Meniscal tears of or extending into the posterior root are often associated with meniscal extrusion, as the meniscus loses its attachment to the tibia and subluxates medially. This, in turn, impairs the meniscal ability to absorb the load and accelerates osteoarthritis changes - as seen in this case. Root tears can be repaired but they are often missed at arthroscopy, so it is important to always check the areas of the meniscal roots on MR.