Blues general manager Doug Armstrong confirmed Tuesday that Pietrangelo will have minor surgery on a lower-body issue.
Pietrangelo did suffer a sprained knee in Game 1 of the Western Conference semifinals against the Los Angeles Kings when he was shoved awkwardly into the boards. He missed Game 2 before returning to play in Games 3 and 4 of a series the Kings won in a four-game sweep.
Pietrangelo said at the team's exit meetings in May and again last month there was no need for any surgical procedure on the knee, so it is possible it will be done on another area.
Pietrangelo is not expected to miss any time when training camp opens Sept. 21.
The 22-year-old, who played 81 games last season and posted career highs in goals (12), assists (39) and points (51), skated voluntarily last month at the Blues' training facility at St. Louis Mills. He finished fourth n voting for the Norris Trophy.