The injury took place when Kelly collided with former Ottawa teammate Chris Neil. Kelly needed help getting off the ice, placing little weight on his left leg.
Team doctors had to wait until swelling subsided to diagnose Kelly with the injury.
The Bruins have yet to recall a center to replace Kelly. Rich Peverley centered the third line in last night’s 3-2 loss to Pittsburgh. The Bruins are carrying one extra forward.
Kelly has two goals and four assists in 23 games. This is the most significant injury of Kelly’s career. The Bruins have not said whether Kelly will require surgery.