Mucoid Degeneration of the ACL
Imaging Findings:
 • T2-hyperintense fluid-signal within the enlarged ACL on both the Sagittal and Coronal sequences.
 • The anterior cruciate ligament fibers are intact and parallel to the intercondylar ridge (Blumensaat's line) with no laxity of the fibers (arrows showing parallel configuration of ACL with the intercondylar ridge).
Case description:
 • The ACL is enlarged with low-signal fibers separated by interposed hyperintense mucinous signal on MRI.
     - This is the classic "celery stalk" description.
 • The ligament will often be NORMAL on arthroscopy, as the superficial surface of the ligament is intact.
 • Can present with chronic pain and restricted range of motion. However, surgery usually not required.
Differential Diagnosis:
 • ACL tear
     - Disruption of the ligament with laxity of fibers or disorganized appearance.
     - Loses parallel configuration with intercondylar ridge on sagittal.
 • ACL ganglion cyst (cruciate ganglion)
     - Circumscribed mass within substance of ligament, measurable, and expands OUTSIDE the confines of the ligament.
     - Can cause similar expansion of ligament and is hyperintense.

Dr. Donald von Borstel @DrvonBorstel

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