[Aetiology, therapeutics and prognosis of osteochondrosis dissecans of talar dome (author's transl)].

1. It must be considered a fact that in the genesis of osteochondrosis dissecans of the medial as well of the lateral talar dome a traumatic event is of decisive importance. In regard to the idiopathic type of osteochondrosis dissecans, it is usually the medial talar dome which is affected, but even here the traumatic genesis is prominent. Proof of a traumatic genesis is established once the following suppositions are satisfied: a) diagnosis of an adequate trauma, b) a nearly uninterrupted anamnesis of pain, c) a process at the edges visible in the radiogram. 2. Surgical treatment is imperativ in cases of cartilage floating with the danger of blocking. Excision of the focus including the injured and necrotic subchondral spongiosa and transplantation of healthy spongiosa can ward off a dissecation and thus damage of the joint cartilage as well as a sinking of the cartilage into the focus. However, there is no imperious indication for surgical intervention. 3. Development of arthrosis is rare, even after a long follow-up period up to 25 years. Serious complaints like pain during stress or rest are eceptional. Arthrodesis of the ankle joint as suggested by Schnabert (1939), is not necessary even in cases there the talar dome appears to be totally decayed in the radiogram, since over the years there is a definite discrepancy between the findings in the radiogram and the subjective complaints. 4. We noted an enlargement of the osteochondrotic process in singular cases, and parallel to this a deterioration of the clinical picture. Restitutio ad integrum in the radiogram has never been seen even in patients who have been free of symptoms for 25 years.