BOULDER, Colo. — One year ago this week, Tim Don was on a final training ride in preparation for the Ironman World Championship in Kona, Hawaii, when a truck turned in front of his bike. The impact of the collision not only destroyed Don’s ability to compete in an event he was favored to win, it nearly cost him his life

The British three-time Olympian was in the best shape of his life. He had won five of the six races he had competed in that year and crushed the world Ironman record by four minutes in Florianopolis, Brazil, finishing in 7 hours 40 minutes 23 seconds. At 39, he was poised to reach the pinnacle of his career with a win in Hawaii that would provide financial security for him, his wife and their two young children.

Instead, Don was suddenly facing the prospect that he might never be able to walk again, let alone compete as a world-class triathlete. The crash on Oct. 11, 2017, broke Don’s C2 vertebra — an injury known as a “hangman’s fracture.” Within days, he would face a stark choice — fuse the spine or wear a halo, a medieval-looking iron ring bolted into his skull. The first was less painful. The second gave him a chance of competing again. Don chose the halo.

His determined and at times agonizing recovery — chronicled in the documentary “The Man With the Halo”culminates Saturday when Don is slated to compete in the 2018 Ironman World Championship in Kona a year after his accident.

Don compared his missed opportunity of a year ago to a test. “When you study for an exam and you fail it, fair enough,” he says. “But what if they tell you, ‘I’m sorry, you aren’t coming in to take it. You failed it’?”

Don has trained his way back for that test. While he says he doesn’t expect to win this time, he’s happy to be back to close that circle and start anew.

“I’m not superhuman by any stretch of the imagination,” he says. “I’m literally just trying to do something I love.”

Choosing the halo

When Don reached Kona’s remote emergency room by ambulance last October, agent and friend Franko Vatterott was there to meet him. Vatterott recalls a lot of worrying and waiting for scans to be interpreted by a specialist in Honolulu. This only exacerbated Don’s anxiety as fear of the unknown consumed him.

“His chest was going up and down, rising like a loaf of bread due to panic,” Vatterott said. The nurses told him if he didn’t calm Don down he could further injure his neck. So Vatterott did what he had done with his own children: He put his hand on Don’s chest to calm him but looked away. “Every time we’d look at each other, we’d both start tearing up.”

The Kona doctors feared the worst. Depending on the angle of the C2 fracture, the spinal cord could be injured, resulting in paralysis or death.

Waiting to hear whether you will ever walk again, let alone live, is one thing, but to wait without pain medication is agony. But neither Don nor Vatterott wanted to take any chances. If there was a possibility Don could recover and still race, his system couldn’t be laced with drugs. “I actually declined the morphine for Tim at the hospital originally, but after a couple hours, he couldn’t take it anymore and ended up taking some via a drip,” Vatterott said.

It’s no surprise, despite his mental state, that Don was concerned about the drugs. In 2006, he served a three-month ban after missing three out-of-competition drug tests (a mistake he said was due to forgetfulness and a lack of understanding of a new reporting system).

Fortunately Don’s spinal cord wasn’t damaged, but he did have a broken neck.

On Friday the 13th, Don was transported to a hospital in Boulder, where he lives. He was given two choices: a fusion of vertebrae above and below the fracture or the installation of the halo — not the light and glowing halo you imagine earning after dying but a carbon brace that immobilizes the spine and neck for three months so the break can heal.

Neurosurgeon Alan Villavicencio, an ultra-endurance athlete, recommended the halo if Don wanted to race as an elite athlete again. If he opted for the fusion, he not only would have significantly decreased range of motion in his neck but in 10 to 15 years might need another fusion.

That Friday, the halo was bolted onto Don’s head. It was attached to four stabilizing rods via titanium screws — two in the front, two in the back — that penetrated at least a centimeter into his skull. Doctors attached the device by hand using a torque wrench. To dull the pain Don was given a local anesthetic.

The halo was attached to a solid plastic brace, lined with itchy fake sheepskin, that limited almost all torso movement. On the front of the brace was a warning label explaining how, if Don went into cardiac arrest, the brace must be removed with an Allen key he carried with him at all times.

Two days after the halo installation, the hospital morphine had worked its way out of Don’s system. By Sunday night, the pain from the screws became excruciating, prompting Don to request another pain prescription.

To say the medicine didn’t settle well is an understatement. “When you throw up, you go like this with your neck,” Don said, mimicking the motion. The restrictive nature of the halo made these spasms unbearable. He had reached a point of desperation that sent him to the garage in search of tools to remove the halo. His wife stopped him.

While that Sunday night seemed like the longest night of his life, he began practicing the survival technique that would get him through the next three months: set small achievable goals and move forward. Minute by minute, he counted down before he could take another pain pill.

