Osteochondrosis dissecans is a clinical picture described by bone necrosis (lat. : osteonecrosis) at a specific joint surface. In the further course of the disease, osteonecrosis dissecans is accompanied by a splitting off of joint fragments.
The detached fragment is also called “joint mouse” or “joint dissatisfaction”. The knee is an extremely predisposed (susceptible) site for osteochondrosis dissecans. Other locations such as the upper extremity (elbow joint) or the foot (ankle joint) may also occur. and cartilage flake
Cause
Despite today’s medical progress, the exact causes underlying osteochondrosis dissecans are still unclear and not defined in detail. However, there is general agreement that the most common cause is overloading of the knee joint; for example, through competitive sports. This is compatible with the fact that it is primarily children or adolescents who are affected.
After all, it is precisely at a young age that the sporting phase of competitive sport begins, which can quickly lead to chronic mechanical overloading. This clinical picture often occurs at the end of the growth phase. This implies that children are very often affected.
In principle, the knee is an anatomical structure that is subject to extreme stress, since it is exposed to almost every sport except swimming, pressure or pulling. Cartilage and bone damage as well as torn meniscus and cruciate ligaments are not untypical. In addition to mechanical overload, poor circulation or traumatic events (fractures, compressions, etc.)
can also be triggers for bone necrosis with a joint dissatisfaction. The knee joint is particularly susceptible to osteochondrosis dissecans at the medial femoral condyles (lat. femur: thigh bone, lat. condyles: joint process).
Stadiums
The course of the disease can be divided into four successive stages. The severity of the clinical picture thus increases with the stages.
- In the first stage, bone necrosis is subchondral (below the cartilage) and the cartilage is not yet involved.
- In stage 2, a demarcation between healthy and diseased bone tissue (=demarcation) is visible. This is accompanied by softening of the joint capsule and a sclerosing border.
- In the third stage, the damage progresses so far that a joint fragment is released from the joint bed, which now has free space in the joint fluid of the joint space.
- In the fourth stage this “joint mouse” now causes a joint defect.