Henderson missed Thursday and Friday's practices with swelling in his knee, but the swelling and soreness isn't unprecedented.
"I have felt that swelling before, especially after the amount of plays that we played on Sunday. Expected it to flare up a little bit, but just not that much," Henderson said, referring the 77 snaps the Vikings defense was on the field.
While Vikings coach Leslie Frazier said doctors didn't think the swelling was related to the rod in his leg, Henderson said he "definitely" thinks it is.
"The knee always swells up where they had to insert the rod. So, it's something that we're used to, just something that we've got to watch and treat and get ready for Sunday," Henderson said.
Henderson had the knee drained on Thursday, a procedure he had once last year on a Friday and didn't miss any time, so he was "pretty confident" that he would be able to play Sunday against the Tampa Bay Buccaneers.
"We'll see how it feels in the morning. We'll see how it feels in pregame and see if I can rock," he said.
Frazier confirmed that Henderson's availability Sunday would be a game-time decision, but E.J.'s younger brother Erin, who would replace him if necessary, sounded the most confident of anyone that E.J. would play.
"I know my guy. I know my brother. We come from a place where, if you can, you do," Erin said. "If he's feeling up to it and he's feeling able and his knee is holding up and everything's good, I know he will be out there. I know he'll be giving us everything he's got once he steps on the field."
While E.J. sat out the last two days of practice, he has been attending meetings.
Henderson woke up Thursday morning with swelling and soreness in his knee. He had an X-ray on Thursday and Frazier said it revealed there was no structural damage.
If Henderson isn't able to play Sunday, Erin would move from weakside linebacker to the middle and Kenny Onatolu would play weakside. After only one start at weakside linebacker, the adjustment, if necessary, would be formidable for Erin.
"It's just your eyes are in different places," Frazier said. "You have to be able to see the triangle between the guard and center and quarterback. Whereas in Erin's position at the Will, his normal position, he's primarily looking at the tackle position and sometimes the guard. Your vision has to be a lot different and your responsibility is a lot different. You're calling the defense, you're getting people lined up. You're making sure that the front is where it should be, so there's a lot more responsibility in that role as a middle linebacker."
Linebacker Chad Greenway, who will remain on the strong side, is keeping an optimistic approach to the situation.
"We're just hoping he gets back. I am not sure what his status is exactly, but … it would be difficult [without him]. He's obviously the [leader] of our defense. Unfortunately, it's something we have to get past. But when you lose a veteran, somebody steps in. We'll be good. We'll be good."
Henderson came back from a devastating fractured femur suffered in December 2009 and started all 16 games last year, finishing second on the team with 139 tackles and had eight or more tackles in 11 games. He was fourth on the team with seven tackles for a loss.
In the first 98 games of his career, Henderson had just two interceptions, but he had two in one game to almost singlehandedly beat Dallas last year and finished the year with three interceptions, tying Husain Abdullah for the team lead.
In 2008, Henderson played in only four games before multiple dislocated toes took him out of action for the season after a fast start. Before going on injured reserve, he registered 39 tackles, two QB hurries, one forced fumble, one fumble recovery, one sack, three tackles-for-loss and two passes defensed.
Henderson led the team in tackles in 2007 with 155 while adding 4.5 sacks, six passes defensed, a team-leading 14 tackles-for-loss, one forced fumble, two fumble recoveries and 19 quarterback hurries. He led or tied for the team lead in tackles in 12 games and was a Pro Bowl alternate.
He is in the final year of his contract after signing a five-year, $25 million extension in 2006 that included $10 million in guaranteed money.
Tim Yotter is the publisher of Viking Update. Follow Viking Update on Twitter and discuss this topic on our message boards. To become a subscriber to the Viking Update web site or magazine, click here.