The 28-year-old defender was playing through the pain barrier in the final few weeks of the campaign, and eventually decided to have an operation before Monday's visit of Hull.
Bramble said: "I've had the problem for four or five weeks, and the scans showed it was a stress fracture.
"But I was determined to play on and do my bit for the team, and it was just a case of waiting until we were safe to get it sorted.
"I can't remember a single incident where it 'went', but obviously the wear and tear over the weeks meant it was gradually getting worse.
"I finally had the operation last Thursday, and the surgeon put two pins in to hold it in place.
"I've got two weeks of rest now before the hard work begins with the rehab."
Bramble looks certain to miss the start of pre-season, and there is a chance he may be ruled out of action in August too.
He told the Wigan Evening Post: "I've been told it might take up to three months, but hopefully I will be fine for the start of next season."