Lions head coach Jim Caldwell told reporters X-rays were negative on the injury, noting the bruise.
The team originally announced he was questionable to return and he was replaced with Jake Rudock. While Stafford had 292 passing yards before the injury, the second-year backup threw an interception that was returned for a touchdown on his first drive. Stafford did not return to the game.
Since missing a combined 19 games in his first two seasons, Stafford has been an iron man for the Lions. The 29-year-old has started every game since 2011 and was rewarded with a five-year contract prior to the start of this season.
Stafford did battle ankle and quad injuries leading into Detroit's Week 6 game against the Seattle Seahawks, but he was able to make it through the week to continue his streak of not missing a start.
The former No. 1 overall pick continues to get better for the Lions. Stafford entered the week with 21 touchdowns, six interceptions and an interception percentage of 1.5, his lowest since 2010 when he only played in three games.
The Lions are chasing the Minnesota Vikings atop the NFC North, so losing Stafford for any length of time significantly diminishes their chances of making it back to the postseason.