The Broncos placed second-year S Quinton Carter on injured reserve, the team announced Saturday.
Carter suffered a left knee injury last weekend and will miss the rest of the season. Mike Klis of the Denver Post reported that Carter will undergo microfracture surgery on the knee next week. It's the same knee that needed arthroscopic surgery in the offseason.
Carter started 10 games last season.
The Broncos signed rookie S Duke Ihenacho and second-year LB Mike Mohamed from their practice squad Saturday to fill out their roster, as LB Joe Mays will serve a one-game suspension in Week Four for an illegal hit on Texans QB Matt Schaub.