LATEST RESEARCH NEWS
This page presents a summary of the latest research news from the 18th International Symposium of the ISSS held in Garmisch-Partenkirschen 26 April - 2 May 2009. ISSS meetings bring together researchers from ski areas worldwide to share knowledge and research findings in the area of alpine sports injuries. Specialist fields include epidemiology, orthopaedics, biomechanics, engineering, psychology and more! Hot topics in recent years have included debate regarding current standards for ski binding settings, the issue of helmet and wrist guard use and the biomechanics of snow sports equipment.
This page attempts to present a summary of the main research presentations from this symposium. I am not commenting on every paper but concentrating on those that present findings of interest to a general audience. I apologise if I offend any colleagues I don't mention who presented papers! In time, the other pages of this website will be updated in detail with more specific information. I have grouped the information together under specific topic sub-headings and the page will continue to grow as I add more information. As ever, this is my interpretation of the research presented - sometimes it can be difficult to decide what to think when even respected experts cannot agree! So if there is something here you do not agree with, please feel free to email me using the contact page.
Injury epidemiology
Unfortunately, due to my son falling ill with chickenpox at the last minute (!) I missed the presentations on epidemiology but will do my best to summarise the main findings. The first thing to say is that the absolute rates of injury have not shown a significant change in recent years.
Risks of injury amongst older participants
Previous ISSS meetings have heard work relating to the increased risk of injury amongst children on the slopes. This time, there were two presentations on the risks of injury amongst older skiers. Shealy et al presented work from their ongoing study in Sugarbush USA showing that the regressed mean age of the control population at Sugarbush has increased from 22.9 years to 35.8 years. The NSAA in the US have also found that the % of skiers/boarders aged 55 years or older on the slopes in the US has increased from 1.8% to 5.5%. There are concerns that older skiers may be at higher risk of injury due to decreased muscle and bone strength. Their data however showed that the over 55 skier group was not at greater risk of injury than the general skiing public, except for a slightly increased incidence of tibial plateau fractures (but this still only represented 0.5% of all injuries)
A much larger study from the MdeM group in France looked at injuries amongst the over 75s and did find a larger incidence of leg fractures, shoulder fractures and dislocations and head and face trauma compared to younger participants.
Potential effects of smoking and alcohol on injury risk
A small but interesting study from Werner Nachbauer's group in Innsbruck compared the effects of smoking and/or alcohol consumption on the frequency of falls in male and female skiers. They found that for female skiers the combination of smoking and drnking alcohol increased the risk of falling by more than 4 times! In males, the risk was only increased in those aged over 29 years and by a lesser extent (2.2 x higher). I shouldn't really tell you this, but previous work by others has actually shown that drinking alcohol actually has a protective effect on ski injuries.....!
Wrist injuries amongst snowboarders
The issue of wrist injuries and wrist protectors for snowboarding continues to be a hot topic. Just to remind those of you who don't yet know, wrist injuries are the number one risk for boarders constituing up to 40% of all injuries seen. A study from the trauma clinic of Garmisch-Partenkirschen of 1929 snowboarders demonstrated that wrist injuries constituted 50% of all injuries seen, of which 80% were fractures. This was the highest level of all the age groups studied. Tracey Dickson from Australia presented a study of risk factors associated with wrist fracture. The most significant risk factors were age < 16 years and being a first day participant - risk factors we have shown previously in Scotland. Although the numbers involved were small and so we should interprete the results with some caution, Tracey also found that wearing a short palm sided wrist guard increased the risk of a wrist injury by a factor of 3 compared to long, back of wrist or double-sided guards (the type that I advocate).
This work was not presented, but I was pleased to catch up with my friend from St Moritz, Georg Ahlbauemer. He informed me that he has unpublished data on 45,000 snowboaders and showed a 4.5x lower rate of wrist injury in those wearing any kind of wrist guard but a 7.5x reduction in those wearing his brand of guard - Biomex. Further evidence of the benefit of wrist guards but do remember that its unpublished so we don't know the full details of how the study was conducted.
Protective equipment
Helmets
The issue of helmets and head injuries raced back to the top of the agenda again during the 2008/09 season following several high profile deaths in Europe and the tragic death of actress Natasha Richardson in Canada in March 2009. The rate of helmet use in most countries continues to rise - in Switzerland where the bfu organisation has undertaken a large scale education campaign, almost 60% of all slope users now where a helmet (with rates amongst children exceeding 90%). In Germany, the figure is lower at 50%. Interestingly, the European country with one of the lowest rates of helmet use is France.
Despite these healthy rates of helmet wearing, there is still no firm data to support the idea that wearing a helmet will protect you against sustaining a serious or fatal head injury. Indeed two studies from the Czech Republic and Switzerland suggested that those wearing a helmet may in fact take more risks and ride faster than those who do not. Remember, a helmet does not make you invincible!
Rick Greenwald, the president of ISSS, started by reminding us all that helmet standards have not been specifically designed to protect children. He then went on to present some more impressive work using his HIT (Head Impact Telemetry) system. This system uses a Giro 9 helmet with six accelerometers placed inside to measure the forces involved during head impacts - for clarity this system measures the forces on the head, not the helmet.. He recorded a total of 674 head impacts amongst young snowboarders supplied with such helmets during the period Feb 07 to Mar 08. On average, a head impact was recorded every other day spent riding. Some riders though recorded 10 impacts in one day! Thankfully, more than 95% of the impacts sustained were less than 50g (roughly the equivalent force to 2 adults wearing helmets standing in front of each other and leaning in to bash heads quite hard).
Finally, some interesting work out of MIT in Boston, presented by Larry Young. His team have been working on interior materials for helmets looking to see if these can be improved. Their conclusions were that a mixture of water and glycerine contained in channels within the helmet liner might provide the best impact attenuation, especially after repeated impacts. The challenge will be to integrate this into the lining of a helmet without compromising comfort, weight and costs.
