Knee replacement

What is a knee replacement?

A knee replacement is carried out to treat knee pain, usually due to knee osteoarthritis, which is gradual wear and tear of the joint. Arthritis accounts for the majority of the 90,000 knee replacements carried out in England and Wales annually.

During the procedure, both sides of the damaged joint are removed and replaced with a prosthesis or implant. If your arthritis is minimal, and you’re under 65, you may be able to have a partial (unicompartmental) knee replacement. With this procedure the surgeon only replaces the damaged compartment, which means that the knee tends to bend better and feel more like a normal knee than after a partial knee replacement than it would with a total knee replacement. Your surgeon will recommend the surgery that’s best for you, depending on your symptoms and X-ray results.

Is a knee replacement right for me?

Your consultant may recommend a knee replacement if:

• your knee pain is so severe that you can’t sleep at night
• you’re having trouble walking
• you’ve tried alternative treatments and they haven’t helped

While most people who have a knee replacement are between 60 and 80 – with the average age at 69 years – many younger patients also benefit from surgery.

The decision to carry out a knee replacement is made jointly between you, your GP and your surgeon. There's almost never an absolute indication for knee replacement surgery, but ultimately the decision is yours.

What are the benefits of a knee replacement?

A new knee can be a new lease on life. You’ll have less knee pain and the joint should move more smoothly, so you’ll be able to walk around more easily and get back to the things you love sooner.

How long do the benefits last?

Knee replacements can wear out over time, depending on your body weight and how active you are. Most people’s knee replacements last around 15 years. After that time, you’ll need a knee replacement revision.

What happens during a knee replacement?

A knee replacement usually takes around 1–1.5 hours.

Before the procedure

There are a few things you can do in the lead up to the procedure to make sure everything goes as smoothly as possible:

• Let your doctor know about any medication you take and follow their instructions
• If you smoke, stop smoking several weeks before the operation
• Try to maintain a healthy weight
• Exercise regularly
• Don’t shave or wax the area where a cut is likely to be made
• Try to have a bath or shower either the day before or on the day of the operation.

During the procedure

To minimise the risk of infection, you’ll be given antibiotics in the operating theatre just before the start of surgery and for two or three doses afterward, depending on the type of drug used.

Surgery is carried out under spinal or general anaesthetic, sometimes with a local nerve block, depending on what you, the anaesthetist and the surgeon decide.

1. Once you’re under anaesthetic, your surgeon will make a cut on the front of your knee and remove the damaged joint surfaces
2. Then they’ll insert an artificial knee joint – this will either be fixed to the bone with acrylic cement, or have a special coating that bonds directly to the bone
3. Finally, they’ll close the skin with stitches or clips, and apply a padded bandage dressing – this will be reduced after around 48 hours.

After the procedure

You’ll be taken to the recovery room where you’ll wake up and a nurse will be there to look after you. You may have a small tube coming out of your dressing to drain away any excess fluid.

You may also have a drip (infusion) going into your arm to keep you hydrated and give you pain relief. The nurse will check your wound, blood pressure and pulse, and when you’re ready, they’ll take you to your room.

Robotic-assisted knee replacement

A number of our hospitals are able to offer robotic-assisted knee replacement surgery using Mako™ robotic-arm assisted technology or the NAVIO® Surgical System.

Mako™ robotic-arm assisted surgery

This type of knee replacement uses robotic-arm assisted technology for greater accuracy. Use of this technology has been shown to result in shorter hospital stays, smoother recovery and increased satisfaction.

In the weeks before your operation, the robotic arm processes information taken from a 3D CT scan of your body. Your consultant then plans the operation to within fractions of a millimetre with the help of the robotic-arm assisted technology.

During the operation your consultant is always in control. The robotic-arm assisted technology allows the consultant to perform the joint replacement with pinpoint accuracy. The consultant uses the technology as an extension of his or herself, guiding surgical tools to the correct position. The robotic-arm assisted technology does not perform the surgery on its own.

Higher accuracy during surgery means the replacement fits as well as it possibly can and ensures the joint functions as normally as possible after surgery. It's been shown to result in a shorter hospital stay, quicker recovery and higher satisfaction. There's also strong evidence of decreased pain and fewer complications following surgery.

NAVIO® Surgical System

The NAVIO® system is a significant advancement in the way orthopaedic surgeons perform knee replacement surgery. The system works in conjunction with the surgeon’s existing skills to achieve accurate positioning of the knee implants based on each patient’s unique anatomy.

Using the NAVIO® system, the surgeon creates a computerised 3D representation of the unique shapes and profiles of the patient’s knee without the need of a pre-operative CT scan. Using all of this information the surgeon can determine the correct size and position of the implant. This is critical to knee alignment, stability and overall functional outcome. Using the boundaries that have now been established, the surgeon uses the robotic-assisted hand piece to remove only the damaged surfaces of the bone, balance the joint and position the implant with greater accuracy.

This added level of accuracy is designed to improve the function, recovery, feel and potential longevity of the knee implant.

Who is robotic knee replacement surgery suitable for?

Robotic knee replacement surgery may not be appropriate for all patients. Your consultant will advise you on the best treatments for your condition.

Recovery from knee replacement

Following your operation you’ll be able to go home when your pain is under control, you can get about safely, and any care you may need has been arranged.

Your wound is likely to take 10-14 days to heal. It may take up to 6 weeks to recover from the operation. It can take up to 12 months ​before you are back to normal activities.

Short-term recovery

When you’re back in your room, the nurse will keep checking on you to make sure you’re recovering well. Once the anaesthetic has worn off, you’ll be able to have something to eat and drink.

You may have help with the circulation in your legs through:

• wearing boots that are inflated with air for the first 2 days
• wearing support stockings, which you should leave on for 4–6 weeks
• daily injections or tablets, which you may have for up to 6 weeks
• taking blood-thinning medication.

