[8] The injury, which was first diagnosed a game earlier as a left foot bruise, included a sprain that kept him out of practices and limited his playing time for the rest of the season.

On September 28, 2009, Johnson suffered an injury when the 275 pounds (125 kg) barbell he was lifting fell on his throat while performing a bench press during a routine team workout.

Bleeding from his mouth and nose, he was rushed to California Hospital Medical Center and had three emergency surgeries to repair damage to his crushed vocal cord, adam's apple and torn muscles.

[11][12] Doctors partially credited his survival to well developed muscles around his neck, which helped him keep open a breathing passage, as well as his level of fitness.

[12] He was moved to Cedars-Sinai Medical Center, and was released on October 15, 2009, though he was still unable to speak and had a breathing tube in his throat.

[12] Later in the 2009 season, the USC football team honored Johnson by wearing helmet stickers that read "STA FIGHT ON" while playing rival Notre Dame.

[15] On January 24, 2011, Johnson sued USC and the former assistant conditioning coach who was present for negligence related to the accident.

He had a close relationship with his grandfather, Larry "Big Dad" Mallory, a father figure who attended practices and games.