Meniscal cysts are little bags of joint fluid under pressure, arising from the meniscus and palpable on the side of the knee.


Diagnosing a meniscal cyst

Meniscal cysts are more frequent on the lateral side of the knee, usually appearing as a tender lump along the joint line. External rotation of the tibia may cause the lateral mass to become more prominent, while internal rotation of the tibia may cause the mass to completely disappear. The diagnosis can be confirmed with MRI.

meniscal cyst originating from a horizontal cleavage tear of the meniscus They are frequently associated with horizontal cleavage tears of the meniscus.  
Meniscus cyst

Meniscal cyst

A horizontal meniscus tear can 'blow out' into a cyst.



Meniscal cysts. Lantz B and Singer KM. Clin Sports Med. 1990 Jul;9(3):707-25.

A contribution to Pisani's sign for diagnosing lateral meniscal cysts: a technical report. Pinar H, Boya H, Satoglu IS and Oztekin HH. Knee Surg Sports Traumatol Arthrosc. 2009 Apr;17(4):402-4. doi: 10.1007/s00167-008-0718-4. Epub 2009 Jan 31.

MRI characteristics of cysts and “cyst-like” lesions in and around the knee: what the radiologist needs to know. Perdikakis E and Skiadas V. Insights Imaging. 2013 Jun; 4(3): 257–272.

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