Why are so many top football stars suffering ACL knee injuries?

Doctor says women are at much greater risk of being sidelined by the injury

When Arsenal football club announced new signing Jurrien Timber faced a lengthy spell on the sidelines due to a serious knee injury sustained on his Premier League debut, sports fans questioned why so many top professionals have been struck down with the same injury in recent weeks.

The Dutch defender, who signed for the North London club only last month, faces lengthy rehabilitation and a similar recovery programme to Real Madrid stars Thibaut Courtois and Eder Militao, who also damaged their anterior cruciate knee ligaments (ACL) during pre-season training.

And they are not the only ones.

Christopher Nkunku, one of Chelsea’s many star summer signings, has a similar injury, while teammate Wesley Fofana had surgery on his ACL last month.

Aston Villa defender Tyrone Mings was another who crumpled to the floor on the opening day of the Premier League season after sustaining a serious ACL injury.

The Women’s World Cup in Australia and New Zealand, which draws to a close on Sunday, has been without 30 top players because of ACL tears, including England stars Leah Williamson and Beth Mead.

This year’s Rugby World Cup will be without one of its biggest stars – France fly-half Romain Ntamack – who has been ruled out with a ruptured ACL.

This may seem like a mini-pandemic in the world of top-level sport, but experts say there is little evidence to suggest the injury is becoming more common.

“The incidence of these type of injuries has not changed, but we may see them more commonly because more people are active and involved in collision-type sports,” said Dr Erik Hohmann, an orthopaedic surgeon who has worked with Australian professional rugby teams and FC Bayern Munich.

“Football is big and the injury has a high incidence but the absolute number of ACL injuries per hours played has not changed.”

The ACL in the knee connects the shin bone to the thigh bone and is vital for pivoting, jumping and landing.

Women more at risk

While a series of high-profile ACL injuries may be a freak occurrence this summer, studies have shown the injury is becoming more common in young people, while women are also more susceptible.

Research by the University of Minnesota Medical School showed ACL tears in people aged six-18 have increased by 2.3 per cent a year over the past two decades.

Data showed girls reported higher rates of ACL tears, peaking at age 16 with 392 injuries per 100,000 people per year.

In the male population, ACL injuries peaked at age 17, with 422 injuries per 100,000.

There are on average 200,000 reported ACL tears per year in the US.

“Females in general are more vulnerable, maybe as much as eight times, due to a couple of factors,” said Dr Hohmann, who now works at Burjeel Hospital for Advanced Surgery in Dubai.

“Men have more testosterone and women have more oestrogen that makes the tissue more elastic and [leads to] a higher risk of injury.

“If we look at the hormonal cycle of women, as soon as there is a high oestrogen push and they are ovulating, they are at more risk of an ACL injury.

“When they perform jumping sports like handball or basketball, women have different landing patterns.

“They are landing with knock-knees so are extending their knees more and they are not bending as much [as men].

“These are risk factors, whereas men are more bow-legged and bend their knees more, with more muscle strength per square cm, so it is a hormonal, anatomical and biomechanical problem.”

While that could explain the high number of injuries at the Women’s World Cup, there are still questions over the recent spate of injuries in men’s football.

When a player has to undergo surgery to repair a damaged ACL, doctors will often look at several options.

Repairs can be made with tendons extracted from the hamstring or patella or even with a synthetic alternative.

Each option has different properties and recovery times, said Dr Hohmann.

“The patella tendon is generally stiffer and heals faster, which is why we take this option with professional athletes,” he said.

“In recreational athletes, we tend to use hamstrings and recovery is slow.”

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