The snatches of thoughts that flashed through his mind in a moment of crisis were like a brutal cinematic scene. A little over a year ago, Laurent Koscielny lay on the pitch at Atlético Madrid’s Wanda Metropolitano one hand balled into a tight fist thumping the ground in unbearable frustration, the other clasped to his ankle.

His mind whirred back to a conversation with Francis Coquelin, who had just been through a rupture in the place where he felt overwhelming pain. “Like a knife cutting your achilles.” That was the feeling. “The pain, from one to 10, it’s an 11.” There had been no impact. His body just gave way all by itself.

Arsenal’s medical team rushed over and Koscielny’s wails gave away the seriousness of the injury. “He wasn’t screaming in pain, it was a worse cry – of fear, of anxiety, of anguish,” the club doctor, Gary O’Driscoll remembers. Koscielny was shouting that Diego Costa had kicked him. The Atlético striker came over and tapped the medic on the shoulder. He told the doctor he did not kick him. He had heard a snap.

Later, while being attended to in the dressing room, Koscielny received a visitor from the opposition, Antoine Griezmann, who recognised a serious injury at this particular time could only mean one thing. The compatriots hugged. There were no sufficient words. Koscielny was trying to process a lot. “My game is over. My season is over. My World Cup is over,” he remembers thinking. Then aged 32, with all the years of stretching every sinew for the defensive cause, it would be only natural to feel crushed by the worries about a full recovery.

June, St-Raphaël, Côte d’Azur. After an operation to repair the rupture, Koscielny returned to France for his rehabilitation with a specialist. It’s not unusual for a player with a long-term fitness battle to have a change of scene for this phase. “For me it was not a holiday,” he recalls, discussing the rigour required during Stronger, a detailed documentary made by Arsenal to chart his path back from injury. For 10 weeks he trained with relentless dedication. “When you are fit you have a lot of friends and a lot of people who love you. When you are injured all these people forget you. You miss a lot of things. You miss the love of your teammates, you miss the pitch, you miss all the conversations,” he says.

Koscielny sent a message to the France team that Didier Deschamps gave out to the whole squad. Olivier Giroud, who goes back a long way with his pal from Tours, in Ligue 2, found it especially touching. “He wrote a letter basically to tell us it’s important that we get on well together and act as a team rather than a bunch of individuals. A strong message,” Giroud says.

Laurent Koscielny suffers his achilles injury at Atlético Madrid last May. Photograph: Juan Medina/Reuters

The rebuild is gradual. Walking, climbing steps, jumping, running, hurdling, ball work and sprinting. With every milestone Koscielny sent videos to the Arsenal medical team in London. They were astounded how resilient he was. “What people on the outside don’t see is just how hard it is to keep motivated, to be determined and driven to do really mundane, boring, repetitive exercises, that you can’t see progression from,” O’Driscoll says. “It is hugely frustrating for athletes who have played at the highest level. The way Laurent responded was first class. Every question is: can I do more?”

July, Luzhniki Stadium, Moscow. Koscielny was invited to attend the World Cup final. He went, although he admits he had mixed emotions. In jeans and a white shirt, he felt a step removed from the purity of the joy experienced by the teammates who did it.

December, London Colney. After seven months of diligent rehab, Koscielny was told he was ready to return to the pitch. He played four games in 13 days – an extraordinary gamble. Arsenal were woefully short of defensive players because of injuries and suspensions. Koscielny was not afforded the chance to ease his way back into sharpness. He was rusty, and critics cast quick and unkind judgment. Doubts that he could rediscover his old qualities, that he could regain the standards that made him such an important defender with his club, were rife.

April, Emirates Stadium. All doubts were obliterated. This time the spell was three games in nine days and Koscielny was outstanding. Leading the defence who built a string of clean sheets in vital games against Manchester United, Rennes and then Napoli in the Europa League, his wholehearted efforts on the pitch summed up the resilience he showed for months to return to his best levels. Alexandre Lacazette speaks for the whole team when he outlines his admiration. “He worked all summer to come back as quickly as possible and when he came back he played four games in a row after a big injury. That is really hard. He has helped us all season to be better in defence. We all have big respect for Laurent.”

Laurent Koscielny prepares to board the flight taking Arsenal to Baku for the Europa League final. Photograph: Stuart MacFarlane/Arsenal FC via Getty Images

May, Europa League final, Baku. When he leads out Arsenal on Wednesday it will be a moment of personal vindication. Walking with a limping gait, 34 in September and a player who has spent almost a decade at the club since signing for £8m, who worked his way from being a substitute in the French second division to an international, was never someone likely to give up easily. He never believed injury would signal the end of his career. “You are a better person. You are a better man. When you come back you are so hungry. I don’t agree with people who say you are not as strong as before. I think you are more mentally strong than people who didn’t have an injury like you had. To play again is the best trophy I could have.” Now, another important one is 90 minutes away.