- Upper prosthesis
- Lower prosthesis
A replacement knee will not last forever, but an artificial knee will probably last at least 10-15 years, depending on how active you are and the type of replacement you have.
As new technology continues to be developed, this figure is likely to increase.
Why knee replacement is necessary
Knee replacement surgery (arthroplasty) is usually necessary when a health condition or injury disrupts the normal working of the knee joint so that :
How the knee should work
- Your mobility is severely reduced
- You experience pain even while resting.
The knee joint acts as a hinge between the bones of the leg.
It is actually two joints: The major joint is between the thigh bone of the upper leg (femur), and the shin bone of the lower leg (tibia). The smaller joint is between the kneecap (patella) and the femur.
A smooth, tough tissue called articular cartilage usually covers the ends of the bones within the knee joint. This protects the ends of the bones and allows them to slide smoothly over each other, without pain or too much effort.
The synovial membrane that covers the other surfaces of the knee joint produces synovial fluid. This lubricates the joint, reducing friction to further help movement.
Replacing a damaged knee
Pain and difficulty moving the knee joint commonly happens when the articular cartilage has become damaged or worn away. This means that the ends of the bones start to rub or grind together, instead of smoothly sliding over each other.
Replacing the damaged knee joint with an artificial one can help reduce pain and increase mobility.
The most common reason for knee replacement surgery is osteoarthritis.
Osteoarthritis in the knee occurs when the articular cartilage becomes damaged or wastes away through natural wear and tear. The bones then have little or no protection to prevent them rubbing against each other when the knee moves, causing pain.
The bones may then compensate by growing thicker and producing bony outgrowths to try and repair themselves, but this can actually cause more friction and pain.
Other medical conditions that may make a knee replacement necessary include:
- Rheumatoid arthritis,
- Disorders that cause unusual bone growth (bone dysplasias) and bone death following problems with the knee's blood supply (avascular necrosis).
There are alternative surgeries to knee replacement, but results are not as good in the long term :
Arthroscopic washout and debridement :
An arthroscope (a tiny telescope) is inserted through small incisions in the knee. The knee is washed out with saline and any bits of bone or cartilage cleared away. It's not recommended if you have severe arthritis.
This is a keyhole (minimally invasive) operation in which small holes are made in the surface layer of bone with a small sharp Ďpickí. This allows cells from the deeper, more blood-rich bone beneath to come to the surface and stimulate cartilage growth. It can be a good option if you have just a small area of damaged cartilage. However, the benefits are not well proven and the results are not as good as knee replacement for severe arthritis.
This is an open operation in which the surgeon cuts the shin bone and realigns it in order to shift the load through the knee joint away from the area affected by arthritis. Sometimes used for younger people with limited arthritis, it may allow a knee replacement to be postponed. You'll usually need a knee replacement at a later date and the operation may make knee replacement surgery more difficult if it is needed.
Autologous chondrocyte implantation :
This is when new cartilage from your own cells is grown in a test tube and introduced into the damaged area. It is usually used for accidental injury to the knee rather than arthritis. As yet, it's only available in trials.
Mosaicplasty (cartilage replacement):
This is an arthroscopic (keyhole) procedure that involves moving round plugs of hard cartilage, together with some underlying bone from another part of your knee, to repair the damaged surface. Currently, it's only available in trials.
When it should be done
You may want to consider surgery if :
- Pain is so severe it interferes with your quality of life and sleep.
- Medications and other treatments havenít worked or are causing severe side effects.
- Everyday tasks such as shopping or getting out of the bath are difficult or impossible.
- You're feeling depressed as a result of the pain and lack of mobility.
- You're unable to work or have a normal social life.
If you're offered a knee replacement you'll normally be experiencing severe pain, swelling and stiffness in your knee joint, and will usually have a significantly reduced ability to move the joint.
However, a knee replacement is major surgery, so it's normally recommended only if non-surgical options have not helped to reduce pain or improve your mobility.
Knee replacement may be considered for adults of all ages, although young, physically active people are more likely to wear out their replacement joint. As a result, those recommended for knee replacement are typically older, less active people, as the replacement joint is less likely to wear out and need to be replaced again.
Most people who undergo a total knee replacement are aged 60-80. They will need to be well enough to cope with both a major operation and the rehabilitation afterwards.
Recently, younger and more active people have had better results with knee replacement as many replacement knees now last up to 20 years and beyond.
If youíre having a knee replacement because of arthritis and also need a hip replacement, you should have the hip done first as you will need a flexible hip to do the exercises needed after a knee replacement operation.
What should I be looking for in a specialist?
The key is to choose a specialist who performs knee replacement on a regular basis and can discuss their results with you.
This is even more important if you're having a second or subsequent knee replacement, known as revision knee replacement, which is trickier to perform. Look for a specialist who will work with you to find the best treatment for you.
