Revealed: The tiny ball bearings that could mitigate football’s growing ACL problem

Pablo Gavi of Spain reacts after injury during the UEFA EURO 2024 European qualifier match between Spain and Georgia at Jose Zorrilla on November 19, 2023 in Valladolid, Spain

One of them is in his thirties, with the majority of a glorious career behind him. The other is only 19, with so much more to come. Two players at different points of their lives, with different hopes and ambitions, but both have been struck down by the same dreaded diagnosis: a torn anterior cruciate ligament (ACL).

For Neymar and Gavi, there can be no telling whether life will ever be quite the same once they have recovered. Both are at the start of a long road, with Neymar undergoing surgery earlier this month and Gavi, the outrageously talented Spain midfielder, set to do the same in the coming days.

It is an injury that is perhaps feared above all others in football, and Neymar and Gavi are far from the only elite stars who have felt that pain this season. In the Premier League, Aston Villa’s Emi Buendia and Tyrone Mings, Arsenal’s Jurrien Timber and Chelsea’s Wesley Fofana have all suffered the same setback in recent months.

Across Europe, there are many others. And within the women’s game, where research shows female athletes are up to six times more likely to suffer a non-contact ACL injury than their male counterparts, the number of serious knee injuries is a source of constant anguish and angst.

There is currently no obvious solution to the problem. But that does not mean a solution will never be found and, up in Scotland, there is a potential glimmer of hope – which comes in the shape of a tiny ball bearing.

The idea belongs to Knox Chate, an independent product developer based in Edinburgh. Chate’s background is in trainer design, rather than football boots, but for the past four years he has been working on a product which he believes could reduce the risk of serious injuries, including ACLs, in a variety of sports.

Chate’s design is known as the “anti-grip stud”, and it is effectively a stud which has a ball bearing on the end – much like a ballpoint pen but bigger. The purpose is to reduce “rotational traction”, allowing for smoother changes of direction and lowering the risk of studs becoming caught in the turf, which is a major cause of serious injury.

Studies have found that a high level of rotational traction is associated with a significant increase in the risk of lower limb injuries, especially ACLs. Chate’s goal has been to lower that traction without compromising the fundamental purpose of the stud.

Clearly, if all of the studs on the sole of your boot had ball bearings on them, you would slide across the pitch. Chate’s recommendation, therefore, is that only three anti-grip studs are used at once – in the areas of the foot that have the most pressure going through them when an athlete changes direction (one at the base of the big toe, and then two at the heel).

“You still need traction,” Chate tells Telegraph Sport. “You just don’t need too much of it, because that is how you get stuck and injured. You need the right amount.

“It is not a cure [for serious injuries]. But it is like a seatbelt. It does not mean you can’t have an accident, but it reduces the risk. That is the objective.”

Knox Chate
Knox Chate says his studs would be like a seatbelt in reducing the risk of ACL injuries

At this early stage, the stud has been designed primarily for artificial surfaces. But Chate has no doubt that it would function effectively on the “hybrid” pitches used by many clubs in the professional game. On soft and squelchy grass it would be ineffective in its current form but, if a surface is firm, the ball in the stud will hopefully glide (especially if greased).

Now for the inevitable caveat: these are early days indeed, and much more examination of the technology is required. There is a long way to go before elite athletes can start screwing anti-grip studs into the soles of their boots.

The preliminary research, though, is promising. The studs were examined in a study by the physiology research group at the University of Stirling, in which a collection of amateur male rugby players were put through tests involving acceleration, slaloming and sprinting.

The results showed that, when wearing the anti-grip stud, the participants experienced a slight drop-off in straight-line acceleration speed. But they then made up for that lost time when they were slaloming between cones, suggesting that the anti-grip stud could be assisting them when changing direction at speed.

As the stud is designed to help athletes change direction more smoothly, it was seen as an encouraging result. At the very least, it proved that the studs had a material impact on the movement of a player.

Neymar waves his arm in pain after injuring his ACL playing for Brazil against Uruguay in October

It was not the university’s goal to look directly at whether the studs reduce injury risk. Such precise research would take years to complete.

“What we decided to do was to look at whether we could identify known mechanics of injury, specifically within football and rugby, and see if we can manipulate those by inclusion of this stud,” says Dr Lewis Macgregor, a lecturer in physiology at the University of Stirling.

It is too early to say for certain whether the studs do indeed manipulate those mechanics but Dr Macgregor’s view, based on his preliminary research, is that they merit closer examination. “From a purely scientific interest point of view, I think it is worth looking further at this,” he tells Telegraph Sport.

Working for his brand, Troup-O-One, Chate’s initial plan is to create a boot that is specifically designed for women. He adds that the door is open for his invention (which is patented) to be licensed for use by larger sportswear manufacturing companies.

For football as a whole, it is clear that something needs to change. Data from Premier Injuries shows that there have been 196 injuries since the start of this Premier League season – an increase of 15 per cent when compared to the past four campaigns.

No stud or boot could ever fully prevent serious injuries, of course, and there is not yet enough definitive evidence to say that these anti-grip studs will definitely have an impact. But if they could indeed make a difference – even just a small difference – then those injured footballers, ruled out of action for months, would surely be the first to say that they are worth a close look.