Artificial Knee
A healthy diet is important after a total knee replacement. ©Askar Abayev/CC0

How do you live with an artificial knee? What are you allowed to do, what should be avoided? Some important aspects are mentioned here.

After knee surgery, you got used to your knee prosthesis in a rehabilitation hospital for three weeks. You regained your mobility and are back home to resume your everyday life. You can contribute to an optimal recovery by checking health-related aspects of your diet, exercise and sleep.


Your treating doctor recommended the implantation of an artificial knee as a consequence of gonarthrosis, the joint wear in your knee. Causes of joint cartilage wear are inappropriate mechanical stress or overloading of the knee. Although you have an artificial knee joint which will enable you to move free of pain soon, the arthritic changes in your body are still going on. A healthy diet and the avoidance of overweight can help you to keep the knee prosthesis as long as possible and to prevent a second surgery as well as further joint wear of the hip or the other knee for example.

Adiposity (pathological overweight)

In general, overweight leads to an increased mechanical stress of the joints. Especially the hip and knee joints are severely affected. The hip and the knee transfer the whole weight of the upper body onto the feet and thus make it possible to walk upright – step by step. Only five kilograms of overweight doubles the risk of an arthritic disease. In Denmark, researchers have proven that pain can be significantly  minimized by reducing the weight by just a few kilograms, even if the damage to the knee can already be detected with x-ray. So don’t underestimate the positive effect of weight control. Even if you only lose a few pounds, your body will reward you.

Overweight is often accompanied by metabolic diseases such as high blood pressure, high plasma lipid concentration, reduced activity of the pancreas or diabetes. Excess calories and fat which your body cannot burn are mainly stored under the skin. The formation of fat tissue promotes in turn the creation of hormone-like substances, the adipokines. Adipokines cause the production of inflammatory hormones and these continuously degrade the cartilage tissue. Further metabolic diseases which stimulate the degradation of cartilage tissue are for example gout. If you are suffering from one of the pre-existing conditions mentioned above, talk to your treating doctor about the effects on your recovery.

Weight reduction and diet suitable for arthrosis

How can you achieve a healthy and controlled weight reduction? You only have to adhere to some nutritional principles – preferably not only after surgery but your whole life:

  • Avoid frozen and convenience food. It often contains synthetically produced fats which can only be processed by the body with great effort. They are eventually stored in the fatty tissue going the long way round.
  • Choose the right side dish. Go for a Hay diet (food combining diet) and don’t combine carbohydrates and proteins, or proteins and fats. Salad will become a loyal companion on your plate.
  • Olive oil instead of butter! Pay attention to your cholesterol level by avoiding butter, margarine or cream. An elevated cholesterol level are considered a risk for vascular wall diseases which in return contribute to inflammatory reactions in the body.
  • Put fruits and vegetables on your diet plan. Like this, you cover your daily requirement of vitamins and nutrients and prevent the development of other diseases at the same time.
  • Drink enough! You need two to three liters of still water so that your circulation and kidneys function optimally.
  • You can already contact a nutritionist in your rehabilitation hospital. Ask for cookbooks or get information online from the association CookUOS.

Besides weight reduction, you can also switch to a diet which is suitable to arthrosis. Here, the focus is on anti-inflammatory food, plants and oils which reduce inflammatory reactions and pain. The following aspects are important:

  • Avoid sugar and carbohydrates. Reduce white flour products in general as these promote inflammatory reactions.
  • Take omega-3 fatty acids. They support the body in fighting inflammations. Omega-3 fatty acids can also be found in fish such as salmon and herring. Alternatively, put a splash of flaxseed oil on your salad.
  • Vitamins for the joint cartilage: silicon (found in silicic acid) is especially stabilizing for the cartilage. Silicic acid is found among other things in oats, brown rice, barley or millet.
  • Some fruits, vegetables and herbs also have an anti-inflammatory effect. Some examples are broccoli, horseradish, spinach, garlic, blueberries, oranges.

Exercise and sports

After surgery, your muscles need a recovery of six weeks. Then, you will usually have enough strength to perform everyday movements on your own again. However, the duration of the recovery also depends on your age, the condition of your muscles, your general state of health and especially your motivation to do physiotherapeutic exercises at home. The range of motion after a total knee replacement is often up to 100 or 110 degrees. However, you should avoid crouching or kneeling down and crossing your legs. Usually, you can go back to work after three months and do sports that is suitable for your new joint after three to six months.

Regarding sports, it is important that you get as much exercise as possible, but it should be easy on the joints. This means that sports which are easy on the joints are perfect for you.

