MRI appearance of Wrisberg variant of discoid lateral meniscus

OBJECTIVE: A discoid lateral meniscus is a common normal variant, occurring in approximately 3-5% of the population. A subgroup of the discoid lateral meniscus known as the Wrisberg variant occurs when there is no posterior attachment of the lateral meniscus. Instead, Wrisberg's ligament becomes the only lateral meniscus posterior stabilizer, with a symptomatic hypermobile meniscus. Although it is commonly described in the orthopedics literature, to our knowledge the Wrisberg variant of the discoid lateral meniscus is not mentioned in the radiology literature. This article describes the MRI appearance of this important yet often unrecognized process. CONCLUSION: The Wrisberg variant of the discoid lateral meniscus is a rare condition with a highly suggestive clinical history. The musculoskeletal radiologist should consider this diagnosis whenever a discoid lateral meniscus is identified because making this elusive diagnosis may prove immensely useful for the orthopedic surgeon.