Sydney - Experts have warned rugby players not to rely on neck-braces to stop spinal injuries but to focus on prevention as concerns grow over increasingly heavy collisions following the three neck fractures suffered by Australia's Pat McCabe.
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The Wallabies centre ended his career last week after suffering his third neck-break in the Wallabies' Test against the All Blacks, an incident which underlined safety worries as players get ever bigger, faster and stronger.
"It's shattering thinking I'll never play for the Wallabies or the Brumbies again," McCabe said.
"But it wasn't a particularly hard decision in the end. I'm lucky to be able to walk away from the game after three serious injuries intact. It's a blessing."
The 26-year-old's retirement comes after Newcastle Knights forward Alex McKinnon suffered a severe spinal injury in a spear tackle during a National Rugby League game in March, leaving him wheelchair-bound.
Rugby union's blackest day came at the 1995 World Cup in South Africa, when Ivory Coast winger Max Brito was paralysed below the neck after a ruck collapsed on top of him in a match against Tonga.
And as professional rugby players grow in size and athleticism, especially among the backs, experts say more can be done to minimise the risks.
Welsh winger George North, All Blacks centre Ma'a Nonu and Wallaby fullback Israel Folau are examples of hulking modern-day backs, tipping the scales around 105kgs and capable of incredible acceleration.
North, who stands six foot four inches (1.94m) tall and weighs 109kgs, has been timed running 40m in less than five seconds.
Rugby's injuries debate mirrors similar situations in other sports such as American football, where concern over the effects of concussion is growing. Peter Milburn, head of the School of Allied Health Sciences at Griffith University on Australia's Gold Coast, played, coached and refereed in rugby union, and among his primary research interests is player welfare and injury prevention.
He told AFP that sports bodies could do more to protect players, for instance by strengthening their necks or outlawing tackles above the shoulder.
"Physical preparation of players is paramount and the responsibility of all players. Strengthening the neck musculature is the single best preventative measure as there is nothing else that can provide the stability to withstand the loads on the neck," Milburn said.
"Neck braces are not effective and may give the player a false sense of security and, in fact, increase their risk if they know their neck is vulnerable."
He said the laws of the game should be applied and any tackle above the shoulder penalised, so it becomes an anatomical fact rather than an interpretation by the referee.
"Players should also be coached in the correct technique, not just to avoid making high tackles, but to ensure their head is behind the player in a tackle, not in front," he said.
Milburn said in McCabe's case his research involving retired players found a high incidence of cervical spine degeneration in the form of narrowing of the spinal canal.
"The question is whether this is congenital, developmental or acquired, but for whatever reason, the presence of a narrower canal significantly influences the risk of injury," he said.
Milburn added that the risk of re-injury to the cervical spine was reported to increase by 17.2 percent following an initial injury, and the twice-injured player had an 87 percent chance of being hurt again.
"This places a player like Pat McCabe at a much higher risk of injury following his initial diagnosis," he said.
McCabe, who played 24 Tests, first fractured his neck in 2012 on the Wallabies European tour and hurt it again against the British and Irish Lions last year which ruled him out for the season.
He then suffered a jarring knock in Australia's 51-20 loss to the All Blacks at Auckland's Eden Park in August, which was later diagnosed as a third break to his C1 vertebrae.
Andrew McIntosh, from the Federation University in Ballarat, Victoria, has undertaken biomechanical research of neck injuries in rugby union and other football codes.
He said while rugby had done much to reduce the incidence of spinal injury, current protective equipment was not effective in reducing serious neck injuries.
"Through the scrum laws, policing the tackle (high tackles and spear tackles) the incidence of serious and catastrophic neck injury had been reduced. However, it is challenging to prevent all forms of spinal injury in a contact sport," McIntosh told AFP.
"Programmes, like the Australian Rugby Union's SmartRugby, through which coaches and match officials are trained on safety practice, have been shown to be effective in reducing spinal injury," he added.
McIntosh said preventive measures such as policing tackles and improving tackling skills, reducing accidental hits and identifying players at risk, were more effective than using protection like neck braces.
"At present, and in the foreseeable future, it will be unlikely that personal protective equipment (PPE) can be used to prevent this type of spinal injury," he said.
"One reason is that players need to have mobility. Another reason is that fractures often happen earlier in an impact event, that is before PPE such as a neck brace would function."