Best-Case, Worst-Case Injury Scenarios for Julius Thomas' Ankle Sprain

The Denver Broncos' trip to St. Louis went from bad to worse on Sunday when tight end Julius Thomas went down with an ankle injury, a sprain that could seriously change the face of Peyton Manning's dynamic offense.

According to The Denver Post's Mike Klis, ankle X-rays came back negative, implying Thomas did not suffer a fracture. A source of NFL Network's Ian Rapoport called it a sprain, and information relayed by ESPN's Adam Schefter provided reassurance against a high-ankle injury.

What's next for the Broncos' star tight end? Let's play best-case/worst-case to find out.

Brief anatomy review

Before prognosticating, let's make sure we are on the same page.

Low-ankle sprains often occur when a player "rolls" his ankle. The movement can over-stretch or tear one or more ligaments that connect the bottom of the fibula—a long bone in the lower leg that runs alongside the tibia, or shin bone—to the bones of the heel.

A complete ligament tear can lead to significant ankle instability and a several-week recovery. In some cases, such an injury can require surgery. On the other hand, a slight over-stretch may lead to no missed time whatsoever.

A high-ankle sprain injures the ligaments that connect the tibia and fibula to each other. They frequently stem from a tackle or hit that forces a player's foot to sharply rotate outward relative to his leg.

Like low-ankle sprains, high-ankles can range from quite mild to very severe. However, in general, they heal more slowly than their low-ankle counterparts, and a tear that causes the tibia and fibula to separate necessitates surgery.

Best-case scenario: Low-grade low-ankle sprain (day-to-day)

Minor low-ankle sprains can cause pain when a player pushes off his foot and cuts, but low-grade injuries can still leave the joint fully functional.

Furthermore, athletic trainers can apply supportive taping either inside or outside of a player's shoe, providing both physical and mental support for the injury.

Thomas, who makes his living as one of the best receiving tight ends in the game, relies on his agility and ability to cut away from defenders. A sprain will limit him from doing so somewhat, but if his injury falls on the very mild end of the severity spectrum, he can still play well.

Worst-case scenario: High-grade or recurring low-ankle sprain (out several weeks)

Thankfully, Thomas' negative X-rays rule out an ankle fracture—one that, if unstable, would need surgery and end his season. However, a Grade-2 or Grade-3 low-ankle sprain—a partial or complete ligament tear, respectively—can leave the ankle joint quite loose, not to mention cause significant pain, swelling and range-of-motion limitations.

Furthermore, playing on a moderate or severe sprain can dramatically increase the risk of further injury. As such, Thomas could need a few to several weeks to allow his injured ligament to scar down and complete his rehab, depending on the extent of the injury.

Ankle sprain setbacks can also occur at any time. One misstep could take a player who is fighting through an injury out for another week or two.

Additionally, though Schefter's source suggests concern for a high-ankle sprain is low for Thomas, a surprising Monday MRI finding is not impossible. A moderate high-ankle sprain could lead to an absence of a month or more.

Dr. Dave Siebert is a second-year resident physician at the University of Washington and a member of the Professional Football Writers of America. He plans to pursue fellowship training in Primary Care (non-operative) Sports Medicine.

Follow @DaveMSiebert