Does displacement meniscus cause painful clicking, grinding and clicking of the knee joint mostly medial? Can a tear happen in the back of the knee?

Yes. Yes to all of the above. Grinding sounds unusual though. If the noise comes from kneecap then it is the kneecap and not menisucs. However it sure sounds like it based on what you describe. Exam is very unreliable though and MRI is usually necessary.
Meniscal tears. You can tear the medial or lateral meniscus in the anterior or posterior horns, or even within the body of the meniscus. Each tear has its own personality, which usually includes some degree of locking, buckling, or painful clicking. Sounds like you are a scope candidate.

Related Questions

I have chronic clicking and clunking of the knee joint. What coul be the problem? What is the difference of a displacement of the root or meniscus?

Could be arthritis. The clicking and clunking can be arthritis or a cartilage tear. The meniscus is a piece of cartilage that acts like a shock on a car. It goes in between the two bones. But like shocks on a car, it can wear out and tear. The second part of your question is the same thing. They are describing the part of the meniscus -- i.e. The root of the meniscus -- which is where it attaches to. Read more...