A glance at the operation statistics reveals that the number of endoprostheses continues to increase every year. In Germany, the knee is most frequently affected, closely followed by the hip joint replacement. In addition, there are also possibilities today to treat the shoulder or the wrist with joint replacements. For a long time now, not only the elderly have been affected. Also, more and more young, sporty people need a joint replacement early, mostly at the knee, hip or in the shoulder area.
In everyday life, the hand and thus also the wrist is a true "high-performance organ" of the body. We feel, touch, work and carry loads with our hand. It is all the more painful when an accident or decades of overstraining the wrist causes it to fail or hurt. Ligament tears occur quite frequently, as well as fractures of the fine joint bone caused by falls or accidents. If the wrist can no longer be surgically maintained, it must be replaced by a hand endoprosthesis.
In general, an artificial joint must meet many requirements in order to be used safely. For example, it should be physically stable, i.e. it will not change in the body even years later. In addition, an artificial joint must be compatible with the body so that it neither causes immune reactions nor organ damage. A certain stability against fractures and a light construction are important as well.
Meanwhile, there is already a whole range of possible materials available for a hand endoprosthesis. Metal alloys, e.g. iron, cobalt and titanium, have been researched best so far. Plastics such as polyethylene, ceramics or bone cement are also used.
So far, however, research has not succeeded in imitating the synovial fluid that occurs naturally in the joint. Depending on the material used, the lack of lubrication causes friction and slackness in the bone, which can lead to abrasion and loosening of the endoprosthesis in the bone. Granulomas as well as metal and ceramic fractures have also already been described. Corrosion can also be expected due to the humid and warm body environment.
However, researchers worldwide are continuing to work on developing an increasingly natural joint replacement that meets the requirements for longevity and low complication rates.
Unfortunately, complications can never be completely ruled out despite very good care conditions at specialized joint replacement clinics. In older patients, for example, prosthesis loosening may occur in some cases due to insufficient bone regeneration. This affects about 8% of all joint endoprostheses within a period of 10 years after implantation. The loosening of the prosthesis makes the entire joint unstable, which is why the only remaining measure is often a second surgery.
Prosthesis abrasion is also possible. The material of the prosthesis is released by the increased friction on the joint surface. Studies on knee joint prostheses, for example, have previously shown that titanium particles were rubbed off from the endoprosthesis and then accumulated in cells of the immune system, leading to inflammatory reactions at the joint replacement.