"I think after the (Kevin Durant injury) everyone's erring on the side of caution, but quite frankly this is not even in the Achilles tendon. It's in another area. It's a bone," Irsay told SiriusXM NFL Radio, according to ESPN. "You know I'm not good at these things. ... It's a small little bone."
Irsay didn't specify which bone is ailing.
Luck has been hampered during training camp due to pain in his calf.
The 29-year-old quarterback isn't expected to participate in joint practices with the Cleveland Browns this week, head coach Frank Reich said, according to Andrew Walker of Colts.com. Luck sat during the Colts' preseason opener and it's becoming increasingly likely he'll miss Saturday's game against the Browns.