[The synovial cavity of the knee joint and its major communicating bursae].

The knee joint, its physiological details and normal variants have been studied in about 2,000 arthrograms. The functional anatomy and the biomechanics of the joint are described and the pathogenetic significance of the septum and of the suprapatellar bursa and of the popliteal capsular enlargement are discussed. The width of the opening in the septum, the involvement of the septum in synovial processes, absence of communication between the bursa and the newly described ventral 'synovial cysts' are potential factors in producing abnormalities in the suprapatellar region. The synovial space is best demonstrated by pneumoarthrography. This is more informative than positive contrast methods, sonography or arthroscopy.