What can i do to help unlodge a piece of cartilage from my knee?

Tough one: There's really nothing you can do. I imagine you ask this because it keeps catching or clicking or locking up on you. Take less stairs to help reduce those symptoms. Eventually it may degrade enough to stop catching or catch so bad between the joint it tears some. Then once the pain subsides it may be better, but f it gets worse the only way to fix it is an arthroscopic resection of the torn piece.

Surgery: If you have a locked knee due to a displaced meniscus, it needs to be addressed surgically. It many spontaneously unlock but the problem of the torn minic remains. Could give out or re-lock at a time that it puts you at risk for more serious injury.