The former Middlesbrough full-back has been suffering from a swollen knee in recent weeks and Birmingham are not taking any chances as he only returned from 10 months on the sidelines in September.
"He has had an injection and it's basically starting him up again, putting him through the process and seeing how his knee reacts to the different type of stresses at various stages," Blues boss Lee Clark told the Birmingham Mail.
"Certainly he will not be available until Christmas or thereafter.
"We're looking around about six weeks, if everything goes to plan. That's without any setbacks.
"So that's what we are considering there."