Maryland strong free safety Matt Robinson hurt his left shoulder during practice on Tuesday, and it’s unclear the severity of the injury or how long the sophomore would be out, Coach Randy Edsall said.

Robinson started the first three games last season before injuring his right shoulder. The injury ended his season and required surgery from which he was still recovering during spring practice.

“I didn’t see if he was using the proper technique, if he turned his shoulder or if he went in and it was one of those freak things,” Edsall said. “I’ll have to take a look at it on film.”

Robinson is considered an integral part of Maryland’s defense, which is undergoing a transformation to a 3-4 alignment under first-year defensive coordinator Brian Stewart.

Last season Robinson was second the ACC and tied for seventh nationally in tackles per game (12) before the injury.

The All-Met from Atholton High School played in 13 games as a freshman with the Terrapins, including starting once at safety. His 29 tackles were second among Maryland’s reserves.

“It’s unfortunate with Matt in terms of what happened to him,” Edsall said. “Again we’ll see where it is, but like I said, it’s a great message and great lesson for all these other guys to say, ‘Hey, I’ve got to be out here doing everything that the coaches want me to do and executing the proper way because I’m going to get an opportunity sometime when I least expect it.’ ”

Sean Davis played with the first-team defense in Robinson’s absence. Davis is a non-redshirt freshman who played high school football at Maret.

In other injury news, right guard Josh Cary, fullback Tyler Cierski and left tackle Mike Madaras did not practice.

Cary has an ailing knee, Edsall said, that will keep the junior with starting potential out one to two weeks. Cierski, a sophomore starter, probably will be back in a day or two while nursing a sore hamstring.

Madaras (Good Counsel), listed third on the preseason depth chart, is out with a sore shoulder.