(Fig 1-C.07) Meniscal shape deformation and torn lateral discoid meniscus

https://youtu.be/z-ElsrteYGw

https://youtu.be/VHbQLFiofuc

Meniscal and Shape Deformation in Discoid Lateral Meniscus:

• Meniscal Deformation: Indicates peripheral detachment through abnormal infolding, buckling, and shifting.
• Shape Deformation: Signals early instability with surface changes, meniscal shifts, and development of meniscal megahorns. Important imaging signs include:

Additional Key Features:

• Chicken Drumstick Appearance:
  On MRI, the meniscus may bulge at the free edge and flatten elsewhere, resembling a chicken drumstick in the coronal plane, often with an increased intrameniscal signal.
• Pseudo–Bucket-Handle Tear:
  Refers to a centrally flipped discoid meniscus (DM) or middle segment into the intercondylar recess without a longitudinal tear, indicating underlying hypermobility and peripheral rim instability.
• Posterior Megahorn:
  Results from progressive anterior capsular detachment leading to instability. Conversely, an anterior megahorn indicates a Wrisberg-type DM with absent posterior attachments.

 

Restrepo R, Weisberg MD, Pevsner R, Swirsky S, Lee EY. Discoid Meniscus in the Pediatric Population:: Emphasis on MR Imaging Signs of Instability. Magn Reson Imaging Clin N Am. 2019 May;27(2):323-339

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