A mensicus usually refers to the cartilage
in the knee.
If the cartilage comes loose and bend or moves as the knee is moving, then it can get caught in the joint between the bones, and will be pinched. This can cause pain, can cause a piece to be broken off and get loose in the knee and can cause problems for you. If you are concerned, see an orthopedist or your pcp. May need more diagnostics.