Whiplash: 28.35 grams (1oz) of Prevention is worth a 0.453 kgs (1 lbs) of Cure

Happy 2011, folks.  It seems another holiday season has come and gone but winter is going nowhere fast...  Snow, ice, frigid temperatures, dead batteries, window scraping, slippery streets, and fender benders - all things Manitobans have become used to as part of our daily lives.  I don't have any good advice for avoiding the trials and tribulations of winter, however, I may be able to help you avoid the injuries caused by the fender benders and collisions that seem to be so common in Manitoba during our long winter season.  Having completed the Whiplash and Brain Injury Traumatology program with the Spine Research Institute of San Diego, these injuries, and their prevention, are of particular interest for me.

First of all, when I say fender bender I mean car accident or, as it is sometimes called, a motor vehicle collision or MVC.  It used to be called a motor vehicle accident (MVA), but it was felt that 'accident' referred to something unavoidable so the term was changed to collision.  Makes sense to me, I guess. 

There are many types of MVC's, the most common being the low speed rear impact collision (LoSRIC) or, as we know it, the rear-end fender bender.  This can happen at places like stop lights, stop signs, in traffic, and in parking lots and can occur at as little as 10km/hr or about the speed of a person running (Castro, et al., 1997).  Actually, it is not the speed that matters as much as the change in velocity (speed and direction), scientists call this delta-v.  When a moving car stops very quickly (for example by hitting another car) or when a stopped car moves very rapidly (for example by being hit by another car) the difference between the velocity before impact and the velocity after impact is the delta-v. The greater the change in velocity, or delta-v, the greater the risk of injury.

When this happens, a complex series very rapid movements occur in the spine that create a significant risk of an injury called WHIPLASH.  The term healthcare providers use for whiplash is Whiplash Associated Disorder (WAD) or Cervical Acceleration-Deceleration disorder (CAD) - not particularly clever names, but I'm just thankful they are not in Latin. To help prevent this type of injury, it is important to know how it happens.  Whiplash is caused by a rapid speeding up (acceleration) and stopping (deceleration) of the head and neck (cervical), followed by a reversal of the movement.  Although the neck is the most common area injured, other spinal areas may also be involved.  If one is rear-ended a series of events happen in the spine.

First, as the collision occurs the person is pushed back in their seat.  The occupants foot may come off the brake pedal, which further increases the acceleration of the rear-ended car.  As the seat becomes more stiff and stops the occupants upper back, their head and neck slide back, the torso lifts up compressing the spine, then the neck tilts back very quickly.  The further back the head and neck go, the greater the likelihood of injury.  These very rapid movements - they occur in under a second - will stretch tissues in the front of the neck and compress tissues in the back of the neck.

Then the movements reverse, the head is pressed down on the neck, again compressing the spine, then the body is propelled forward followed by a 'whip-like' motion of the head and neck as they are flung forward and down.  This compresses the structures in the front of the neck and stretches the structures at the back of the neck.

It is the extent and speed of these movements that is associated with the degree of injury.  By minimizing these movements we can significantly decrease the risk of injury.  So, you're probably wondering, "How do we do that?"

Well, there are a few things we can do.  Although wearing your seat belt won't prevent whiplash, it does prevent more serious injuries, including fatalities.  Step one, every time, should be ALWAYS WEAR YOUR SEAT BELT!



The middle of your head should be
 at or near the bottom of the
blue zone



The next important thing to consider is the 'backset', or the distance from the back of the occupants head to the head restraint. Backset is one of the most critical elements in whiplash (Zuby & Lund, 2010; Ivancic, et al., 2009).  It is extremely important to set your head restraint properly.  Notice I said head restraint, not head rest - it is not to rest your head on but to restrain your head in the event of a collision. To set it properly, raise the restraint until the head restraint is at or above the top of the head.  If your seat is leaning back quite a bit, you may also notice your head is poked forward and away from the restraint.  Ensure your seat back is up enough so that your head is as close as possible to the head restraint.

If your car is equipped with a head restraint that can be brought forward, make sure it is about 2cm from the back of your head.  By properly setting your head restraint, you will decrease the movement of your head and neck in the event of a rear-end crash.

Here are two examples of the way to set your head restraint if you've always wanted whiplash...

     

...and here are the correct ways to set your head restraint if you'd rather just avoid whiplash altogether

      

Here's kind of what I just said in a short clip...

A myth I often hear is, "If you're going to be in an accident, go limp so you don't get injured".  We've all heard this one. The problem with this is that when you 'go limp' your neck structures are allowed to move a lot further and more freely - not a good thing in the case of whiplash.  A better strategy, believe it or not, is to look straight forward and tighten up as much as possible before the collision.  This decreases the amount of head and neck movement and your chances of getting whiplash.

Now, we don't always see it coming so we may not be able to prepare ourselves for the impact.  If we decrease the change in velocity (delta-v) we will also decrease the risk of injury.  One way to do this is to keep you foot firmly on the brake when at a stop.  If your foot is lightly on the brake it is more likely to come off the pedal during the collision, thus speeding up more, then slam back on the pedal afterward, thus slowing down more.  This will increase the delta-v and your risk of injury.  Keeping your foot firmly on the brake will help prevent this. 



In this same line of thinking, good winter tires will prevent sliding more than all season radials or worn out tires.  Good tires will keep you from speeding up too much when hit from behind as well as stop sooner to help prevent the crash in the first place.  Make sure you pay attention to wear the rubber hits the road.

Finally, if you are in the market for a new car, pay attention to the safety details.  They may not seem important when compared to the colour or interior fabrics and quadraphonic sound of the stereo, but believe me, if you are in a collision you will appreciate the safety elements more than the new car smell.



The adjustability of the head restraint is important.  When evaluating head restraints in a new car, you should ask yourself, "can this head restraint be adjusted to decrease the amount of backset?"  Here is a rule of thumb: backset (head to restraint distance) should ideally be about 2cm and never above 8cm (Ivancic, et al., 2009) - the less the backset distance, the greater your protection from whiplash.

As well, many new cars are designing anti-whiplash seating systems and head restraints.  Be sure to keep this in mind when considering a new car purchase.  Here are some things to think about...

Remember, everything I've mentioned applies to the driver AND the passengers, including children.  Back seat head restraints and child seat restraints are just as important (some may even say more important) as the driver's head restraint.

However, sometimes despite our best efforts things happen.  If you are in a motor vehicle collision and are having problems - don't suffer with the pain - Chiropractic can help...

Spectrum Health Centre

677 Portage Ave.,

Winnipeg, MB R3G 0M5

(204) 772-7700

We are open Monday to Friday from 7:30am to 5pm, and Saturdays 9am to 1pm.

Be Safe, Be Happy, Be Healthy