For Thornton, it will be the third game he has missed with a knee injury. He's getting closer to being back, as earlier in the week Chuck Pagano described him as "day-to-day" instead of "week-to-week," but it was clear as he didn't practice this week that he likely wouldn't be ready for this Sunday. He has started eight games at right guard this year, though as previously mentioned this will be his third straight missed with the injury. His injury has been a sort of addition by subtraction for the Colts, however, as he was playing very poorly before he was injured and his replacements have looked better.
Of course, his replacement was Joe Reitz, but he too will miss this Sunday's game. He injured his ankle last week and was described by Pagano as "day-to-day" as well. He too missed practice this week and seemed unlikely to play. He has started the past two games at right guard and was filling in well there.
So here's what this means for the Colts: they'll be without their top two right guards on Sunday as they face the Texans and J.J. Watt. But the positive news is that they have a couple of guys who have played there and done well - A.Q. Shipley and Khaled Holmes. Holmes filled in last week after Reitz went down, but it was in part because he was the last lineman available for the Colts to use as Shipley was filling in at center. With Jonotthan Harrison starting on Sunday at center, that leaves both Shipley and Holmes (as well as Lance Louis, who has been inactive recently) should the Colts wish to use any of them. Chuck Pagano would not say on Friday who will start (because he's gotten very good at not giving out much information recently), but my guess would be that Holmes will make his first ever start for the Colts along the offensive line.
In other injury news, Vontae Davis is getting close to playing for the Colts. Pagano says that he has one more step left in the concussion protocol before being cleared. He is listed as probable. For the Texans, wide receiver Andre Johnson has not yet been cleared in the concussion protocol.