When Gabriel Jesus fell to the grass clutching his knee around 30 minutes into Arsenal’s FA Cup tie against Manchester United this month, it looked like the Brazilian’s night was over. But after the Arsenal physio ran onto the pitch and carried out tests on the 27-year-old’s left knee, he was back on his feet and deemed fit to continue.
Around 10 minutes later, after sprinting to reach Bruno Fernandes on the edge of the Arsenal box, Jesus was down again, clearly in distress. This time, the striker was not able to get back on his feet and left the field on a stretcher, with the club later confirming he had suffered an injury to the anterior cruciate ligament (ACL) in his left knee.
A similar incident took place in August 2023, when Arsenal defender Jurrien Timber was treated on the field for a knee injury just before half-time against Nottingham Forest, but surprised many by emerging for the start of the second half. A few minutes after the restart, however, the Dutchman was down again, having pulled up in pain after playing a simple pass.
“The physio and doctors looked at him and were happy to continue,” said Arsenal manager Mikel Arteta in the post-match press conference.
While, clearly, there were no scans to prove damage to their ACLs happened before they went down for a second time, there are many more examples of players continuing to play after damaging that important ligament. One is Newcastle’s Dutch centre-back Sven Botman, who last year revealed he played on for two more (full) games after rupturing his ACL in September 2023.
Sven Botman reveals he played on for two games after tearing his ACL ligaments — without knowing:
“I did my knee against Brentford but then played two games after that (without realising). It blew up the day after Sheff United game & the scan showed some big damage in my knee… pic.twitter.com/jQOvGhSwe5
— Keith Downie (@SkySports_Keith) January 1, 2024
Manchester United’s Aoife Mannion tore her ACL during the first half of a game against Chelsea but played the full 90 minutes: “I think my body knew,” the defender told The Athletic in an interview in 2022. “I remember at half-time not feeling like I was present in the team talk… it’s only looking back that I can join the dots and realise that quite a crucial ligament wasn’t there anymore.”
How can this happen? Given what we know about ACL injuries — that they are one of the most significant setbacks a footballer can suffer, ruling them out for eight months on average (longer if other ligaments or cartilage are involved) — how is it possible that a player can suffer such an injury on the pitch and still play on? How common is it for that to happen? And what does the physio do when he or she runs onto the pitch?
Geoff Scott, a high-performance specialist who has worked in the Premier League for 20 years, most recently as head of medicine and sports science at Tottenham Hotspur, explains…
When a player goes down with an apparent knee injury, what are the first things a physio does?
They’ll take the knee through passive movement; flex it and extend it, make sure nothing is dislocated and that there is normal anatomical movement. They will talk to the player too, asking him or her what happened.
Players who don’t have English as their first language will quite often start speaking in their mother tongue during a moment of severe pain and trauma. It’s really common around major injuries. So there is the potential for communication issues between the player and the on-pitch physio.
(Design: Drew Jordan)
The player will likely tell them something has happened to their knee but they won’t know more than that. They might say, ‘I twisted it and I heard a crack,’ but that’s probably about as much information as you’re going to get.
Then you go through the movements: first active, meaning the player can use his own muscles to flex and extend the knee, and then passive (whereby the player relaxes and the physio does it for them). If the player can actively move it then you progress to passive movements of the same motions: flexion and extension right through range. Then you move on to more specific ligament testing if you are suspecting a knee ligament injury.
What happens then?
To test an ACL you can do an anterior drawer test or a Lachman test.
In the first, you’ll see the knee bent to 90 degrees, the foot secured and the physio place their hands just below the knee with their thumbs over the kneecap. They’ll then pull the knee forward to test the anterior movement of the tibia or shinbone. If the tibia has more movement, or if the ligament is loose compared with the other knee, the anterior drawer test is considered to be positive — indicating an injury to the ACL.
With the Lachman test, you place one hand on the lower thigh and the other just below the knee with your thumb over the top part of the tibia and pull the tibia forward. An intact ACL should prevent forward translational movement of the tibia on the femur — if not, there is a suspicion of an ACL injury.
Jurrien Timber in the match where he injured his ACL in 2023 (Clive Mason/Getty Images)
Is it difficult to diagnose immediately?
Yes. If a player comes off during the game with a suspected ACL and is in the physio room, I would normally be assessing them for some time before I was confident about the diagnosis. There is a systematic approach to the assessment, as you work through all the structures in the knee to check and test. It takes time.
