It is not known when the injury occurred, although Ridley was unable to practice this past week following Sunday's 30-23 win over Atlanta.
Ridley is the leading rusher for the Patriots' 11th-ranked rushing attack, with 174 yards on 47 attempts this season. The third-year running back gained over 1,200 yards in 2012, scoring 12 touchdowns and averaging 4.4 yards per carry while starting 12 games. This season, the Patriots have turned to a group rushing attack, with Ridley only getting 11 carries in each of the past two games.
The injury could mean a bigger workload for LaGarrette Blount, who is still looking to recover some of the magic experienced his rookie season with Tampa Bay. After putting up over 1,000 yards rushing and six touchdowns in 2010, Blount had just 151 yards on 41 carries in 2012 before leaving the Buccaneers for New England.