BOSTON — Even before Johnny Boychuk was knocked to the sidelines by a Chris Neil hit and ensuing concussion symptoms, the Bruins knew they had to add at least one more veteran defenseman for depth before the stretch run and playoffs.

General manager Peter Chiarelli today added two blueliners, one more prominent than the other, before the 3 p.m. trade deadline.

Chiarelli’s biggest of two deals today shipped Steven Kampfer to Minnesota for Greg Zanon. The Bruins’ second deal picked up two veterans Brian Rolston and Mike Mottau, who probably won’t be counted on to play much, in exchange for minor leaguers Marc Cantin and Yannick Riendeau.

Zanon is a perennial presence among the NHL’s top four in blocked shots every season. This year, he missed 16 games with a groin injury in the fall. With Zanon’s acquisition, one of Adam McQuaid or Joe Corvo might be pushed into the role as seventh defenseman. For now, the Bruins need a replacement for Boychuk.

Mottau, a native of Avon, Mass., just returned from a 26-game absence due to a concussion. Rolston also missed time with a concussion this season and has 4-5-9 totals and a minus-12 rating in 49 games. Rolston, who previously played for the Bruins 2000-2004, was waived by the Islanders Sunday and cleared waivers today.

For more on the trades, including Chiarelli’s comments, check out my pieces. And for my take on how the Bruins fared at the deadline, go to