Your knee joint is made up of many different structures – bone, ligaments, cartilage, joint capsule and muscles attached on all sides. The synovial fluid inside your knee is like the oil in your car’s engine that allows everything to move smoothly. All these elements need to work for you to get up out of a chair, walk, jump, climb steps and everything else that involves bending and straightening your knee.

After a bad fall, with knee osteoarthritis, rheumatoid arthritis or sometimes after a knee infection there can be damage to the cartilage and bony parts of your knee joint. Osteophytes (bony spurs) start forming inside the joint and the synovial fluid becomes more sticky and syrupy. This is your body’s way of improving stability around your knee to make up for the damage to the cartilage and bone. However, like an engine with rusty parts and too little oil, this means that your knee doesn’t move smoothly like it should, causing extra strain on your ligaments, muscles and already damaged cartilage.

From there on it becomes an uphill battle with stiffness, pain and instability. However, a total knee replacement doesn’t have to be your first option. Even though cartilage doesn’t heal, it’s quite common to have damaged cartilage without pain. Prostheses don’t last forever, so ideally a knee replacement should be a last resort. Your body is stronger and more resilient than you think, so call us to find out how we can help you with a non-surgical option for your painful knee. The key is to start physiotherapy before you hit that point of no return where you need more aggressive management i.e. a complete knee replacement.

A knee replacement involves replacing the damaged parts of your knee with metal and polyethylene plastic.

Total knee replacement

In a total knee replacement the bottom part of your femur (thigh bone) and top part of your tibia (shin bone) will be removed. Afterwards the doctor will insert metal prostheses in the place of the bone that was removed. Most surgeons use joint cement to reinforce these structures, but in some cases the knee replacement will be uncemented. With an uncemented knee replacement the surgeon will use bone growth

A polyethylene plastic piece will be placed inside the “new” knee as a shock absorber. What happens to the other structures around your knee will depend on your surgeon. Your patella (knee cap) may be replaced or resurfaced and your cruciate ligaments (the ligaments inside your joint that help you with stability) may be removed or preserved.

The surgery usually lasts 1-2 hours and afterwards you are transferred to an intensive- or high care unit, depending on the doctor. Nurses in this unit monitor your vital signs (heart rate, blood pressure etc) and you move to a general ward once the surgeon is satisfied that you don’t need constant monitoring.

Partial knee replacement

In this operation only one part of your knee is replaced – either your knee cap, the inner part or outer part of your knee. The benefits of a partial knee replacement are that your recovery is faster and you won’t lose as much movement after the operation. However, if more than one part of your knee is damaged this option will not be effective.

What happens after a knee replacement?

Your total knee replacement is only the beginning – the correct exercises and rehabilitation are crucial for long-term results. After a knee replacement there is a lot of tissue damage and swelling around the joint. The body’s natural reaction to all this damage is to keep the joint as still as possible to help the healing process. However, staying still means that your knee will heal in that one position. Think of the hinge on a door that hasn’t been opened in a while – it becomes rusty and stuck in that position. As your knee heals it forms scar tissue inside the joint. This new connective tissue needs to be moved and stretched to adapt to all the movements your knee should be able to do.

Another important part of rehabilitation is getting your knee strong again. Pain and swelling after your operation will inhibit the muscles around your knee. So spending time and effort on just getting your knee moving won’t be enough. If your muscles aren’t strong enough to move and protect your knee, the stiffness in your knee will always come back no matter how much you stretch.

Having a total knee replacement causes a lot a damage to your knee. A large cut is made through your skin to get to the joint, most of the joint is removed and artificial parts are inserted. All this damage triggers an inflammatory response in your body which starts the healing process. Part of this response is swelling around the “injury”.

The function of swelling is to help with stability and to keep your knee still while it heals. As the new joint gets stronger and your stability improves, the swelling isn’t necessary anymore. So why do you still have swelling around your knee weeks or months after your operation?

Your muscles act like the shock absorbers in a car – they should keep most of the stress away from your joints when you use your knee like during walking, twisting or squatting. If there’s too much stress on your knee joint, your body will “help” by allowing swelling around your knee. That’s why you might get up without a swollen knee and notice it gets puffier as the day goes on. Strengthening exercises for the muscles around your knee will improve its stability, thereby reducing the stress on the joint when you move around and use your knee. We can help you with the right exercises at the right time to get rid of the swelling around your knee.

Possible complications after your knee replacement

• Deep vein thrombosis (blood clots)

  After any surgery there is a risk of developing blood clots. This is because of the inflammation and damage done to your body during the operation. Another reason for this increased risk is that you will try to stay as still as possible due to pain. However, staying still means that there will be less blood flow to your arms and legs. It’s important to get moving again after your knee replacement to improve your blood circulation and decrease your risk of developing blood clots.

• Wound infection

  The wound over your knee will take time to heal and close, so during this time there will be a risk that bacteria can get into the wound. This bacteria can cause an infection either in the skin around your wound or inside the new joint. Your physiotherapist is trained to recognize signs of infection, so be sure to let them know if you notice a sudden change in your pain or swelling.

