Although E.J. Henderson is optimistic about his recovery from the broken femur he suffered in his left leg last March, the reality is that the doctors will have to clear his eventual return to the field.

It remains uncertain when Henderson will get that OK, meaning that for the short term Jasper Brinkley will be the Vikings' middle linebacker. Brinkley certainly will be working with the first-team defense at the three-day minicamp that will open on Friday afternoon at Winter Park.

A fifth-round pick in 2009, Brinkley took over for Henderson last December and ended up having to learn on the job. This offseason he has had more time to work on his game and prepare to play a starting role until Henderson returns.

"Jasper has really improved," Vikings defensive coordinator Leslie Frazier said. "We have no qualms with Jasper being our starting linebacker if that's the case. He's really improved and the more snaps he gets the better he's going to get. He's been everything we've hoped for knowing the possibility that E.J. could be injured. That's why [Brinkley] was drafted and he's been great."

Henderson, who would like to be back for training camp, also has tried to help play a role in Brinkley's improvement.

"When we're in the meetings, we still exchange thoughts," Henderson said. "When I see some of his tape from last year I always give him my thoughts. Jasper is a second-year player now, but his mindset is way older than that so I don't think we have to worry too much about him being prepared or him ready to play if knock on wood something happens where I can't play. I don't think we have to worry about him."

Asked what impressed him most about Brinkley last year, Henderson said: "Just being a rookie. I remember how it was for me being a rookie coming in on a good team, one of the top-rated defenses and coming in and having to run the show. I know the amount of pressure that he was under. I know the amount of strain that he had to deal with. I just think he handled it about as good as you can for a rookie.

"I think he made some plays, like he's capable of doing, gave up some plays, but who doesn't as a rookie? If I had to give him a grade I'd give him a B-plus for being a rookie, stepping in there with the guys around him and the type of defense that he had to play. I'd definitely give him a B-plus."