Guest Blog by BJSM Associate Editor – Dr John Orchard

Jake Ballard- ACL injury in 4th quarter, photo: deadspin.com

Being an injury geek, the most interesting part of  last week’s Super Bowl was hearing that two New York Giants players had suffered ACL injuries on the FieldTurf surface. I have previously made the comment that the football codes are to Australians what languages are to the Swiss. Sadly most Australians, including myself, are monolingual, only being proficient in the English language (and for many Australians even this is open to argument). The Swiss, by comparison, are masters of many languages, including English and their four native ones, but many of them only follow one type of football. As an Australian, I can hold a conversation about most of the football codes and American Football is perhaps my fifth or sixth football “language”¹.

I have long had a strong interest in the relationship between ACL injuries and the playing surface². I think the published research from the various football codes can be combined to get a true understanding of ACL shoe-surface risk factors. Interestingly, ACL injuries are relatively uncommon in the EPL³ compared both to other football codes and soccer played in other countries. I believe that this is the case because the vast majority of EPL matches are played on ryegrass.

Ryegrass is to ACL tears what the Mediterranean diet is to heart disease⁴. The football (soccer) teams playing in Australia’s A-League get more ACL injuries than EPL teams, even though the schedule has less than half as many games. On a population basis, the rate of ACL injuries in the UK⁵ is about a quarter of the rate in Australia⁶. Obviously there are many confounders, but I am certain that climatic factors are at least partially responsible for the large discrepancy.

Ryegrass has less 'grip' than most other turfgrasses as it has no thatch/lateral growth. More pics and comment at the 'further reading' link (below) or in the 4th edition of www.clinicalsportsmedicine.com

I studied ACL injuries in the NFL about a decade ago¹. This study compared rates of ACL injuries on natural grass compared to artificial turf, at that stage primarily Astroturf. The rates on Astroturf were not significantly higher than natural grass – however the circumstances under which the ACL injuries occurred varied substantially according temperature with respect to artificial turf¹.

In domed stadiums, the ACL injury rate was constant (and fairly high) throughout the season. In artificial turf stadiums there that were in the open air, with variable temperatures, the ACL injury rate was very high early in the season (hot weather) and much lower later in the season (outside air was cold).

These data tell me that artificial turf may be quite safe, possibly even desirable, in very cold weather, but in warm/hot weather it may be associated with an increased risk of ACL injuries. The majority of NFL stadiums that use artificial turf have switched to newer products in recent years — FieldTurf is the number one brand. FieldTurf performance is better than the older generation artificial surfaces with respect to player satisfaction, probably because the surface is softer and ‘feels’ more like natural grass.

However, the shoe-surface traction may be at least as high with FieldTurf as with older artificial surfaces. Player satisfaction is actually quite high when shoe-surface traction is high, but this may be associated with higher ACL injury risk². Although I haven’t seen any data with respect to FieldTurf and temperature, the null hypothesis is that shoe- surface traction is higher on all artificial surfaces in hotter weather and lower in colder weather⁷.

MARCH 2010 STUDY – WHERE ARE THESE DATA?

A study which I have only seen in abstract form, presented at a conference in March 2010, showed that FieldTurf was associated with an 88% greater relative risk of ACL injury compared to natural grass surfaces in the NFL over a seven year period (which was highly significant)⁸. I have been eagerly awaiting the full paper, as I would expect it to perhaps show that the FieldTurf stadiums which were in the open air in cooler climates didn’t have a problem, but those in domed stadiums or in warmer climates were of higher ACL risk. If such results were observed, it doesn’t mean that FieldTurf or artificial surfaces shouldn’t be used for football. It would just mean they should be reserved mainly for the situation where common sense suggests they should be used – in cold climates where natural grass doesn’t grow well in winter. My question is, where are the data? The BMJ recently emphasized the importance of airing the results of clinical trials.

The Sydney University women’s first grade football team played their home matches last year on an artificial (not FieldTurf) surface, one of the few in Sydney. They apparently had zero ACL injuries in their away games (all on natural grass) and three ACL injuries on their artificial (home) surface. This is not statistically significant but when you sift through the surface literature you have to wonder why you would take the risk of playing on artificial turf in a warm climate like Sydney where natural grass grows beautifully and is cheap to maintain? The main papers that report that new generation artificial turf has acceptable injury rates were either conducted in cold climates⁹ or sponsored by industry¹⁰. It is frustrating that there has been a long delay in seeing a paper which I believe will more accurately reflect the risks involved, but when the Hershman study appears as a full paper, I think it will be a landmark one and worth the wait ⁸.

