"We got lucky," said Dr Yacine Zerguini, smiling when he thinks back to the important breakthrough that has facilitated his work as a member of FIFA's Medical Committee. "We were able to determine that the cartilage around the distal extremity of the radius at the wrist fuses in men around the age of 17."

That single discovery, made in 2006, could well have a significant impact on the 16th edition of the FIFA U-17 World Cup, which kicks off in Chile on Saturday.

"We carried out a number of Magnetic Resonance Imaging (MRI) scans on the wrists of players between the ages of 15 and 19," added Dr Zerguini, speaking to *FIFA.com *in the Chilean capital of Santiago. "Next we got people whose birth dates we were sure of and carried out a classification. That confirmed that no one under the age of 17 had fused cartilage."

This scientific advance was the fruit of work carried out by FIFA and the FIFA Medical and Research Centre (F-MARC), which Dr Zerguini, an orthopaedic surgeon from Algeria, has been a member of since 1994. Around the turn of the century, FIFA asked its Medical Committee if it was possible to develop a method to verify player ages.

"At the time there wasn't one," he explained. "But that's one of the roles of F-MARC, one of FIFA's specialist committees: to find techniques in the world of science and medicine to carry out this kind of thing. And that's what happened. Since 2006, we've been able to say whether a player is older than 17."

*Health and equality

*"In all its competitions, FIFA has two priorities when it comes to the Medical Committee," said Dr Zerguini, who was involved in every stage of the project. "Firstly, there's the priority of looking after the health of players. That's the most important thing for us. Secondly, we have to guarantee fairness and equality. In youth competitions, you have to think that people might be tempted to cheat regarding player ages and field players a little older in order to win tournaments."

To ensure that the 504 youngsters gearing up for Chile 2015 are the correct age, FIFA therefore requested that each of the competing teams' member associations carry out MRIs, with FIFA then following up with random tests on four players.

"The new idea was to use MRIs because the other techniques to determine bone age depend on traditional radiology, which emits radiation,"Dr Zerguini explained. "From an ethical point of view, radiographies are not permitted without a medical reason. And, in any case, we wouldn't have done it just to verify the age of a player. But MRIs pose no danger, so we can impose them on teams."

Dr Zerguini is also keen to banish certain preconceptions. "Scientifically, I can tell you there is no link between somebody's appearance and their age," he said. "If you take a basketball player who is 7'3 at the age of 20, he couldn't be 4'11 at 16.

"It's the same for secondary sexual characteristics, such as facial hair; that varies a lot and doesn't mean anything. And there is a lot of variation according to ethnicity as well. That's why we carried out our study in each of the confederations – in Asia, Africa and elsewhere – to be able to say that it works."

For the moment, the test is only applicable to male players at U-17 level. "We applied the same method to girls and we noticed that [cartilage fusion] happens a little sooner with them," says Dr Zerguini, who is also hopeful of developing a procedure for U-20 tournaments. "There are study programmes under way at the moment to do the same thing with U-20 players, but it's still too early to talk about those yet."