With the Lachman test, if the individual has particularly strong muscles (as most footballers do, particularly when it comes to their quads) then the test is less reliable. Huge quadricep muscles mean the translation (movement at the joint) doesn’t happen so much because of the size of their muscles, which means the test is less accurate than it would be on a less muscular individual.
On top of that, when you’re trying to test ligaments around a joint you really need the muscles to be relaxed, otherwise it’s really difficult to feel how much laxity the ligaments have within them because the muscles are essentially ‘locking up’ the joint. If the muscles are tight and actively firing it doesn’t matter if the ligament is there or not, you can’t feel it.
The patient really needs to relax so that the muscles are no longer preventing the movement in the knee that we are trying to assess. Getting a player to relax in that way is really difficult on a football pitch and when they might be in pain. Ideally, they need to be lying down on a physio table.
Why else do we see so many examples of players playing on?
If the explanation the player gives you is, ‘I pivoted, it felt like it gave way and I heard a crack,’ then of course you will have a high suspicion and remove them from the field of play. But if they don’t say that and instead say something like, ‘It’s a little twist, I think I’m OK,’ it can be hard. Players are professionals and are focused on winning the game, so will do everything they can to stay on the field.
While everyone watching on TV has seen the mechanism of injury through multiple replays, the physio running onto the pitch has not. That’s a key point. The one person making the on-field decision does not have direct access to a video replay. However, the medical staff on the sideline at Premier League matches will have access to a video replay system called Hawk-Eye and they will be reviewing the video footage immediately and radioing to the on-pitch physio what they think is a possible diagnosis. But again, that isn’t foolproof — sometimes it’s really clear-cut but for other movements, it’s less obvious.
A football pitch environment can be really challenging for the on-pitch physio. It’s a noisy stadium, the crowd are cheering, your team are asking questions through a radio earpiece wanting information so they know whether they will need to bring on a sub, and the whole game is on hold awaiting your decision — and it’s such an important one. If you take off a player unnecessarily, you could cost the team the game, but if you allow them to play on with an injury you risk a player’s health.
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Isn’t it painful?
Elite footballers are used to running through pain and in a game, the player has adrenaline pumping through their body, which can further mask symptoms. The moment of an ACL tearing is painful but severe pain often only lasts for a few seconds. Once a ligament is torn, it doesn’t really hurt anymore — the nerves are torn as well.
If it was partially torn and you kept pulling on a partially torn ligament you can imagine it hurting because it keeps getting stretched. But once it’s gone, it’s gone. It doesn’t really hurt. And because it’s so early — within a minute or so of the injury occurring — there’s no significant bleeding into the joint at this stage, so it’s not swollen. It will eventually swell because of the ACL tear, but that will normally take an hour or more.
While the majority of players will be unable to run/walk after tearing an ACL, the reaction can also be player-dependent. There are some who have high pain tolerances, are desperate to continue, and with the adrenaline pumping, will be able to stand up and jog. He or she might feel a bit of pain but all they’re thinking is, ‘Can I play football?’
But what you now have is a functionally unstable knee because the ACL is no longer doing its job. They will find it possible to run in a straight line and possibly even sprint but any kind of pivoting or twisting movement is going to challenge them more and without that intact ACL, their knee is likely to give way on them.
Sven Botman scored against Sheffield United in 2023 despite an ACL injury (Darren Staples/AFP/Getty Images)
Does playing on make it worse?
There is always the potential to cause more damage. ACLs are often injured along with a medial ligament (MCL) strain and a meniscal tear. When all three occur it’s termed the ‘Terrible Triad’. Sometimes you get an isolated ACL tear but often it’s all three, or two.
An MCL might take six weeks to heal. A meniscus might take three months, but the ACL takes nine months. So even though one of those other injuries was made slightly worse, it is less important because the ACL is the most significant injury.
Could there be a protocol to test for an ACL injury, like the concussion protocol?
All you can do is the clinical tests — the Lachman test and anterior drawer. There is another one called the pivot shift test, which is slightly more aggressive and you probably wouldn’t see them do it on the pitch.
You bend the individual’s knee, put quite a strong force through it and then you extend, and if there’s a ruptured ACL you get this big clunking feeling. But it can be an unpleasant test for the individual, whether the ACL is gone or not. You wouldn’t do it on a pitch where everyone is watching and it looks like you’re actually hurting your player.
How often does it happen that a player continues after injuring their ACL?
If I had to hazard a guess, I’d say probably a quarter of them try to carry on but this is dependent on the severity of injury and the player’s pain tolerance; every injury is slightly different, as is every player’s reaction.
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(Top photo: Gabriel Jesus by Mike Egerton/PA Images via Getty Images)
