Presentation
Knee pain and swelling of 2 weeks duration after football game.
Patient Data
Complete peripheral vertical longitudinal tear of the posterior horn and body of the lateral meniscus has allowed the vast majority of the posterior horn to flip into the intercondylar notch and the body to flip directly posterior to a truncated anterior horn. There is resultant 'ghost meniscus sign' posteriorly with only a tiny remnant of peripheral meniscus and the meniscopopliteal fascicles evident. A double delta sign is seen anteriorly on the sagittal images while a double PCL sign is evident in the intercondylar region.
Case Discussion
A flipped meniscus is a sub-type of bucket handle tear where a large portion of meniscus flips to lie adjacent to the anterior horn leaving an empty space at the donor site. It implies either meniscocapsular / meniscopopliteal fascicle detachment or peripheral vertical longitudinal complete tear as was the case here.