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 his knee inward, thereby causing the MCL sprain. In football, simultaneous high-ankle and MCL injuries are not uncommon.
Isolated MCL injuries in the knee usually do not require surgery. Rather, relative rest, icing and physical therapy adequately treat most.
Carr's Best-Case Scenario: Low-grade Sprains, Stable Tibia and Fibula
Smith reported after the game that X-rays on Carr's ankle came back negative. In other words, the quarterback did not suffer a fracture.
The Raiders medical staff may have also performed "stress" X-rays. For a stress X-ray, Carr would turn his toes outward as if to recreate the high-ankle sprain mechanism. If the image showed separation of his tibia and fibula due to this movement, a more serious injury becomes more likely.
Whether or not a report of negative ankle X-rays in the NFL media implies only the absence of a fracture or both the absence of a fracture as well as a stable tibia and fibula is not clear.
According to Vic Tafur of The San Francisco Chronicle, Carr himself is optimistic he will return to action following the Raiders' Week 5 bye:
Carr's timeframe will probably turn out to be a bit optimistic, but if the rookie's sprains are of the low-grade variety, it's not out of the realm of possibility—assuming an MRI shows no surprise injuries in his ankle or knee, that is.
Carr's Worst-Case Scenario: Medium-Grade Sprains or Recurrent High-Ankle Injuries
Nevertheless, high-ankle sprains generally require a longer recovery time than their low-ankle counterparts. As such, a multi-week absence for Carr is not hard to envision despite his optimism. Furthermore, the slow healing time allows for plenty of opportunity for setbacks, and many high-ankle sprains need a full four to six weeks of rest and rehab.
A Grade-2 MCL sprain could also sideline the Raiders signal-caller for up to a month. A Grade-3 MCL injury—a complete tear—seems unlikely based on the injury mechanism, but surprise MRI findings are, regrettably, not uncommon. A complete MCL tear could take Carr out for up to three months.
Further tests will paint a clearer picture.
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.