Abnormality of Meniscus in Family

We report the abnormality of the meniscus in family.Case 1 was a ten-year-old boy who complained of pain and locking of the right knee. On magnetic resonance imaging of the bilateral knee, there was a high intensity area on the posterior portion of the bilateral lateral meniscus. In arthroscopic findings, the medial meniscus of the right knee had abnormality of attachment on the anterior portion. The bilateral lateral meniscus comprised of two parts which were completly separated 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. The medial meniscus of the left knee had two layers on the anterior portion (double-layers medial meniscus).Case 2 was a seven-year-old girl who was the sister of case 1. She complained of pain of the right knee, and instability of the bilateral patella. On magnetic resonance imaging of the right knee, there was a high intensity area on the posterior portion. In arthroscopic findings, the shape of the bilateral lateral meniscus was almost the same as case 1.We could not find literature on this abnormality of the lateral meniscus in family.