Knee Replacement Surgery


Types of Surgery

Partial Knee Replacement

There are three compartments of the knee – the inner, the outer and the kneecap. If arthritis affects only one side of your knee – the inner or outer side – it may be possible to have a half-knee replacement (sometimes called unicompartmental or partial replacement). Because this involves less interference with the knee than a total knee replacement, it may mean a quicker recovery and more normal function. Another partial replacement is called a patellofemoral replacement. In this surgery, the end of the thigh bone is replaced, and an artificial surface is used to line the back of the kneecap.

Partial knee replacements can be carried out through a smaller cut (incision) than total knee replacement, using techniques called reduced invasive or minimally invasive surgery. A smaller incision may reduce the recovery time.

Partial knee replacement isn’t suitable for everyone because you need to have strong, healthy ligaments within your knee. Sometimes this won’t be known until the time of surgery. Even though partial knee replacement involves less interference with the knee it is often a more complex operation than total knee replacement.

Research shows that people who have partial knee replacements are more likely to have the knee revised (re-operated) than people who have a total knee replacement.

Total Knee Replacement Surgery

In total knee replacement surgery, the ends of the damaged thigh and lower leg (shin) bones and sometimes the kneecap are capped with artificial surfaces. These surfaces are made of metal and plastic. The plastic acts like hard cartilage, helping your joint to move freely. The metal and plastic parts of the artificial joint allow your knee to bend while also making it more stable. In most cases, the surgeon replaces the entire surface at the ends of the thigh and lower leg bones. Surgeons usually secure knee joint components to the bones with cement. 

Joint changes caused by osteoarthritis may also stretch and damage the ligaments that connect the thigh bone to the lower leg bone. After surgery, the artificial joint itself and the remaining ligaments around the joint usually provide enough stability so that the damaged ligaments are not a problem.

Why it is done

Doctors recommend joint replacement surgery when knee pain, disability and stiffness have a serious effect on your daily activities and when medicines and other treatments like physiotherapy and weight loss no longer relieve symptoms.

Doctors may not recommend knee replacement for people who have:

  • poor general health
  • active infection or are at high risk of developing an infection
  • severe weakness of the quadriceps muscles at the front of the thigh so they might not be able to support the new joint or severe deformity of the leg related to muscle weakness or paralysis

Some doctors will recommend other types of surgery, if possible, for younger people and those who do strenuous work. A younger or more active person is more likely than an older or less active person to have an artificial knee joint wear out. People who are very overweight are also more likely to have an artificial knee joint fail from the extra stress on the joint.

How well it works

Most people will have much less pain after knee replacement surgery and will be able to do many of their daily activities more easily. After surgery your knee will probably not bend quite as far as it did before you developed knee problems, but you should be able to stand and walk for longer periods without pain. Some people will still have some pain in the knee even after it has been replaced with an artificial knee joint. Usually the pain will be less than it was before the surgery.

After surgery, you may be allowed to resume activities such as golfing, riding a bike, swimming, walking for exercise, dancing, or cross-country skiing (if you did these activities before surgery). Your surgeon may discourage you from activities that put a lot of stress on your joint like running, playing tennis, and squatting.

The younger you are when you have the surgery and the more stress you put on the joint, the more likely it is that you will later need a second surgery to replace the first artificial joint. Over time, the components can sometimes wear down or may loosen and need to be replaced.

Your artificial joint should last longer if you are not overweight and you do not do hard physical work or play sports that stress the joint. If you are older than 60 when you have joint replacement surgery, the artificial joint will probably last the rest of your life.

If you wait to have surgery until you have already lost a lot of your strength, flexibility, balance, endurance, and ability to be active, then after surgery you might have a harder time returning to your normal activities.

Doctors usually don't recommend knee replacement surgery for people who have very high expectations for how much they will be able to do with the artificial joint. (Examples are people who expect to be able to run, downhill ski, or do other activities regularly that stress the knee joint.) The artificial knee allows a person to do ordinary daily activities with less pain. It does not restore the same level of function that the person had before the damage to the knee joint began.


