NEW YORK — Rob Gronkowski, tight end for the New England Patriots, became the 40th NFL player to suffer a season-ending knee injury this season on Sunday, a 60-percent increase over 2011 that comes as defenders have sought to avoid penalties and fines for hits to the head.

Gronkowski, a two-time Pro Bowl tight end who has scored 42 touchdowns in his 44 career starts, was injured during the third quarter of New England’s 27-26 win over the Cleveland Browns. After catching a pass down the middle of the field, Gronkowski was hit in the right knee by Browns defensive back T.J. Ward. He will miss the rest of the season with torn anterior cruciate ligament and a damaged medial collateral ligament.

Losing the hulking 6-foot-6, 265-pound Gronkowski will have a major impact on the Patriots (10-3). After missing the first six games recovering from offseason back and forearm surgeries, he quickly returned to being a favorite target of quarterback Tom Brady with 39 catches for 592 yards and four touchdowns in seven games.

In those seven games with Gronkowski in the lineup, the Patriots averaged 32 points a game. Without him for the first six weeks, they averaged 20.8 points a game.

But now Gronkowski is the 40th ACL injury of the season, according to ESPN, up from 32 last year and 25 in 2011. The league has put a focus on preventing head injuries with increased in-game penalties as well as hefty fines and suspensions, but an unintended byproduct is that defensive players wary of incurring fines and penalties are hitting low.

“You see what defenders are doing – they’ve been put into a tough position getting away from the head,” said Merrill Hoge, who retired as a running back because of concussions and is now an NFL analyst for ESPN. “When you lose a guy like that, that hurts not just the New England Patriots, that hurts the National Football League because he’s a guy that people identify with, he’s a significant player and he’s a difference-maker.”

Ward, whose hit forced Gronkowski to be taken off the field on a cart, said the rule changes have made many defensive players go low to make tackles.

“If I were to hit him up high, there’s a chance I would be fined, so I was just being safe,” said Ward, at 5-foot-10, 200 pounds. “Gronk’s a big dude, he’s not small by any means, it just makes it difficult. My intention is not to hurt anyone, that’s not what this game is about and that’s not how I play.”

With the loss of Gronkowski, the Patriots’ odds of winning the Super Bowl moved to 8-1 from 6-1 at the Las Vegas Hotel’s SuperBook. The Patriots are tied for the third-best record in the NFL, with three games left in the regular season.

“I don’t think too many teams have players of that caliber at any position to just put in another Rob Gronkowski,” Patriots Coach Bill Belichick said Monday on a conference call. “One way or another, we’ll have to adjust.”

Indianapolis Colts wide receiver Reggie Wayne and running back Vick Ballard, St. Louis Rams quarterback Sam Bradford, New York Jets running back Mike Goodson, Miami Dolphins tight end Dustin Keller and Cleveland Browns quarterback Brian Hoyer are among players to suffer ACL injuries this season.

In an effort to reduce concussions and brain trauma, the NFL has cracked down on hits by defensive players to the head and neck area of offensive players. Safeties Dashon Goldson of the Tampa Bay Buccaneers and Brandon Meriweather have both been suspended one game this season for repeated helmet- to-helmet hits on defenseless receivers.

“The defenseless receiver rule has to extend not only to the head, but also to the knees,” said Terrell Davis, the league’s most valuable player in 1998 who now is an analyst for NFL Network.

The Patriots also lost Aaron Hernandez in the offseason when he was charged with murder and that made Gronkowski even more valuable. Now the team must fill a gap at tight end with Matt Mulligan, a Maine native and former University of Maine player, the only healthy tight end on the roster. But he is primarily a blocking tight end, so Michael Hoomanawanui, who is nursing an injury of his own, and fullback James Develin will help as well. The Patriots also re-signed tight end D.J. Williams, who was released last week.

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