[A construction worker with acute knee pain].

Background: Out of all peripheral arterial aneurysms, 70% are located in the popliteal artery; less than 4% of these rupture. Ruptured popliteal aneurysms may be mistaken for deep venous thrombosis.

Material And Methods: From March until June 2001 three patients were primarily admitted with a diagnosis of venous thrombosis. This delayed the appropriate treatment of a ruptured popliteal aneurysm considerably. Two patients were first anticoagulated with warfarin before being transferred to the surgical ward. All the patients were operated on with the exclusion of the popliteal aneurysm and a femoropopliteal bypass conduit.

Results: The haematoma from a ruptured popliteal aneurysm presenting with pain and venous swelling is easily mistaken for a deep venous thrombosis. In these three patients the correct diagnosis was made respectively 18, 2 and 20 days after the onset of swelling and pain.

Interpretation: Ruptured popliteal aneurysms can be mistaken for a venous thrombosis or a Baker cyst. A Duplex scan will most often lead to a correct diagnosis. Surgery is mandatory. Delayed diagnosis and treatment increases morbidity and may lead to loss of limb.