[Chronic ankle instability].

Chronic ankle instability represents a typical sports injury. After an acute ankle sprain 20-40% of the injured develop chronic ankle instability. From an orthopaedic point of view chronic ankle instability can be subdivided into lateral and medial instability or a combination of both, the so-called rotational ankle instability. From a pathophysiological point of view, chronic ankle instability can be either mechanical with a structural ligament lesion or functional with loss of neuromuscular control. For the physician chronic ankle instability is a difficult entity as the diagnosis is usually complex and the therapy often surgical. This review on chronic ankle instability deals with the pathomechanisms, diagnostics, indications for conservative and surgical treatments, and possible long-term sequelae, such as ligamentous osteoarthritis.