, a total knee replacement is the only option – and it’s a perfectly good one.

However, where a partial knee replacement is a viable option, it can typically present some advantages over total replacement:

  • Hospital time is shorter
  • Recovery is swifter
  • The improvement in function is greater
  • The risk of complications is lower
Partial or total knee replacement
Female runner after knee replacement

Will A Partial Knee Replacement Last As Long As A Total Knee Replacement?

For some time, there has been a question over whether a partial knee replacement will last as long as a total replacement.

Data now suggests that 70% of partial replacements last 25 years. Whilst this is slightly lower than the 82% rate for total replacements, it’s worth remembering that once a partial knee replacement wears out, you can still have a total knee replacement. That option doesn’t exist when your first knee replacement is total.

What Happens During A Knee Replacement?

Find out what happens before, during and after your operation here.

Hear the experiences of Yorkshire Knee Clinic patients who have had knee replacements

What Are The Risks Of Knee Replacement?

There is no operation that does not carry some risks.

The main risks of knee replacement are:


The chances of a serious deep infection affecting a knee replacement are approximately 1%.

This is a major complication which can require further surgery to clear the infection. Up to 2-3% may develop a simple wound infection.

Please note – all knee replacements can be warm and swollen for up to three months following surgery. This does not necessarily indicate infection.

Deep Vein Thrombosis

A DVT (blood clot) affecting the lower leg can occur but we take precautions to reduce the chance of this either in the form of blood thinning tablets or injections, or special calf pumps to keep the blood flowing.

Pulmonary embolism (PE) is a rare but serious complication arising when a blood clot obstructs some of the veins in the lungs. NICE (National Institute for Health and Clinical Excellence) issues guidelines for hospitals to reduce risks –

Nerve Damage

Nerve damage can occur, but in most patients this is seen in the form of a numb patch of skin to one side of the scar.

It is extremely rare to have nerve damage from a knee replacement causing weakness in the leg or foot.


Sometimes, despite having a technically successful operation, the knee can be stiffer than hoped for which can result in aching and general dissatisfaction. It is not always possible to find a reason for this.

The above are some of the major and more commonly occurring early risks from total knee replacement but your knee surgeon or physiotherapist will discuss and answer any more specific questions with you.

On average, you have approximately a 90% chance of achieving an excellent result from a knee replacement, giving you pain relief for at least 10-15 years. Research now suggests the upper limit for implant life may now extend beyond 25 years in most cases.

A further 6-8% of patients are much improved compared to previous symptoms. Eventually knee replacements can fail by wearing out or loosening. Occasionally, this can occur in the first few years.

What Is Knee Cap Resurfacing?

If your arthritis affects only the joint between the knee cap and femur (the patello-femoral joint) it may be suitable for patello-femoral resurfacing. In patello-femoral resurfacing, your knee surgeon places a plastic component on the back of the knee cap and a metal component on the front of the femur leaving the main knee joint between the tibia and the femur alone.

Some selective patella resurfacing may also be carried out as part of a total knee replacement. If we believe this may benefit you we will discuss it with you.

Knee cap resurfacing is not common but it can be a useful – and successful – form of partial knee surgery for some patients.

Talk to us about treatment for your knee cap problem
Treatment options for younger patients

What Is Joint Offloading?

Younger or more active patients with arthritis affecting only one side of the knee may be suitable for ‘offloading’ treatment options.

As the name suggests, this treatment uses various methods to shift the weight from the worn side of the knee. Treatments may include bracing, which can be effective, and load absorber surgery.

This has produced good outcomes in the majority of patients with some now still doing well at over 10 years but the programme is currently on hold while changes to the surgical technique are evaluated.

Talk To Us About Your Knee Replacement

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