Last October, I hurt my lower back from years of bad posture, not working out my core muscles, and curving my back on leg presses. Now, I cannot do squats or deadlifts, which have really halted my gains, but oh well. My leg routine is now as follows...

warmup:
2x sets 15x reps of leg extensions
2x sets 15x reps of leg curls
1x set 15x reps on leg presses

heavy:
4x sets 15x reps on leg presses
3x sets 10x reps on each leg of lunges
3x sets 10-15x reps of leg extensions
3x sets 10-15x reps on that machine that works your hamstrings and glutes, where you are standing and you push your leg back behind you.

Can you guys think of anything else I could use to switch up this routine, because I certainly don't want to plateau from doing the same exercises over and over. I can't put any weight on my back, so squats are off limits, and i can't do stiff legged dead lifts for hams either.

P.S. calves are done on a different day.