Orton was taken off the practice field on a cart Friday just two days after signing as a free agent. He was on the practice squads of Denver for part of the 2011 season and all of the next season and of the Patriots from Dec. 31 to May 22.
The Patriots also say they've signed wide receivers Brian Tyms and Cole Stanford.
Tyms had two catches for 12 yards in seven games with Cleveland after starting last season on Miami's practice squad.
Stanford is a rookie free agent from Cal Poly who had 43 receptions and 314 yards rushing in 42 college games.