What does medial meniscus with extrusion mean? it also says rupture of the posterior root is this a tear?

Extrusion: Meniscal extrusion refers to cartilage extending beyond the tibial margin. Basically, a piece of cartilage is where it shouldn't be. This can result from several pathologies, such as: --presence of development of cartilage disruption and osteoarthritis or, in your case: --meniscal tears: can occur with many tears, but especially root tears Time to see an orthopedic physician.