Breaking Down Dee Milliner's Achilles Tendon Tear, Mechanism of Injury

New York Jets cornerback Dee Milliner's injury-plagued 2014 NFL season likely came to a close on Sunday due to an Achilles tendon tear.

Milliner went down early on Sunday during a Denver Broncos field-goal attempt, and New York Daily News' Seth Walder later tweeted the Jets ruled him out for the game. NFL Network's Ian Rapoport, citing a source, later added the team believes the cornerback tore his Achilles.

Unfortunately, those watching the game could predict such an outcome, as Milliner's mechanism of injury mirrored that of many other Achilles tears in weeks and seasons prior.

The Anatomy

The Achilles tendon connects the bulky calf muscles to the back of the heel. When the muscles contract, they pull up on the Achilles tendon, which, in turn, pulls on the heel.

The end result? Plantarflexion—or pointing of the toes. Dorsiflexion, on the other hand, describes the opposite motion of pulling the toes upward toward the body.

Strong plantarflexion allows a player to drive his toes in order to push forward or leap up off the ground.

The Play

Tendon injuries often occur in the NFL as a result of something suddenly counteracting the action of a contracting muscle. For example, when a hit bends a player's elbow while he attempts to straighten it—while pushing off an opponent, for example—the triceps tendon can tear. Veteran Chicago Bears defender Charles Tillman's season ended in such a manner earlier this year.

In the case of Achilles tendon tears, sudden and forced dorsiflexion (toes up) while a player plantarflexes (toes down) is often to blame—as it was for Milliner.

The above video shows Milliner drive his right heel to the ground just as he tries to push forward out of a three-point stance. Driving his heel down provided dorsiflexion, and contracting his calf to push forward provided plantarflexion. The opposing forces proved too much for the cornerback's Achilles tendon to withstand, leading to the tear.

Screenshot from above NFL.com video with edits by the author.

A close look at Milliner's gait following the injury also suggested an Achilles tear. Over his next two steps, he plants his right foot on the ground entirely flat and does not drive forward with his toes. After all, without an intact Achilles, he probably physically couldn't withstand any significant amount of strength.

The Recovery

NFL players usually go under the knife following an Achilles rupture. Surgical intervention offers a lower chance of re-injury. However, it usually carries with it a recovery time to the tune of six months or more.

While a serious injury in any light, players return very well from Achilles tendon tears much more frequently nowadays than in the past. Physical therapists can carve out individualized exercise regimens to slowly work the tendon back into shape, and while setbacks or re-injuries are always possible, nothing yet suggests Milliner can't return to full speed before next season.

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