PMC6698273_01
MR images before first arthroscopic surgery for the left knee.. Coronal (a) and sagittal (b) proton density-weighted images show a complete discoid lateral meniscus. Growth plates are visible.
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Magnetic resonance imaging (MRI) revealed a complete lateral discoid meniscus with degeneration within the meniscus (Fig. 1).
Arthroscopic findings.. Complete discoid lateral meniscus with radial tear (a: black arrow) was treated by partial meniscectomy (b). Images from re-arthroscopy 7 months after the first arthroscopic surgery reveal that the anterior and posterior horns of the lateral meniscus are connected by meniscus-like tissue to resemble a ring-shaped meniscus (c: black arrows).
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Complete lateral discoid meniscus with a radial tear was confirmed on arthroscopic examination (Fig. 2a), and partial meniscectomy was performed (Fig. 2b). During arthroscopy, we found that the anterior and posterior horns of the lateral meniscus were connected by meniscus-like tissue forming a ring-shaped meniscus (Fig. 2c).
Histologic findings for the newly formed interhorn meniscal bridge.. Hematoxylin and eosin staining shows areas of chondrocyte-like cells mixed in collagenous fibers (a), and capillary vessels infiltrating the region (b), indicating the newly formed interhorn meniscal bridge comprises meniscus-like tissue appearing secondary to tissue repair.
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Hematoxylin and eosin staining of the newly formed interhorn meniscal bridge showed areas of chondrocyte-like cells mixed in collagenous fibers (Fig. 3a), with capillary vessels infiltrating the region (Fig. 3b).