AP

The Bears’ reluctance to offer a lucrative long-term contract to Matt Forte stems in part from concerns that his knees won’t allow him to remain an upper-echelon NFL running back for much longer.

The wear and tear Forte took during a college career at Tulane in which he had nearly 1,000 touches was a concern entering the 2008 NFL draft, and a source told David Haugh of the Chicago Tribune that with more than 1,200 touches under his belt in the NFL, the Bears wonder how long Forte’s knees will hold up.

Forte’s knee injuries include a torn posterior cruciate ligament in his left knee in 2006, a sprained medial collateral ligament in his left knee in 2009 and a sprained medial collateral ligament in his right knee in 2011. The Bears may be concerned about the possibility of arthritis becoming a problem for Forte.

Although he’s only 26 years old and was having a great season when he got injured in the 12th game last year, the Bears have shown very little interest in signing Forte to anything other than the one-year franchise tender. The reality for NFL running backs is that teams toss them aside once they’re used up, and the Bears may think Forte’s knees are close to used up.