How Injuries Occur

The cause of Accidents

The risk & safety industry uses a phenomenon known as the Swiss Cheese Effect to describe how accidents occur. Imagine you've got 5 slices of Swiss cheese ( all with holes in them and each hole representing an accident risk factor). If you stack the slices together to make one super-thick slice, you then can see if the holes line up. If the holes from all 5 slices line up, then your super-thick slice has a clear hole going through it – the equivalent of an accident occurring in risk & safety terms. If only 3 or 4 of the holes line up,  then no complete hole ( accident ) occurs.

This is often used to describe the cause of aeroplane crashes: in rare cases it is one huge event that proves detrimental e.g. a bomb on board , but in most cases it is 3 or 4 factors superimposed on each other that culminate in the crash. Each factor on its own wouldn’t cause the crash, but when added to all the others, the crash occurs. This shows how even low-risk factors can be detrimental if added to larger ones.

History and Buddhism

The Swiss Cheese effect also occurs we take when we take a look at large historical events, like World War 1. While the catalyst was the assassination of Archduke Franz Ferdinand of Serbia, the other ‘causes’ ( according to chat GPT - ( the last time I studied history was in the 1980s!) were the following: 1) militarism 2) alliances 3) imperialism and 4) nationalism. If one of these four causative factors did not exist, then WW1 would not have occurred at that time in that way.

This interacting-effects model also happens to be a tenet of Buddhism in explaining how things come to exist (Stay with me, I'll get to the injuries...!). When I was first learning to meditate, the Buddhist meditation teacher explained how the chair we sat on didn’t just come into being and exist, but that each was the result of a complex interaction of events that unfolded: the forest where the tree grew, the climate in that forest, the men who cut it down, the mode of delivery, how the wood was stored or treated, the person who sold it onwards, the skill of the carpenter, all the carpenters who had taught him his skill, the individual taste of the person who bought it, the person who placed it in the room. If any of these steps had not occurred, then each chair would not be exactly the one that we were sitting on. 

How Injuries Occur:

And so it is with injuries. This was never stressed in my training, but the longer I worked as a physio the more I observed that this interaction of factors was also at play in how injuries occur. The truth is that while injuries CAN occur because of a single event e.g a car crash and there may also be a catalyst that SEEMS like the cause, most injuries occur because a series of factors interact and cause it to evolve.  Let’s look at some examples using back, neck and knee pain.

Here’s a list of some of the common factors, that I come across and search for, in patients whose pain comes on ‘for no reason’ i.e. no recent injury to explain it. In most cases, I find 3-5 factors have interacted to cause the pain. As a physio, if I eliminate two or three factors, the pain usually goes ( I remove the hole in some of the slices of Swiss Cheese). However, if I want to future-proof the person and prevent recurrence, I try to address all of the risk factors that I can.

Have a look:

Back pain	Neck Pain	Knee Pain
Weak back muscles	Poor posture	Genetics –  arthritis runs in the family
Job sitting a lot	Poor desk set up	Old injury to knee
Sedentary lifestyle	Stress or emotional upset	Wear and tear  (if over 40)
Previous injury to back	Weak neck muscles	Hypermobility
Childbirth and pregnancy	Hypermobility, clicky neck	Flat feet
Job doing a lot of bending	Previous neck injury	Job spent squatting or kneeling a lot
Hip or knee injuries	Longstanding back pain	Pro-inflammatory diet
Long back (greater leverage)	Weak back muscles	Weak hip and back muscles
Genetic factors	Weak shoulder and shoulder blade muscles	Injury to hip or feet
High BMI (weight)	Genetic factors	Weakness hamstrings or Quads
Fatigue or illness	Pro-inflammatory diet	Fatigue or stress
Hypermobility	Sedentary life-style	High BMI (weight)
Wear and tear	Fatigue	Too much exercise too soon
Pro-inflammatory diet	Wear and tear	Sports: soccer is very hard on the knees; contact sports
Stress	Sports: front row rugby for example!	Poor walking or running mechanics

Not only does this model of interacting factors explain how injuries occur, it also explains how totally different interventions work for similar people with apparently the same condition.

 Here's an example: Two similarly overweight individuals get knee-cap pain after doing a 10k walk. Mary has been sick and put up 2 stone in the past year and was trying to get back some fitness when she did the 10k. Peter, on the other hand, has always been overweight and regularly does 10k walks. He did, however have a minor fall onto his knee about 6 months ago. In Mary’s case, my advice is going to center around losing her extra weight and being more gradual in her approach to fitness, whereas with Peter I am more likely to go looking for scar tissue left over from his fall and has begun affecting his walking mechanics. Make sense?

Gut health, stress and unfairness!

Note from my table above that diet can affect things like joint pain. FINALLY gut health is having its day in the sun, with lots of research emerging about potential causes for chronic diseases and illnesses and explaining how dietary changes can impact inflammatory joint pain. You will also notice that stress and tiredness impact your likelihood of getting all injuries. Period. (Take stress seriously my friends and while you're at it, go read my blogs on relaxation and fatigue)!

 If we accept that Swiss Cheese effect is at play in causing injuries and that the very same injury can have very different contributing factors in two individuals, we can now see how making dietary changes or reducing stress makes a huge impact to pain for some people ( because these were amongst their causative factors) but not for others in whom it wasn't a contributor at all. Or why that fancy office chair made was the answer to somebody's neck pain, but made someone else's pain worse. For us physios, it also explains why making changes to back posture can make a massive change for a patient's back pain while their best friend has the worst posture in the world but hasn’t a pain or an ache in sight!

 Widening things out a bit, it also explains why someone can smoke their head off for 60 years with no ill-effects ( their genetic risk was incredibly low) despite the fact that for half of all smokers, it will cause most definitely be a major cause in their death.

The complexities of research

In my opinion, the  Swiss Cheese Effect is also the reason why it can be super-hard for some research methods to show the real-life impact of risk factors on injuries. A lot of research is designed to look for a cause-and-effect using ONE factor, but the truth is that many risk factors aren’t strong enough to cause an injury ON THEIR OWN and so they get dismissed as statistically insignificant. They only become active when added to other risk factors. It also leads to some research findings that are counter-intuitive: my favourite example is the study that proves that poor shoulder posture does NOT cause shoulder pain, and yet every physio worth their salt addresses postural issues because our daily experience shows that it IS a cause of pain WHEN ADDED TO OTHER FACTORS.

We recently saw this Swiss Cheese in our lymphoedema research and it was class! ( I’ll tell you all about my nomogram for predicting arm lymphoedema in a future post…)

So there you go, this is the theory I go by for the genesis of injuries. Next time you get an injury, look for a few factors and don't just pin it on one thing. Remember that to get a sustained and long-term result from a physio programme, you need to get rid of ALL or most of your contributing factors and not just finish when your pain is gone ( we're not just trying to get more money out of you!)

By the way, you can have hours of fun with this theory. In my year of Thankfulness, I used to sometimes think of that lovely cup of coffee  that I was thankful for and of all the people involved in the steps to bring it to my mouth: the person who tilled the land and grew the beans, the person who picked them, the delivery truck drivers, those that mined the petrol to run the delivery trucks (!), the person who bought the beans, the airline pilot who flew the plane that transported it to Ireland, the persons who designed and built the plane, the coffee shop owner, the barista, the waitress….all the people involved in bringing me that one cup of coffee….mind-blowing really. And you thought it was just you and the barista involved…..!

By the way, I got a serious craving for Swiss Cheese while writing this and had to go out and but some to put on my poached egg. Yum.

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