Don later learned only about five individuals a year in the Denver area have a halo attached, and at least two of those have it removed because they can’t stand the pain.

It’s no surprise that he lasted the full three months; Don comes from a family of high achievers. His father was an acclaimed international soccer referee, his sister went to Oxford, and his wife, Kelly Caffel, was a professional runner.

“I’ve always said if you want an apple off the tree, just take it. I’m very practical,” Don said. However, the scaffolding was anything but practical. For three months Don couldn’t sleep lying down, shower or drive. He couldn’t take his 3-year-old son, Hugo, for a bike ride. “You’ve got to crack on with your life. I couldn’t let them down,” he said.

Hugo and Don’s 8-year-old daughter, Matilda, had an amazing capacity for looking beyond the halo or at least seeing it as needing decoration in the case of Christmas dinner. “Everyone was sitting at dinner with cracker hats on their heads, and I sat there with flashing bloody fairy lights on my halo,” Don recalled, smiling.

Don prevailed thanks in part to his support system. Every other night, from the night of the accident until Christmas, friends in Boulder delivered a meal to them. His kids’ school sent out newsletters advertising a custom-made bike racing kit whose profits went to defray Don’s medical bills (barely touched by the truck driver’s insurance payment of $10,000).

Speaking about his greatest source of strength, his wife, brings Don to tears. “Kelly doesn’t like the word ‘carer.’ But when I was there crying, ‘I can’t freakin’ take this anymore,’ she encouraged me before walking out of the room just as upset as me.”

As a former elite track runner, Kelly understood what it meant for Don not to have achieved what he wanted after everyone had sacrificed so much. “The halo just became part of our daily routine,” she said. This involved cleaning the open crusty screw wounds to prevent infection, bathing her husband and driving him to get the screws tightened.

Because of the training regimen, Don had begun while wearing the halo, the screws had to be retightened three times because they kept jiggling loose. This wasn’t a simple operation; tightening one screw affected all of them.

Don simply would call up Brian Koster, a clinician for Hanger Clinic, and tell him his screws were loose — no appointment, no medicine to dull the pain. “I’d just sit there and look out at the Boulder Flatirons as I felt it grinding into my skull,” Don said.

When it got close to the correct torque, there was a click so it couldn’t be overtightened. Don felt that click vibrate in his head. At one point a screw was so loose that Koster could move it with his fingers. On a fourth visit, a fifth screw was installed because tightening the original screw might have pierced his brain.

“You don’t reach a goal by a straight line,” Don said, making a series of circular movements with his fingers.

Pain is relative

Only a couple of weeks after having the halo installed, Don was riding his bike for 20 minutes on a trainer, strengthening his legs in the gym or going for an hour walk. But recovering wasn’t just a matter of regaining strength. It meant retraining muscle memory and breaking up scar tissue around his neck — something he describes as so painful that he passed out during one massage. He still has considerably less range of motion on one side of his neck and a tight left hip.

A little over two months after the halo was removed (and five months after the accident), Don achieved his first big goal by running the Boston Marathon, despite a cold, pouring rain, in a remarkable 2:49:12 — almost a minute faster than his target.

Athletes who compete in elite Ironman competitions — they must swim 2.4 miles, complete a 112-mile bike ride and run the equivalent of a marathon (26.2 miles) — are among the fittest in the world. Up until the accident, 80 percent of Don’s income came from wins and bonuses. Not racing meant he would have to rely on the 20 percent supplied by sponsors. Notably, none of Don’s sponsors dropped him after the accident. In fact, many stepped up their offers. The Swiss running and apparel company On went beyond re-signing Don’s contract; it made the documentary detailing Don’s recovery.

“One of the key ingredients we look for when recruiting athletes is that they are eternal optimists,” On co-founder David Allemann said. On enlisted Emmy-winning director Andrew Hinton to write and film “The Man With the Halo.”

With the documentary screened all over the world, Don is now known just as much for his halo as for his athletic accomplishments.

On June 24, Don took another big step forward when he won the Costa Rica 70.3 (a half-Ironman). On July 29, he faced a bigger test: Ironman Hamburg, his first Ironman since his accident. His ninth-place finish was enough to earn him a spot on the starting line at Kona.

Despite the adversity, Don said he still believes, “The harder you train, the luckier you get.”

Yet, Don said, if he had the choice to do it over again, he would choose the spinal fusion over the halo. “When someone tells you it’s going to be painful, you have no idea how painful because pain is relative,” he said.

But it is less his personal physical pain and more the painful emotional impact of the halo on so many friends and relatives that makes him now question his choice.

“Don’t be afraid to lean on people because someday they’ll need to lean on you,” Don said. “And you can always draw energy from different places.”

On Saturday, Don will find himself in a very different place compared with last Oct. 13, still with something to prove, lining up with the best triathletes in the world — where he belongs.

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