PMC4900104_01
Discoid lateral meniscus in a toddler. (A) Coronal, T2-weighted, fat-suppressed MR image of the right knee posteriorly demonstrates a homogeneous hypointensity (white arrow) extending across the entire lateral joint space, indicative of a discoid meniscus. There is hyperintensity in the meniscal body with an oblong focus in the intercondylar notch (black arrow) representing a torn meniscus with a flipped anterior horn posteromedially. (B) Sagittal, T2-weighted, fat-suppressed MR image of the middle right knee (at slice thickness of 3 mm with slice spacing of 3.3 mm) demonstrates a homogeneous area of low signal intensity extending anteriorly to posteriorly (vertical arrow) with thickened posterior meniscal tissue (angled arrow) and absence of the anterior portion of the discoid meniscus, resulting in loss of the normal "bow-tie" configuration.
gr1.jpg
PMC4900104_01_gr1.jpg
fig1
MRI demonstrated a normal, triangular-shaped medial meniscus (Fig. 1A). T2 sagittal sequence, demonstrating the absence of the "bow tie" (Fig. 1B). There was increased height and globular configuration of the posterior meniscus, consistent with a flipped posterior medial fragment tear. The thickening of the meniscus in the coronal view extending across the entire condyle was consistent with a discoid meniscus.
Discoid lateral meniscus in a toddler. Static arthroscopic images of the right knee demonstrate the posterior horn of the lateral discoid meniscus with tear (white arrow) (A), as well as the anterior horn (B) (N- notch; P- posterior horn; B- body; A- anterior horn).
gr2a.jpg
PMC4900104_01_gr2a.jpg
fig2a
The patient subsequently underwent arthroscopic reduction and fixation of the unstable anterior horn with a single suture using an outside-in technique, as well as debridement of the posterior horn tear and saucerization of the discoid meniscus (Figure 2, Figure 2).