Bradshaw could only make 11 yards for his team from seven carries and four receptions on Sunday as they went down 42-20 to the New England Patriots.
And coach Chuck Pagano has further issues to contend with after Bradshaw's status for the Colts remaining six regular-season games - as well as a potential play-off run - was plunged into huge doubt.
Pagano said: "He's been seen by our doctors, our specialists and he's going to see a couple more.
"I'll have more information in the coming days.
"It kills you because he's a warrior.
"He loves football. He loves his team-mates. He loves competing.
"We are going to miss his energy, his passion, everything he brings to the table.
"We've got a lot of football left, that's why we are keeping our fingers crossed."