As a result of the injury, the Bruins signed veteran netminder Marty Turco to a one-year contract.
Turco, 36, played in only four regular-season games for EC Red Bull Salzburg in the Austrian First Division this season. He will be placed on NHL waivers, and if he clears, he will join the Bruins on Wednesday. If he clears waivers, Turco will not be eligible for the Stanley Cup playoffs because he will join the Bruins after the trade deadline.
Turco's contract is pro rated for $600,000, a league source tells ESPN.com's Pierre LeBrun.
Turco played 10 seasons in the NHL with the Dallas Stars and Chicago Blackhawks. He has a 273-165-43 career record with a 2.35 goals-against average and a .910 save percentage. He posted 41 career shutouts and compiled six 30-plus win seasons.
After playing the first nine years of his career with Dallas, Turco spent the 2010-2011 season with the Blackhawks and posted an 11-11-3 record with a 3.02 GAA and an .897 save percentage.
Rask suffered the injury at 9:01 of the second period while making a save against the New York Islanders last Saturday at TD Garden. He fell to the ice in pain and needed to be helped off. At the time, the score was tied at 1-1, and the Bruins eventually lost 3-2.
Rask is 11-8-3 with a 2.05 goals-against average and a .929 save percentage in 23 games this season.
With Rask sidelined, the Bruins recalled goaltender Michael Hutchinson from the Providence Bruins of the AHL. At the time of his recall from Providence, Hutchinson was 6-11-0 with a 2.62 goals-against average and a .920 save percentage.
Tim Thomas, the Bruins' primary goaltender and the reigning Vezina and Conn Smythe trophy winner, is 27-15-0 with a 2.28 GAA and .926 save percentage in 45 games this season.
Joe McDonald covers the Bruins for ESPNBoston.com.