Elite skiing and snowboarding
Part of the ISSS 2009 conference was devoted to a joint session with the F.I.S. medical committee relating to the risks of injury amongst elite skiers and snowboarders. I have now added a separate page to this site that reports in some detail on these risks - you can access it here. In a nutshell, one in three elite athletes is injured every season and many of these injuries are seious, leading to more than 28 days absence from training or competition.
Many of the injuries that elite skiers sustain result from non-release of their bindings - ski racers tend to be paranoid about their bindings releasing inadvertently and so dial them up far tighter than the settings normally recommended for recreational skiers. Whilst this may ensure their bindings do not release, it also means that they are suceptible to injuries when they do fall and the ski does not release - for an example, have a look at the YouTube clip below. Perhaps if the left ski binding had been able to release, the injuries sustained would have been less severe.
An interesting potential solution to this problem has been put forward to incorporate an emergency release system into a ski racer's binding. Basically similar to the technology employed in car air bag systems, the Pyro Safe system remotely detonates a small explosive charge inside the ski binding which releases the skier from their binding in an emergency situation and hopefully before they sustain an injury from the ski remaining attached to their leg(s). Whilst the theory is good and the device would appear to work, the exact way the device is deployed and by who still requires more work. Some possibilities include the skier using a predetermined codeword to trigger the device, or perhaps (more controversially) their coach having the ability to trigger the device. The obvious concern is that inappropriate triggering could in fact lead to injury itself!
Biomechanics and injury
ACL injury
Some more work illustrating why modern ski bindings to date have been unable to protect the ACL (remember of course that this was not what they were originally designed to do!). Basically, biomechanical modelling has shown in typical ACL injury scenarios that whilst the forces across the ACL are high, the forces felt by the binding do not reach the levels required to release the binding.
As you will read on other pages of this site, there are new bindings on the market now that claim to offer ACL protection by providing lateral release at the heel of the boot. Perhaps not surprisingly, opinions seem to be divided amongst the experts as to whether this will actually be as effective as the binding manufacturer hopes it will be. Proving it to be effective through epidemiology would be an extremely expensive and difficult task to undertake.Perhaps the best we can hope for just now is individual feedback from those who have purchsed and used the skis. Personally speaking, I think that any binding that offers a new dimension of release, as long as it does not lead to an increase in inadvertent releases, has to be a good thing.
Electronic bindings
More work was presented on the concept of electronic or smart bindings. The technology available is now allowing for the recording of thousands of data points from recreational skiing which may allow for the development of new algorithms for ski binding release. The hope is that these will lead to bindings being more sensitive to releasing when they are required to without an increase in inadvertent release.
Injury prevention campaigns
ISSS 2009 saw several presentations by Othmar Brugger from the bfu in Switzerland relating to their injury prevention campaigns for snow sports. They certainly have a huge budget to work with - a cool 2.5 million swiss francs (compared to my budget of £0!) but they also see 70,000 Swiss people injured from snow sports every year and 10% of these injuries affect the head. They have been encouraging the use of helmets on the slopes for several years now - one example was a high profile campaign in 2007/08 with the slogan "1000 injuries per day". Helmet use in Switzerland has risen from about 15% in 2002/03 to the current level of 65%, although this % does vary by age group with children being the group most likely to wear a helmet.
Finally, an interesting presentation from the ACC in New Zealand, who have conducted an extensive review of the literature relating to ski bindings. They have decided to adopt the French AFNOR binding standard in New Zealand in the hope of reducing the number of knee injuries seen. They also surveyed 212 individuals working in ski rental facilities in New Zealand and found lareg inconsistencies. 82% of respondents stated that they used a reference table when setting bindings, but 39% admitted relying on the skier's "guestimate" of their own weight and 24% on the skier's estimate of their height. About 18% admitted only "sometimes" even asking about height and weight. Only 13.8% of respondents had checked their ski binding functionality with a calibration machine. These findings are broadly in agreement with those presented at a previous ISSS meeting by Veit Senner et al showing a fairly low standard of ski rental binding adjustment in Germany. One interesting comment was that ski rental technicians did not appreciate their crucial role in the prevention of injuries.....
The ACC now plan a concerted campaign to promote ISO standard 13993 (relating to rental ski practice) and also campaigns to encourage skiers to look after their bindings better. Hopefully in conjunction with AFNOR, this will lead to a reduction in the number of knee injuries seen.
Terrain Parks
Not as much on terrain parks at this meeting as the last, but still some work reported on (separately) by Scher/Shealy and LaHart. Both groups are interested in the dynamics and mechanics of terrain park jumps - LaHart is planning a major piece of work on this and outlined her methodology to the meeting. Scher and co-workers have been using video to study terrain park jumping and the correlation between speed and jumping distance, comparing a large jump to a smaller jump amongst other things. They report that fixed starting points for jumps have been suggested as a measure to ensure that all jumpers would reach the minimum required speed to successfully tackle the jump and reduce the chances of excess speeds being attained. However (just like in nordic ski jumping where there is a fixed starting point) performance seems to vary considerably dependant on a whole range of factors, not just rider speed. Interestingly, they found that the majority of riders hit the jump with more speed than they actually need and then attenuate their jump depending on what tricks etc they plan to perform.
In their second presentation, Scher et al found that the correlation between take off speed and jumping distance was weak for big jumps but better for smaller jumps. So what else might influence jump performance? Rider techniques at take off such as pops (where the rider jumps) or buckles (where the rider actively tries to absorb the jump) are some of the many possibilities.
That's all for now - I look forward to another fascinating ISSS meeting in the USA in 2011.
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