A FEW MRI MENISCUS ABNORMALITIES 2: MRI MENISCUS DEGENERATION MACERATION FLAP TEAR EXTRUSION AND MENISCOCAPSULAR SEPARATION

• Meniscocapsular separation is a separation of the attachment of the external margin of the body of the medial meniscus from the Posterior Oblique ligament.
  
  

• Normally they are tightly attached and there should be no high signal between them.
  
  

• Here we see a rim of high signal where the two have separated.

• A flap tear of the meniscus is a horizontal type tear where one side of the meniscus rotates away.

• Most commonly its in the medial meniscus body.

• One fragment is displaced out of the joint to lie between the sMCL and tibia or femur.

• Meniscal extrusion is when part of the meniscus is displaced from the joint.

• This is measured on a coronal scan.

• Displacement of the meniscus more than 2.5 - 3mm from the edge of the medial tibial plateau indicates extrusion.

• The two causes of extrusion are:

1. Reduction in joint space from loss of cartilage.
2. Tear of the posterior horn root.

Edge > 2.5 - 3.0 mm from Medial Tibial Plateau Margin).

• Maceration of the meniscus is the most severe form of meniscal degeneration. What to look for? Technical term alert…Looks like mush 😀

• Think of grinding up something in a mortar and pestle and that’s what you get in maceration.

• The meniscus generally retains it's shape but is ill defined and intermediate in signal.

• Due to the degeneration it's more likely to tear and it also stops functioning like a normal meniscus.