For further reading on ACL injury prevention follow this link to Dr. Orchard’s Article on page 17 of Sport Health.

POST SCRIPT FEBRUARY 22nd – ACL rupture at Widnes Vikings in Super League – ‘pitch not to blame”

References

1. Orchard J, Powell J. Risk of knee and ankle sprains under various weather conditions in American football. Medicine & Science in Sports & Exercise 2003;35(7):1118-23.

2. Orchard J. Is there a relationship between ground and climatic conditions and injuries in football? Sports Med 2002;32(7):419-32.

3. Walden M, Hagglund M, Ekstrand J. Regional differences in injury incidence in European professional football. Scand J Med Sci Sports 2011:in press.

4. Orchard J, Chivers I, Aldous D, Bennell K, Seward H. Ryegrass is associated with fewer non-contact anterior cruciate ligament injuries than bermudagrass. Br J Sports Med 2005;39:704-09.

5. Jameson SS, Dowen D, James P, Serrano-Pedraza I, Reed MR, Deehan D. Complications following anterior cruciate ligament reconstruction in the English NHS. Knee 2011.

6. Janssen K, Orchard J, Driscoll T, van Mechelen W. High incidence and costs for anterior cruciate ligament reconstructions performed in Australia 2003-04 to 2007-08: time for an anterior cruciate ligament register by Scandinavian model? Scand J Med Sci Sports 2011:doi: 10.1111/j.600-0838.2010.01253.x.

7. Torg JS, Stilwell G, Rogers K. The effect of ambient temperature on the shoe-surface interface release coefficient. Am J Sports Med 1996;24(1):79-82.

8. Hershman E, Powell J, Bergfeld J, Johnson R, Spindler K, Wojtys E, et al. American Professional Football Games Played on FieldTurf have Higher Lower Extremity Injury Rates. American Academy of Orthopedic Surgeons Annual Meeting. San Francisco, 2010.

9. Ekstrand J, Timpka T, Hägglund M. Risk of injury in elite football played on artificial turf versus natural grass: a prospective two-cohort study. Br J Sports Med 2006;40:975 – 80.

10. Meyers M, Barnhill B. Incidence, causes and severity of high school football injuries on FieldTurf versus natural grass. Am J Sports Med 2004;32(7):1626-38.

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John Orchard BA, MD, PhD, FACSP, FACSM, FFSEM (UK), is a Sports Physician, and an Adjunct Associate Professor at the University of Sydney, School of Public Health.

Reporting from UKsem 2011 – the largest Sports and Exercise Medicine and performance Conference in Europe. London’s Excel conference centre 23rd November – no downtime for the BJSM blog!

Richard Frobell opened with 3 major revelations. #1. ACL injuries are associated with arthritis – whether you have a reconstruction or not.  (citation classic, 103 citations to date).

#2. Give a piece of rehabilitation a chance! Not everyone needs a knee reconstruction. Really? New England Journal of Medicine RCTs demonstrating that = 1; disputing it = 0. (See Frobell, 2010, 53 citations already), THE hot topic of 2010/2011 and great to have Dr Frobell here himself. Audience experts included the IOC’s Lars Engebretsen so discussion was energetic. They were seen breakfasting together later so no risk of Scandinavian Spring just yet.

#3. There is limited return to sporting activity after ACL rupture. With or without surgery. This is where I was about to slash up. Depressing keynote stuff. Who chose him?

But then the good news. Prevention is key and possible. There are success stories. More of that tomorrow’s program. Sessions on prevention of football and tennis injuries, of knee and groin debacles. Hope springs eternal, no need to jump into the boxing ring that is available here for conference attendees. No need to walk up to the fencers, brandishing only the complimentary Prograin Minitub from maximuscle and say in true Homer Simpson fashion, ‘give it your best shot pal, I don’t need that poncy white protective gear, go on, try me!’.

Seriously though, I am a Frobell fan as BJSM readers and podcast listeners know. Great clinical insights, great presentation. Privilege to be in the shop at the same time as the KneeMaster.

Great day planned for Thursday 24th and BJSM Blog will be there. Blair, Dvorak, Daniel Coyle from the Talent Code, Bahr, Franklin-Miller. Track us on @BJSM_BMJ and you’ll be first with the updates. And competitions are in the wings!

Say hi to journal manager Claire Jura at the BJSM booth (ground floor, right side) and sign up for free stuff.

