From Rotoworld.com

Steelers LBs coach Keith Butler says it would be "miraculous" if 2012 third-round pick Sean Spence played football again.
Spence destroyed his left knee last preseason, tearing his ACL and LCL, dislocating the knee, and suffering a damaged nerve behind the knee. GM Kevin Colbert previously called it an "unknown injury" in the sport. The Steelers do plan to carry Spence on a reserve list in 2013 to see if he can contribute by 2014.