Your local hospital trust site will show which specialists in your area do knee replacement. Your GP may also be able to recommend someone.
How can I prepare for going into hospital?
How can I prepare for the operation?
- Get informed : Find out as much as you can about what is involved in your operation. Your hospital may provide written information or videos.
- Arrange help : Line up a friend or relative to help you at home for a week or two after coming home from hospital.
- Sort out transport : Arrange for someone to take you to and from the hospital.
Prepare your home. Before you go for your operation put your TV remote control, radio, telephone, medications, tissues, address book and a glass on a table next to where you will spend most of your time when you come out of hospital.
- Stock up : Get in a stock of food that's easy to prepare, such as frozen ready meals, cans and staples such as rice and pasta, or prepare your own dishes to freeze and reheat during your recovery.
- Clean up : Before going into hospital have a long bath or shower, cut your nails Ė donít forget to take off any nail polish Ė and wash your hair. Put on freshly washed clothes. This helps prevent unwanted bacteria coming into hospital with you and complicating your care.
Stay as active as you can. Strengthening the muscles around your knee will aid your recovery. You can be referred to a physiotherapist who can give you helpful exercises. If you're able keep up any gentle exercise, such as walking and swimming, in the weeks and months before your operation so much the better.
What will happen before the operation?
A couple of weeks before the operation you'll usually be asked to attend a pre-operative assessment clinic to meet your surgeon and other members of the surgical team.
They will take a medical history, examine you and organise any tests, such as blood and urine tests, ECG and X-rays needed, to make sure you're healthy enough for an anaesthetic and surgery. They will also give you advice on anything you can do to prepare for surgery and ask you about your home circumstances so your discharge from hospital can be planned. If you live alone, have a carer, or feel you need extra support, tell the surgical team so that any help or support can be arranged before you go into hospital.
Take a list or packets of any medication you're taking. Some (rheumatoid) arthritis medications suppress the immune system, which can affect healing. For this reason you may be asked to stop taking your medication before surgery. Your surgeon can advise on alternative medications. There may be leaflets, booklets and videos to look at or take away that can help to inform you further about the operation.
Make use of this time before surgery to ask any questions you have.
How is Knee Replacement Surgery performed?
You will usually be admitted to hospital the day before your operation. The surgeon and anaesthetist will usually come and see you to discuss what will happen. Donít be afraid to raise any anxieties you have.
What will happen?
You will not have anything to eat or drink for approximately six hours before your operation. The ward staff will help you to take a bath or shower and put on a surgical gown. You'll also have to remove make-up, nail polish and jewellery, except wedding rings, although it's advisable to leave valuables at home. If you wear glasses or false teeth, these can be removed in the anaesthetic room. You'll then be escorted to theatre by a nurse.
Who will actually do the operation?
The operation will be performed by a senior level surgeon in India. He will be helped by junior doctors. You should be told at your pre-operative assessment who will be doing the operation. If you arenít, donít be afraid to ask.
How is the operation carried out?
Modern knee replacements involve removing the worn ends of the bones in your knee joint and replacing them with metal and plastic parts (a prosthesis).
You may have either a 'total' or a 'half-knee' replacement. This will depend on how damaged your knee is. Total knee replacements are the most common.
Total knee replacement
In a total knee replacement, both sides of your knee joint are replaced. The procedure takes one to three hours.
- Your surgeon makes a cut down the front of your knee to expose your kneecap. This is then moved to the side so the surgeon can get to the knee joint behind it.
- The damaged ends of your thigh bone (femur) and shin bone (tibia) are carefully cut away. The ends are precisely measured and shaped to fit the appropriate sized prosthetic replacement. A dummy joint is then positioned to test that the joint is working properly. Adjustments are made, the bone ends are cleaned, and the final prosthesis is fitted.
- The end of your femur is replaced by a curved piece of metal, and the end of your tibia is replaced by a flat metal plate. These are then fixed using special bone 'cement', or are treated to encourage your bone to fuse with the replacement parts. A plastic spacer is placed between the pieces of metal. This acts like cartilage, reducing friction as your joint moves.
- The wound is closed with either stitches or clips. A dressing is then applied to the wound, and sometimes a splint to keep your leg immobile.
- Long lasting. Typically, a new knee lasts about 15 years.
- Tried and tested treatment that has stood the test of time.
Partial (half) knee replacement
- Longer operation, bigger incision and more bone needs to be removed.
- Longer hospital stay and recovery period.
- Blood transfusion is sometimes needed.
- You may be aware or clicking or clunking in the knee.
- You're still likely to experience some difficulties in moving, especially in bending your knee, and kneeling may be difficult because of the scar.