Walking around after a knee replacement

To help make your recovery go as smoothly as possible, we need to start getting you active and mobile as soon as you’re able. We understand you may be nervous about getting up for the first time, but we’ll be there to help you whenever you’re ready. Getting mobile is all about confidence, which is why we help you to progress through a range of walking aids until you’re independent.

• Day of surgery: A physiotherapist will give you some exercises to do while you’re in bed to help your new knee joint move and strengthen the muscles around it. Then they’ll help you to get out of bed and start taking your first steps with a frame – this is to prevent stiffness and maintain a healthy circulation.
• Day after surgery: You’ll have an X-ray to check the position of your new knee, as well as some routine blood tests. If you haven’t started walking around yet, the physiotherapist will help you with this – otherwise you’ll continue practicing to walk using a frame with your nurse until you can do so on your own.
• Second and third day after surgery: An occupational therapist will give you some tips for washing, dressing and getting on and off the bed, chair and toilet. The physiotherapist will help you transfer to crutches or a walking stick, before giving you some more exercises to increase your movement.

Going home after a knee replacement

You’ll be able to leave as soon as you can safely walk up and down stairs on crutches, and the healthcare team are happy you are medically fit. You won’t be able to drive, so you’ll need someone to come and take you home.

We’ll train you to manage stairs in the following way:

1. Use a handrail where possible with a walking aid in the opposite hand
2. If going down stairs, move the crutch or stick onto the lower step, put your weight on the crutch or stick as you move your operated leg onto the step alongside it
3. Bring your non-operated leg onto the same step and repeat
4. Do the opposite on the way back up.

Find out more about getting out of the car with crutches and getting into bed with crutches.

Managing your recovery at home

To begin with, it’s normal to experience:

• tiredness – get plenty of rest, but then it’s important to slowly increase your activity
• swelling – to ease this, keep your leg raised when sitting and use the cryocuff cold compress we gave you, or apply an ice pack wrapped in a tea towel
• pain – take any painkillers we’ve prescribed until you’re pain free

Here are a few things you can do to strengthen your knee, avoid damaging it and help your wound heal:

• Keep your wound dry for 4–5 days afterwards, and use a waterproof dressing when you have a bath or shower
• Continue the exercises the physiotherapist showed you
• Try low-impact activities like walking and gradually increase how far you walk
• Keep using your crutches or walking stick for as long as you feel you need to
• Don’t lift anything heavy or do any strenuous exercise
• You’ll be able to bend your knee 90-120 degrees, but you should avoid kneeling down
• Don’t sit with your legs crossed for the first 6 weeks
• Avoid twisting at your knee

Call the healthcare team if you have any questions or concerns about anything. If your calf becomes swollen, inflamed or painful, seek medical advice as soon as possible.

Knee replacement recovery exercises

Initially, as you increase your activity the knee can be sore, but with appropriate medication and gentle exercise, your recovery should proceed smoothly.

We’ll prescribe a set of exercises for you to do at home. Every programme is different, but here are a few exercises we regularly ask patients to do. You should aim for 3 sets of 10 reps per exercise every day:

• Stair lunges: Stand at the base of the stairs and place your operated foot on the first stair. Lunge forward slowly bending at the knee only as far as is comfortable
• Bed exercise: Push the knee flat into the bed to fully straighten the leg
• Mini-squats: Stabilise yourself by holding on to a kitchen bench, door frame or heavy table. Keeping your back straight, lower you buttocks bending, at the knees. Only go as far as is comfortable.

Driving after a knee replacement

You should be able to start driving again after about 6–8 weeks, as long as you can operate the pedals and control your car in all situations. Any earlier than this and your reaction times may be too slow, particularly for emergency stops. Always check with your insurance company and your doctor first.

Time off work after a knee replacement

It’s important to take time off to rest, but getting back to your routine as soon as possible can help you recover faster. If you have a desk job, you’ll be able to return to work after around 8 weeks. If you job is more physically demanding, you’ll need to wait around 12 weeks. If you’re not sure, check with your doctor.

Follow-up appointments

You’ll usually need to come back to have your stitches or staples removed about 2 weeks afterwards, unless your surgeon used dissolvable stitches. Then you’ll have a check-up with your consultant around 6–12 weeks after your surgery to make sure you’re recovering well. We’ll arrange these appointments with you before you leave the hospital.

Further physiotherapy sessions are based on clinical need and vary from patient to patient. Your physiotherapist can refer you to our Recovery Plus programme after being discharged from their care. This includes three months’ free access to your local Nuffield Health gym.

You’ll also be recommended to have a check-up X-ray 12 months after surgery, as well as prosthesis monitoring.

Alternative treatment options

You don’t always need surgery for knee pain, and usually it can be eased through non-invasive measures:

• Painkillers can help control the pain
• Using a walking stick can make walking easier
• Wearing an elasticated support on your knee can help it feel stronger
• Regular moderate exercise can reduce the stiffness in your knee
• Physiotherapy can strengthen weak muscles
• Losing weight if you’re overweight can reduce the load on your knee
• Joint injections, such as steroid or hyaluronic acid, can reduce pain and stiffness for several months

Risks

Complications are rare but possible. However, rest assured that your consultant will weigh up the risks and advantages with you when deciding if they recommend surgery. Your consultant will also discuss any additional risks that apply to your situation at your initial consultation.

The risks of knee replacement surgery can include:

• knee stiffness
• infection of the wound
• infection of the joint replacement, needing further surgery
• unexpected bleeding into the knee joint
• ligament, artery or nerve damage in the area around the knee joint
• deep vein thrombosis (DVT)
• persistent pain in the knee.