Wembley Stadium Playing Surface

Any football (soccer) fan who tuned into the FA Cup semi-finals last weekend would have found it hard not to notice the terrible state of the pitch at Wembley.  It made for less than flowing football with players looking like Bambi on ice at times rather than the elite professionals they are.  Twice as painful for me on Sunday as a Tottenham Hotspur fan as I had to watch Portsmouth FC’s Frederic Piquionne tap one home from close range after being gifted a clear path only due to a slip by Michael Dawson on this dreadful embarrassment of a playing surface.

Understandably the FA have been getting a bit of a hard time in the press regarding the playing surface (and not just from disgruntled Spurs fans).  It is well documented that the schedule at Wembley is very heavy, and includes many other events such as rugby, motor racing and music concerts, and the pitch seems to have been in trouble since day one – having been re-laid 10 times already since July 2006.  The FA released this statement today:

A Wembley Stadium spokesperson said: “We accept and understand the frustrations around the standard of the pitch at Wembley for last weekend’s FA Cup Semi-Finals.

“The problems faced on Saturday were due to the way the surface was prepared and the measures used overnight were unable to resolve the situation sufficiently for the match on Sunday.

“There is a unique challenge with the surface at Wembley and we are working with expert pitch consultants to get it right. Wembley Stadium is a multi-purpose venue and we have to hold other events as part of the business plan, which means regular pitch replacements each year.

“Football is the number one priority and we understand we have to find a way to deliver and sustain a consistent quality pitch and replicate the successful formula that we developed in the second half of last year.

“We are currently reviewing all options to provide the best surface for the busy period going forward, including a probable pitch replacement. We will make this decision after the weekend.”

However in the two weeks running up to the England Vs Mexico friendly on May 24^th the Wembley surface is still to be used a further 5 times:

1. FA Trophy Final on May 8^th
2. FA Vase Final on May 9^th
3. FA Cup Final on May 15^th
4. Football Conference Final on May 16^th
5. Championship play-off Final on May 22^nd

I for one will be watching our last international friendly before the squad leaves for South Africa very nervously, as I feel the pitch in its current condition is nothing less than a major risk to the safety of our players.

Playing surfaces and the relationship with shoes (and injury)

Football is characterised by sprinting, stopping, cutting and pivoting – situations where shoe-surface interactions are essential and frictional resistance must be within an optimal range.¹ Not to mention of course that when playing football you are also required to spend a lot of time on only one leg, so a stable base of support is crucial.  Research has suggested that the footing or ‘grip’ a playing surface provides (its traction) may relate to injury in football.^1,2

The BBC commented that one word used to describe the pitch at Wembley by Premier League managers was ‘spongy’.  The most common compensation for a very soft and slippery pitch that players will make is to wear boots with longer cleats/studs as this will increase traction and therefore decrease slippage.³ This was illustrated clearly in the first half of the Aston Villa and Chelsea game on Saturday with many players running to the side lines to change their boots.  My main concern here being that longer studs have been shown by many studies to increase in shoe-surface traction (torque) possibly outside of the optimal range, and with it increase the risk of knee injuries.^4,5

The majority of the literature on surface traction suggests that increased shoe-surface traction may be a risk factor for non contact lower limb injury in football.⁶ A pitch such as Wembley encourages players to take measures to increase this shoe-surface traction as we have discussed above; as performance considerations (i.e. not falling over) will trump this relative increase in injury risk (in their minds anyway).

The sort of injuries most of the aforementioned studies refer to are the non contact kind where the shoe-surface relationship is the primary cause, the key injury generally considered to be knee injury.  However as those with a knowledge of the game know, different playing surfaces do tend to result in the timing of tackles or challenges varying greatly which can often lead to knocks being picked up which ordinarily may not have been.

My closing comment on this is simple.  I think the FA would find itself in a very uncomfortable situation if one of our key players was to get injured (due to the playing surface) just a few weeks before the start of the World Cup Finals.  To see Rooney, Gerrard or Terry damage their anterior cruciate ligament just because it’s part of the FA’s business plan to keep Wembley as a multi-purpose venue would be very difficult to swallow.

References

1. Nigg, B. M. & Ekstrand, J. (1989). Surface-related injuries in soccer. Sports Medicine. 8(1), 56-62.
2. Milburn, P. D. & Barry, E. B. (1998). Shoe-surface interaction and the reduction of injury in rugby union. Sports Medicine. 25(5), 319-327.
3. Yu, B., Kirkendall, D. & Garrett, W. (2002). Anterior cruciate ligament injuries in female athletes: anatomy, physiology and motor control. Sports Medicine & Arthroscopy Review. 10, 58-68.
4. Lambson, R., Barnhill, B. & Higgins, R. Football cleat design and its effect on anterior cruciate ligament injuries: a three-year prospective study. American Journal of Sports Medicine. 24(2), 155-159.
5. Torg, J. S. & Quedenfeld, T. (1971). Effect of shoe type and cleat length on incidence and severity of knee injuries among high school football players. Research Quarterly. 42(2), 203-211.
6. Orchard, J. (2002). Is there a relationship between ground and climatic conditions and injuries in football? Sports Medicine. 32(7), 419-432.

