Virtanen received a major penalty and a game misconduct after the incident occurred at 2:01 of the second period. Polak went to the locker room briefly after the late, blind-side hit from Virtanen before returning.
Virtanen will be fined $9,614.70 under terms of the Collective Bargaining Agreement and the money given to the Players' Emergency Assistance Fund.
Goaltender Robin Lehner will miss the rest of the NHL season after undergoing surgery on his right ankle, the Buffalo Sabres announced.
Lehner, 24, was limited to 21 games this season and posted a 5-9-5 record with a 2.47 goals-against average and a .924 save percentage. He last played in a March 16 game against the Montreal Canadiens.
Florida Panthers center Vincent Trocheck will miss the remainder of the regular season after suffering a foot injury during Tuesday night's game against the Toronto Maple Leafs.
Trocheck's foot was in a cast to help speed healing and he was using crutches after being struck by a puck during the Panthers' 5-2 loss to the Maple Leafs.
Panthers coach Gerard Gallant told reporters on Wednesday that Trocheck, 22, is out for the final six games of the regular season but hopes to return for the start of the NHL's Stanley Cup playoffs.
Four years after being drafted in the first round, center Mark Jankowski signed a two-year, entry-level contract with the Calgary Flames.
Jankowski, selected No. 21 overall in 2012, just completed his senior year at Providence College, leading the Friars in goals with 15 and assists with 25 in 38 games this season.
The contract begins with the 2016-17 season. The Flames announced that the 6-foot-4 Jankowski, 21, will report to Stockton on an amateur tryout agreement.
Jankowski said signing with Calgary was "a dream come true."
The Arizona Coyotes signed defenseman Kyle Wood to a three-year, entry-level contract and recalled forward Eric Selleck from Springfield of the American Hockey League.
Wood, 19, was acquired by the Coyotes in a trade deadline deal with the Colorado Avalanche on Feb. 29.
Wood has eight goals and 31 assists in 49 games for the North Bay Battalion in the Ontario Hockey League this season.
The Montreal Canadiens agreed to terms with free agent goaltender Charlie Lindgren on a two-year, two-way contract through the 2016-17 season.
Lindgren, 22, appeared in 40 games with the St. Cloud State Huskies this season, posting a record of 30-9-1.
The St. Louis Blues signed forwards Mackenzie MacEachern and Adam Musil to entry-level contracts.
MacEachern, 22, was signed to a two-year contract and Musil, 19, to a three-year deal.
The Winnipeg Jets agreed to terms with free agent college forward Brandon Tanev on a one-year, two-way contract.
The deal is for the remainder of the 2015-16 season at a pro-rated average annual value of $925,000.
Tanev, 24, just completed his senior year at Providence College where the left winger tallied 28 points (15 goals, 13 assists) in 38 games for the Friars, and their game-winning goal in the 2015 NCAA Men's Hockey Championship final against Boston University.
The Boston Bruins recalled forwards Austin Czarnik and Seth Griffith on an emergency basis from Providence of the AHL.
This is the first career NHL recall for Czarnik, who has skated in 59 games with Providence this season and recorded 52 points (15 goals, 37 assists).
Griffith, 23, has played in 51 games with Providence this season, recording 67 points (22 goals, 45 assists) and 32 penalty minutes.