David Wilson, the 23 year old running back for the New York Giants might have played his last NFL game. His career apparently cut short due to a neck injury. You can read the story here.
Houston Texans running back Arian Foster considered retirement during the off season due to his back injuries. You can read the blog on the Houston Chronicle.
Neck injuries forced Green Bay Packers running back Johnathan Franklin to retire this off season. He was a fourth round pick by Green Bay in 2013. You can read the report in the L.A. Times.
Two running backs this off season /early training camp have had their careers called short. Another running back considered retirement due to back and neck injuries. I know there has been more throughout the leagues history. Just sames a lot so far this season. Of course football is a dangerous, hard hitting sport, that does take a toll on the players who play the game.