Hypermobile discoid Lateral Meniscus in 9yo M with 2 mos posterior knee pain

There is posterocentral subluxation of the complete discoid LM with bright intrasubstance signal and expansion of the posterior horn region, but no visible surface defect.  Wrisberg (which doesn't look thick) inserts onto the PH region.          

   I cannot see popliteomeniscal fascicles, which I presume are developmentally absent.