And do your ACL prevention exercises daily!

Teaser video – Richard Frobell kindly agreed to do a 20-second spot for the podcast of a conversation on ACL management he had with Lars Engebretsen. The discussion will be hosted on the BJSM podcasts – which are getting 4000 listens per month!

Looking for a world class conference bringing together sport and exercise medicine, conditioning and science with nutrition, rehabilitation and high performance coaching?. This conference will provide new knowledge for those working with elite sport and recreational athletes as well as those presenting to all clinicians for exercise prescription. See the UKsem home page including the concise video (and Andy Franklin-Miller’s very modish shirt)…Will you be there?

The UKsem site is the best place to find the conference program. Names I am looking forward to hearing from include Roald Bahr (sports injury prevention-always great value), Dan Lieberman (the ‘barefoot doctor’), Damien Comolli (the secret to Liverpool’s success), Vern Gambetta (the art and science of coaching).Vern has over 4000 followers as @coachGambetta on Twitter so you know he’s doing something right.

‘Sleepers’ for many will be Carl Askling on hamstring rehabilitation and Richard Frobell on conservative management of ACLs. The former has terrific programs for both prevention and treatment. He discovered the difference between ‘type I’ (sprinters/football players) and ‘type II’ (stretching/dancer’s) hamstring strains and their very different prognoses. Great teaching videos for both rehab and determining return to play.

Dr Frobell headed up the New England Journal of Medicine RCT which randomized ACL patients to rehab or surgery. Not every conference presenter can open up with that claim…’Thanks for coming and if you doze off during my talk you can read all about in the NEJM….’. Good one. 10 years of hard work to become the overnight sensation. BJSM comments on that paper are here in a WarmUp and here in a podcast with Dr Frobell and his research team. Do your homework and then ask him the stumper at UKsem. Or buy him beer for the great effort!

I’ll stop there as I want you to use your coffee break to go to the UKsem site, not to read this. And by ‘sleepers’ – I meant – ‘under the radar’ — not lectures to sleep in. I would reserve sleeping for Friday morning 9:35 – 10:05. Something about how Mad Men, the Marlboro Man and Freakonomics have the answer to ‘smokadiabesity‘? Weird!

The UKsem site is great but if you insist on only following BJSM pages you can see Andy Franklin-Miller’s WarmUp about the conference here and listen to two interviews with the mellifluous BBC-trained sports physician and fashionista.

July podcast – his conference highlights

October podcast – lower limb biomechanics plus a sneaky conference plug in the last 3 minutes of this 24 minute file.

Nice shirt….

Bit of local bias in today’s blog – and I have to declare a conflict that the CPA has put me up in the very nice Hilton Hotel at the base of Whistler Mountain.

So if I say the Hilton has delicious breakfast cereal and great local art galleries next door, you need to be aware that I paid for the former, and am trying to avoid my wife seeing the latter.

More importantly Professor Carolyn Emery, internationally renowned physiotherapist and paediatric sports injury prevention researcher, shared advances in a well-attended session yesterday. She is a leader at the Sport Injury Prevention Research Centre (SIPRC), University of Calgary.

Take home message for me? 10-15 of the right type of neurodynamic (what we used to call balance/strength/coordination) exercises can prevent lower limb injuries and likely ACL rupture. Some coaches are ‘buying’ in but there is a way to go. Coaches – how can you sleep at night if you are NOT doing this in youth soccer, handball, and likely other sports. How can we sleep while the kids aren’t learning (to perform these prevention exercises) [apologies to Midnight Oil and some readers will know what I mean]. Thanks Carolyn Emery.

I was reminded of Roald Bahr’s thoughtful editorial in BJSM. Also, remember the Review and Summary Statement from the IOC ACL prevention meeting – always in BJSM’s top 10 downloads per month.

Today, I look forward to Uni of Queensland’s Michele Sterling this morning – Whiplash: Minor Injury but Complex Condition.

What am I speaking about for my supper? A meeting with young researchers in the morning – how to get published. Later, in a session on scope of practice in physiotherapy (very hot topic), I contribute the exercise prescription part. There’ll be some overlap with an Editorial that got posted in BMJ today – although the BMJ piece has doctors as the target audience for obvious reasons. And I’ll give the smokadiabesity a run here in Canada – see what folks think! The point of the editorial and my talk today? What can clinicians do get people moving. Exercise is Medicine — we know that. The challenge is implementation (see the current issue of BJSM!).

Have a great Saturday!