Why don’t chimps sprain their ankles?

26th September 2016

In the lead up to our ‘Sporting Ankle’ course on the 25^th and 26^th November 2016, we are focusing our next few blogs on the foot and ankle region. We hope that this introduces some of the themes that will be covered on the course and re-enforces the importance of refining clinical skills in this interesting and challenging area of sports medicine.

Many athletes (and some practitioners) still regard ankle sprains as simple injuries requiring little more than some ice, a few painkillers and a wobble board. In a recent study, the average time for athletes to return to sport post ankle sprain was just 3 days!(1) Way, way too soon and a premature return to sport is just one of the reasons why many athletes fail to recover fully after ankle sprain. Figures consistently show that in the year post ankle sprain, at least 1 in 5 athletes will develop chronic ankle instability, a clinical condition characterised by long term pain, complaints of weakness, giving way and re-injury. There are further sequelae however and according to a recent consensus paper from the International Ankle Consortium,(2, 3) ankle sprains can often have a long term and deleterious impact on our physical activity levels and health-related quality of life.

Food for thought – but the area that intrigues me most, is the sheer number of ankle sprains that occur in physically active people each year. They comprise 3-5% of patients attending Emergency Departments in the UK,(4) equating to around 1-1.5 million visits each year. A large review of epidemiological data in sports (5) also shows that ankle sprains are consistently the most common injury occurring in court and field based sports. With further evidence that around 85% of ankle sprains involve the lateral ligament complex, it seems that the anterior talofibular ligament is one of the most commonly injured structures in an athlete’s body. A design fault if ever there was! But perhaps it wasn’t always like this?

Although I have no actual evidence (as epidemiology isn’t that old), I would bet that the prevalence of ankle sprains was much lower in early humans. This was because 3 million years ago (or longer depending on what you read), we had a number of novel anatomical traits including: abducting toes, grasping feet and long muscle/tendon units crossing the ankle joint with distal attachments on the forefoot. Each of these anatomical traits contributed to a very stable foot and ankle system (albeit with less capacity for forward propulsion).

The shift to bipedalism, was therefore only possible through a number of ‘stepped’ changes to our anatomy and function. We now have a non-grasping foot, limited capacity for toe abduction, and a decreased base of support. Perhaps the most important evolutionary change was that the subtalar joint axis gradually moved closer to the long axis of the foot. Indeed, some say that the medial twist in our talus, bony torsion at our lateral 4 metatarsals, and the general ‘twisted plate’ appearance of our feet are remnants of this change. The long tendons, such as fibularis longus now attach more proximally (at our midfoot) leaving us with less capacity to generate internal pronation moments (vs external supination moments associated with lateral ankle injury). A related limitation is that most of the long tendons crossing our ankle demonstrate a frontal plane dominance; this means that if (or when) we catch the outside of our foot playing sport (creating an adduction moment on the foot), we have less stability in the transverse plane. Just look at how much foot adduction is occurring below!!!

As well as being twisted, our talus is now also asymmetric from back to front (fatter at the front); this needs to be accommodated and we do this by having: a mobile joint between our tibia and fibula (our ankle syndesmosis); and a weaker and more compliant lateral ligament complex. Moving to bipedalism also means that our feet and ankles need to multitask, acting as both mobile adaptors and rigid levers. Switching between these roles numerous times during the gait and running cycle automatically creates an additional neuromuscular challenge. Finally, and to top things off, we have moved from barefoot, straight line running on softer surfaces; to shod (slightly plantar flexed), dynamic, multidirectional movements on a hard high traction surfaces. The corollary is a perfect (biomechanical) storm for lateral ligament injury.

 Injury epidemiology and functional anatomy are just some of the engaging themes that Dr Chris Bleakley and Simon Harland will cover on ‘The Sporting Ankle’ course. RE:PLAY Clinic, Belfast on 25 and 26^th November 2016. The Sporting Ankle course is innovative, practical and is informed by contemporary clinical research. It will be delivered through formal lectures and practical skills training. By the end of the course, attendees will have enhanced anatomical knowledge, core assessment skills, manual and taping techniques relevant to the ankle region. The tutors will also use a series of clinical vignettes to develop diagnostic decision making and rehabilitation prescription, for common sporting injuries at the ankle complex.

Throughout the course, Chris and Simon will cover the following topics:

• Ankle anatomy: From talar geometrics to surface palpation
• Ankle joint biomechanics and the forgotten joints (subtalar/talonavicular, and calcaneocuboid)
• Clinical assessment: evidence based techniques and clinical pearls
• Manual therapy and taping techniques: What’s new? What works?
• Rehabilitation: Lateral Ankle Sprain/ High Ankle Sprain/ Chronic Ankle Instability
• Ankle injury mechanisms in sport: Prevention Strategies
• Dealing with insidious onset problems and the difficult ankle. Case studies will be used to cover:
  (a) medial ankle pain;
  (b) lateral ankle pain;
  (c) nerve entrapment

1. Medina McKeon JM, Bush HM, Reed A, Whittington A, Uhl TL, McKeon PO. Return-to-play probabilities following new versus recurrent ankle sprains in high school athletes. J Sci Med Sport. 2014;17(1):23-8.
2. Gribble PA, Bleakley CM, Caulfield BM, Docherty CL, Fourchet F, Fong DT, et al. 2016 consensus statement of the International Ankle Consortium: prevalence, impact and long-term consequences of lateral ankle sprains. Br J Sports Med. 2016.
3. Gribble PA, Bleakley CM, Caulfield BM, Docherty CL, Fourchet F, Fong DT, et al. Evidence review for the 2016 International Ankle Consortium consensus statement on the prevalence, impact and long-term consequences of lateral ankle sprains. Br J Sports Med. 2016.
4. Lamb SE, Marsh JL, Hutton JL, Nakash R, Cooke MW, Group) CASTC. Mechanical supports for acute, severe ankle sprain: a pragmatic, multicentre, randomised controlled trial. Lancet. 2009;373(9663):575-81.
5. Doherty C, Delahunt E, Caulfield B, Hertel J, Ryan J, Bleakley C. The incidence and prevalence of ankle sprain injury: a systematic review and meta-analysis of prospective epidemiological studies. Sports Med. 2014;44(1):123-40.