People default to thinking about big heavy deadlifts, but it really doesn't need to be. The muscle activation, posture, etc from light deadlifts is really good. It strengthens your back. (Talk to your doctor blah blah blah.)

Start with a bar, get your form down. Add weights very slowly (like you should be getting frustrated by how little weight you're lifting). Keep adding making sure form stays perfect. If back starts hurting drop down in weight, and start doing back and core and glute strengthening exercises. Continue.

It's not a cure, but it's pretty close.