Using a mattress topper as a base for pocket sprung mattress

Hello,I've read a lot of your Q&As which advise to place a flat surface (mdf board) over sprung slatted frames to accommodate pocket sprung mattresses. I was wondering if as an alternative you could use a mattress topper to sit the pocket sprung mattress on instead (a bit backwards I know!) to help avoid the ridging effect over time? Perhaps a mattress topper which offers a firmer support. Any advice would be appreciated. Thanks