[Baker cysts: an accompaniment of chronic diseases of the knee joint (author's transl)].

One hundred and twenty one Baker cysts demonstrated by arthrography have been analysed. Morphologically one must distinguish between distension cysts and dissection cysts. Distension cysts are more common with various diseases of the knee joint (68% of all cysts). Dissection cysts (32%) are found particularly with inflammatory-rheumatic diseases and are rarely of degenerative or post-traumatic origin. Acute rupture of the cyst was observed on ten occasions. Repeated rupture, which had only been suspected previously, was demonstrated by arthrography in four patients. It is pointed out that Baker cysts may imitate the features of acute thrombophlebitis.