www.nfl.com/news/story/.../article/tony-romo-has-fractures-in-transverse-process
Nov 1, 2014 - A source close to Tony Romo informed NFL Media's Desmond Purnell on Saturday that the Dallas Cowboys quarterback has twofractures in his transverse process, but it is possible he could still play Sunday against the Arizona Cardinals. ... NFL Media Insider Ian Rapoport reported that ...
that's from google search
I think he returned briefly after that, then got injured again and required back surgery but no idea whether it was related. He never played again, since Prescott killed it as a rookie.