Common types of meniscal tears
- • Horizontal or oblique tear is the most common type, frequently involving the posterior horn of the medial meniscus. This is a degenerative type tear rather than a traumatic type tear.
- • Longitudinal tear is a vertically oriented tear that extends parallel to the circumference of the meniscus and is almost always associated with traumatic injury.
- • Radial tear occurs in vertical orientation perpendicular to the long axis of the meniscus. This is often seen as a cleft in the meniscus or with a truncated meniscal contour. If the tear is along the imaging plane, the absence of the meniscus on one image can be used to make the diagnosis (“ghost meniscus” sign). A radially torn medial meniscus will often extrude medially, extending beyond the margin of the tibial plateau by greater than 3 mm.
- • Complex tear is a tear that extends in more than one plane. This tear has extensive distortion of the meniscal substance and results in multiple flaps.
- • Bucket handle tear is a type of a longitudinal tear where the inner edge of the meniscus is displaced. This type of tear can be identified by noting absence of the inner margin of the bow tie as seen on sagittal images. The displaced fragment can lie anterior to the posterior cruciate ligament (PCL) (“double PCL” sign) or may have flipped anteriorly to abut the anterior meniscal horn (“double anterior horn” sign).
- • Displaced flap tear occurs when a fragment of the meniscus is displaced away from the site of tear. This most commonly occurs in the medial meniscus where the fragment is displaced into the medial gutter along the tibial plateau. The clinician should be alerted of this finding because it can be overlooked during arthroscopy if the surgeon fails to probe the medial gutter.
- • Meniscal root tear is a subtype of radial tear that occurs most frequently at the posterior medial meniscal root. This tear cannot resist hoop stress and often leads to complications such as meniscal extrusion, early secondary osteoarthritis, and subchondral insufficiency fracture.