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Achilles Tendon Rupture

David Beckham.  Arguably the most iconic professional footballer on the planet.  A point that hasn’t been overlooked by the likes of Adidas, Gillette and Armani.  A man who in my opinion has also probably done more for promoting certain sports injuries than anyone else.  In 2002 he literally taught every lay person in the UK what a metatarsal was.  The aircast boot was anecdotally referred to as the ‘Beckham boot’.  And I for one had a sudden influx of patients in my clinic presenting with foot pain and telling me in the first few minutes of the consultation that they thought it was their metatarsal.  And now he’s done it again.  The entire country is talking about the Achilles tendon.

Personally, I cried into my cornflakes on the morning of Monday 15^th March as I read he had a suspected (at that time) Achilles tendon rupture.  If a similar heel injury was responsible for the death of Achilles during the Trojan war perhaps it didn’t bode well for David making a record breaking trip to South Africa in under 3 months time.

So what actually happened?

Sunday 14^th March.  AC Milan are hosting Chievo in a Serie A game.  It’s the 87^th minute.  David Beckham receives the ball in the centre of the pitch with plenty of space.  He takes a touch with his left foot, opens up his body and looks up to see where his team mates are as he is stepping back on his left foot…

If you look closely as his left heel nears the floor you can almost see it ‘pop’.  Watch David’s immediate reaction – he turns to see who is there.  I guarantee if he ever speaks of this experience he will explain the way he thought someone had kicked him.  After trying to take one step on it he knew he was in trouble.  He then feels the back of his ankle, and would not have felt the prominent firm tendon which he has probably felt every single day for the last 20 years.  At this point he would immediately have realised how serious his injury was.  Some newspapers report he looked over to the bench and made a ‘breaking twig’ gesture with his hands.  Within 48 hours he has been operated on by Professor Sakari Orava in Finland and knows his World Cup dream is over.

The Achilles tendon

The Achilles tendon is one of the most commonly ruptured tendons.¹ It is well documented that it has a zone of hypovascularity, ^2,3,4 which is an area of reduced blood supply and is located approximately 2-6cm up from the heel bone.  This zone of hypovascularity is the site of around 80% of all Achilles tendon ruptures.⁵ Despite the Achilles tendon generally being referred to as the strongest tendon in the human body, there is good research which actually disproves this and found that its material properties are instead similar to most other tendons.⁶ However we do know it has to cope with far more mechanical loading than most other tendons which may explain the relatively high incidence of Achilles injury.

The Achilles tendon can cope with loads of approximately 100N/mm² and can be stretched approximately 8% of its length before rupturing.⁷ To put this into perspective, an Achilles Tendon with a cross sectional area of 90mm² (which is about normal for an adult male) could theoretically cope with a force of approximately 1 tonne.  In a 75kg man (David’s current weight according to Google) this equates to twelve times his body weight.  So considering this tensile strength, how and why do they suddenly rupture?

All human tissues are what we term viscoelastic.  This basically means they will change shape (or deform) when a force is applied to them, but then return back to normal once the force is removed – a bit like an elastic band.  If they are deformed or stressed outside of the limits of their tolerance they will fail (in our elastic band example it snaps, in our Achilles tendon example it ruptures).  I explain this in a bit more detail on my website here.  When reviewing David’s mechanism of injury it is difficult to imagine the tendon being loaded with a force it couldn’t cope with (or equivalent to twelve times his body weight).  He was simply moving in a way he has done hundreds of times a day for almost two decades ; and therein may lay the key.

David has been playing the highest level of football for 18 years, ever since he made his professional debut for Manchester United back in 1992.  He has played for three of the biggest clubs in the World (four if you are a Preston North End fan).  He is the most capped outfield England player in history and has played in three FIFA World Cups.  This is undoubtedly a huge demand on the human body (and testament to what a conditioned athlete he is that he hasn’t been injured more in my opinion).  He is world renowned as being one of the best dead ball specialists in the modern game.  It is no secret that he often stays behind after training and practises his free kicks again and again.  And he is right footed.  So it would be reasonable to assume he has spent a lot more of his life balanced only on his left leg (just take a look at his left foot in the picture and imagine the strain on the Achilles tendon).  He certainly has the repetitive load history which could have led to some tendon/collagen deterioration, and it is my belief that the seemingly innocuous movement he made in the San Siro stadium less than a week ago was simply the ‘straw that broke the camels back’.

