The Bruins on Wednesday released a more detailed explanation of the injury and the resulting infection that defenseman Charlie McAvoy sustained during the 4 Nations Faceoff from team physician Dr. Peter Asnis:

“Charlie McAvoy sustained an injury to his right shoulder acromioclavicular joint in Team USA’s 4 Nations Face-Off game against Finland on February 13. He underwent treatment, which was administered by Team USA’s medical staff. Upon returning to Boston, he developed increasing pain, for which he was evaluated by the Boston Bruins’ medical staff. After undergoing x-rays, MRIs, and bloodwork, he was diagnosed as having an infection in his right shoulder, as well as a significant injury to his AC joint. He underwent an irrigation and debridement procedure at Massachusetts General Hospital on February 18. He remains in the hospital, where he is being treated with IV antibiotics, and his condition is improving.”

In the Finland game, which Team USA won 6-1, McAvoy was checked into a goal post by Joel Armia. Whether tat’s where he suffered the injury is not clear. McAvoy finished that game and then played a big role with his physicality in Team USA’s victory over Canada last Saturday in Montreal.

Team USA return to Boston early Sunday morning and McAvoy was admitted into Mass General Hospital on Monday night.

No timetable has been given yet for McAvoy’s return, which is not good news for the Bruins, who will resume their battle for an Eastern Conference playoff spot on Saturday night against Anaheim.

Losing a key player for the stretch run, however, is the risk that all NHL teams take when sending players to this highly competitive tournaments like the 4 Nations Faceoff or, next season, to the Olympics.

“Every team goes into it a little bit on edge about their players,” Bruins coach Joe Sacco said on Tuesday. “It’s obviously a great tournament, it’s great notoriety, it’s great publicity for the game, for the sport. I think every teams are a little bit nervous when they send their players but it is the game of hockey and things happen. You just hope the best, pray for the best when they’re out there that those injuries don’t occur.”