Sports you should avoid are:

  • Martial Arts
  • Rugby
  • Hockey
  • Team sports such as soccer, basketball, handball and volleyball, where it often gets hectic and puts you at risk of falling.

The following disciplines are suitable for you:

  • Cycling on even paths. Pay attention to the height of your saddle, if the seat height is too low, you have to bend your knee more and thus put more weight on it.
  • Gymnastics, also in warm water
  • Swimming
  • Dancing
  • Walking
  • Golfing

Don’t forget to wear your knee supports and to warm up. This prevents torn ligaments and muscles or a sudden overload. If you’re not sure whether your favorite sports is still suitable for you, ask your treating doctor.


After two to three months, you can also plan your first bigger holiday trips. You can use different means of transport which have advantages and disadvantages. Please bear in mind that you have to sit longer during longer journeys. Stretch your legs as often as possible. If you are obliged to stay in your seat for a longer period of time, think about your skeletal-muscle pump. You can stimulate the blood circulation in your legs by bending your foot in the direction of your body and then stretching it again. Thus, the blood won’t accumulate in the legs and you reduce the risks of edema forming at your ankles.


The advantage of a car journey is that you are flexible. You can take a break whenever you want to. If you’re not the driver, think about your skeletal-muscle pump here as well. If you’re sitting in the back seat, you can prop up your operated leg.

You can drive a car by yourself four to six weeks after surgery at the earliest. Your leg has to be fit enough to not put yourself and other road-users at danger. Besides painlessness, it’s also important how safe you’re feeling with your new joint. Bear in mind that in emergency situations, you may have to step on the breaks quickly and forcefully.


For shorter domestic trips and journeys to the neighboring countries, you should prefer the train to the airplane or car. It’s not only more environmentally friendly but you also have enough space to prop your leg up. In addition, you can stretch your legs in the train compartment. The train station’s support service helps you carry and stow away your luggage.


If you choose to travel by air, bear in mind that you barely have any space to move. Especially during long-haul flights, you have an increased risk of thrombosis shortly after surgery. Contact your treating doctor before an air journey. They can prescribe you pre-filled syringes for thrombose prophylaxis. Due to the easy handling, you can administer them yourself or ask your travel partner to help you. Also keep in mind that you drink enough water, preferably one glass per hour. At the terminal, you can also ask the support service to carry your hand luggage. The steward in the airplane can stow away your luggage in the overhead compartment.

During the check-in, the metal detector may set off an alarm because depending on the type of protheses, there are metal alloys in your knee. However, implants rarely set off an alarm. It depends on how sensitive the detectors are set to metal parts though. Thus, it is recommendable to issue an endoprosthesis pass before your departure. In this pass, the date of surgery, the type of prosthesis, the material of the parts of the endoprosthesis and the date of the control examination are registered. The implant pass is not an officially recognized document, but it can however help you in such situations.


After the operation, you should initially sleep on your back. The lateral position is possible with a cushion between your legs. You should avoid sleeping on your stomach during the first three weeks because it can cause irritations of the wound or scar. If your leg hurts lying on the back with a stretched knee, you can support the back of the knee with a small cushion or a sandbag. Slightly bending your knee and supporting it at the same time should alleviate your pain.

When getting up and lying down, you should bear in mind to do controlled movements. Support yourself. Like this, you reduce the risk of falling and prevent the knee from twisting or bumping. After one month, you can sleep in your usual sleeping position again.


During the first six to eight weeks, caution is advised also for sex. Passive positions where you lie on the back can be performed safely. Always make sure that you are not in pain during the sexual act. Shortly after surgery, it’s possible that you don’t have the desire for sex due to the exhaustion caused by the operation. Talk to your partner about this. Take your time until you feel fit and comfortable again. It’s normal to be scared of wrong movements in the beginning. Take some time, caution and gather information on suitable positions and you will soon have an active sexual life after surgery again.

Operated women

In general, you should choose positions where neither your weight nor your partner’s weight strains your knee. Operated women can lie on their back, so that the man is at the top (missionary position). She must not bend the knee more that 90 degrees. Avoid positions where the knee is bent too much towards the stomach or the operated leg is pulled towards the center of the body. Also avoid positions that force an internal rotation of the knee. This occurs when the toes are turned inwards.

Operated men

The same applies to men: Avoid strong bending and angling of the knee joint. You can also use cushions and rolled towels to support your knee. Therefore, during the first six months after the operation, positions where the woman is on top and the man lies on his back are just right. Sex in a sitting or spooning position.

Even though sexuality is a sensitive topic, contact your treating doctor if you have any questions or pain. This is not an unusual subject for your doctor and they have all the information you need.


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