The former Burnley full-back will have a scan in September and while the injury would appear worse than first feared, Coyle is keeping his fingers crossed that the 28-year-old can still play a part for the club this season.
"He's in plaster but didn't need an operation to this point," he told the Bolton News. "He goes back to hospital in a month's time and hopefully the X-ray will show the injury will heal naturally.
"If that's the case, then I think we're looking at something like five months. That would be the best scenario."