Pastrnak was injured Sunday night after falling while leaving a sponsorship dinner, Sweeney added. He's expected to play again this season.
Boston sits third in the Atlantic Division with 70 points - one point back of the Toronto Maple Leafs and one point clear of the Montreal Canadiens. Pastrnak's recovery timeline leaves the Bruins without their leading scorer at least until the trade deadline, but his absence won't change the club's approach leading up to the big day, Sweeney said.
Pastrnak, 22, has been dynamite for the Bruins this season. He ranks seventh in the NHL with 66 points in 56 games and second among all players with 29 power-play points.