Arthrosis of the joint is not a sudden, acute event, but is usually the result of decades of incorrect loading in the joint. As a result, joint abrasion is increased and the joint surfaces are destroyed by inflammation. If the bone surfaces that form the joint rub directly against each other, this is associated with severe pain. In the ankle joint, this results in a considerable restriction of movement at an early stage. The following findings at the ankle joint promote joint arthrosis:
- Bone cartilage trauma, i.e. blows or impacts against the joint, e.g. as a result of competitive sports,
- ligament instabilities, so the joint has too much freedom,
- Malpositions of the legs, such as O or X legs,
- Asymmetry in the position of the ankle in relation to the ankle fork,
- Foot arch changes, such as kink and flat foot,
- Joint bleeding in connection with hemophilia (haemophilia)
- metabolic diseases, such as diabetes mellitus or gout,
- Bone fractures and related ligament injuries.
Arthrosis is an irreversible destruction of the joint and, depending on the extent of the damage, it can be slowed down or an ankle prosthesis is necessary at the end of what is usually a long period of suffering. The prosthesis is usually made of titanium with a movable polyethylene core. In this way, mobility of the ankle joint can usually be maintained. A joint stiffening in the area of the ankle joint (= ankle arthrodesis), however, is not an option, as it not only impairs the rolling of the foot when walking, but also the posture of the body. In the worst case, this in turn causes further joint diseases and incorrect loading.
The ankle endoprosthesis is inserted under general anaesthesia or local anaesthesia. The patient lies supine during the operation. As a rule, the blood flow in the affected leg is throttled with the help of a thigh cuff, so that a "bloodless" operation is possible.
Often, hardly bearable pain in the ankle is the necessary prerequisite for the installation of an ankle prosthesis. And indeed, the pain will quickly improve after the operation and suitable rehabilitation. The joint replacement also helps to maintain a normal gait pattern, which further reduces the pressure on the joint itself.
Patients with ankle prostheses are generally much more mobile than before the operation and also participate more actively in life again. Although the artificial joint no longer achieves the mobility of a natural ankle joint in any case, the extent to which movement is facilitated is completely sufficient for normal walking in everyday life. Surveys have also shown that up to 90% of patients are now satisfied with ankle prostheses due to new techniques and replacement materials.
In the following cases, however, no new ankle joint may be inserted, e.g:
- in immunosuppression,
- for active infections
- for joint necrosis,
- Problems with body awareness,
- high load on the joint, e.g. due to high weight or excessive sport activity.
It is also particularly important for those affected to know how long such joint endoprostheses will last. According to the Swedish Endoprosthesis Register, the main issue seems to be the implantation time. Endoprostheses implanted between 1993 and 2005 held for at least five years in 78% of patients, and for up to ten years in 62%. Within the first five years, 19% of the artificial joints had to be operated on and replaced again.
Today, prosthesis design in ankle prosthetics is already much more advanced than 20 years ago, so that significantly longer durability can be expected. The degree of experience of the surgeon is of no less importance for the success of the operation. For an experienced specialist in orthopaedic and trauma surgery, 30 operations are a threshold value that should not be undercut.