The play occurred in the first half of the third period when Pionk leaned in to hit Sandin as he took a shot on goal. The Maple Leafs defenceman was helped off the ice and appeared as though he could not put weight on his right leg.
No penalty was assessed on the play but Toronto forward Jason Spezza went after Pionk hitting the Jets defenceman in the head with his knee as he was falling to the ice.
After the game, head coach Sheldon Keefe said he had no update on Sandin's condition. The 21-year-old has seven points in 24 games so far this season.
In the third period alone, the Maple Leafs and Jets combined for 38 penalty minutes with Leafs forward Wayne Simmonds leading all skaters with 18 penalty minutes.