Risks from knee replacement surgery include:

  • blood clots
  • infection in the surgical wound or in the joint
  • nerve injury
  • bleeding (a small number of people need a blood transfusion)
  • problems with wound healing
  • lack of good range of motion (stiffness)
  • continued pain in the knee
  • dislocation of the kneecap
  • fracture of the kneecap or other bone around the knee
  • instability in the joint
  • wear and loosening of the artificial joint (especially in younger or heavier patients)
  • anesthesia risks and medical complications of surgery

Pre-operative visit

Most hospitals will ask you to come in several weeks before your joint replacement surgery to review your situation and talk about what will happen. It’s a good idea to bring a family member or friend to this visit to take notes and ask questions. You will be given lots of information, and this can be overwhelming and difficult to remember if you don’t have someone with you.

During the pre-operative visit, the team will talk about what kind of anaesthesia is best for you. This depends on many things, including your age and general health and preference. The team may suggest a regional anesthesia so you don't feel the area of the surgery, with this option you'll also have medicine that makes you relaxed or lightly asleep but you will breathe on your own. Alternatively, your team may suggest a general anesthesia that puts you asleep during the surgery, with a breathing tube down the throat and attached to a breathing machine.


Physical activity

The best way to strengthen your legs in preparation for surgery is to walk regularly. Don’t be afraid to walk while waiting to have your surgery – it won’t harm your knee joint. Follow the “two hour” pain rule: If your joint hurts for longer than two hours after your walk, you have done too much. Do what you can to manage the pain and walk a bit less the next day.

Besides walking, your surgeon may recommend that you do some regular pre-operative exercises. Some are aimed at strengthening your arms and shoulders, which will help you cope with crutches or a walker after surgery. Others will help maintain the strength of your leg muscles.

Your home

Your house or apartment may need certain changes to meet your needs after your operation. Look around now and see what has to be done.

  • Arrange or remove furniture for a clear path around your home.
  • Remove small mats and area rugs. Tape down the edges of larger rugs so you won’t trip over them.
  • Use armchairs because you’ll need the arms to help you sit down and stand up. Make sure you have at least one chair with a strong seat (not too low), a backrest and sturdy arms. Avoid chairs that rock, roll or glide.
  • You can raise chair heights either by using lifts under the legs or by placing a firm pillow on the seat.  
  • Keep rooms and hallways well-lit so you can see obstacles.
  • Make sure all stair railings in and outside your home are secure.
  • Keep cords out of the way.
  • Getting in and out of bed can be difficult after joint replacement surgery. It’s important that your bed isn’t too low.
  • The edge of the mattress should be no lower or higher than the backs of your knees. If your bed is too low, you may need to raise it to a better height by having someone place it on sturdy blocks. If it's too high, you may need to adjust the height by adjusting the bed frame.
  • If there is no bathroom nearby or it is on a different level, you may need to purchase or borrow a bedside commode (a chair with a built-in bed pan) for use at night.
  • Install a raised toilet seat
  • Get a rubber (non-skid) mat for your bathtub or shower stall so you don’t slip. A tub bench is also helpful. Purchase a long, handheld sponge to help you wash.
  • If grab bars around the toilet, tub or shower are necessary, make sure they are installed before your surgery.

What to expect after surgery

Right after surgery

The routine may vary between hospitals, but here is what is likely to happen:

  • You will find yourself attached to an intravenous (IV) line which is dripping fluid, antibiotics, pain medication and blood-thinning drugs into your body.
  • There will be a gauze dressing or bandage over your knee.
  • You may also have a compression pump or compression stocking on your leg. This device squeezes your leg. It keeps the blood circulating and helps prevent blood clots.

The pump and IV line will be disconnected over the next day or two, depending on how well you are doing. It is important that you get out of bed and start moving around as soon as you are able after surgery. This will help to decrease the chance of complications such as blood clots and will improve your recovery.

You will probably start feeling some discomfort in your new joint when you wake up. This is completely normal. Let your nurse or doctor know if you are in pain so they can adjust your medication.

It is not unusual to have an upset stomach or feel constipated after surgery. Talk with your doctor or nurse if you don't feel well.

Your doctor may teach you to do simple breathing exercises to help prevent congestion in your lungs while your activity level is reduced. You may also learn to move your feet up and down to flex your muscles which increases blood flow and helps prevent swelling and blood clots.

