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Displaced lateral meniscal flap tear

Case contributed by Bálint Botz
Diagnosis certain

Presentation

Lateral meniscal tear?

Patient Data

Age: 55 years
Gender: Male
  • medial kissing contusion pattern indicative of prior valgus stress. 
  • edematous Hoffa's fat pad
  • moderate joint effusion
  • discrete, wavy appearance of the ACL but continuity is maintained
  • complex tear of the lateral meniscal anterior horn and body, with resultant partial "ghosting". The displaced flap is well visualized in a dorsally displaced position inferior to the posterior horn, the latter appearing unusually bulky as a consequence (best appreciated in the sagittal plane).
  • Resultant about 4 mm meniscal protrusion.
  • Oblique tear of the dorsal horn of the medial meniscus reaching the lateral free surface
  • about 40 mm fluid signal lesion medially in the popliteal fossa pathognomonic for Baker cyst

Case Discussion

Displaced flap tears of the lateral meniscus are fortunately relatively uncommon, as these usually result in severe functional impairment. 

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