Knee Replacement Surgery

This is a very successful operation for getting rid of the pain of arthritis in the knees. It involves removing the diseased joint surfaces of the knee and resurfacing them with a prosthesis, normally under a regional anaesthetic. Knee replacements should be expected to function well up to around 20 years.

When is it recommended?

Surgery is offered when you have a condition that is affecting your everyday activities due to pain or stiffness, as well as your ability to sleep and where other treatments have failed to improve your symptoms.

What does surgery involve?

During surgery, which is normally carried out under a regional anaesthetic, the surgeon removes the damaged cartilage from the end of the femur (thigh bone), top of the tibia (shin bone) and the patella (knee cap). The end of the femur is resurfaced with a metal femoral component/prosthesis, as is the top of the shin – this then forms the main part of the new knee joint. The patella is resurfaced to replace this joint (patellofemoral joint) thus replacing all the worn moving parts of the knee  allowing the joint to move smoothly without pain. These components are held to your bone with cement.

What are the risks of surgery?

Complications following knee replacement surgery are rare. However, they can include:

  • Infection: 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 is then re-replaced, either during the same operation or after an interval of 4-6 weeks.
  • Deep vein thrombosis (DVT): The risk of this is less than 1% and is unusual if you move around as much as possible after surgery. You will be given blood thinning injections to reduce this risk and you will be advised to wear compression stockings for up to 2 weeks after surgery. Symptoms of DVT include pain, swelling, warmth and redness of the calf (however, thigh and knee swelling are normal after hip replacement surgery)
  • Swelling: Swelling and bruising around the knee joint and in the thigh and knee is common after knee replacement surgery. The swelling may feel tight and uncomfortable.
  • Stiffness: Most people experience stiffness initially after the operation, but this will improve with exercise and physiotherapy
  • Nerve damage: Small nerves that supply sensation to the skin near the operation site can be damaged leading to scar numbness. Injury to the major nerves supplying the muscles of the leg is a very serious complication but fortunately extremely rare (less than 0.2%)
  • Wear and loosening: Modern knee replacements are expected to last at least fifteen to twenty years. However, over time the artificial knee may wear or loosen and if this happens, a further procedure to change the implants (revision surgery) may be necessary. However, huge advances in the field of revision knee surgery mean that in most cases the outcome is good
  • Fracture: This is rare, occurring in around 1% of cases. This will be noticed intraoperatively and treated appropriately. Rarely small fractures are picked up on the post op xray, which is routinely performed the next day after surgery, generally these are treated with changing the amount of weight you are allowed to put through your operated leg.

How long does it take to recover?

You’ll be in hospital for 1-4 nights and will be shown how to walk using crutches (which you may need to use for up to six weeks).

  • Swelling: It’s normal for the whole leg to swell after a knee replacement, and to be at its most swollen around a week after surgery.
  • Bruising: It’s also normal to have bruising in the knee and  occasionally for the wound to leak blood onto the dressings for the first 1 or 2 days.
  • Rehabilitation/exercises: You’ll be given exercises to stop you becoming too stiff.  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.  For the first 2 weeks the focus is on minimizing swelling and pain (ice is helpful in this phase) Improving range of motion (aiming for 0-90 degrees bend).  From 2-6 weeks focus continues to be increasing the range of motion and developing strength in the surrounding muscles, and improving balance.  Using an exercise bike from two weeks onwards is encouraged.

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 4 weeks, gradually returning to normal after six weeks (if your job mainly involves sitting down). Commuting during rush hour is not recommended for at least six weeks after knee replacement surgery. Manual workers may need up to three months to return to normal.

When can I start to drive again?

The DVLA states that it’s the responsibility of the driver to ensure they are always in control of the vehicle. A good guide is if you are confident walking without crutches and can get into your car without help, which is usually around six weeks after surgery. Vehicle insurance companies also usually suggest a six-week period off driving, although you should always check with your car insurance company first.

Will having surgery limit my sporting activities?

It’s important to discuss any concerns you may have with your specialist and to have realistic expectations about what is possible with this procedure. In most cases, people who have total knee replacement surgery have dramatically reduced levels of pain and increased ability to carry out everyday tasks. However, it is recommended to avoid impact sports that put particular stress on the joint such as running, jumping, downhill skiing, hockey, football, rugby, and squash. Sports that are less likely to cause problems include walking, swimming, golf, cycling and other low impact activities.

Your knee replacement should continue to improve for up to a year after surgery, and sometimes longer for younger patients.

Will I need physiotherapy?

Most people can bear weight on their leg soon after the operation and should be able to walk confidently without crutches within six weeks. For the first 2 weeks the focus is on minimizing swelling and pain (ice is helpful in this phase) Improving range of motion (aiming for 0-90 degrees bend).  From 2-6 weeks focus continues to be increasing the range of motion and developing strength in the surrounding muscles, and improving balance.  Using an exercise bike from two weeks onwards is encouraged.

You will also be advised to arrange to see a physiotherapist so that you can begin to follow a rehabilitation programme that will help you return to fitness as soon as possible.

Will the metal in my knee set off a metal detector?

knee replacements may set off airport security detectors but in most cases, you won’t need to go into great detail about your surgery with the security staff; many people have had some type of surgery involving a metal device and a brief explanation should be enough.

How can I avoid damage to my replacement knee?

Looking after your replacement knee will help protect and extend its life. You can do this by:

  • Exercise: to maintain mobility and build strength, also keeping your weight down will increase the life of your hip
  • Avoiding falls: as breaking a bone in your leg may involve further surgery
  • If you need a dental procedure: let your dentist know as you may need to take antibiotics before your treatment to avoid any infection that might affect your hip replacement
  • Avoiding high impact activities: jumping, skydiving, sprinting, squash, rugby, football, downhill skiing on rough terrain, ski jumping etc

Here are some examples of Knee Replacement Surgery X-rays:

A 70y old patient who had arthritis in both knees, treated with bilateral knee replacements:

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