The old towel bar with porcelain supports became a grab bar for my mother until it broke. I was asked by her caregivers to put up a grab bar. The supports were cemented in and after removal I found they were "near" studs. To hide the giant holes removal made and make use of the studs, I presume I would use a backing board, say of 3/4 inch oak and screw that to the studs and the grab bar to it. As I began looking into this approach, I found the wall was curved to the point where to put up a 24 inch grab bar, the wall is concave by about 1/8 of an inch. Very visible when you put a plank against the wall like this. I wonder what is the solution for this (maybe some kind of moulding?) - or would someone say I'm going about it all wrong? Any help would be greatly appreciated.