O'Hearn, 33, was helped off the field during Friday night's matchup against the Cincinnati Reds after he was unable to put any weight on his leg while running to first. The veteran, who was seen with a crutch in the clubhouse, had already missed 13 games this season with a quad strain.
He's slashing a solid .270/.334/.454 this season, while his 17 home runs are tied for a single-season career high. O'Hearn already set a personal best with 69 RBI through 96 games.
The Florida native signed a two-year, $29 million deal with the Pirates during the offseason and recently made history after becoming the first player in franchise history to ever record 10 RBI in a single game thanks to a trio of home runs.
Pittsburgh currently boasts a 55-56 record, sitting third in the National League Central division, as they sit 2.5 games out of a Wild Card spot.
MAJOR LEAGUE BASEBALL
The MLB regular season is now in its final two months as the countdown to the Postseason begins!
