The defensive end, who broke his leg after playing in 10 games during the 2007 Super Bowl season, was optimistic this injury would subside with time and he could resume playing again this season.

The Kiwanuka move was made so the Giants could sign kick returner Will Blackmon.

Kiwanuka, 27, said he will remain with the Giants until his contract expires at the end of the season. Depending on what transpires with the collective bargaining agreement, Kiwanuka will be looking for a new contract and possibly an opportunity to start at defensive end. The Giants have starters Osi Umenyiora and Justin Tuck. Rookie Jason Pierre-Paul is also waiting for a chance.

"Like I said before, I felt like, given enough time, I could've made it back this season, but it's the nature of the business," Kiwanuka said in a statement. "The Giants had to move on, and I had to be OK with it. Regardless of what happens to me as an individual, I'm definitely still going to work with the Giants organization throughout the term of my contract."

It seemed inevitable Kiwanuka's season would end on IR. Kiwanuka hasn't played since the team's loss to Tennessee in the third week of the season.

He led the team in sacks through the first three games with four while thriving in Perry Fewell's new system at defensive end and linebacker. But days before the Giants' win over Chicago, he was diagnosed with a bulging disk in his neck, a similar injury to the one that ended Antonio Pierce's season and career.

Kiwanuka spent much of this past month seeing various doctors. It was after a recent visit to spine specialist Robert Watkins that Kiwanuka's injury was diagnosed as a herniated disk, instead of a bulging disk, meaning it had ruptured. But Kiwanuka said doctors told him his disk will heal on its own without surgery due to the slight degree of the herniation and the alignment of his spine. It just requires time.

"I want to avoid surgery," he said. "The consensus is that if I take the proper amount of time off, there is a very good chance that it'll heal on its own. That's what the goal is right now. If it doesn't happen, we'll cross that bridge when we get to it. Regardless of whether or not it requires surgery, I'll still be back by the opening of training camp."

Kiwanuka is one of Tom Coughlin's favorite players and the head coach said he wants to see the defensive end stay with the Giants next season. Kiwanuka has been one of the team's most selfless players. He switched positions from defensive end to linebacker and back to defensive end. He also played special teams in the past.

"We held out hope as long as we could," Coughlin said. "Finally, by consensus, the doctors came to this decision. You have to make the right choice and the decision was made that he could not play again this season. My concern is for Mathias. He loves the game, he loves to play, he's proven his versatility this year beyond any question. He's given great effort and he has proven that he is a team player. I feel badly for Mathias because I know how important playing the game of football is to him. Let's get him healthy, back on the field, playing for the New York Giants."

Now the Giants move on without their 2006 first-round pick, who was a valuable chess piece in Fewell's schemes. Umenyiora will have to continue his torrid pace. Since Kiwanuka has been out, Umenyiora has seven sacks and six forced fumbles.

"We had to change a little bit when Kiwi went out," Fewell said on Wednesday when asked about how much he had to change schematically without Kiwanuka. "Kiwi is a special kind of guy, so we looked around and we searched for some guys to take over those roles and we have some guys that can assume that role, but not play it like Kiwi plays it, so that's a special little deal."

The Giants have used three safeties on the field quite a bit and safety Deon Grant sometimes lines up at linebacker. Linebacker Keith Bulluck's recent return from a toe injury helps and Fewell will need Pierre-Paul, who was drafted in the first round as a luxury, to continue his progress. Pierre-Paul doesn't have a sack yet but he has impressed coaches with his play on defense and special teams.

"He is making progress for us and we want to get him more involved and he will become more involved," Fewell said. "It just depends on how much more he can handle and execute. So the more he can take on and execute, the more we'll give him. It's up to him."

Blackmon, who played the past four seasons for the Packers, will come in and immediately compete for the kick- and punt-returning duties. Darius Reynaud, who was acquired in the Sage Rosenfels preseason trade from Minnesota, has been a disappointment. Reynaud is averaging 18.4 yards per kick return and just 5.9 yards per punt return.

"Blackmon had a very good workout for us and showed that he has recovered nicely from a serious knee injury," Reese said of Kiwanuka's former Boston College teammate who played in just three games last year due to an ACL injury. "We expect him to get into the mix quickly on special teams. He has experience and production as a return specialist and cover specialist. He also has played both safety and corner, which gives us some flexibility there as well."

Kiwanuka is looking forward to reuniting with his college buddy.

"It's tough, because we were a couple of weeks away from playing together again," Kiwanuka said. "He got his papers from Green Bay, I was excited and heard there was a chance that he might come here, so I've been talking him up around the locker room. Man, he's a great player. I told everybody he's definitely the most talented and gifted athlete that I ever played football with, hands down. He made the switch from DB to wide receiver [in college] and didn't miss a beat, and obviously he is a very talented return guy, too. He can do it all."

Ohm Youngmisuk covers the Giants for ESPNNewYork.com. You can follow him on Twitter