Armond Armstead redshirting 2011

LOS ANGELES -- University of Southern California defensive tackle Armond Armstead, who has not practiced since last year with an undisclosed medical condition, will redshirt the 2011 season, Trojans coach Lane Kiffin announced Tuesday.

Armstead, a fourth-year senior and two-year starter for the Trojans, spent five days in the hospital in March undergoing a series of tests. He has had no further known complications since then but has not been allowed to fully participate in USC's practices.

The question of whether or not he'd be medically cleared to play this season had dragged on well past the season opener, and Kiffin said last week that a decision would be made in the near future.

"After meeting with everybody involved, everyone has come to the same conclusion: The best thing is to redshirt him right now, being this late in the season and having missed so much practice time and so much game time," Kiffin said Tuesday. "That's the best thing for his future so we'll look to the future for it. He's going to probably graduate, finish his degree this semester and we'll have him back next year."

Kiffin said he would not "go into" whether Armstead had been medically cleared for competition.

"That's family business," Kiffin said. "We know whether he is or he isn't but that's not for (the public) to know. If the family wants to tell you, that's their business."

Armstead, who was not in attendance at practice, was not made available for comment by USC officials. His father, Guss, visited practice last week and met with USC football staffers in what he said was an attempt to find out more information on his son's situation.

Armstead, 21, was expected to start on the defensive line this season. He could have declared for the NFL draft after last year -- most outlets had him as a projected late-round pick -- but chose to return for his senior season.

He faces a similar decision this time around, as he could leave and attempt to prove to NFL teams he's healthy enough to play at the highest level.

"That's a decision they'll have to make as a family," Kiffin said. "He's definitely a great player, so I'm sure he'll look at that. He's gonna get his degree here and then figure out whether he wants to come back here for another year or move on to the next level.

"I hope he's back. We lose a lot of guys. He could help our front."

Armstead could also transfer to another school for next season under the NCAA's graduate school policy, where student-athletes can spend their final collegiate year at another university if it offers a post-graduate program the original school does not.

Former Oregon Ducks quarterback Jeremiah Masoli used that provision to enroll at Mississippi when he was dismissed from Oregon, and current Wisconsin quarterback Russell Wilson also did so in leaving North Carolina State.

Armstead's younger brother, Arik, is currently committed to USC as part of the school's 2012 recruiting class. He's a 6-foot-7, 280-pound offensive tackle/defensive end who also plays basketball and plans to play at the college level.

Arik Armstead is ranked by most recruiting services as one of the top prospects in the state of California and one of the top 25 seniors in the country. He plans to enroll at USC in January 2012.

Pedro Moura covers USC for ESPNLosAngeles.com.