Threadbare and Worn out

Threadbare adjective - Showing signs of advanced wear and tear and neglect.

Worn out is a synonym for threadbare in worn topic. In some cases you can use "Worn out" instead an adjective "Threadbare", when it comes to topics like hackneyed.

Worn out adjective - Drained of energy or effectiveness; extremely tired; completely exhausted.

Threadbare is a synonym for worn out in shabby topic. You can use "Threadbare" instead an adjective phrase "Worn out", if it concerns topics such as worn.