Butler was forced out of the recent win over Millwall at the Weston Homes Stadium after a heavy challenge early in the game.
The 27 year-old had been a Posh ever present until the injury. There is a chance he might not play again this season.
Posh are understood to have bid for a new full-back on New Year’s Eve, but even if he signed as soon as the transfer window opens on January 1 he wouldn’t be eligible to play at Bournemouth on January 3.
The referee for the game at Bournemouth is Leigh Doughty who also refereed the Posh match at home to Millwall.