According to a source, the troublesome knee, which limited Moreno's participation in the final two weeks of the team's offseason training program, needs to be "cleaned up." The procedure isn't expected to be invasive.
Coincidentally, Moreno underwent arthroscopic surgery on his right knee following the conclusion of the 2012 season. During that operation Moreno reportedly had stem cells harvested from bone marrow in his pelvis and injected into his knee. The next season he rushed for a career-high 1,038 yards.
Moreno tore the ACL in his right knee at the end of the 2011 season, but this injury is not the same knee.
Moreno, whom the Dolphins signed to a one-year, $3 million contract this offseason, was expected to unseat Lamar Miller as the team's starting tailback, and serve as the all-purpose back the Dolphins didn't have last season.
If Moreno, who contributed 1,586 combined yards and scored 13 touchdowns as the Denver Broncos' starter, has the procedure done this week he'll likely be healthy enough to participate in Miami's exhibition season, which begin on Aug. 7 with a road against the Atlanta Falcons.
Moreno will have 11 weeks to get himself healthy, and in shape for the Sept. 7 season-opener against the New England Patriots.
Moreno, who turns 27 next month, has played in 60 NFL games in his five previous NFL seasons, starting 45 of them. He's only played in all 16 games twice in his NFL career.
The Dolphins presently have seven tailbacks on the training camp roster, and only two of them - rookies Damien Williams and Orleans Darkwa - lack NFL experience.
The Dolphins started Miller, a 2012 fourth-round pick, for 15 games last season, and the former University of Miami standout gained 709 rushing yards and scored two touchdowns on his 177 carries.
Daniel Thomas, a 2011 second-round pick, has rushed for 1,312 yards and scored 11 touchdowns in his three seasons. But Thomas has a disappointing 3.6 yards per carry average.
Former Gators standout Mike Gillislee, whom the Dolphins selected in the fifth round of the 2013 NFL draft, is entering his second season. And former CFL standout Marcus Thigpen has spent the past two seasons working as Miami's return specialist, and a tailback who can be used as a pass catcher/slot receiver.