That's the same injury that prompted Roddick to pull out of the U.S. Davis Cup team's quarterfinal at Croatia last week.
Tournament director Kevin Martin says he's disappointed but he understands Roddick's decision to put his health first.
Martin says he's working to secure a commitment from James Blake, who's ranked No. 17 in the world, to take the final wild card before the draw is released.
The Indianapolis tournament began Friday with qualifying.
Nadal to return next monthZokora targets Sevilla glory
