I agree that 5x5 is sufficient volume
Also, at 140 you need to gain strength as a priority and take the mass gains that come with strength...when you gain 20 lbs on a basic strength program, you can start thinking about volume focused workouts.
I like the suggestion for unilateral BW work if you have a spine injury because it will strengthen your deep core and keep your legs fit...however, giving in to the injury and avoiding squats/dead lifts is not a solution. I herniated 2 lumbar discs and had surgery and squats/DLs were a key part of my recovery.
Best of luck!
"You must have a very strong reason for doing an exercise. If you don't, scrap it and move on." -Jim Wendler