Investig Magn Reson Imaging.  2016 Sep;20(3):191-195. 10.13104/imri.2016.20.3.191.

Displaced Double-Layered Lateral Meniscus That Mimicked the Bucket-Handle Tear: a Case Report

• Kwak MJ
• Kim SK
• Kim KJ
• Lee BS
• Kang J

• KMID: 2354801
• DOI: http://doi.org/10.13104/imri.2016.20.3.191

Abstract

Among the various types of congenital meniscal anomalies, the double-layered lateral meniscus is extremely rare. The double-layered meniscus consists of both the upper additional and the lower normal meniscus. As the upper additional meniscus is mobile, it can be easily displaced, while the lower lateral meniscus is usually normal in shape and volume. A 42-year-old woman suffering from pain and locking of her left knee underwent Magnetic resonance imaging (MRI) examination and an arthroscopic surgery. A rare meniscal abnormality was seen in her left knee, which presented as a double-layered lateral meniscus with displacement. It was remarkable that the upper additional meniscus was displaced over the intercondylar eminence of the tibia and it mimicked a bucket-handle tear. Even though it is rare, it is necessary to consider the possibility of displaced double-layered meniscus in the differential diagnosis of a bucket-handle tear. Here, we report the MRI and arthroscopic findings of a displaced double-layered lateral meniscus, which was similar to the bucket-handle tear.

Keyword

Double-layered lateral meniscus; Bucket-handle tear; Knee

MeSH Terms

Adult
Arthroscopy
Diagnosis, Differential
Female
Humans
Knee
Magnetic Resonance Imaging
Menisci, Tibial*
Tears*
Tibia

Figure

• 

  Fig. 1 A schematic illustration of the double layered lateral meniscus, which is characteristic that the upper additional meniscus overlays the normal lateral meniscus. ACL = anterior cruciate ligament, AH = anterior horn, LTP = lateral tibial plateau, NLM = normal lateral meniscus, PCL = posterior cruciate ligament, PH = posterior horn, UALM = upper additional lateral meniscus

• 

  Fig. 2 Left knee MRI of a 42-year-old female presenting pain. A coronal proton density (PD) weighted spin-echo image (TR/TE, 2180/11) shows a double layered lateral meniscus, which includes the upper additional meniscus (black arrows) overlying the lower normal lateral meniscus (a, b) and a displaced meniscal fragment (white arrows) over the intercondylar eminence of tibia, mimicking the bucket-handle tear (b-d). A sagittal PD weighted spin-echo image (TR/TE, 2450/11) also shows the upper additional meniscus (black arrows) overlying the normal lateral meniscus (e) and a displaced upper additional meniscus (white arrows) over the intercondylar eminence of tibia (f).

• 

  Fig. 3 Arthroscopic view of the lateral compartment shows that the upper additional meniscus overlying the normal lateral meniscus is displaced toward the intercondylar notch and mimics the bucket-handle tear; while the shape, margin and volume of the lower lateral meniscus is completely normal. These findings are suggesting a displaced double-layered meniscus. AHLM = anterior horn of lateral meniscus, LFC = lateral femoral condyle, LTP = lateral tibial plateau, PHLM = posterior horn of lateral meniscus

• 

  Fig. 4 Histology of the resected upper meniscus shows dense collagen fibers in multiple layers with normal organization, and fibro-chondrocytes that are linearly arranged, consistent with a typical meniscal tissue (H&E stain, × 200).

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