Leaving the hospital

You will probably stay in the hospital for 1 to 4 days after surgery. You can go home from the hospital if you have care at home and your recovery is going well. It will be very helpful to have someone stay with you for the first few days and you will likely need help with cooking, cleaning and other chores for the first couple of weeks after surgery.

You may go to a rehabilitation centre if you need extra care and are not able to move around safely enough to look after yourself shortly after surgery. You can go home when you've recovered enough to move around safely and care for yourself.

Moving around

Most people who have knee replacement surgery start to walk with a walker or crutches the day of surgery or the next day. Unless your surgeon has told you otherwise, you can place full weight on your operated leg as soon as you feel able to do so.

Many people are afraid to bend their knee after surgery, thinking this could be harmful - especially since bending the knee is painful at first. You will be encouraged to start bending your knee right away. Do it gently at first, but keep doing it. Your therapist will also begin some simple exercises to help strengthen your leg muscles. It is very important to get your knee bending right away after knee replacement surgery as this will help to avoid stiffness, which can be permanent.

Do not rest your operated knee over a pillow in a bent position. This can cause stiffness in both your hip and knee, making it harder to straighten your leg.

Rehabilitation after a knee replacement is intensive. The main goal of rehabilitation is to allow you to bend your knee at least 90 degrees. That much bend is enough for you to do daily activities, such as walk, climb stairs, sit in and get up from chairs, and get in and out of a car. Most people can bend the knee more than 90 degrees after surgery. One thing that affects how much bend you get after surgery is how much bend you had before surgery. Another thing that affects how much bend you get is how quickly you start moving and bending your knee after surgery. You should try to bend your knee a little bit more each day after surgery, with the goal of getting to 90 degrees as soon as possible. Ask your physiotherapist to explain to you how much bend is 90 degrees and make sure you know how many degrees your knee bends while you are recovering. To get the most benefit from your surgery, it is very important that you do your physiotherapy. You will get this therapy both while you are in the hospital and after you go home. Doing your regular daily activities is also part of your therapy and will help to get your knee moving and bending. Be sure to walk several times each day and to keep moving. Try not to spend too much time lying down or not moving your leg.

Continued recovery

Call your surgeon or family doctor if:

  • you develop a temperature higher than 38 C. (101 F.)
  • you notice any change in the amount, colour or odour of drainage from your incision or a sudden increase in pain around the incision
  • you notice increased pain, swelling or tenderness in the calf or thigh of either leg
  • you notice that either leg appears pale or bluish in colour
  • you notice that either leg feels unusually cool to the touch
  • you suddenly have trouble walking

Rehabilitation continues after you go home from the hospital. You will get rehabilitation until you are able to function on your own and you get back as much strength and range of motion in your knee as you can. You will keep working on increasing the amount you can bend your knee and on building strength and endurance. Rehabilitation after surgery will take several months and you may continue to improve (especially strength and endurance) for up to one or one and a half years after surgery.

Don't drive until your doctor says it is okay for you to drive.

You will have an exercise program to follow when you go home, even if you are still having physiotherapy. You should also take a short walk several times each day. If you notice any soreness, try a cold pack on your knee. You might also cut back on your activity a bit but don't stop completely. Staying on your walking and exercise program will help you recover faster. Your doctor may recommend that you ride a stationary bike. It can help strengthen your leg muscles and improve your knee bending. Swimming is also a good exercise after knee surgery but don't go in the water until your stitches or staples are removed and your incision is completely healed (no scab, just a pink line).

Living with a knee replacement

Your doctor may want to see you from time to time for several months or more to monitor your knee replacement. Over time, you will be able to do most of the things you could do before surgery.
Controlling your weight will help your new knee joint last longer.

Stay active to help keep your strength, flexibility, and endurance. Your activities might include walking, swimming (after your wound is completely healed), biking, dancing, or golf. You should avoid high impact activities — such as jogging, downhill skiing, competitive tennis and other sports that involve contact or jumping. Talk to your doctor about your situation.

Your doctor will probably want to see you at least once every few years to check your knee.

