The patient is lying half naked on the treatment table in a clinic not far from Harley Street watching his feet being pressed together, rotated, tested. His pelvis is checked and he is asked to open his mouth. Finally Jean-Pierre Meersseman, founder of the world-renowned Milan Lab and special advisor to Milan, speaks. "Your pelvis is tilted, one leg is shorter than the other and you have suffered from groin injuries," he says, correctly. He then applies local anaesthetic to an impacted wisdom tooth and suddenly the range of movement in the right leg significantly widens. "Ah, just like Clarence Seedorf!" he exclaims.

"When Seedorf came to see me he had continuous groin pain which had been bugging him for a year and a half," Meersseman says. "He couldn't practise properly and was on a downward spiral. I remember the first day he was at Milan I had his wisdom teeth pulled out. The pain in his groin went away immediately and that helped rebuild his career."

It is an anecdote that short-circuits the senses. It sounds too fantastical to be true. But this is Meersseman's forte: doing the unusual with the unorthodox, combining his specialisms of kinesiology and chiropractic with traditional approaches. Still the question needs to be asked: what would the sceptics make of how he treated Seedorf?

"It's not accepted in evidence-based medicine but I don't give a damn about that," he says, genially but firmly. "I've seen it work. We've done over one million tests at Milan. And our mathematicians and engineers have developed a formula which has a high success rate of predicting and managing injuries."

Meersseman backs up his case by citing the steep decline in days lost to injury after Milan Lab was set up in 2002 thanks to a programme that also helped enabled Paolo Maldini and Alessandro Costacurta to play into their 40s, with Serginho and Cafu not far behind.

"Paolo Maldini was written off at 32 and he played another nine years," Meersseman says. "And I remember when Cafu came in, somebody called me up – I won't say who – and said I know for sure he is gone. He played another four years at a very high level."

And David Beckham? A warm glint appears in Meersseman's eye. "David is one of the most interesting men I have ever met," he says. "When he joined Milan he kept a very low profile. But he was very respectful, always the first to come to the training ground, always the last to leave. He knew everybody by name, including the cleaning ladies. He had a kind word for everyone. You can't help but like the guy.

"He also responded exceptionally well to what we did," he adds. "I was hoping he was coming back to Milan in January but it didn't work out."

Meersseman was given the task of reducing injury rates at Milan after Fernando Redondo, the brilliant Argentina midfielder, suffered an injury that was to end his career shortly after joining from Real Madrid in 2000. The club asked itself: why did we not see that? They started to talk about prevention. And Meersseman starting looking for answers.

"With Redondo we did a complete medical examination when he signed – and I mean complete as it involved 10-12 different specialists, from the tip of his head to his toes," Meersseman says. "He was in perfect condition. And then he was walking on the treadmill and he tore a muscle. I'd never heard of anyone doing that. He never really came back."

So what changed? "Just by using kinesiology we are able to see better what is going on but that was my opinion against someone else's," he says. "That was one of the reasons why I started measuring everything. All the top clubs have cardiologists, knee specialists and so on – but sometimes it's difficult to look at the whole and that's what we are trying to do."

Now Meersseman is seeking a new challenge working with Premier League footballers in London. The sports lawyer and agent Carly Barnes, who is representing Meersseman, says she has been "inundated" with people keen to see him. "Players are now enormous assets and, if they get injured, a club risks an enormous plunge in value," she says. And Jean-Pierre's results are there for everyone to see."

Meersseman is also excited at the new venture. "I'm not stimulated all that much by regular cases," he says. "I like the idea of taking someone who has been written off and trying to fix them."

But what of his role at Milan? Surely given their form over the past 18 months, they need fixing most of all? "They stopped the Milan Lab project three years ago," he sighs. "It's still being applied in the athletics sector but not in the medical sector. And we've had more injuries in the past two years than in the eight years before that put together."

Why? "When things are going very well sometimes you believe you can start to cut things," he says. "For instance I had the players eating carbohydrates within 20 minutes after a game. Being in Italy it would be spaghetti. A cook would come in the locker room. It was a hassle to do but it worked. Then they cut it out. They cut here. They cut there. And all of a sudden it doesn't work. These days I mainly check the players when they come in and go out.

"The last signature when a player signs for Milan is [chief executive Adriano] Galliani's. The one before is mine." And when they leave? "The same but the decision is often based on what the data is telling us."

So how many times has he sold a player only to see him improve elsewhere? Meersseman shakes his head. "I can't think of any. Quite a few have played worse." He is too polite to say whom but Andriy Shevchenko and Kaká leap out.

He is just as diplomatic when he is asked how Milan will fare against Barcelona in the Champions League on Wednesday. "It's always possible because the ball is round," he says with a twinkle. "But it's going to be very difficult. Very difficult indeed."