Arthritis in the Knee. FAQ

When should you go to the doctor for joint pain?

Painful and lasting more than a few weeks – if these criteria match your symptoms you should definitely go to a doctor. The same applies if your joint 'locks' and especially if it hurts when bearing greater stress or is swollen. Also if you have a temperature for no apparent reason and joint pain, this should be clarified.


When should you have a knee joint operation?

We believe: The right time for an operation has arrived when quality of life is considerably impaired. When mobility is greatly reduced, pain has become barely tolerable and conservative methods have not brought sufficient improvement. Speak to your doctor at any case about it.

Would you answer all the questions with 'yes'?:

  • Do you have severe pain?
  • Is your knee action severely restricted?
  • Does the affected knee heavily impact on your daily life?
  • Do you suffer from chronic pain when resting and at night?

Are there alternatives to a joint replacement?

By cleansing a joint an attempt can be made during an operation to delay an artificial joint replacement or even postpone the implantation of a prosthesis. By means of this process the joint surfaces are rebuilt. Also axial corrections or cartilage plasties delay the implantation of prostheses. A good supplement is treatment with hyaluronic acid. This is injected directly into the joint and acts as a lubricant thereby reducing not only friction but also inflammation.


What risks are there with a joint replacement operation?

Artificial joints are foreign bodies which are generally tolerated well by the body. There is often poor circulation in the area around the prosthesis. As with any operation there is the risk of thrombosis, intolerance to medication or damage to the surrounding structures of the joint: Vessels, nerves, bone, muscles. If your immune system is weakened or you belong to a risk group then there is a greater risk from infection. The following count as belonging to a risk group

  • Diabetics
  • Patients who are older than 75 or 80 years of age
  • patients who have previously had an operation
  • People suffering from rheumatism
  • Patients with arterial circulation disorders.

How long does the operation take to implant an artificial knee joint? How long will I have to stay in hospital?

Implanting an artificial knee joint usually takes an hour but depends of course on the type and scope of the operation.

The follow-on inpatient stay lasts around 8 to 10 days. Better implants and gentler operation techniques also ensure a shorter duration of stay during follow-up rehabilitation. In earlier times this was 6 weeks but today only 3 weeks are necessary. Most patients can therefore manage their everyday activities on their own after about 5 weeks and be discharged home.


What types of prostheses are there?

The medial unicompartmental knee replacement is preferred if the joint cartilage in the knee is only worn on one side.

The medial unicompartmental knee replacement is preferred if the joint cartilage in the knee is only worn on one side.

Depending on the degree of wear and tear on the joint there are various joint prostheses. The medial unicompartmental knee replacement for example can be minimally invasive. In this case the arthritis should not be too advanced and usually only apparent on one side. The knee implant takes on the function of the joint cartilage as a place holder and helps to guide the joint bones.

There is also the partial total surface replacement and the surface replacement. Here only the uppermost layer of the joint bone is replaced. The artificial joint is superimposed on the existing joint bone. Again the artificial joint if anything takes over the function of the joint cartilage.

The use of partly and fully coupled prostheses is also an option. Coupled knee endoprostheses have central mechanical joint tracking in the form of a fixed axis or a different coupling mechanism. This allows a rotation of the lower leg around its own axis similar to the natural knee joint. Coupled knee prostheses are preferred if the ligamentous apparatus is no longer sufficiently stable.

The decision as to which prosthesis to use is discussed individually with each patient and depends on malpositions, ligament stability, bone quality and concomitant diseases.


How much friction is there in the joint from a prosthesis?

The articulating parts of the prosthesis are usually made from metal, ceramic and polyethylene. These materials are very well tolerated and ensure low friction. Nevertheless over the years there will be minimal amounts of friction – rather like an eraser. The 'fluff' from the eraser in this case remains in the joint. Nevertheless this friction is significant after many years. Deposits form between the bone and the parts of the prosthesis and encourage bone break up and ultimately loosening of the prosthesis.


Can I do sports with a knee prosthesis?

Cycling is certainly possible after a resting period of around 6 months.

Cycling is certainly possible after a resting period of around 6 months.

The aim of every treatment from implantation is to increase quality of life and to make pain-free everyday living a possibility. Thus being able to play sport is not top priority. Many patients however can continue to play sport and pursue their previous activities with enthusiasm – and precisely those people who have surface replacement prostheses.

You can start again with some types of sport after a resting period of 6 months, others are better avoided because they put a greater strain on the knee joint.


Types of sport you can take up again around 6 months after surgery:

  • cycling
  • Hiking
  • light jogging
  • Walks lasting 1 - 2 hours are safe. You should take breaks during these walks
  • Swimming (when doing the breaststroke: avoid abduction motions)
  • Light tennis with good technique
  • Golf


Types of sport better avoided after surgery:

  • Mountain skiing is generally unsuitable (leave at least one year if you do); cross-country skiing is also unsuitable due to the risk of falling, also unsuitable are
  • all competitive contact sports
  • strength training alone of the muscles in the hip is not recommended
  • Patients should refrain from carrying heavy loads

Does the artificial joint feel like a foreign body?

Every artificial joint is initially a foreign body which is accepted by each person differently as good or bad. Modern prostheses are built however very well to imitate our own natural anatomy so that the feeling of a foreign body usually disappears quickly.