For at least 2 years after your surgery, your doctor may want you to take antibiotics before dental work or any invasive medical procedure. This is to help prevent infection around your knee replacement. Speak to your surgeon to decide whether you need to take antibiotics. Your general health and the state of your other health conditions will help them decide.

Frequently Asked Questions (FAQ)

  • What about pain relief after surgery?

    After your joint surgery is over, you will experience some pain, but there are several ways this can be managed. Your surgeon will decide which pain relief method is right for you, based on your medical history and other factors. Here are some possible options, which may or may not be available at your hospital: 

    • Oral medication (pills) taken every few hours may be enough to control your pain. Your doctor will prescribe the drug(s) and dose(s) based on your overall health and level of discomfort. You will likely be given a combination of different medications that work to reduce pain in different ways. Using several different medications can reduce your pain more than simply taking a higher dose of a single strong pain medication. 
    • You may be given a peripheral nerve block to help reduce pain after surgery. This involves injecting an anaesthetic around the major nerves in the area being operated on, which numbs the area for several hours during and after surgery, reducing pain and the need for strong pain medication. This is usually done by a specially trained anaesthesiologist before the surgery starts or by the surgeon during the surgery. 
    • You may be given an injection of local anaesthetic directly into the operative site by the surgeon during your surgery. This can help to numb the area for several hours after surgery, reducing pain and reducing the need for you to take strong pain medications. 
    • You may be given a dose of pain-relieving medication by needle (injection) which goes directly into your IV or into the muscle of your arm, leg or buttock. Injections are typically used when a patient is not able to take anything by mouth.  
    • Patient-Controlled Analgesia (PCA) is sometimes used. This is when you are instructed how to take small doses of pain medication when you need it (either by pushing a button attached to a pump that delivers an IV medication or by taking a pill from a supply left at your bedside). PCA can give you a feeling of control over your pain management, which can relieve anxiety and help reduce pain for some patients. 
    You should always use a combination of other pain medications (such as acetaminophen and anti-inflammatory medications) to address your pain first BEFORE using strong opioid medications. To reduce the risk of overdose or abuse, you should use opioid medications in the smallest possible dose for the shortest possible time. 
  • What is the difference between unilateral (one side) and bilateral (two sides) joint replacement surgery?

    Most people who undergo knee replacement surgery have the procedure done on just one side (either the right or the left). This choice has to do with the fact that their symptoms - usually pain, stiffness and limited mobility - are mostly one-sided. 

    If your symptoms are occurring on both sides, or if tests show serious problems in both joints, your surgeon may recommend you have both knees replaced in a single operation. This is known as "bilateral" joint replacement surgery.  You will need a minimum of six to eight weeks off work whether you have unilateral or bilateral surgery. 

    Here are some things to be aware of around bilateral joint replacement surgery: 

    • You will likely need two crutches and/or canes to help you get around during recovery 
    • You may need to spend time in a rehabilitation hospital after surgery 
    • In-hospital recovery time is usually longer than for unilateral (or one knee replacement) surgery 
  • Will I need a second operation?

    There are many reasons why someone who already has an artificial knee joint might need to have another operation to replace the old joint with a new one. This procedure is known as "revision surgery." 

    Most joint replacements last between 20 and 25 years. If you require revision surgery, it's likely that the first artificial joint has simply worn down or become loose, which can cause pain and dysfunction. Other reasons for revision surgery include an infection in the joint or a fracture around the artificial joint. 

  • What if I need to take a shower or a bath after surgery?

    You should not take a bath until your incision is completely healed. Fresh incisions should not be soaked, which means no baths, swimming, hot tubs, etc. until the incision has healed fully. Some hospitals tell patients they shouldn’t take a full bath – directly sitting on the floor of the tub – until three months after surgery. 

