Morphologic variants of the proximal knee-joint cavity. An anatomical and radiological study.

To study the shapes of the suprapatellar bursa and the suprapatellar septum, 210 specimens were examined anatomically and 2056 patients radiologically. It is possible to classify the variants of the suprapatellar septum into four types on the bases of anatomical aspects. The type of suprapatellar septum determines the communication between the suprapatellar bursa and the knee-joint cavity and influences the proximal extension of the knee-joint cavity. A suprapatellar lateral recess shaped like a saccular space was found on the lateral side of the suprapatellar bursa in just under 20% of the knee joints. There was no corresponding suprapatellar recess on the medial side. Pneumoarthrography is an effective tool for demonstrating the variable structures and spaces of the synovial cavity of the knee joint. The radiological findings correlate with the results of the anatomical studies.