(Reuters) - The undefeated Houston Texans were dealt a major blow after learning that leading tackler Brian Cushing will miss the rest of the 2012 National Football League (NFL) season with torn knee ligaments, the team said on Tuesday.

The 25-year-old linebacker, who is also one of the defensive leaders for the 5-0 Texans, was injured in the second quarter of Houston's 23-17 win over the New York Jets on Monday.

"(It's) a big blow to our team," Texans head coach Gary Kubiak said on the team's website. "You feel bad for Brian because he works so hard and is playing so well."

Cushing is expected to undergo surgery in two-to-three weeks once swelling on the injured knee goes down.

The Texans' most valuable player in 2011, Cushing leads the NFL's third-ranked defense this season with 29 tackles and had five on Monday before exiting under his own power after a block by Jets guard Matt Slauson.

Taken in the first round of the 2009 NFL Draft, Cushing had 133 tackles as a rookie, earning him a trip to the Pro Bowl and defensive rookie of the year honors. He also led the team in tackles in 2011.

"You don't replace players like (Cushing)," said Kubiak. "The rest of your football team has got to pick it up and play better. We're going to be calling on everybody else to do their job a little bit better."

(Reporting by Steve Keating in Toronto; Editing by Frank Pingue)