If only one side of your knee is damaged, you may be able to have a partial, half-knee or unicompartmental replacement. This is suitable for around one in four people with osteoarthritis.
- Smaller operation, smaller incision and less bone removed.
- Shorter hospital stay and recovery period.
- Blood transfusion rarely needed.
- Better movement in the knee, which feels more like a natural knee. You may be able to be more active than after a total knee replacement.
- Not quite as reliable as a total knee replacement in eliminating pain.
- Tends not to last as long as a total knee replacement, which is likely to mean further surgery at a later date.
- Less suitable for a young, active person.
Talk to your surgeon about the type of surgery they intend to use and why they think it's the best choice for you.
If just your kneecap is damaged, an operation called a patellofemoral replacement or patellofemoral joint arthroplasty can be performed. This involves less major surgery with a faster recovery time. However, the long-term picture is still unclear. According to the Arthritis Research Campaign the operation is only really suitable for about one in 10 people with osteoarthritis.
Mini-incision surgery (MIS)
This new technique can be used for either total or half-knee replacements, but it is currently more commonly used for half-knee replacements.
The surgeon makes a smaller cut over the front of the knee than in standard knee replacement surgery. Specialised instruments are then used to manoeuvre around much of the tissue, rather than cutting through it. This should result in a quicker recovery.
If you are considering MIS for your knee replacement, you should discuss these issues with your doctor. If you do go ahead with it, you may be asked if your details can be used to help gather more information.
Bilateral Knee Replacement
Bilateral knee replacement surgery means that both knees are replaced. Patients who have severe knee arthritis in both knees may be good candidates to undergo bilateral total knee replacement. In general, there are two types of bilateral knee replacement surgery:
Simultaneous Bilateral Knee Replacement
A simultaneous procedure means that both knees are replaced at the same surgery, in one day.
Staged Bilateral Knee Replacement
A staged procedure means that the knees are both replaced, but not on the same day. The second surgery may be performed as early as several days after the initial surgery, or several weeks or months later.
Who should consider bilateral knee replacement?
Patients who have severe knee arthritis in both knees may be candidates for bilateral knee replacement surgery. The same criteria used to determine if a single knee requires replacement are used to determine if both should be done.
What are the risks of a simultaneous bilateral knee replacement?
There are concerns about performing a simultaneous knee replacement because it is a longer surgery and is more demanding on the body. Because of this, patients who have cardiovascular problems, pulmonary disease, or are over the age of 80 are often advised against a simultaneous knee replacement procedure.
Studies have shown patients undergoing simultaneous knee replacement have a slightly higher risk of cardiac events and needing blood transfusion. Overall, the risk of severe complications such as infection, blood clots, pulmonary embolism or death is about the same for both simultaneous and bilateral procedures.
Another disadvantage of the simultaneous knee replacement is that the early rehabilitation can be more difficult as patients do not have a "good leg" to work with.
What are the benefits of a bilateral knee replacement?
The benefit of simultaneous knee replacement is that both problems are taken care of at one time. The overall rehabilitation is a shorter time, and there is only one hospitalization. Patients also only require one anesthesia.
Is having a bilateral knee replacement my decision to make?
Yes and no. Patients who are appropriate candidates for a simultaneous knee replacement can decide if they want both surgeries at the same time. However, your doctor may recommend against a simultaneous procedure if you have medical conditions that may place you in a higher risk category.
Can partial knee replacement be done as a bilateral procedure?
Yes. The same criteria are used to determine if patients who require bilateral partial knee replacement are appropriate to undergo this procedure as a simultaneous surgery.
The surgeon performs this operation using computerised images, which are generated by attaching infrared beacons to parts of your leg and to the operating tools. These are tracked on infrared cameras in the operating theatre. Results so far suggest this may enable the new knee joint to be positioned more accurately. Most hospitals, however, do not yet have the equipment to do this and only around 1% of knee replacements are performed in this way.
Risks of surgery
As with any operation, there are risks as well as benefits. Although most people who have a knee replacement experience no problems at all, complications arise in about one in 20 cases. However, most of these are minor and can be successfully treated.
Your anaesthetist and surgeon will be able to answer any questions you may have about your personal risks from anaesthetics and the surgery itself.
Risks include :
- Infection of the wound. This will usually be treated with antibiotics, but occasionally the wound can become deeply infected and require further surgery. Very occasionally, it requires replacement of the artificial knee joint.
- Fracture in the bone around the artificial joint during or after surgery. Treatment will depend on the location and extent of the fracture.
- Excess bone forming around the artificial knee joint and restricting movement of the knee. Further surgery may be able to remove this and restore movement.
- Excess scar tissue forming and restricting movement of the knee. Further surgery may be able to remove this and restore movement.
- The kneecap becoming dislocated. Surgery can usually repair this.
