In sport, joints are exposed to forces that rarely occur in everyday life: twisting with the foot planted, stopping abruptly, landing after a jump, falling onto an outstretched arm. The knee and shoulder are affected particularly often, in football and handball as well as in skiing or tennis.
The anterior cruciate ligament protects the knee against shifting and twisting. When it tears, many people feel a pop, the knee swells and gives way under load. Not every tear needs surgery; for people with high sporting demands or an unstable knee, the ligament is usually replaced with one of the body’s own tendons – cruciate ligament reconstruction.
The two menisci are crescent-shaped cartilage discs that absorb shocks in the knee and distribute the load. A tear shows itself through pain when twisting and squatting, and sometimes the knee locks. Where possible, the meniscus is stitched arthroscopically to preserve it; otherwise, only the damaged part is removed.
In the shoulder, the head of the humerus usually slips forwards out of the shallow socket. After it has been put back, the stretched capsule and the torn labrum often do not heal firmly enough, especially in young, active people. If the shoulder dislocates repeatedly, arthroscopic stabilisation can help.