These types of isolated complex tears are a bit unusual in a patient so young; however, if we look closely, we can see
degenerative signal within substance of the lateral meniscus. Many Radiologists and Orthopedic Surgeons will casually refer to such tears as "degenerative tears" because of this. It's better to simply be descriptive, noting the size, location, and extent of the tear, as well as the fact that the affected portion of the meniscus has degenerative signal.