Ring-Shaped Lateral Meniscus of the Knee: A Case Report

Abstract

We present a case of a ring-shaped lateral meniscus in combination with anterior cruciate ligament (ACL) rupture. A 20-year-old man was admitted to our hospital for the purpose of the ACL reconstruction of his right knee. He had a history of valgus stress injury during a badminton game seven months ago. Physical examinations showed anterior instability of the knee, but there were no signs suggesting tear of the lateral meniscus. Magnetic resonance imaging revealed tear of ACL and a fragment-like meniscus structure of the lateral meniscus in the intercondylar notch. Arthroscopic examination showed a ring-shaped lateral meniscus in addition to the ACL tear. The intercondylar portion of the lateral meniscus was well attached to the intercondylar notch. The rest of the lateral meniscus was normal with an intact rim and had a smooth margin.