Krejci will likely be unable to participate in the World Cup of Hockey, which begins Sept. 17, and could miss the start of Bruins training camp, which begins later that month.
Defenseman Torey Krug, scheduled to become a restricted free agent July 1, had right shoulder surgery April 21 that will keep him out six months. He finished his third full season in Boston with NHL career highs of 81 games played, 40 assists, 44 points and 33 penalty minutes.
Forward Matt Beleskey will need six weeks of recovery time after having surgery on his left hand April 14. He had NHL career highs of 80 games, 22 assists, 37 points and 65 penalty minutes in the first of a five-year, $19 million contract he signed with the Bruins on July 1.
The Bruins (42-31-9) finished fourth in the Atlantic Division and missed the Stanley Cup Playoffs for the second consecutive season.
