Dolphins offensive coordinator Mike Sherman acknowledged Monday that Thomas is likely to miss several games.
He injured his left ankle in the third quarter of Sunday's loss to the Carolina Panthers and didn't return.
Thomas led the team in rushing in Miami's Week 11 win over the San Diego Chargers, gaining 57 yards on 10 carries and also scoring a touchdown.
Marcus Thigpen, a kick returner with three caries in two seasons, and rookie running back Mike Gillislee will get backup reps behind starter Lamar Miller next Sunday against the New York Jets, Sherman said.
Thomas, 26, has rushed for 279 yards on 77 carries with three touchdowns this season. He also has 12 receptions for 54 yards and a touchdown.
ESPN.com Dolphins reporter James Walker and information from The Associated Press contributed to this report.