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.