According to a source, the surgery took place this Wednesday in Boston and was considered routine.
Vollmer had experienced swelling in his knee during the 2012 season, but only missed one game -- Nov. 22 against the New York Jets. His absence was notable because the game was played on a Thursday, and the short turnaround -- playing four days after a win over the Colts -- was too much for him to overcome.
Vollmer is one of the Patriots' best players scheduled for unrestricted free agency, along with receiver Wes Welker and cornerback Aqib Talib.
The timing of the knee scope comes two weeks before the start of free agency, which adds another layer to his free-agent status. Vollmer had missed most of 2012 training camp with a back ailment, and was eased into action the first two games of the season, splitting snaps with Marcus Cannon before assuming a full-time role until the knee injury knocked him out of the Nov. 22 game against the Jets.