Jordi Sanchez-Ballester

FRCSEd FRCS Trauma & Orth

Consultant Foot, Ankle & Knee Surgeon

Fairfield Independent Hospital, St Helens

Spire Cheshire

Fairfield Independent Hospital

Crank Rd

St Helens

Merseyside WA11 7RS

01744 739311

Spire Cheshire Hospital

Chris Davies

Fir Tree Close

Warrington WA4 4LU

0845 602 2500

Medico Legal

Nuria Roig

07894 717377

St Helens & Knowsley

Claire Lomax

0151 290 4234

Knee Replacement for Arthritis

Knee replacement surgery can help relieve pain and restore function in severely diseased knee joints. During knee replacement, a surgeon cuts away damaged bone and cartilage from your thighbone, shinbone and kneecap and replaces it with an artificial joint made of metal alloys, high-grade plastics and polymers.

The first artificial knees were little more than crude hinges. Now, you and your doctor can choose from a wide variety of designs that take into account your age, weight, activity level and overall health. Most knee replacement joints attempt to replicate your knee's natural ability to roll and glide as it bends.

A normal knee functions as a hinge joint between the upper leg bone (femur) and the lower leg bones (tibia and fibula) (figure 1). The surfaces where these bones meet can become worn out over time, often due to arthritis or other conditions, which can cause pain and swelling.

Reasons for Knee Replacement

Total knee replacement is one option to relieve pain and to restore function to an arthritic knee. The most common reason for knee replacement is that other treatments (weight loss, medicines, and injections) have failed to relieve arthritis-associated knee pain.

The goal of knee replacement is to relieve pain, improve quality of life, and maintain or improve knee function. The procedure is performed on people of all ages, with the exception of children, whose bones are still growing.

Approximately 80.000 knee replacement procedures are performed annually in the UK. This number is projected to increase significantly by 2030 .

Alternatives to Knee Replacement

While total knee replacement can be helpful under the right circumstances, you should discuss the risks, benefits, and alternatives with a doctor. Alternatives to total knee replacement include:

Nonsurgical treatment — Nonsurgical treatment methods are initially recommended for patients with osteoarthritis or inflammatory arthritis. This includes:

Weight loss


Medications, including over-the-counter and prescription. These include pain relievers such as acetaminophen and antiinflammatory drugs such as ibuprofen or naproxen. Patients should discuss use of these medications with their primary care provider and pharmacist to be sure the risk of side effects is acceptably low.

Knee bracing or shoe inserts, both of which may help align the knee and balance the weight on the joint

Injections, either with a cortisone-like drug or a hyaluronic acid derivative.

Patients with rheumatoid or other inflammatory arthritis should try physical therapy and medicines before considering total knee replacement.


Arthroscopy is a minimally invasive surgical procedure in which a doctor examines the inside of a joint with a device called an arthroscope. The doctor can repair any damage through small surgical incisions in the skin.

Arthroscopy is only helpful for a certain type of knee problems. Arthroscopic surgery has not demonstrated significant benefit for patients with osteoarthritis.


Osteotomy is a surgical procedure that involves cutting the leg bone, realigning it, and allowing it to heal. It is used to shift weight from a damaged part of the knee to a normal or less damaged one. Osteotomy is not recommended for patients older than 60 years of age or for those with inflammatory arthritis (such as rheumatoid arthritis).

Partial Knee replacement

A “partial” or unicompartmental knee replacement involves replacing only one part of the knee joint. There is debate about the benefit of partial knee replacement compared with total knee replacement, but some studies have shown favorable results [3]. You should talk to your doctor about the possible risks and benefits.

Knee Replacement

Knee replacement is performed in an operating room after you are given anesthesia. The surgery takes two to three hours. After surgery, you will be monitored in a recovery area for several hours, until the effects of the anesthesia wear off.

Most people stay in the hospital for two to four nights after surgery. During this time, you will be given pain medicines.

