Figure 4. A 18-year-old male with pain in both knee joints. (a) Coronal proton density-weighted image reveals a medial discoid meniscus (arrows) in the right knee joint. (b) Sagittal T2 weighted image of the controlateral left knee joint shows the anomalous insertion of the medial meniscus (AIMM) inserting into the anterior horn of the medial meniscus (arrows). (c) Coronal T2 weighted image of the left knee joint demonstrates a lateral discoid meniscus (arrows).