Complex sentence: Kampfer suffered a minor knee injury on April 9,2011 while playing a game for the AHL's Providence Bruins, and he has been recuperating since that time, unfortunately, he was not able to rejoin the Boston team during the 2011 Stanley Cup Playoffs.
Split into simpler sentences: Kampfer suffered a minor knee injury on April 9,2011 while playing a game for the AHL's Providence Bruins, and he has been recuperating since that time. Unfortunately, he was not able to rejoin the Boston team during the 2011 Stanley Cup Playoffs.