Knee Arthroplasty

The Artificial Knee Joint

In unicompartmental replacement, which is also known as a sliding prosthesis, only the medial (rarely only the lateral) part of the knee joint is replaced, as the lateral (medial) part still appears to be largely healthy.If both the medial and the lateral knee joints are destroyed, replacement of the complete knee joint (total knee arthroplasty – TKA) is considered. Here, a surface replacement prosthesis is frequently used. It is also possible to implant a coupled knee prosthesis (hinged prosthesis); however, this is rarely used as an initial implant, but rather in particular situations and in the case of revision surgery.Furthermore, there are different anchoring techniques in knee replacement. The knee prosthesis is either implanted using cement or in a cementless way.What determines the decision regarding which procedure to use is mainly the quality of the bone. If the bone is soft and offers little potential for growth, as in the case of osteoporosis, the cement procedure is preferred, for it makes little sense to implant a cementless prosthesis if the bone (the spongiosa) does not grow into the implant and thus does not anchor the prosthesis.

The so-called bone cement is not “construction cement”, but rather an acrylic compound, which is always mixed up freshly during surgery and which is initially a gum-like mass. This is spread onto the prosthesis and when the surface replacement is implanted, it penetrates the honeycomb structure of the bone. Within about ten minutes, the bone cement hardens and can thus bear the full weight. When the cementless anchoring technique is used, the surface replacement is first jammed. Over time, the bone then grows into the specially constructed surface structure of the prosthesis and anchors it.

If the firm connection between the bone and the prosthesis/bone cement is broken, the result is that the prosthesis becomes loose, which should be dealt with surgically as soon as possible because loosening entails a loss of bone substance. If the orthopedist or general practitioner treating you has recommended knee joint replacement, just make an appointment in our outpatient clinic by sending us an email or calling us. In the context of one of our regular information nights, you can get advice about inpatient stays, rehabilitation, and all the issues that are important in the context of knee arthroplasty.

Knee Arthroplasty and Navigation

Since 2007, almost all implant surgeries in knee arthroplasty performed in our hospital have been using navigational monitoring. That is more than 200 times per year. On average, only about 30 percent of all surgeries performed in Germany are done with this optical/computer support. Regardless of which model of prosthesis is used when implanting a knee joint prosthesis, a straight mechanical leg axis must be reestablished so that the transfer of forces takes place centrally via the joint and so that lateral forces, which would result in unnecessary friction and non-physiological structural strain, can be avoided. The rotation of the prosthesis components must be correct in order to ensure that the joint is guided by balanced tension of the ligaments. If the ligaments are too tight, mobility is impaired and painful; if they are too loose, on the other hand, the result may be instability in terms of weight-bearing with subjective insecure gait or, in rare cases, even luxation of the joint. A well-structured and tissue-preserving surgical technique helps to prevent additional tissue damage and to minimize mistakes during the implantation. With the help of a navigation system, the above-mentioned parameters can be monitored and changed such that the desired result is achieved. Thus, a possible cause of early failure or untimely degeneration of the implant is eliminated. On the basis of the experiences we have made to date with the use of this system, we are firmly convinced that we are on the right track. We are increasingly using this aid also when implanting hip endoprostheses.

Aftercare for Knee Endoprostheses

The aim of aftercare is to enable your knee to bear weight as painlessly as possible and to restore the greatest possible mobility so that your quality of life, which was severely reduced as a result of the arthrosis, can be increased significantly once more. Despite all efforts and research, however, the results – and patient satisfaction – following implantation of a knee endoprosthesis are not quite as good as, for example, in the case of hip replacement. The reasons for this are various and are being studied continually by many physicians and implant manufacturers. One important consequence of this observation is that such a surgery should never be performed too early – only when mobility impairment and pain have reduced the quality of life to such an extent that it can simply not go on “like this”. In aftercare, we usually do not distinguish between cementless and cemented knee arthroplasty. You will receive professional care from our Physical Department. The surgery is followed by intensive aftercare with passive motion on a continuous passive motion (CPM) device during your entire inpatient stay.

On the first day after the operation, you will get up from bed under the guidance of a physiotherapist and already take a few steps using crutches. In the next days, you will walk more and practice climbing stairs. But you can only achieve satisfactory mobility of your “new” knee joint if you actively work with us. You should definitely continue doing the exercises you learn during your stay after you get home in order to get a good treatment result and be satisfied.

We generally recommend that after this operation, you accept the offer of follow-up treatment, where you will receive further physiotherapy. This follow-up treatment can be performed as outpatient or inpatient treatment. We will discuss this issue with you on time while you are an inpatient in our hospital. If you want to get follow-up treatment, we will prepare the corresponding documents for submission to your health insurance company and will then usually transfer you directly to a rehabilitation clinic on the day of your release. Of course, other solutions are also possible, and we will be glad to support you in organizing them.

When you are wearing an endoprosthesis, you should get regular check-ups. When you are released from the hospital, you will get a prosthesis pass from us as a reminder. You should keep it together with your other hospital documents in the folder “My New Joint”.

If there are no particular symptoms, your artificial knee should be X-rayed at the end of the follow-up treatment, after twelve months, and then every 2 years so that any possible loosening can be detected and treated in time. Any decision about extending these check-up intervals can be made on a case-by-case basis. 

Contact Person

  • Dr. Werner Hauck

    Chief Surgeon

    Specialist in Orthopedics, Trauma Surgery, X-Ray Diagnostics

    Send email

    06371 84-2701

    06371 84-2710

  • Andreas Pfeifer

    Senior Physician

    Specialist in Orthopedics, Trauma Surgery

    Send email

    06371 84-2701