Unfortunately for David (and every English football fan) he was also in the right demographic for an Achilles tendon rupture.  It is more common in males ⁸, and more common between 30-50 years old.⁹ I don’t know David’s blood group (even Google can’t tell us that) but individuals with blood group O have been shown to be at higher risk of tendon rupture ^10,11 so it would be interesting information to know.

Recovery

Professor Orava tells us the operation was successful and David will make a full recovery.  I am no surgeon, and do not profess to know what procedure was performed, but in simple non surgeon speak the tendon would have been sewn back together (possibly requiring a graft of tissue from another part of his body).  A task which no doubt requires serious skill and expertise on the Surgeons part.

For David the worst is probably yet to come.  Long rehabilitation is a certainty, and from the sportsmen I have spoken to regarding their ruptures, the first two months are miserable and they wouldn’t wish the injury on their worst enemy.  Assuming there are no post-operative complications (incidence of deep vein thrombosis following Achilles tendon rupture is high¹²) many months of Physiotherapy await.  It pains me to say it, but David may have played his last game for England (I hope he proves me wrong).  He has almost certainly played his last game in a World Cup.  So, is his career over, or will he return to elite sport and be back to his best?  I wouldn’t like to say.  Recent research on recreational athletes suggested significant reductions in playing sports following a rupture.¹³ However, that was recreational athletes – what about the professionals?  A study showed that 32% of professional American Football players who sustained Achilles tendon ruptures between 1997-2002 never returned to play in the NFL and on average players experienced a greater than 50% reduction in power ratings following the injury.¹⁴

Get well soon Becks.  I genuinely hope to see you play again.

References

1. Kannus, P., & Jozsa, L. (1991). Histopathological changes preceding spontaneous rupture of tendon. Journal of Bone & Joint Surgery, 73, 1507-1525.
2. Carr, A. J. & Norris, S. H. (1989). The blood supply of the calcaneal tendon. Journal of Bone & Joint Surgery Br, 71, 100-101.
3. Schmidt-Rohlfing, B., Graf, J., Schneider, U. & Niethard, F. U. (1992). The blood supply of the Achilles tendon. International Orthopaedics, 16, 29-31.
4. Theobald, P., Benjamin, M., Nokes, L. & Pugh, N. (2005). Review of the vascularisation of the human Achilles tendon. Injury International Journal of the Care of the Injured, 36, 1267-1272.
5. Lesic, A. & Bumbarsirevic, M. (2004). Disorders of the Achilles tendon. Current Orthopaedics, 18. 63-75.
6. Wren, T. A. L., Yerby, S. A., Beaupre, G. S. & Carter, D. R. (2001). Mechanical properties of the human Achilles tendon. Clinical Biomechanics, 16, 245-251.
7. McNeill Alexander, R. (1994). Human elasticity. Physics Education, 29, 358-362.
8. Leppilahti, J., Puranen, J. & Orava, S. (1996). Incidence of Achilles tendon rupture. Acta Orthopaedica Scandanavia, 67(3), 277-279.
9. Wapner, L. K. (1999). Achilles tendon ruptures and posterior heel pain. In: Kelikian AS (Ed). Operative treatment of the foot and ankle. Stanford, Connecticut; Appleton & Lange. P369-387.
10. Jozsa, L., Balint, J. B., Kannus, P., et al. (1989). Distribution of blood groups in patients with tendon rupture. An analysis of 832 cases. The Journal of Bone & Joint Surgery Br, 71(2), 272-274.
11. Kujala, U. M., Jarvinen, M., Natri, A., Lehto, M., et al. (1992). ABO blood groups and musculoskeletal injuries. Injury, 23(2), 131-133.
12. Nilsson-Helander, K., Thurin, A., Karlsson, J. & Eriksson, B. I. (2009). High incidence of deep vein thrombosis after Achilles tendon rupture: a prospective study. Knee Surgery, Sports Traumatology, Arthroscopy, 17(10), 1234-1238.
13. Kinner, B., Seemann, M., Roll, C., Schlumberger, A. et al. (2009). Sports and activities after Achilles tendon injury of the recreational athlete. Sportverletz Sportschaden, 23(4), 210-216.
14. Parekh, S. G., Wray III, W. H., Brimmo, O., Sennett, B. J. et al. (2009). Epidemiology and outcomes of Achilles tendon ruptures in the National Football League. Foot & Ankle Specialist, 2(6), 267-270.

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