The Big Question: Why is Jonny Wilkinson injured so often, and is rugby just too dangerous?

Why are we asking this now?

It was nothing worse than a twisted ankle – sustained by England's World Cup-winning fly-half during a training session in Versailles on Tuesday. But it was enough, as one headline put it, to throw "England's world into chaos," coming just four days before the start of their 2007 World Cup campaign.

The brilliant Jonny Wilkinson was injured yet again, jinxed as he seemingly has been almost from the moment his drop-goal in the closing seconds of the 2003 World Cup in Sydney secured the trophy for England for the first time and sent fans wild. A succession of injuries have raised fears both about Wilkinson's own future and about the physical toll that rugby union imposes on players generally.

How much has Wilkinson played since 2003?

Not a lot. "No rugby player on earth is more familiar with pain than Wilkinson," says Chris Hewett, rugby correspondent for The Independent, describing his career since 2003 as "a lengthy treatise on orthopaedic medicine." Wilkinson had surgery to repair ravaged nerves in his neck – a high-risk procedure – followed by a series of other problems: a blood clot on his biceps, damaged knee ligaments, persistent groin trouble, a lacerated kidney. Shoulder injuries have dogged him, and he also had to deal with appendicitis.

England have played 41 matches since winning the World Cup four years ago, and Wilkinson – the biggest star that the English game has ever produced – has appeared in just seven of them. And as a result of his latest injury he will miss England's opening match in the 2007 World Cup, against the United States on Saturday in the northern French town of Lens.

Why is Wilkinson so injury-prone?

Certainly he has been very unlucky. It's also the case that as the linch-pin of any side he plays in – fly-halves dictate tempo and tactics – he is specifically targeted by opposition players. One factor is his total commitment to the game. As one commentator put it, Wilkinson will never become a wily old pro. He is not a play-within-your-limits player, he is a bust-a-gutter. He is incapable of giving less than everything and his total lack of inhibition – glorious to his fans but unwise to his doctors – brings him back again and again to the operating table.

How bad is his latest ankle injury?

Hard to say but given that it happened not as the result of a crunching tackle but simply because he landed awkwardly – in the way it could happen to anyone – it is unlikely to be serious in itself. But it is the accumulation of damage that is the problem coupled with the extraordinary stresses on the joint imposed by the game. For a player in Wilkinson's position – having to twist and dodge charging forwards, release the ball and kick on the run – the pressure is extreme. It is not the first time that this ankle – the right one – has been injured. He damaged ligaments in it in 2002, but nobody imagined then – ahead of his golden World Cup moment – what kind of travails it presaged.

What do Wilkinson's troubles tell us about modern rugby?

They tell us something very worrying – and not just because Wilkinson is among the players that fans most want to see performing at their best on the pitch. The injury toll in rugby is alarmingly high, raising questions about whether we are testing our players to – and beyond – the limit. With games played as often and as hard as professional rugby demands, and bodies bigger, stronger and faster than ever before, it is hardly surprising that the battering they receive is doing serious damage.

How worrying is the toll of injuries?

The British Journal of Sports Medicine published a full evaluated injury audit last year. It showed that teams in the Premiership – the top level of English club rugby – recorded more than 2,000 injuries over the two seasons from 2002 to 2004. That works out at 92 injuries per team per season.

There were 263 injuries to players in games for England – the full international side, the second-string A side, the under-21s and the seven-a-side team. Together these 263 injuries caused more than 5,000 days of absence. Overall, one in four players from each club was under treatment, or undergoing rehabilitation, during the period of the study. Each player spent 19 per cent of the year injured, on average.

When are injuries most likely to occur?

Just over half happened as a result of tackles. It is hardly surprising that when two 18st behemoths collide, something is going to give. This is the area of the game that causes greatest concern to doctors and is being closely scrutinised for ways to minimise the damage. Modern forwards are almost a stone and a half heavier than their predecessors a decade ago and backs are more than a stone heavier. Added to this, rule changes mean that the ball is in play 30 per cent more than it was a decade ago, so there is less time for rest and more for injury. A high number of injuries happen in the last 20 minutes of matches – when players are weary.

Can anything be done to reduce the injury rate?

The International Rugby Board launched a study last year into the dangers of the rugby tackle – involving 6,000 tackles in Premiership matches of which 500 caused injury to a player. According to Professor Angus Wallace, orthopaedic surgeon and council member of the Faculty of Sport and Exercise Medicine in the UK, who has done research on shoulder injuries, vulnerable players can be identified and all tacklers trained to go in closer to avoid opponents "running through" them, bending the tackler's arm back and causing a dislocation.

Other measures include reducing training – unexpectedly, studies show that players who train for more than 10 hours a week suffer injuries twice as severe as those who do just 7.5 hours – and reducing the number of competitive matches players participate in. But whether any of this would have allowed Wilkinson to play more in the past four years is a moot point.

How seriously are rugby's authorities taking the issue?

Dr Mick Molloy, medical officer of the International Rugby Board, speaking last October, said: "The Premiership is the toughest competition in the world , week in and week out, and the guys who play in it are under enormous pressure. The structure of the season has to be looked at very closely because the potential consequences are very considerable indeed."

So can Wilkinson put injury behind him and return to peak performance?

Yes...

* The problem affecting his ankle is relatively minor, and he is otherwise injury-free

* He is a player who has always shown total commitment, never allowing injury to affect his confidence or ambitions

* The World Cup that is about to begin is rugby's ultimate prize, and he will be determined to be part of England's defence of their title

No...

* As Wilkinson has learnt to his cost, rugby injuries are very common and cause cumulative damage to muscles, ligaments and bones

* It is not the first time that Wilkinson has injured his ankle, and he carries the legacy of numerous other injuries

* At 28, he is an age at which injuries are likely to increase, and the physical toll of the modern game is becoming ever more extreme