Notre Dame lost two players for the rest of spring practice, the university announced Wednesday.
Sophomore-to-be running back Cameron Roberson will not return for the rest of spring after suffering a torn lateral collateral ligament and partially torn anterior cruciate ligament early in Saturday's practice. Senior-to-be Anthony McDonald will also miss the rest of spring camp after sustaining a partially torn pectoral muscle.
Both players will undergo surgery to repair their injuries, the university said.
Roberson was running as the third-string running back behind Cierre Wood and Jonas Gray, who are the Irish's only two scholarship backs remaining for the rest of spring.
Roberson, who didn't play last season as a freshman, doesn't have a set return date, according to the university.
His injury sent Notre Dame looking for walk-on running backs Monday, and the Irish added one.
Tyler Plantz, a freshman fro Providence Catholic High School in New Lenox, Ill., joined the team, and he practiced for the first time Wednesday, the university announced. Plantz's father, Ron, played offensive guard at Notre Dame from 1982-85.
"I gained one, that's good. We were plus one today," running backs coach Tim Hinton said. "He will help us in whatever we need to do. Obviously, he is way behind in the learning curve.
"He had a good time today. A little nervous and a little shell shocked, but he did well."
McDonald, who was taking reps with the first-team defense with linebacker Manti Te'o limited because of injury, is expected to return by the start of fall practice, the university said.
McDonald has previously dealt with knee and head injuries.
Notre Dame also added Ryan Liebscher to the receiving corps as a walk-n. Liebscher is a freshman from Colorado Springs, Colo.