Most likely , if your drop foot is from a lower back disc injury , start slow and easy at 1st your back will either say hey that feels good and help the pain or it will say dont do that again *******.I'll have to get one of those accu balls. I wonder if this will help with my foot drop syndrome.
Get any hard ball for now a lacross ball or even tennis ball to see if it helps before buying anything fancy. The ball just needs to have some firmness to dig in.