Partial deficiency of the lateral meniscus.

We report an abnormally shaped lateral meniscus. As far as we know, the present case is the first description of partial deficiency of the lateral meniscus in the literature. Although it is a rare abnormality, arthroscopic surgeons should be familiar with this entity for the differential diagnosis of bucket-handle meniscal tears, not only for magnetic resonance imaging, but also for arthroscopic evaluation. This entity could also be an aggravating factor for instability symptoms of partial or total anterior cruciate ligament-deficient knees.