Johnny Boychuk, defenseman for the Boston Bruins hocky team, sprained his left knee during Tuesday's game against the Pittsburgh Penguins. The injury happened during the third period when he collided with Arron Asham. 

A knee sprain happens when one of the ligaments in the knee is stretched or partially torn. For a mild knee sprain, the most common treatments are ice, a compress or brace to keep the knee from moving while injured, and rehabilitation exercises. If the ligament is torn bad enough, it may need surgery, but that seems unlikely for Boychuk's injury. 

It can take anywhere from 2-6 weeks for a knee sprain to fully heal depending on how bad the sprain is. Fans are still hoping that Boychuk will heal in time for the NHL playoffs, but with game one less than a week away it doesn't look likely.