Over the course of less than 24 hours, the NFL saw three of its players go down with Achilles tendon tears, the third such injury belonging to Indianapolis Colts linebacker Robert Mathis. ProFootballTalk's Mike Florio reported the tear Monday afternoon.
Kansas City Chiefs linebacker Derrick Johnson and defensive tackle Mike DeVito also went down with tears on Sunday, according to Dave Skretta of The Associated Press (h/t The Topeka Capital-Journal).
All three players will miss the rest of the 2014 season, but the trio also highlights a troubling trend from recent seasons: a rate of Achilles tendon injuries that seems to be increasing quite rapidly.
Or is it? Let's take a closer look.
The Achilles tendon—the strongest tendon in the body—connects the calf muscles to the foot. When the calf contracts, it pulls on the Achilles, which in turn pulls on the back of the heel.
The end result of this process? Plantarflexion—or pointing of the toes.
In football, the Achilles and calf help a player push his toes into the ground in order to drive forward or leap upward. The stronger the calf, the stronger the drive or higher the jump.
Achilles tendons tear when the load an athlete places on it—either via very strong calf muscles, an outside force or both—exceeds the amount it can withstand. Injury mechanisms include:
- Stepping backward onto the toes in order to push off the ground to suddenly start forward
- Pushing forward into opposing players by standing on the toes and driving the heel to the ground
- Stopping suddenly on the toes in an attempt to quickly change directions
Whenever the Achilles lengthens too much too sharply, it can rupture. Pre-existing tendinitis—or tendon inflammation—can weaken the tissue and predispose to a tear.
Achilles tendons do not carry robust blood supplies. As such, they do not heal well on their own. Additionally, the proximal portion of the tendon—the torn half closer to the calf and leg rather than the heel—can retract upward after the injury occurs.
While non-operative treatment is possible, the evidence suggests it leads to a higher re-injury rate, probably as a result of one or more of the above factors.
According to a 2014 meta-analysis—a study of multiple studies—by A. Amendola in the Clinical Journal of Sports Medicine, conservatively managed tears re-rupture at a rate of 8.8 percent compared to 3.6 percent following surgery. With that in mind, most elite athletes elect to go under the knife to reattach the tendon.
During the operation, a surgeon exposes and identifies the two ends of the Achilles and sutures them together under a precise amount of tension. Too little tension leads to relative calf weakness, as the loose tendon cannot transmit the force of the calf muscles to the heel as efficiently. On the other hand, a tight repair may lead to decreased range of motion.
Recovery times usually approach or exceed six months. The athlete must slowly and gradually increase the stress he or she places on the healing tendon. After all, it carries a large burden of function and must meet very large physical demands.
The Rate of Tears
Over the past few seasons, Achilles tendon ruptures showed up on NFL news feeds seemingly much more frequently than years past. As The New York Times' Judy Battista noted in 2011, training camps following the lockout saw a particularly large number of tears. Specifically, 10 players went down in less than two weeks.
ESPN's John Clayton noted last month that 10 tears already occurred in 2014 as of Aug. 10. Week 1's developments add three more, bringing the total to at least 13.
According to a Dec. 2011 article in Discovery News, these numbers differ tremendously—and in the wrong direction—from previous estimates of four to 10 per regular season and one to three per preseason. The article attained these figures via Timothy Hewett—director of sports medicine research at Ohio State University Medical Center—and colleagues' manuscript in the Journal of Orthopaedic and Sports Physical Therapy.
That said, Dr. Elliott Hershman—chairman of the NFL's Injury and Safety Committee—pointed out to Battista that teams carry more players on preseason rosters than ever before. As such, more players have opportunities to suffer the injury.
Furthermore, definitively proving a bona fide trend of an already-rare event is extremely difficult. Individual spikes in injuries may represent nothing more than the luck of the draw, even over the course of a few different seasons.
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.