Richardson failed to practice at all this week, leaving backup quarterback Joe Flacco to possibly get his fifth start of the season.
"We'll see how the next 48 hours go," said head coach Shane Steichen.
The Colts (7-8) are still in the hunt for a playoff spot but are on the outside looking in. In order to just stay alive, the team needs to win their next two games against the New York Giants and Jacksonville Jaguars. But they also need the Denver Broncos and Los Angeles Chargers to lose their games this week.
Richardson is having a brutally awful year, completing just 47.7 percent of his passes with 1,814 yards and only eight touchdowns with 12 interceptions.
Indianapolis was 1-3 under Flacco earlier this season, throwing for 1,167 yards with nine touchdowns and five interceptions.
The Colts are 7.5-point favorites over the Giants.