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Findings: There is a large bucket-handle tear of the medial meniscus of the right knee with displacement of a large low-signal fragment into the intercondylar notch. Also seen is extensive fragmentation of the residual posterior horn. An ACL tear was also present.

Diagnosis: Large displaced bucket-handle tear of the medical meniscus with complete ACL disruption of the right knee.

Discussion: Magnetic resonance imaging of the knee is one of the most frequently used modality for examining the knee secondary to its inherent accuracy in depicting internal derangements. The normal menisci of the knee are fibrocartilagenous C-shaped structures that are characteristically low in signal intensity on both T1 and T2-weighted sequences.

Meniscal tears present in different configuration and locations; however, the most common is an oblique tear extending to the inferior surface of the posterior horn of the medial meniscus. Another common tear of the medial meniscus is the bucket-handle tear. Typically, this is a vertical or oblique longitudinal tear that results in the inner free edge of the meniscus being displaced into the intercondylar notch. The displaced inner edge of the C-shaped meniscus resembles the handle of a bucket and hence its name. This bucket-handle tear is a full thickness longitudinal tear that is displaced anteriorly into the notch by compressive forces and is seen as a low-signal band anterior and parallel to the PCL on sagittal images. Hence this band may simulate a second or double PCL. The presence of this curvilinear low signal above the tibial cortex which is anterior, inferior, and parallel to the PCL should not be mistaken for the ligament of Humphry - which is a normal accessory meniscofemoral ligament extending from the posterior horn of the lateral meniscus to the lateral aspect of the medial femoral condyle and is typically seen anterior to the margin of the PCL. However in the intercondylar notch, the ligament of Humphry is a smaller, thinner, and more rounded structure than the bucket-handle fragment. The more peripheral non-displaced meniscal segment typically appears as a truncated or foreshortened triangle.

References:
Brant WE, Helms CA. Fundamentals of Diagnostic Radiology. Baltimore: Williams and Wilkins, 1994, pp 988-989.

Singson RD, Feldman F, Staron R, Kiernan H. MR imaging of displaced bucket-handle tear
of the medial meniscus, AJR 1991; 156:121-124.

Weiss KL, Morehouse HT, Levy IM. Sagittal MR images of the knee: a low-signal
band parallel to the posterior cruciate ligament caused by a displaced bucket-handle tea. AJR 1991; 156:117-119.

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