absent bow tie sign

bowtie (in case you’ve never seen one)

IMAGING, ORTHOPAEDICS

A radiologic sign consisting of the loss of the normal bow tie appearance of the menisci on parasagittal MRI, which is diagnosed when less than 2

bowtie is present (normal finding)

sagittal T1 weighted images demonstrate a normal body of meniscus (bow tie), or when 2 or more consecutive sagittal images lack a normal meniscal body segment. Absent bow tie is suggestive of meniscal injury, and 

usually indicates a bucket handle tear of the meniscus, where the displaced fragment corresponds to the “handle” of the bucket.

Background Normally, the medial and lateral menisci* (of the knee) appear as low signal bowtie-shaped structures between the femoral condyles and tibial plateaux^†.

As the normal meniscus laterally measures 9mm–12mm in width, the bow tie appearance should be seen on several adjacent slices (2 to 3 images if imaged with 3mm thick slices and 1mm skips).

*The correct plural of meninscus, not meniscuses, as some authors have written it. ^†The correct plural of plateau–because it is originally a French word; that said, only the Brits use plateaux; in American, Canadian, Australian, and New Zealand English, plateaus is the norm.

References http://radiopaedia.org/articles/absent-bow-tie-sign

Am J Roentgenol. 1998 Jan;170(1):57-61

Radiology 2000; 215:263-265.