In addition, safety T.J. McDonald also was placed on IR after Fisher said he would have season-ending shoulder surgery.
Quinn hasn't played since Week 10, when he saw just 15 snaps against the Bears due to a banged-up knee. A hip injury kept him out of the lineup in subsequent weeks, but the back pain has been an issue since last month.
The Rams haven't been the same without their uber-disruptive pass rusher in the lineup. After an NFC-leading 19 sacks in 2013 and another 10.5 last season, Quinn's limited availability and compromised health left him with just five quarterback takedowns this autumn.