A bursa that was deep to the tibial collateral ligament and adjacent to
the semimembranosus tendon was studied in fifty cadaveric knees; a vinyl
solution was injected into four of the specimens in order to facilitate a
study of the relationship between the bursa and its surrounding structures.
The bursa had the shape of an inverted U: the superficial arm was an
elliptical pocket that was located between the semimembranosus tendon and
the tibial collateral ligament, and the deep arm was a triangular pocket
that was located between the semimembranosus tendon and the medial tibial
condyle. The bursa measured, on the average, twenty-one millimeters in its
greatest anteroposterior dimension and ten millimeters in its greatest
superoinferior dimension. Magnetic resonance images were made of two
patients, and they showed fluid in the bursa.