Popliteomeniscal Fascicles: Anatomic Considerations Using MR Arthrography in Cadavers

Abstract

This study was performed to examine the normal MR arthrographic anatomy of the popliteomeniscal fascicles with specific reference to the number of popliteomeniscal fascicles, thickness and course of the fascicles, and presence of other posterior attachments from the medial aponeurosis of the popliteus musculotendinous region. Multiplanar 1.5-T MR arthrography of 10 cadaveric knees was performed using a quadrature knee coil. Specimens were frozen and sectioned in the sagittal (n = 4), axial (n = 3), and coronal (n = 3) planes. MR images and anatomic specimens were correlated by two musculoskeletal radiologists. Three popliteomeniscal fascicles were identified on MR arthrography: anteroinferior and posterosuperior fascicles in all 10 knees and posteroinferior fascicles in four of the knees. The posterosuperior popliteomeniscal fascicle was uniform in thickness, and the anteroinferior popliteomeniscal fascicle was variable in thickness. The anteroinferior popliteomeniscal fascicle formed a conjoined fibular attachment with the popliteofibular ligament. A medial aponeurotic extension from the popliteus musculotendinous region gave rise to the posteroinferior popliteomeniscal fascicle, which extended upward and attached to the inferomedial aspect of the posterior horn of the lateral meniscus. Additional attachments from the medial aponeurosis of the popliteus musculotendinous region to the posterior cruciate ligament, posterior capsule, oblique popliteal ligament, and posterior meniscofemoral ligament of Wrisberg were seen. Three popliteomeniscal fascicles were identified on MR arthrographic images. The popliteus muscle-tendon unit forms robust attachments in the superior, inferior, medial, and lateral oblique aspects, highlighting its importance in posterolateral stability of the knee.