Total Knee Replacement Surgery
What is knee arthritis?
The normal knee is comprised of the femur (thigh bone) on the tibia (shin bone), with the patella (knee cap) gliding up and down in a groove on the front of the femur. The ends of the bones are covered by a layer of articular cartilage (joint space cartilage). Between the two bones there is a meniscus on each side, which is a thick pad of cartilage that acts a shock absorber between the two bones.
Knee osteoarthritis is a process in which the surfaces of the knee joint wear out. As the articular cartilage and the underlying bone are worn away, the joint surface becomes rough. The joint also loses the cushioning that the articular cartilage and the menisci provide, so more forces are transmitted directly to the adjacent bone. This results in pain in the knee with movement and weight bearing.
Assessment of your knee
When you come to see Justin, he will take a full history from you about your knee. He will ask about the problems it is causing you, and what sorts of sports, exercise and other activities you want to be able to do. He will also ask about any other medical problems you might have.
Justin will fully examine your knee to assess how well you walk, as well as the movement and stability of the joint. He will then look at your x-rays and any scans you have had to determine the severity of the arthritis and what treatment is appropriate.
Once he has completed his assessment of your knee, Justin will explain the cause of your knee problems and will discuss the treatment options with you.
Managing your knee
In the early stages, arthritis can be treated non-surgically with medication, walking aids and a strengthening program. For more information on the non-surgical management of arthritis, click here.
If symptoms are severe despite non-surgical management, a knee replacement is a very good solution. If the arthritis only affects one part of the knee joint, you may be a candidate for a partial knee replacement (click here for more information). Otherwise, a total knee replacement is recommended.
Once you decide to proceed to a knee replacement, we will organise for you to be seen by one of our Physicians. The physician will organise blood tests, and ECG and a chest x-ray and will make sure that any medical issues you have are optimised as much as possible. He will also see you each day while you are in hospital after the operation.
Justin also recommends that you do pre-operative rehabilitation (“prehab”). This is aimed at building up some strength in the muscles before surgery and it also teaches you some of the exercises that you will do afterwards. Most patients find that this makes the post-operative recovery easier. You can do this with your own physiotherapist or we can organise for you to see one of the physios in our network of allied health professionals.
How is a total knee replacement performed?
You will be given an anaesthetic so that you do not feel anything. An incision is then made over the front of the knee to expose the joint. The ends of the femur and tibia are then cut and reshaped to fit the prostheses. The femoral and tibial prostheses are then cemented in place and a polyethylene plastic liner is locked onto the top of the tibial component. If the patella is very worn, this is also cut flat and a plastic button is cemented on.
The bones need to be cut very precisely because that is what determines the final positions of the prostheses. Justin now does all of his total knee replacements with a surgical robot, as this allows him to customise the positioning of the implants to your individual knee. For more information on robotic knee replacement surgery, click here.
After surgery, you will remain in the theatre recovery room for about an hour before going to the ward. It is important that you let the nursing staff know if you have pain so that you can be given painkillers. You will also have ice placed over the knee to reduce swelling and pain. It is much better to stay on top of the pain, rather than let it get away from you.
The next day, you will be seen by a physiotherapist, who will help you get up and will teach you to walk. Initially, you will use a walking frame, but once you are walking well, you can progress to crutches. The walking aids are there for balance and support but you are encouraged to put as much weight through the leg as you are able to. You will also be given exercises to do to get the knee bending and straightening and to help strengthen the muscles.
Usually, you would stay in hospital for about three nights. Most people would then go directly home and usually your health insurance will pay for a physiotherapist to visit you at home once a week. If you need more time, you might be transferred to a rehabilitation hospital for a week.
You will be discharged with painkillers and blood thinners to minimise the risk of developing blood clots. It is also recommended that you wear compression stockings to reduce swelling and further minimise the chance of blood clots.
Justin will review you two weeks after surgery to check the wound and to make sure that the knee is starting to move well. Leave the dressings intact until then. If you are having problems with the dressings, please call our office.
What is the recovery like?
Total knee replacement is a big operation and it does take a long time for the knee to recover. The knee can be very painful, especially in the first two weeks after surgery. It is important to take regular pain killers so that you are comfortable enough to do the physiotherapy exercises.
For the first two weeks, you can just do the exercises you were taught in hospital. After your check-up appointment at two weeks, please see your physiotherapist. If you don’t have one, we can help you find one that is close to where you live. It is important to do the physiotherapy exercises regularly. They help you regain the bending in your knee as well as the strength in your muscles. With the strengthening exercises, stay within your comfort zone so that you don’t strain the muscles, which will be very weak to begin with. When you are doing the bending exercises, you can try to push through the discomfort a bit so that you make faster gains. The more you can bend your knee in the first several weeks, the better you will do long term. Also spend time with your foot propped up on a stool or chair to allow the knee to straighten under its own weight. The straighter you can get it, the more comfortable you will be when walking.
It is recommended that you do the exercises at least once a day, every day, for at least six weeks. You will get better long-term results if you continue the exercises for three months.
It is common to need crutches for a little while for balance and support but you can put your full weight through the leg.
The knee will be very swollen for the first few weeks. As you do more walking, some of the swelling will go down the leg with gravity and cause some swelling around the ankle. Over time, the swelling will decrease, but it tends to flare up again when you do more with the knee. It can take a few months for the swelling to settle completely.
Long term outcomes
Research shows that about 85% of patients are satisfied or very satisfied with their knee replacement. The knee is usually either pain free or there might be some minor discomfort with strenuous activity. You can return to most activities including golf, doubles tennis, cycling and light jogging. You should, however, avoid repetitive high impact activities and contact sports. It is safe to kneel on the knee but many people find that this can be uncomfortable because of alteration of the feeling in the soft tissue at the front of the knee.
You may notice some numbness in the skin on the front of the knee from the scar to the outer side of the knee. This is because one of the skin nerves crosses the front of the knee and is always cut by the surgical incision. The numbness may change a bit over time as nerves from surrounding areas grow in but it will always feel a bit different to the other knee. It won’t affect your strength or movement.
It is common to have some minor clicking in the knee. This is because there is often some minor laxity in the joint which allows the metallic femoral component to click against the plastic liner. The only way to eliminate this would be to tighten up the knee but this would result in a stiffer and more painful joint. The clicking tends to decrease as your muscle strength improves.
Non-surgical management of arthritis