UPDATE: Adam Caplan of the NFL Network reports that the Vikings are expecting an 8-week recovery time

This is fantastic news, and will not only allow the Vikings to better assess the running back situation as soon as possible, but likely means the injury isn’t serious in the context of affecting his movement and long-term ability to play. Original story below, including the speculation that proved to be ultimately incorrect about McKinnon’s recovery time.


The Minnesota Vikings have announced through their Twitter accounts that running back Jerick McKinnon will be placed on season-ending injured reserve. He was listed as out for the last two games with a lower back injury sustained during weightlifting. They have decided to promote defensive end Justin Trattou to take his place, and signed former Baylor Bears (and former Chicago Bear, for a brief time) safety Ahmad Dixon to the practice squad (as a “defensive back,” but likely safety). The Vikings had Ahmad Dixon on their practice squad earlier.

Twitter user @Kurmudge, who has a medical background, has made an educated guess on the nature of Jerick McKinnon’s injury, arguing that there’s a good chance it was a slipped disc or disc tear in the back while weightlifting.

For a graphic (it’s a non-graphic graphic) and brief description of the injury, click here. It sounds bad, but this describes the worst case scenario:

Like most other injuries, the body will attempt to heal the annular tear by filling in the gap with scar tissue. depending on the amount of degeneration within the disc, anecdotally, healing times can be 18 months or even more. New blood vessels will grow from the periphery of the disc down toward the nucleus through the annular tear (it is these blood vessels in part that supplied the building blocks needed for the scar tissue to form). Unfortunately, pain-carrying new nerve fiber acompany the blood vessels down into the center of the disc! This is not a good thing, because now has a higher capacity to generate pain because it has more pain-carrying nerve fiber within it. This phenomenon, as well as a similar phenomenon which may occur vertebral endplate, is most likely the reason why patients with annular tears often suffer bouts of pain throughout their lives.

Still, there’s a lot of different things that can happen here, and it may be the case that there is no disc injury at all. Even if there was one, surgery and other options can reduce the recovery time, especially if we’re not dealing with the worst case scenario.

Regardless, it’s a really depressing addition to a season full of depressing injury news. McKinnon had shown tremendous promise this season, and the Vikings will have to really determine what they’re going to do with the running back situation—a sticky situation now made stickier by the uncertainty of McKinnon’s condition. Move running back up the needs board, even if the Vikings entertain the idea of keeping Peterson on the roster.

For now, the Vikings will split carries between Matt Asiata, Joe Banyard and Ben Tate. Who will receive the majority share of the carries remains to be seen—though Tate and Banyard show much more physical upside than Asiata, who at the moment displays better vision. Banyard was pulled from last week’s game after missing a pass-rushing assignment and Ben Tate had a very mixed performance in his stead.