I would think him on his back and you on top, or him on his side

I agree with the side by side. I refer to these as the "X" and "Y" depending upon the positioning of the legs. The nice thing about these are that they work for pregnant women, also, and are great because there is no pressure on the spine. If he is comfortable lying on this side then give these a try, also.

Another thing to explore is to go to the site's Home Page and look through the animated illustrations of sexual positions and pick one or more that interest you.

If I am on my back, I am a woman, I like a pillow under the small of my back for support.

Back injuries of various sorts exclude some positions. His doctor may be able to recommend the least uncomfortable for his specific condition.

I think what positions are best might vary from person to person, depending on the nature of the back problem.

I have a bad back, too, which gives me some problems from time to time. When mine acts up, I find the better positions are the ones where I am on top, or side by side. If I am lying on my back, I find the weight of her on top of me can sometimes aggravate the problem.

Have him lie on back and NOT move - you get to ride him. Spooning is also good. IF standing is good for him, then lie with your rump right at the edge of the bed and let him stand up.