• Nerve damage

  All the nerves going to the skin and muscles in your lower leg have to pass through or around your knee, so with any major surgery to your knee there will be a risk of injury to a nerve. If this happens you will notice numbness or tingling and even weakness of the muscles that move your foot and ankle.

• Dislocation
  

  A dislocation is when the joint surfaces (thigh bone and shin bone) move away from each other. This is not a common complication after a knee replacement and will usually be due to a fall or hard impact on your leg. Under normal circumstances (before a knee replacement) the muscles and ligaments around your knee will keep the thigh bone and shin bone from moving too far apart. However, while your knee replacement is still healing, the muscles around the joint aren’t strong enough to protect your knee from sudden strong forces.

• Ongoing pain

  Post-surgical (after the operation) pain is normal and can last for weeks or months, but should gradually improve over time. As your knee heals the inflammation caused by the operation will gradually resolve. You will notice that the pain improves a lot as your knee gets stronger and you get your mobility back.

• Swelling

  The swelling after a total knee replacement can be quite prominent and may take weeks to go away. If any fever or redness develops with the swelling you should contact your surgeon as soon as possible as this could be a sign of infection.

• Stiffness

  In the first weeks after your knee replacement most of your knee stiffness will be due to swelling. Just keep doing your exercises and follow the advice of your physiotherapist and doctor.  If you don’t do your exercises and move your knee in the first weeks after the operation you will risk developing scar tissue inside the joint. This scar tissue can cause permanent stiffness and keep you from regaining full movement in your knee.

Not realizing how important it is to see a physio after your knee replacement

The physiotherapist will give you basic bed exercises to start with in hospital after your knee replacement. These exercises are mostly for circulation and to start getting some movement and muscle activation around your knee. However, these exercises won’t be enough to get you fully mobile again. Some patients don’t follow up with a physiotherapist after leaving the hospital because they think that these exercises will get the job done. As your knee heals, though, the initial exercises will become too easy and your knee muscles won’t get back to the level of your unoperated leg. To complete rehabilitation and get optimal, long-term results after your knee replacement, your exercise program needs to change as you get stronger. Physiotherapists can evaluate the progress of your knee and change your exercises to match the stage of healing.

Stiffness and pain after a knee replacement

You may have heard that it’s normal to have pain, discomfort and stiffness for weeks or months after your knee replacement. A total knee replacement removes the damaged parts of your knee and you get a brand new, artificial knee. So there’s no reason for you to have permanent pain and discomfort. Physiotherapists are experts when it comes to stretching, strengthening and correcting movements after a knee replacement. If all the parts in and around your new knee are doing what they’re supposed to do, you should be able to do the things you enjoy without struggling with a painful knee afterwards.

Coming in to see a physio before your knee replacement will definitely be worthwhile. We can answer any questions or concerns you may have to prepare you for the road ahead – you will know what to expect and how long your rehabilitation and recovery will take after surgery.

After the operation your knee will be swollen and painful, so getting used to the physio exercises the day after your knee replacement can be challenging. If you make an appointment with us before surgery we can start teaching you the initial exercises and also start strengthening your core muscles and the other leg. These muscles will be working extra hard in the weeks after your knee replacement to take some of the off of your healing knee.

A total knee replacement will follow the normal phases of wound healing. There is usually some overlap between phases, meaning that the one doesn’t stop completely when the next phase starts.

Inflammatory phase

The first couple of days after your total knee replacement you will notice heat, swelling, redness and pain around your knee joint. Your pain will also be at its worst during this phase, so it’s important to use the medication as prescribed by your doctor. This phase usually peaks after 3 days.

Proliferation phase (+ 3 weeks)

The second phase of healing starts about 48 hours after your operation and lasts about 2-3 weeks. During this phase healing takes place, where scar tissue forms in and around your knee replacement. This may sound like a bad thing, but scar tissue is your body’s way of closing the wound and the start to regaining stability inside your knee joint.

Guidance from your physiotherapist is vital during this stage, because the healing tissue around your operation will still be quite fragile. The goal of the exercises and advice from your physiotherapist at this point after your knee replacement will be to support the healing process. Doing too much too soon can interfere with healing, but doing too little will result in stiffness and can interfere with how much movement you eventually regain in your knee joint. By now you should be able to walk, climb steps and get into/out of a chair with your crutches.

Remodelling phase (+ 6 weeks)

In the last phase of healing the scar tissue formed during the proliferation phase matures. This means that it isn’t as fragile and can tolerate more than during the early phases of healing. If you were seeing your physiotherapist regularly up to this point and completed your exercises, by now the muscles around your knee should already be strong enough to support your total knee replacement during everyday activities.

The process described above takes about 6 weeks, but there will be overlap from one phase  to the next. During the first 6 weeks after your total knee replacement you will be seeing your physio about twice a week. By then you should have enough movement and strength in your knee that your exercises will maintain the improvement between sessions. This means that your physiotherapist will start seeing you once every week or two and, as you get stronger, once a month.

