You can watch Kevin Durant tear up his Achilles tendon in gif form if you want. It’s all over the internet—the Golden State Warriors’ scoring machine bouncing the ball between his legs in an attempt to get past Serge Ibaka of the Toronto Raptors, pushing off his right leg and pivoting on his left, showing Ibaka his back. Then when Durant puts his weight back down after the turn, something’s wrong. He has felt a pop, like getting hit in the back of the leg. Durant limps off the court.
He’d later report on Instagram that, yes, his right Achilles tendon had ruptured, that he had gotten surgery to repair it, and that he wouldn’t be playing basketball for a while.
So what happened? Why would a part of a human body, especially one so perfectly tuned to do what it was doing, suddenly break?
What you probably think of as your calf muscle is actually two muscles working together—the gastrocnemius and the soleus. Those attach at the back of the leg, and when they contract they pull the heel bone up—it’s that action that allows a plantar flexion of the foot, which is walking, running, jumping, and cutting. The Achilles tendon is the thing that connects those muscles to that bone, a whitish, shiny, quarter-inch-thick ribbon of collagen just below the skin. It’s viscoelastic, which means it can store and then release energy, almost like a rubber band. “It’s the explosive push-off,” says Drew Lansdown, an orthopedic surgeon at UC San Francisco Medical Center.
So it’s a hell of a strong tendon. “The Achilles tendon is really well designed to withstand loads many times our body weight,” says Jennifer Zellers, a postdoctoral researcher studying Achilles tendon rupture at Washington University in St. Louis. “If I were to try to pull it with my hand, I’d probably just slip off before I could elongate it. With my upper-body strength, I wouldn’t be able to deform it.”
Yet sometimes it goes pop. Usually it happens without any perceivable symptoms beforehand, but that doesn’t mean nothing’s going on. “Number one is degeneration in the tendon, what we clinically call tendinosis,” says J. Turner Vosseller, an orthopedic surgeon specializing in feet and ankles at Columbia University Medical Center. Tendinosis involves changes at the cellular level that end with a breakdown in the collagen matrix—it happens with tennis elbow and rotator cuff injuries too. One study of otherwise healthy young people found that 16 percent of them had tendinosis symptoms an MRI could pick up—what Vosseller calls “crappy tendons.”
And then? In an "eccentric contraction," the muscle contracts to control the foot, but also lengthens to allow dorsiflexion—pointing the toes upward. (A "concentric contraction" points the foot the other way.) "You can get a tear with either type of contraction, but eccentric puts the most stress on the tendon," Lansdown says. Combine a tendon already in trouble and a bit of bad luck, and you can get a rupture.
No one’s really sure why some people get them and others don’t; couch potatoes are probably less vulnerable, and more active people are probably more susceptible. It used to happen in younger people more often, those in their 30s, but as older people have become more active, Achilles tendon rupture has become common among those in their 40s. Before Title IX brought equality to men’s and women’s sports, way more men used to get ruptures than women. These days the ratio is something like three to one.
The question is, what to do about it—for civilians and for elite athletes like Durant. Surgery used to be the common approach, but in the last decade or so nonsurgical options have gotten better. “The goal of the initial treatment after rupture is just to get those two tendon ends close to each other, so they can scar down toward each other and remodel,” Zellers says. “We immobilize people’s ankles in a position where the two ends are able to come together.”
The tendon isn’t so elastic, it turns out, that after a rupture it retracts like a vacuum cleaner cord. In fact, it’ll pretty much stay in place for days—or rather, if upon examination via MRI the ruptured ends are still within about a centimeter of each other, says Zellers, then that person is a good candidate for nonsurgical treatment. Studies indicating the risk of rerupture is low enough with the nonsurgery option have, as a result, led to an increase in this particular approach over the past decade; now almost half of people with Achilles tendon ruptures never go under the scalpel.
Athletes at Durant’s level, though, tend to get surgery. It’s the most predictable way to shorten the time to return to play with as much strength as possible. The incisions have gotten smaller, which physicians think speeds up healing time. Even the treatment you’d think would be most direct—grab the two ends and suture them together—has some dissidents. “We’ve actually looked at the whole tendon in people with Achilles tendon rupture, and often the whole thing is degenerative, not just focally, in one area,” Vosseller says. He points to a cool study out of Denmark, where researchers embedded tantalum beads that an x-ray could see in the ends of ruptured Achilles tendons during repair. Even though the tendon was stitched back together, the beads still migrated apart. “Even though they had done the repair, there was some kind of creep in the system. It elongated,” he says. So now another surgical approach involves putting sutures up nearer the top of the tendon and attaching them to plastic screws driven into the heel bone.
Recovery after surgery takes a long time for anyone to get back to where they were before this kind of injury. Vosseller’s team compared the stats of professional baseball, basketball, and hockey players before Achilles tendon rupture and then one and two years after with statistically matched, uninjured players, and found that—on paper, at least—even those who returned to their teams didn’t regain their earlier proficiency for two years. And the news isn’t great in the NBA: In a small study of just 18 players over two decades, none regained their earlier skill level, and nearly 40 percent of them didn’t come back at all. “Even there, it depends on position. Recovery’s harder for guards, for example, who have to do more cutting and slashing,” says Marc Safran, an orthopedic surgeon and chief of sports medicine at Stanford.
But all is not lost. Durant's teammate DeMarcus Cousins made a remarkable recovery after his own Achilles tear in 2018, for example. “One of the best indicators of how well someone is going to play after they rupture is how good they were beforehand,” Zellers says. If that’s true, it’s hard to think of a better bet than Kevin Durant.