I have 3 injuries, one to my right-lower back, one on a vertebrae in my upper back, one in my neck from an asshole chiropractor who adjusted it and fucked it up.

Lower back: I find it doesn't do much other than help me forget, mainly because it's so spread out.

Upper back: reduces inflamation to the vertebrae significantly, often eliminates pain entirely.

neck: usually eliminates pain entirely. also, the injury caused nerve damage in my neck which causes burning and needles to go down my shoulders and arms. this goes away 100% when I'm high, within minutes of smoking (about 3 minute into being stoned).