    Here are some general tips for taking a shower or a bath: 
    • DO NOT step out of the shower stall or tub onto a rug or towel. If you want a soft surface, tape a non-skid bath mat securely to the bathroom floor beside the tub. 
    • Until you feel steady on your feet, use a shower bench or seat which rests on a rubber mat or non-skid adhesive surface on the bottom of the tub or stall. 
    • A long-handled sponge or hand-held shower hose can be used to wash your lower legs and feet when you are restricted from bending over. 
    • If you will be using any grab bars beside the tub or on the wall, make sure they have been properly installed and can support your weight.  
    • When getting into the shower or tub, carefully lower yourself on the shower seat. Turn to face the faucets and lift your operated leg over the lip of the shower, followed by your non-operated leg. 
    • A walk-in shower may be a better option until you feel more confident getting in and out of the shower or bathtub.  
  • How do I get up and down stairs after surgery?

    It’s important that all stair railings, both inside and outside your home, are secure. In the first few weeks at home after surgery, limit stair climbing to one round trip per day if possible.  

    • Put your hand on the railing. Hold your crutch or cane in the other hand. 
    • Start UP the stairs with the foot of your non-operated leg. 
    • Step onto the step with your operated leg. 
    • Follow with your cane or crutch. 
    • Take one step at a time. Don’t move until you feel strong and steady. 
    • Always start DOWN the stairs with your cane or crutch 
    • Step down with your operated leg. 
    • Then move the foot of your non-operated leg down onto the same step. 
    TIP: An easy way to think about it is: “Up with the good leg; down with the bad.” 
  • How do I get in and out of bed after knee surgery?

    Getting into bed after knee surgery: 

    • Back up towards the middle of the bed until you feel the backs of your knees touching the bed.  
    • Sit down on the mattress, placing one hand on your walker/cane and the other on the bed. 
    • Using your hands for support, slide yourself backward towards the middle of the mattress. 

    Getting out of bed after knee surgery: 

    • Make sure your walker or cane is handy. 
    • Slide yourself over to the edge of the bed. 
    • Slowly move your legs over the edge of the bed and sit up gradually using your arms for support. 
    • Place your operated leg out in front of you. Be sure that the foot of your non-operated leg is flat on the floor, ready to take your weight when you stand up. 
    • Place one hand on your walker/cane and then push up from the bed with your other hand until you are standing. IMPORTANT: Do not pull on the walker or rely on it to support your full weight. It can tip over easily and you could fall. 
  • When can I start driving after surgery?

    How soon you can start to drive depends on many factors: the type of surgery you had, whether your new joint is on your right or left side, and what kind of car you drive. Most patients should wait at least six weeks before driving, although some can start driving a bit sooner than that. Also, strong pain medicines might affect your driving. Do not drive while you are taking these medicines. 

    Before you can get behind the wheel of a car after joint replacement surgery, you MUST have permission from your health care team.  

    Avoid traveling in cars with low bucket seats or trying to climb into the back seat of a two-door vehicle. If you are traveling in a vehicle which sits up higher than most cars (such as a van or sport utility vehicle), you should ask a therapist to instruct you about getting in and out safely. When getting in and out of the car, be sure to move the seat (if possible) to give you as much space as necessary to get in and out comfortably and safely. 

  • How do I use the toilet after surgery?

    Some people who are weak or unsteady after returning home from the hospital arrange to rent a bedside commode (a chair outfitted with a bedpan) for a few days or weeks. This should be sturdy enough to bear your full weight and have non-skid legs.  

    A raised toilet seat with arms may be helpful for those using their own bathrooms. The device fits over your existing toilet seat and is designed to make sitting down and getting up from the toilet easier. 

    • Back up to the toilet seat until you feel it touching the backs of your knees. 
    • Keep one hand on your cane or walker while you reach back with the other hand for the edge of the raised toilet seat. If your seat has arms, reach back for them with both hands. 
    • Keep your operated leg out in front of you so it doesn’t take any weight. Sit down, resting your foot lightly on the floor. 

    When it’s time to get up, reverse the process: 

    • Place one hand on your cane or walker and the other on the edge of the raised toilet seat.  
    • Push yourself up using the arms of the toilet seat and keeping your operated leg out in front of you until you are standing.  
    • Be sure to get your balance before taking hold of your cane or walker. 

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This information was last updated September 2017, with expert advice from:

Dr. Sarah Ward, MD, FRCSC
Orthopaedic Surgeon, St. Michael’s Hospital
Lecturer, Department of Surgery, University of Toronto