INDIANAPOLIS - The Indianapolis Colts believe lingering pain in Andrew Luck's lower left leg will likely force their starting quarterback to miss the rest of the preseason.
They're still unsure about his availability for the Sept. 8 season opener against the Los Angeles Chargers.
Colts general manager Chris Ballard said Tuesday additional testing revealed Luck appears to be suffering from an injury near the front of his ankle, something his previously diagnosed strained left calf might have exacerbated.
"Honestly, I think it's a cumulative thing through the years. Andrew's had some issues with his left (ankle) for a while, so I think it's really a cumulative thing," Ballard told local reporters on a conference call. "We think we've found it. You hope you've found what the cause is. Is there a 100 percent guarantee? No, but we think we have, so we'll move forward and try to treat it."
The injury kept Luck out of all of the team's offseason workouts and all but three training camp practices. He still has not participated in full team drills.
Ballard and coach Frank Reich initially described the injury as a strained calf, but when Luck continued to complain about soreness, team officials started digging deeper to get answers.
On Monday, Colts owner Jim Irsay told SiriusXM radio the team believed Luck had an injury to the os trigonum, a small, accessory bone near the back of the ankle.
But new tests, Ballard said, determined the soreness was coming from the front of the ankle.
"Most of his pain is right below the calf, kind of anklish, up a little bit. Remember, everyone kept focusing on the Achilles and it's not the Achilles," Ballard said. "The issue right now is the side to side stuff, the rolling of the ankle. Anything moving forward is good. It's the moving in the pocket."
In his most recent interview, Luck said he felt as if something was tugging at his lower left leg near the ankle when he ran.
The current diagnosis does not call for surgery, just more rehab and a different routine.
Luck did participate in individual work and some seven-on-seven drills during the first week of camp, but has been limited to working on his own and running walkthroughs since July 29.
Without Luck, Jacoby Brissett has been working with the starting offense