Quinton Carter was never able to put an offseason knee injury behind him. . (Andrew Mason)

S Quinton Carter's knee trouble began when it bothered him in the offseason, and yet he practiced through the pain, putting off surgery. But even having the procedure early in training camp when he was shelved because of a hamstring injury wasn't enough to save his season.

The Broncos placed Carter on injured reserve Saturday. The decision comes at the end of a two-week period in which he was limited by the knee problem in practice, managed to play the following game against Houston on Sep. 23, then missed practice all week.

The Denver Post reports that Carter will undergo microfracture surgery.

Carter's injury ends the question of whether he could replace fellow 2011 draft pick Rahim Moore in the starting lineup. Moore has struggled at times in his brief career; Carter supplanted him in the starting lineup last year and Moore has four 15-yard penalties in the last five games in which he played extensively on defense. But Moore also had arguably the best game of his career against the Texans last week.

The Broncos promoted undrafted rookie S Duke Ihenacho from the practice squad to replace Carter on the 53-man roster. They also promoted LB Mike Mohamed; he will take the spot vacated for this week by the suspended Joe Mays.

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