From SBN's Western College Hockey:
(Sam) Brittain injured himself towards the end of last season, but Brittain and Denver's staff decided to treat the injury with rest, rather than surgery. But Brittain was participating in Hockey Canada's Goaltending Camp this past weekend, and while there, tests on his knee showed that he needed the surgery.
Brittain was a 4th-round selection of the Panthers in June, 2010; he succeeded fellow prospect Marc Cheverie in the University of Denver nets. Godspeed in your recovery, sir.