Yes, I am speaking of the knee. MRI came back with results with mucoid degeneration in the posterior horn of the medial meniscus.
I imagine that your speaking of the knee, where the meniscus is a cartilage between the upper and lower leg bones (femur and tibia).
The meniscus does not get much of a blood supply and does not heal quickly. You're going to have to baby this one -- take it slowly, avoid impact to the leg. No stamping that foot.
And for now, I imagine you've been instructed to treat using RICE -- rest, ice, compression, and elevation.
Ask your doctor how long this should last.