youll still yield results by training your legs without squats. its just squats are very effective. thats not to say you wont get any growth from leg presses, quite the contrary, you will get alot of growth from leg presses. an idea (for a while) might be to really drop the weight on squats for a while so your back can get better and stronger. start incorporating some light lower back work and progress up to where you feel comfortable. work a bit on some ab and lower back work with rotation (slight rotation) and maybe some unilateral leg work (lunges, single leg squats, etc) just so you are stable throughout your trunk under varying conditions.
possible combination:
leg presses (heavier)
reverse, stationary or walking lunges (weighted if you feel up to it)
hyperextensions (not weighted for now)
leg extensions (finish up the quads)
seated or lying leg curls
etc...
then as your back gets back into the groove, throw some light back or front squats, maybe some dbell romanian deadlifts for hammies etc.
hope that helps.