Hobbs was injured in the game against Derby County last month and had surgery this week.
The 26-year-old, faces a total of more than three months on the sidelines.
Head physiotherapist Dave Galley told the club website: "He's having a week of non weight-bearing and then we'll graduate his recovery from there. He'll be like a new signing come Christmas."
Nottingham Forest defender Jack Hobbs has been ruled out until Christmas because of an ankle injury.