Smith's left foot was stepped on Wednesday during a pass-protection drill. He went for tests that detected a broken bone in the foot -- the same one that he broke last season as a rookie.
Bengals coach Marvin Lewis revealed the test results after practice Thursday and said it's unclear whether or not Smith will need surgery. Dennis Roland will replace Smith at right tackle for Sunday's game at Indianapolis.
Smith and Roland have shared time at right tackle the last two seasons. Roland, a former college free agent, started 12 games last season. He also was the starter this year while Smith, a first-round draft pick (No. 6 overall) in 2009, got into shape.
The Bengals re-signed defensive back Rico Murray from the practice squad Saturday to take Smith's roster spot.
The Associated Press contributed to this report.