Meniscal tears with displaced fragments: common patterns on magnetic resonance imaging

To identify the commonly occurring patterns of small displaced tears of the menisci of the knee on magnetic resonance imaging (MRI).

A retrospective review of knee MRI scans over 16 months at two hospitals provided 70 studies with 73 displaced meniscal fragments for analysis. Fragment position was recorded.

Two common positions were identified for medial fragments. For the medial meniscus, 93% of fragments were positioned medially or posterolaterally. The medially displaced fragments were positioned in either the superior or inferior recesses. Lateral meniscal fragments were more evenly dispersed.

The pattern of small displaced tears of the medial meniscus is highly predictable. Awareness of the typical locations of these fragments should aid the reporter in identifying these lesions on MRI.