Air jackets ‘unlikely to prevent eventing fatalities’

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Might legislation ultimately prove necessary in the push to improve rider safety? © Jane Thompson
© Jane Thompson

A British study into eventing safety has found that air jackets are unlikely to prevent a fatality should a horse fall directly on a rider, but the risk of severe chest injury was lessened by 13%.

Similar to the airbag in a car, air jackets are designed to inflate and offer protection when the rider falls from a horse. But their effectiveness at protecting against injuries from a horse falling on a rider is less well understood. In recent years, questions have been asked about the potential for air jackets to prevent serious injuries and fatalities, with many calling for air jackets to be made compulsory.

In research funded by British Eventing, scientists at the Transport Research Laboratory (TRL) looked into the effectiveness of air jackets in protecting riders from crush injuries and also to help understand the forces involved which may help identify better ways to safeguard riders.

A series of controlled tests were performed at the equestrian surgical facility at the Bristol Veterinary School, using both the BETA 2009 Level 3 horse rider body-and shoulder protector that is currently mandatory for cross-country events, and also an existing air jacket.

Tests involved dropping an equine cadaver onto a Hybrid III crash test dummy in both scenarios and measuring the chest deflection, which is a standard measure used to predict the risk of serious chest injury.

Such injuries could include: minor laceration of the aorta, major laceration of other major chest arteries or an unstable rib cage following multiple rib and sternum fractures, leading to suffocation if not treated promptly.

© Adam Wynne
© Adam Wynne

The horse cadaver was sourced from a rescue centre and was euthanised by the Bristol Veterinary School for medical reasons before the tests, as part of the facility’s normal operations.

The drop height was 1.2m above ground level and the pre-mortem mass of the horse was 487kg.

The dummy was supported on a matrix of 123 load cells in order to measure the forces applied by the horse and provide data that could be used to develop a horse surrogate for future testing.

The tests showed that the air jacket slightly reduced the compression of the dummy’s chest and subsequently the predicted risk of severe chest injury fell from 94% to 81%. This means that it could have a beneficial effect in reducing the likelihood of severe injury from a horse falling on a rider.

However, there is still a high probability of riders sustaining a severe injury, even when wearing the air jacket.

One element not measured in the study was whether the air jacket protects the rider in the initial ground contact before crush loading from the horse.

If so, then there could be a benefit in that the horse would be less likely to land on an injured, and therefore weakened, rib cage. This may particularly be the case with partial crush loading, where the horse doesn’t fall as directly or severely on to the rider as investigated in the study.

David Hynd, Head of Biomechanics at TRL, reflects on the company’s recent study:  “Over recent years there have been a number of fatalities resulting from horses falling on riders during the cross-country phase at events.

“BE figures reveal that between July 2013 and June 2014, there were 45 falls on British Eventing cross-country courses in which the horse was caused to somersault by the way in which it impacted the fence.

“Not only can these falls put the rider at risk from injury when hitting the ground, but in the worst case scenario they can result in the horse falling on the rider involved, causing death or serious injury.  In fact, in 2013/14, 16 of these falls resulted in serious injuries and one tragically resulted in a fatality.”

Improving safety of riders has been high on the agenda for a number of years, and as with other biomechanical areas, TRL research has played a prominent part in any improvements.

The latest research study revealed that while air jackets may have some safety benefits, fatal and serious injuries are still highly likely to occur should a horse fall directly on to a rider.

Although the results provide an initial indication of the effectiveness of air jackets, there are a several areas that require further exploration.

"Overall, we found enormous potential for reducing horse-related risk through the risk management strategy of mitigation," the researchers said. © Mike Bain
© Mike Bain

The dummy used in the tests represented the average height and weight of a 45 year old male, so results may vary for riders of different statures and ages.

For example, risks may be slightly lower for younger riders, but substantially higher for older riders, due to the fact that bone condition changes with age.

So there may be combinations of loading condition and rider for which this design of jacket is unable to offer meaningful protection.

It should also be remembered that these tests involved one loading condition, with a relatively low drop height.

The exemplar horse cadaver was also relatively light in comparison with a typical eventing horse; a heavier horse or greater fall height would be expected to increase the risk of severe chest injury.

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