Preoperative magnetic resonance images of the left knee. (a) T2 weighted axial MRI shows a cystic mass measuring 23 mm × 20 mm detected on the posteromedial aspect of the knee. Flattened sartorius muscle (arrows) is noted just over the cyst. (b) Multiple daughter cysts expanding from the main large cyst to posterior and anterior directions were noted on STIR axial image (arrows). (c) A horizontal tear of the posterior segment of the medial meniscus was identified on sagittal proton image. (d) A communicating tract between the cyst and medial meniscus was identified (white arrow). Note that the flattened sartorius muscle is indicated by black arrows.
