Parrot Beak Tear

The vertical flap tear is a displaced type of radial tear that often occurs in the posterior medial meniscus. It presents as a wedge-shaped defect resembling a parrot beak at the free edge of the meniscus as a result of displaced oblique vertical orientation.

Parrot Beak Tear: MRI

Has both vertical and horizontal components occurring at the free edge of the meniscus body, usually at the junction of the body and posterior horn of lateral meniscus, better seen in the coronal projection. One might describe a parrot beak as a compound oblique radial tear.

Parrot Beak Tear: Differentials

Radial tear
Meniscal flounce
Post-meniscectomy

Parrot Beak Tear: Treatment

As parrot beak tears are essentially defined by a displaced fragment, the tear is typically unstable. They are addressed through arthroscopy; however, given that the tear involves the inner portion of the meniscus, it is not usually amenable to repair and is treated with partial meniscectomy.

Parrot Beak Tear: References

Pomeranz SJ. Gamuts & Pearls in MRI & Orthopedics. Ohio, The Merten Company, 1997.

Parrot Beak Tear: Example

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Parrot beak tears start as radial tears and propagate as compound oblique vertical tears. They are seen as vertical signal on coronal and sagittal images, but the key to distinguishing a parrot beak tear from a radial tear is to demonstrate its displacement and vertical extension, which is best seen on axial series. Thin axial slices are helpful to visualize.

Image 2 arrow demonstrates a radial defect in the lateral meniscus body. The tear is seen as blunting in the free edge of image 1. The oblique-vertical orientation of the tear is better demonstrated on axial imaging (image 3), with gapping of the tear suggesting mild displacement.