Blood clots in the legs (called deep vein thromboses) are a common concern after knee replacement surgery.

To reduce the risk of blood clots:

You will take a medicine, either as a pill or a shot. Most patients continue to take this medicine for a few weeks after surgery.

You will need to wear compression boots (devices that go around the legs and inflate periodically) while you are lying down. Once you are able to get up and walk, you will wear antiembolism stockings. These stockings fit snugly around the foot, ankle, lower leg, and knee to help prevent blood clots. (See "Prevention of venous thromboembolic disease in surgical patients".)

Infection is another major concern, and you will be given antibiotics within an hour of the procedure and for up to 24 hours after.


You will be encouraged to start moving your feet and ankles immediately after surgery. Some surgeons use a continuous passive motion device, which raises and slowly moves your leg while you are in bed. It is common to begin physical therapy one day after surgery, while you are still in the hospital.

Physical therapy is an important part of the recovery process. After leaving the hospital, some people have physical therapy in their home or at a clinic, while others stay in a rehabilitation facility or nursing home for a few days.

The rehabilitation program generally includes exercises to improve range of motion (how far you can bend and straighten your knee) and to strengthen your leg muscles. Your surgeon and physical therapist will help to set goals as you progress through rehabilitation.

The goal of the rehabilitation period is to regain strength and movement in the knee; it is important to avoid overworking or straining the knee during this recovery period. You can usually resume your normal activities within three to six weeks after surgery.

After several months of rehabilitation, you will be able to have a more active lifestyle. High-impact sports such as running and sports that involve heavy contact (football) are not recommended, but you should be able to participate in activities like walking, bicycling, and swimming.

Potential complications

Serious complications are not common after knee replacement. However, it is important to be aware of the major potential complications.

Studies have shown that a successful joint replacement partially depends upon the experience of the surgeon and the hospital. In one study, outcomes were better in people who had:

A surgeon who performed more than six knee replacements each year

Surgery performed in a hospital where more than 25 joint replacements were performed per year

Better outcomes included better knee function and lower rates of complications after surgery.

Blood Clot

Having total knee replacement increases the risk of a blood clot forming in a vein (called a thrombosis). The most common place for a thrombosis to develop after knee surgery is in the deep veins of the leg (called a deep vein thrombosis [DVT]). Symptoms of a DVT include leg pain and swelling.

Call your doctor's office if you are worried that you could have a DVT. (See "Patient information: Deep vein thrombosis (DVT) (Beyond the Basics)".)


Infection following knee replacement is a relatively uncommon but serious complication. Signs of infection include fever, chills, pain in the knee that gets worse suddenly, increasing redness, or swelling. Call your doctor's office if you are worried that you could have an infection.

Wound infections are treated with antibiotics and occasionally by draining excess fluid from the joint. If an infection becomes deep or extensive, the prosthetic joint may need to be removed and reimplanted later, after the infection has cleared. (See "Patient information: Joint infection (Beyond the Basics)".)


Occasionally, despite physical therapy, a patient’s knee may get stiff and may not bend or straighten properly. If this occurs, then the patient may return to the operating room in order to bend and/or straighten the knee under anesthesia.

Early Failure

Although most studies demonstrate that 80 to 90 percent of total knees will last between 15 to 20 years, early failures may occur due to a variety of reasons. These include loosening of the implants, infection, fractures of the bone around the implants, and instability. When early failures occur, revision surgery may be necessary.

What to Expect After the Operation


You will have a vertical scar on the front of your leg, approximately 10-18cms or 4-7 inches long. The surgeon needs to make a fairly big exposure of your knee joint in order to insert the new implant accurately.


Your wound will be closed using stitches or staples, which will probably need to be removed after 10-12 days, unless they are the sort which dissolve. Your surgeon will advise you about this.


You will have a large dressing on your knee to protect the wound. You may also have one or two tubes connected to drains in your knee to prevent excess blood from accumulating as the body heals. The tubes will normally be removed after a couple of days.


