Injuries ****, especially when they're clustered in a single position group. Having all 3 RBs dinged up already sucks, but that's why I try and have 4 RB. You might have to have them play hurt, it's not unheard of for players to play hurt.
In MFN context, I once had a LC game against Seth who had a star RB with a 36% healthy foot. I thought no way he plays, but not only did he play, he played well.
It's not like you have to look these guys in the eyes, sending them on the field gimpy. No repercussions, other than maybe hurting him more, so what.
Good luck with however you navigate your backfield.