Cushing, Manning injuries part of trend

If it's seemed like knee injuries have been knocking players out for the season at a higher rate this season, that's because they have.

In light of recent injuries to Cardinals cornerback Tyrann Mathieu and Patriots tight end Rob Gronkowski -- both injuries included anterior cruciate ligament tears -- ESPN Stats & Info examined the trend over the past three seasons.

So far, there have been 11 percent more season-ending knee injuries than there were through Week 15 of last season. And last season's numbers increased from 2011.

Through Week 15 of 2011, 82 players had been placed on injured reserve because of knee injuries. In 2012 that number rose to 99. So far this season 110 players have met the same fate, including two prominent Texans -- inside linebacker Brian Cushing and safety Danieal Manning.

Week 15 is a good measuring stick. The later you get in the season, the less it takes for someone to be placed on IR.

Defensive players warned that the emphasis on not hitting players high would lead to more serious leg injuries. Without taking a more detailed look at exactly how these injuries were sustained, it's hard to know if that's the case.

Of course, Manning's and Cushing's injuries weren't the result of new rules for defensive players. Cushing suffered his broken fibula and torn LCL when Jamaal Charles blocked him low and went into his knee. The two shared Twitter messages which showed there were no hard feelings between the two. Manning severely hyperextended his knee against the Rams the week prior.