Ring-shaped meniscus with absent anterior cruciate ligament: A rare association with review of the literature

A spectrum of congenital and anatomical variants of a lateral meniscus can be encountered, including discoid meniscus, ring meniscus, double-layered meniscus, hypoplastic meniscus, and accessory meniscus in the knee joint. These can be associated with a plethora of abnormalities predominantly involving the anterior cruciate ligament (ACL) of the knee. Morphological abnormalities of the menisci can present in unusual ways, leading to clinical dilemmas and providing a diagnostic challenge. We report a case of a 26-year-old male presenting with a rare combination of ring meniscus, a hypoplastic ACL, and an oblique inter-meniscal ligament to raise awareness of the condition. Pertinent literature is also reviewed.