DeSean Jackson appeared to tweak his hamstring while running a deep route in Thursday's practice session.

Jackson was injured when barely overthrown by Robert Griffin III.

Jackson walked gingerly to the sideline.

Domenik Hixon has suffered another torn ACL, which will effectively end his career.

Hixon signed a one-year deal with the Chicago Bears in March after one season with the Carolina Panthers.

"I tore my ACL today for the third time today!" Hixon wrote. "I'm disappointed that I won't be playing for a Bears team that has the players and coaches to win the Super Bowl. I thank God for letting me live my dream of playing in the NFL for 8 years plus. It has truly been fun!"

Rob Gronkowski isn't participating in the New England Patriots' OTAs as he continues his own rehab from a torn ACL and MCL in December.

Gronkowski hasn't had any setbacks in his work.

Gronkowski had multiple issues last offseason coming back from his forearm surgery.

Sean Lee has been told that he has a torn ACL in his left knee and is expected to miss the entire Dallas Cowboys' season.

Lee tore his right ACL in April 2008 while at Penn State, then partially tore his left ACL during the 2009 season.

"Sean has had to deal with injuries throughout college and also here in the NFL," Jason Garrett said earlier Tuesday. "He really does everything he can to get himself ready to play. Unfortunately, he had to deal with a few of those things, but he's as mentally tough as an individual I've ever been around. Whatever the circumstances are, he always puts his best foot forward and strives to be his best. I don't anticipate this being any different."

Lee appeared to be slipping while being blocked by Zack Martin on a screen pass.

"I don't really know what happened," said Martin, the Cowboys' first-round pick. "Two guys playing hard, running to the ball. We'll see what happens. ... Hope for the best. He's obviously a great player, leader of the defense."

Lee missed five games last season with hamstring and neck injuries. He was cleared from the neck injury at the start of the offseason program in April.

Sean Lee injured his left knee during the Dallas Cowboys' practice on Tuesday.

Players immediately feared that the injury was serious.

Julio Jones won't be "doing a whole lot" during the Atlanta Falcons' offseason conditioning program.

"Our focus is strictly on getting them ready to go for training camp (in late July)," said Mike Smith, who told reporters in April that his star wideout was ahead of schedule.

Jones suffered a season-ending foot injury in Week 5.

The San Francisco 49ers drafted a running back in the second round of last week's draft, but that doesn't mean Marcus Lattimore has suffered a setback.

Lattimore tore three ligaments in his left knee in October 2012 and spent his first NFL season rehabbing.

“It’s been going good,” Lattimore told 49ers.com on Thursday. “I’m real happy because I’ve had no knee problems, nothing in my knee, no soreness, no swelling.”

Dashon Goldson underwent ankle surgery, which will keep him out of all spring work.

Goldson will earn $9 million next year from a contract he signed last year with the previous Tampa Bay regime.