The 32-year-old defenseman was injured in August while training. He will be reevaluated in six months.
Scandella had 14 points (three goals, 11 assists) and averaged 18:08 of ice time in 70 regular-season games last season. He was limited to four games during the Stanley Cup Playoffs because of a lower-body injury.
The Blues open training camp Thursday. They begin the regular season Oct. 15 against the Columbus Blue Jackets.