It was one of a number of injuries sustained by the Seahawks. Pro Bowl defensive end Cliff Avril is dealing with neck and spinal injuries that will sideline him indefinitely.
Seahawks coach Pete Carroll said Carson would undergo surgery Tuesday and said the back has an "outside chance" to return to the field this season. The surgical procedure will address damage from a high ankle sprain, according to Carroll, and is not related to the broken bone.
Carson was carted off the field after going down midway through the fourth quarter when he was tackled for no gain. He finished with 42 yards on 12 carries. Per NFL rules, Carson must spend at least eight weeks on IR.
A seventh-round draft pick out of Oklahoma State, Carson impressed team management in the preseason. He moved past offseason signee Eddie Lacy and got the start in Week 2, rushing for 93 yards on 20 carries.
Carson broke his bone above the ankle and below his knee. Seattle running back Thomas Rawls sustained a similar fracture last season and missed seven games. Lacy and Rawls likely will both see time in Carson's absence.
"Thomas Rawls gets to step up. That's just good fortune and good planning and all of that," Carroll said. "And Thomas is really raring to go, and we are excited to get him to play."
Avril was dealing with some "serious stingers" that will keep him out for a while, Carroll said.
"It's going to be awhile to figure out what he's got. We've got to make sure that we get him cleared and figured out, so there are going to be some tests and stuff like that," Carroll said. "I don't have any timeline on that at all. But we are going to take care of him and make sure we take our time and do this very well, to look after him."
The Seahawks did receive positive news on left tackle Rees Odhiambo, who was hospitalized after experiencing breathing issues. Odhiambo was diagnosed with a bruised sternum and released from the hospital Monday.
Odhiambo, a third-round pick in 2016 out of Boise State, took a hard hit to the chest on an interception in the third quarter and needed medical attention in the locker room after the game when he suddenly had trouble breathing.
The team also signed defensive lineman Quinton Jefferson off the Los Angeles Rams' practice squad and added him to its 53-man roster on Monday.
Jefferson was a fifth-round draft choice of the Seahawks in 2016. He appeared in three regular-season games with Seattle last season before going on injured reserve with a knee injury. Jefferson was signed by the Rams after the Seahawks released him last month.
Cornerback Jeremy Lane sustained a groin injury on the first series of the Indianapolis game, and it is unclear if he will be available for this Sunday's game at Los Angeles against the Rams.