[The localization of postthrombotic changes in the different levels of the venous system of the leg (author's transl)].

In 173 legs with crural ulcers and postthrombotic syndrome proved by phlebography the frequency of involvement of the 4 levels of deep venous system was assessed. The results were compared with those obtained from a group of patients with acute or subacute deep vein thrombosis. The partly very distinct discrepancies may probably be explained by long lasting dynamics of the venous changes (spontaneous lysis, recurrent thrombosis). For the development of severe signs of venous insufficiency the involvement of the lower leg level may be the only cause in many instances.