With just three minutes left in a 5-5 game, Donskoi carried the puck down the right wing and was tripped by Flames defenceman Mark Giordano.
Doonskoi appeared to make contact with Ramo while the goaltender was already sprawled to make a save. Ramo's left leg was slammed against the post.
Jonas Hiller came into the game and made several key stops to take the game to a shootout, where the Flames would eventually prevail.
Head coach Bob Hartley has said Ramo will not play Friday against the Arizona Coyotes.
The Flames were already without forward David Jones, who left the game in the first period after suffering a lower-body injury.
With 5:20 left in the first and the Flames up 4-1, Jones blocked a shot from Sharks defenceman Brent Burns and had to limp off the ice.