Leg Exercises without Hip Flexion

Come December I’m going to receive a treatment on my hip, and for a few weeks afterwards I’m not going to be allowed to do strength exercises that involve more than 20 degrees hip flexion. I would like to try to keep working my legs, so any suggestions? The only exercises I can think of are:
Leg extensions
Leg curls
GHRs

Any others? Thanks for the help.

hm that’s a tough one. Don’t expect your quads to grow any.

Backwards sled drags (crouching as much as you can tolerate)
Sissy squats?
Peterson step-ups