A Case of Abnormality of the Bilateral Medial Meniscus and Lateral Meniscus

We report a case of abnormality of the bilateral lateral meniscus and medial meniscus. A ten-year-old boy complained of pain and locking of the right knee. On magnetic resonance imaging of the right knee, there was a longitudinal tear on the posterior portion of the lateral meniscus. In arthroscopic findings, the medial meniscus had abnormality of attachment on the anterior portion, and the lateral meniscus comprised of two parts which were completly separeted and duplicated at the midportion. The anterior part was connected to the capsule and the posterior part to the cartilage surface of the tibia plateau at the midportion. We peformed meniscorrhaphy for longitudinal tear on the posterior portion.We checked his left knee for bilateral congental abnormalities. In the arthroscopic findings of the left knee, the shape of the lateral meniscus was almost the same as the right knee, and the medial meniscus had two layers on the anterior portion (double-layers medial meniscus). We found a horizontal tear on the posterior portion, and peformed partial menisectomy on it.We could not find literature on this abnormality of the lateral meniscus and double-layers medial meniscus.