- Numbness in the area around the wound scar.
- Allergic reaction. It's possible that you may have an allergic reaction to the bone cement, if this is used in your procedure.
- Unexpected bleeding into the knee joint.
- Ligament, artery or nerve damage in the area around the knee joint.
- Blood clots or deep vein thrombosis (DVT). Clots may form in the leg veins as a result of reduced movement in the leg during the first few weeks after surgery. They can be prevented by using special support stockings, starting to walk or exercise soon after surgery, and by using anticoagulant medicines.
In some cases, the new knee joint may not be completely stable and further surgery may be needed to correct it.
Recovering from Knee Replacement
In the surgical ward, you may be given a switch to enable you to self-administer painkillers at a safe rate, and you may be given oxygen through a mask or tubes. If necessary, you'll be given a blood transfusion.
You'll have a large dressing on your knee to protect your wound and various drains to siphon off blood from the operation site to prevent it collecting inside the wound.
Back in the ward, the team will continue to monitor you carefully. You may be allowed to have a drink about an hour after returning to the ward and, depending on your condition, you'll also be allowed to have food. You'll need help moving position and using a bed pan.
You will need to have your wound dressing changed regularly until it has healed over.
How soon will I be up and about?
As quickly as possible the staff will help you to get up and walk about. If you have had minimally invasive surgery you may even be able to walk on the same day as your operation.
Walking with a frame or crutches is encouraged. Most people will be walking independently with sticks after about a week.
During your stay in hospital a physiotherapist will teach you exercises to help strengthen your knee. You can usually begin these the day after your operation. It's very important that you follow their advice to avoid complications or dislocation of your new joint.
It's normal to experience some initial discomfort while walking and exercising, and your legs and feet may be swollen.
You may be put on a passive motion machine to restore movement in your knee and leg. This support will slowly move your knee while you are in bed. It helps to decrease swelling by keeping your leg raised, and helps improve your circulation.
When can I go home?
You'll usually be in hospital for six to 10 days, depending on what progress you make and what type of knee replacement you've had. Patients who've had a half-knee replacement tend to have a shorter hospital stay.
If youíre generally fit and well the surgeon may suggest an accelerated rehabilitation programme where you start walking on the day of the operation and are discharged within one to three days.
How will I feel when I get home?
Donít be surprised if you feel very tired at first. You've had a major operation and muscles and tissues surrounding your new knee will take time to heal. Follow the advice of the surgical team and donít be afraid to call your GP if you have any particular worries or queries.
You may be eligible for a home help and there may be other aids that can help you. You may also want to make your own arrangements to have someone to help you out for a week or so.
The exercises that your physiotherapist gives you are an important part of your recovery, so it's vital that you continue with them once you are at home.
Your rehabilitation will be monitored by a physiotherapist when you attend your appointments at the outpatient physiotherapy department
You may be given some specific exercises to carry out, as well as advice on taking short walks and carrying out normal household activities, such as walking up and down stairs. These exercises will help restore your movement and strengthen your new knee.
How long will it be before I feel normal?
You should be able to get rid of your crutches or walking frame three to six weeks after surgery and resume normal leisure activities. However, it may take up to three months for your pain and swelling to settle down.
Your new knee will continue to recover up to two years after your operation. During this time the scar tissue heals and the muscles are restored by exercise, so it's important to take care and look out for problems such as stiffness, pain or infection.
Even after you've recovered, itís best to avoid extreme movements or sports where there is a risk of falling, such as skiing or riding a bicycle. Your doctor or a physiotherapist can advise.
When can I drive again?
As soon as you can bend your knee enough to allow you to get in and out of a car and control the car properly, you can resume driving. This is usually around four to six weeks after your surgery, but you should check that you are safe to drive with your physiotherapist or doctor.
When can I go back to work?
It depends on your job, but usually between six and 12 weeks after your operation.
When can I do housework?
For the first three months, you should be able to manage light chores, like dusting and washing up, but you should avoid heavy household tasks such as vacuuming and changing the beds. Avoid standing for long periods as this may cause ankle swelling, and avoid stretching up or bending down for the first six weeks.
How will it affect my sex life?
You may find that having the operation gives your sex life a boost. Your surgeon can advise when it's Ok to have sex again but as a rule of thumb, so long as you are careful, it should be fine after six to eight weeks. You should avoid vigorous sex and kneeling positions.
Will I have to go back to the hospital?
You'll be given an outpatient appointment to check on your progress usually between six and 12 weeks after your knee replacement. The surgeon will want to see you a year later to check everything is Ok, and five yearly after that to X-ray your knee and make sure itís not beginning to loosen.
Will I need another new knee?
The knee can be replaced as often as necessary, although results tend to be slightly less effective each time. Recovery may take longer, but once you have recovered the results are usually good.