General points:
Most common: posterior horn of MM
Usually does not heal on itself as there is general lack of blood supply
Etiological classification:
Traumatic: twisting, blow, squatting,
Degenerative
Clinical features:
Pain at the sides of the knee, improves with rest
Sweeling is not much
Locked in bent position
MRI features:
T1, PD and GRE are more sensitive than T2 in the diagnosis of degeneration or tear
T2* GRE is extremely sensitive
FSE is not very useful due to ghost artefacts and increase in magnetization transfer
MR grading:
Grade 1: non-articular, intrasubstance, focal or globular. Corresponds to early mucinous degeneration
Grade 2: horizontal, intrasubstance, does not involve articular surface. Corresponds to more extensive mucoid degeneration. Usually asymtomatic. Most commonly occurs in posterior horn of medial meniscus
Grade 3: extends to at least one articular surface. Corresponds to fibrocartilageneous seperation or tear. Up to 5% of grade 3 are closed and missed on orthoscopy (false negative).
MR sequences:
All share short TE
Most commonly used sequences: SE or FSE PD with or without FS, T and GRE
Things to describe:
Anterior horn, posterior horn, body
Peripheral third (vascularised zone) or inner two third
Complete (one articular surface to other) or incomplete
Horizontal, vertical or complex
Length of the tear