After your operation you will be working with a physiotherapist, who will monitor your specific needs and help you to regain strength and movement. It’s particularly important that you stick to the exercises the physiotherapist gives you in order to keep your new knee moving and to prevent it from developing problems.


The initial pain of surgery needs to be addressed with fairly strong painkillers for the first few days. You should expect to need to take painkilling tablets for up to 12 weeks after your operation. Your surgical team should be able to provide you with a leaflet about pain management.

Tiredness and Feeling Emotional

Your body is using a lot of energy to heal itself, so you will feel more tired than normal - sometimes it can come upon you suddenly. If you feel upset or emotional in the days and weeks after your operation, don’t worry - this is a perfectly normal reaction which many people experience, particularly when your blood haemoglobin level may be a little lower than normal in the post operative period.

Returning to Work - Fact: Work can be part of your recovery

Everyone needs time off to recover after an operation - but too much of it can stand in the way of you getting back to normal. In fact, by staying off for too long, people can become isolated and depressed. Getting back to your normal work routine sooner rather than later can actually help you to recover more quickly.

Getting Back to Work

How quickly you return to work depends on a number of things:

How you heal

How you respond to surgery

The type of job you do

People whose work involves a lot of heavy lifting, or standing up or walking for

long periods of time, will not be able to return to work as quickly as those who

have office jobs which are less demanding physically.

How Soon Can I Go Back?

How soon you can return to work depends on you:

Regaining the strength and mobility in your leg to be able to use public transport, or drive to get to work

Being able to function adequately when you are there and to be sufficiently agile to use escape routes etc in an emergency.

Not needing to use strong painkillers which may cause drowsiness.

Every person recovers differently and has different circumstances. If you have a desk job, it’s usually safe to return to work around 6- 8 weeks after your knee replacement.

If your job is more physically active, you may need to take longer off work – even as much as 12 weeks. You may decide to make a phased return to work.

If your employer has an occupational health nurse or doctor they will advise you on this. Alternatively your GP can give you advice. Ultimately, it’s your decision when you want to go back, and there’s no insurance risk to your employer if you choose to do so.


Your insurance company should be informed about your operation. Some companies will not insure drivers for a number of weeks after surgery, so it’s important to check what your policy says. Normally, it is safest to avoid driving for 8 weeks after a knee replacement. Discuss this with your insurance provider.

Driving - An Exercise

Before resuming driving, you should be free from the sedative effects of any painkillers you may be taking. You should be comfortable in the driving position and able to safely control your car, including freely performing an emergency stop.

After 6 weeks, you might want to test your fitness to drive, though discuss this with your physiotherapist first. Do this in a safe place without putting the key in the ignition. Simply sit in the driving seat and practise putting your feet down on the pedals. Again, build up gradually. If you feel pain, stop immediately. If you feel sore afterwards, you may need to wait a day or two and try again.

Only when you can put enough pressure on the pedals to do an emergency stop - without feeling any reluctance or inhibition - should you think about driving again.


A knee replacement is a safe, routine operation. Your general health is an important factor in the success of your operation and your recovery, but sometimes complications do occur. The exact risks are specific to you and will differ for every person.  

Infection of the wound or joint -  antibiotics will automatically be administered during and after your operation to help prevent infection

Excess scar tissue forming and restricting movement of the - further surgery may be able to remove this and restore movement.

Risk of developing a blood clot (DVT) or lung clot (PE) -  this could occur in the veins of the leg for up to six weeks after your operation due to the restricted movement - prevention includes the use of compression stockings, starting to walk or exercise soon after surgery and blood thinning injections if required

The new knee joint may become unstable this can occur as a result of the ligaments - you may require further surgery to correct this.

The kneecap becoming dislocated - your knee joint may become loose and you may require further surgery to correct this.

Small cracks in the knee bone - during your operation, small cracks can appear and result in a fracture. Further surgery may be needed and a longer recovery period required.

Damage to nerves or blood vessels. This is usually mild and temporary.