Were you front squatting because of the back injury? I know it goes against some conventional wisdom, but I actually find front squatting harder on the back than back squatting. It's because while I'm more upright, I'm not as stable or tight, and for me being stable and tight is more important than being upright in terms of how my back feels.
I'm not saying you should be back squatting instead, just that I wouldn't assume that front squats would necessarily be better after an injury.