At the end of 6 weeks you should be able to start walking without crutches and put your full weight on your affected knee. Getting into and out of a car will still be slow, but you should be able to do this without help from someone else. Your knee might still be swollen at times, but this is normal and can still happen up to 6 months after your operation. You should be able to start driving at this stage, but that will depend on when your doctor gives you the go ahead.

At 12 weeks

Throughout your rehabilitation e will check on your progress, make sure that you don’t develop any muscle imbalances and clear your knee joint when you have completed rehabilitation. This means that you should have full extension (straightening) and almost full flexion (bending) of your knee. You should also be able to stand on the operated leg with your full weight without pain. After a total knee replacement this is generally at 12 weeks after your operation.

If you followed the guidance of your physiotherapist and did your part by sticking to your home exercises, your knee should be strong and flexible enough to do most of your normal day to day activities. This should include brisk walking, climbing stairs, getting up from a chair and strolling around in a shopping center. Even picking up a shoe or dropped pen should be possible. You should be able to do all of this without using a crutch or walking stick.

What about 6 months and onwards after the operation?

As time goes on your knee will keep getting stronger and you will get more confident in your activities. By the time you reach 6 months post-operatively you should be able to drive your car around town comfortably, climb stairs without hesitation and climb up and down a ladder.

At the one year mark you should be able to do things like drive longer distances, kneel in the garden, sit on the floor with your legs crossed and get up again without difficulty.

Full recovery after a total knee replacement can take up to two years after surgery. How long your recovery takes will depend on many different factors including the extent of the damage to your knee, how long you had the problem and how strong you were before the operation. After 18 months you should be back on the tennis court of golf course, hopping off the sidewalk and almost able to forget which knee gave you trouble in the first place.

Biokineticist

Six weeks after your knee replacement you should be walking comfortably without crutches and be able to bend your knee enough to sit down in a normal armchair. At twelve weeks you should be able to jog, run up and down stairs and starting to play golf. When you reach this point of your rehabilitation, we might refer you to a biokineticist for further strengthening and to maintain the strength around your knee joint. This improves the long-term results after your total knee replacement, because you will be given exercises to do at home and follow-up with the every couple of weeks to check if the exercises need to be changed. If you’re unsure about you exercises or struggle to do them on your own you can even see the biokineticist for an hour every week for supervised exercises.

Chiropractor

For 6 weeks after your total knee replacement it is not advisable to see a chiropractor for adjustments to your knee. Strong techniques during this stage can damage the healing structures around your knee. This will set the healing process back and can cause instability of your new knee joint.

Medication

In the first weeks after your knee replacement pain medication and anti-inflammatory medication can help with pain relief. After about 4 weeks you shouldn’t need to take pain medication regularly anymore as your knee heals and becomes stronger.

Knee braces

At times after your knee replacement you might feel tempted to use a knee brace if your knee feels unstable. A knee brace is not the answer! The instability you feel is due to the muscle weakness around your new knee. The only way these muscles can get stronger is by using them and doing specific strengthening exercises. A knee brace might make your knee feel more stable while wearing it, but the muscles around your knee will become weaker and weaker. Your knee joint also needs movement to heal properly and a brace won’t allow full bending and straightening of your knee.

• Quadriceps tendinitis – your pain will mostly at the front of your knee, just above your knee cap.
• Pes anserinus bursitis – this bursa is on the inside of your leg about 5 cm below your knee, so that’s where you will have pain.
• Hamstring tendinitis – if you have a hamstring tendinitis your pain will be on the outer side and just below your knee.
• Patella dislocation – with a patella dislocation you won’t be able to straighten your knee and you will notice that the position of your knee cap is looks different on your other knee.
• Hamstring strain – pain with a muscle strain will be higher up than your knee, in the muscle belly. With a hamstring strain you will have pain at the back of your thigh.
• Quadriceps strain – the quadriceps muscle is on the front of your thigh, so your pain will be on the front of your thigh.
• Knee tendinitis – also known as patellar tendinitis, your pain will be just below your knee cap.

Manipulation under anesthetic

It’s important to move your knee joint through its full range of movement in the first weeks after your knee replacement. If you avoid bending and straightening your knee, abnormal scar tissue can form inside the new joint. This abnormal scar tissue can cause permanent stiffness that doesn’t improve with stretching and exercise. In this case you will go back into theatre where your surgeon will bend your knee to restore movement while you are under anesthetic.

Revision knee replacement

Years after your knee replacement your knee may start to feel unstable, painful or stiff, so your doctor may recommend a revision. This is because the parts used during the procedure have a lifetime of 10 to 20 years. In a revision knee replacement the orthopedic surgeon will remove and replace some of the parts of the original knee replacement. If an infection develops after a total knee replacement, the knee won’t heal properly and can become loose and unstable. It could even be necessary to remove the original prosthesis to treat the infection. In this case a revision knee replacement will also be done once the infection has cleared up.

Total knee arthroplasty

Complete knee replacement

Full knee replacement