Doctors recently told Detroit Lions quarterback Matthew Stafford that the fractured bones in his back are a six-week injury, league sources told ESPN.

This doesn't mean Stafford will be sidelined six games, but it does provide a glimpse into the severity of the injury that he has played through before the Lions' doctors denied him from playing last week against the Chicago Bears and Sunday against the Dallas Cowboys, according to a source.

Stafford will miss his second straight game Sunday, and the Lions still are unsure when he will be able to return. Last week, a source told ESPN that Stafford "could miss one week, he could miss three weeks."

But Detroit also knows that this type of injury would sideline most players six weeks, if not longer. It is another testament to Stafford's toughness; he had started 136 straight games before last week's absence, the sixth-longest streak for a quarterback in NFL history.

Before last week, the last Lions quarterback to start a game other than Stafford was Shaun Hill in Week 17 of the 2010 season.

Stafford has completed 64.3% of his passes for 2,499 yards, 19 touchdowns and five interceptions this season. Earlier this year, he became the fastest quarterback in NFL history to surpass 40,000 passing yards.

Stafford's current backup, Jeff Driskel, was unable to rally Detroit to a victory in Chicago, but he will get another opportunity Sunday against Dallas, and he could well be getting more in the weeks to come.