The Pittsburgh Penguins have swapped defenders on injured reserve, activating Marcus Pettersson (lower-body) and shelving Kris Letang (lower-body), per a team announcement. Pettersson suffered his injury from an awkward hit into the boards during Pittsburgh’s Dec. 14 loss to the Ottawa Senators. He’s since missed the Penguins’ last six games. Where Letang was injured is less clear. He was a late scratch for Sunday’s game against the New York Islanders and has been designated as day-to-day, per Hailey Hunter of SportsNet Pittsburgh. The Penguins will have the ability