Best-Case, Worst-Case Injury Scenarios for Derek Carr’s High-Ankle, MCL Sprains

Nothing went right for the Oakland Raiders on Sunday, and quarterback Derek Carr's ankle and knee injuries added insult to injury—or injury to insult, as the case may be.

Midway through his team's 38-14 loss, Carr went down awkwardly. Those watching saw him hobble off the field in obvious pain, favoring his left leg. CSN Bay Area's Fallon Smith later tweeted that the quarterback himself said he suffered a high-ankle sprain and a medial collateral ligament (MCL) sprain.

What's next for the struggling Raiders? To help answer that question, let's look at the best- and worst-case scenarios for their young quarterback and his injury combination, starting first with an overview of the sprains themselves.


High-Ankle Sprain Overview

High-ankle sprains involve the ligaments that connect the bones of the lower leg—the tibia and fibula—to each other. They prevent the bones from rotating around each other.

A common high-ankle sprain mechanism of injury involves the foot sharply turning outward relative to the leg. Indeed, replay during the game showed Carr fall over his planted left foot with his knee moving to the inside, forcing his toes out.

Severe high-ankle sprains can cause the tibia and fibula to separate and require surgery to fix them in place while the ligaments heal. Some cases also come with an ankle fracture.


MCL Sprain Overview

The MCL connects the tibia to the femur—the thigh bone. It primarily prevents the knee from buckling inward, but when forced inward motion of the knee over-stretches the ligament, it can tear—a sprain. Grade-1 sprains are minor over-stretches, while Grade-2 and Grade-3 injuries are partial and complete ligament tears, respectively.

When Carr went down, not only did his toes sharply turn outward, he fell with most of his weight pushing hi...

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