Can I get hurt in a car crash with little vehicle damage?

We have spent the last 10 podcasts talking about injuries and what they mean to patients and how we can show causation.  Today I want to talk about MVC’s with minimal damage to the vehicle.  Like I’ve talked about in prior podcasts, I don’t like assumptions that are often used.  I hear there was no damage to the vehicle and therefore there is no way the patient could have been hurt.  I also hear reported that the vehicle was totaled and therefore they were really hurt.  We need to take all aspects of a patient’s MVC, examination and imaging to help determine if this particular patient was hurt.  I really hate when patient’s have obvious injuries and the insurance company denies responsibility due to minimal damage to a vehicle.

Today’s research article was published in the 2001 Orthopedic trauma surgery journal titled Risk factors for long-term treatment of whiplash injury in Japan: analysis of 400 cases by Akihiko Hijjioka et al.  They took 400 patients with whiplash injuries from rear-end collisions.  They screened out all patients with bone lesions or neurological involvement or spinal cord and nerve root involvement.  This study is more specific to patient’s with ligament and muscle tearing, biomechanical changes, disc herniations without nerve involvement and any other whiplash type disorder. 

This study did show that younger patient’s healed more quickly than older patients.   The older patient’s were those 30 or older.  This is an interesting concept to consider.  This shows that younger people statistically need less treatment and this shows that those older than 30 statistically need more time to heal. 

This study showed that patient’s who were admitted to the hospital needed longer treatments than those not admitted.  They showed that people over the age of 30 who were admitted to the hospital needed longer course of care for recovery.  This study showed that not wearing seatbelts also led to more treatment needed.  They also showed that females need more care than males.  We discussed in the first few podcasts ligament damage.  It has been shown that females are more ligament prone than males and this could account for more ligament damage in females.  As we discussed in prior podcasts ligament treatment is complex and is more of an ongoing management and this could account for longer treatment in females. 

One flaw I see in this study is that treatment length was determined by the first treatment until the end of their treatment.  There is no follow up to see if the patients made a full recovery, but just when care was stopped. 

The reason I included today’s study is that they looked at damage done to the vehicle to see if it correlated with how much treatment patients will need.  The assessed vehicle damage on a grade scale of 0-5.  Grade 0 was no damage, grade 1 was slight damage, grade 2 was damage to the bumper, grade 3 was 1/3 of the car was damaged, grade 4 was ½ car damaged and grade 5 was total destruction of the car. 

The results of this study are very interesting.  They showed that patients in group 0, 4 and 5 needed the most treatment.  Groups 1-3 needed less treatment.  Group 0 which was no damage to the vehicle needed that same amount of treatment as group 4 which was the group with ½ of the car damaged.  Group 0 needed more treatment than group 5 that was the total destruction of the car.  The no damage to the vehicle group needed significantly longer amounts of treatment than the grade 1-3 which was slight damage, damage to the bumper and 1/3 of the car damaged. 

On the surface this study may sound strange and not make any sense.  How can people driving the vehicle that has no damage in a collision need more treatment than the people driving vehicles with slight bumper damage all the way up to total destruction of the vehicle? 

I believe this brings up the next flaw in this study and shows the authors bias.  They stated that quote “ this finding suggests that patients in cars that are not damaged might suffer direct forces to the cervical spine or malingering” end quote.  The study results did not show what they expected and the authors reported that maybe these patients were really hurt or maybe they were malingering. 

I believe a closer look at MVCs can help us understand these results.  I believe vehicle have been a part of our lives for a long time and we have grown comfortable with them.  We forget how large these vehicles are.  According to the EPA the average weight of a car is 4,094 lbs. The average weight of a truck is 3-6,000 lbs.  Take a moment to think about how much these vehicles weigh.  Not to mention we can add hundreds of pounds for occupants and thousands of pounds for cargo or trailers.  This mass is certainly capable of creating a lot of energy with even small amounts of movement.  Enough energy to cause serious damage. 

As society gets more used to vehicles we have increased speed limits a lot.  When I was a child the freeway speed limit was 55mph.  Now by my house the speed limit is 70 and then goes to 80mph.  This high speed even with small objects can create a lot of energy.  We wouldn’t want to be hit by a baseball going 70-80mph even though a baseball doesn’t have much mass.  At these high speeds the baseball would be capable of serious injuries. 

It is all about energy.  When was have a large mass like a vehicle and add movement to the mass we have a lot of energy.  So much energy that we have just become accustomed to and don’t give it a second thought.  As we learned from physics this energy can not be destroyed and has to be used.  On a normal day this energy is used to transport us to different locations.  Some of this energy is used with friction.  Some of this energy is used to create sound.  Just think how much energy it would take to push a vehicle by hand and even get going 5mph.  This would be difficult and takes a lot of energy.  This energy would be used quickly to move the large mass a short distance. 

Now think about a MVC.  The built up energy of a vehicle with a large mass traveling at a large speed would be very high.  If we can increase the time it takes to use this energy then the energy will be decreased over time.  Just as it would take a lot of energy to stop a care going 20 mph in 1 feet compared to 100 feet.  The amount of time a collision takes will greatly decrease energy transfer to the vehicle.  This is seen in the equation for acceleration which is the final speed minus the original speed divided by time.  Time being the largest part of the equation.  Similar to if I were to jump off of my roof onto my trampoline.  My final speed would be zero eventually and the original speed would be high given the pull of gravity.  The largest part of the equation would be time.  The time it would take me to come to a complete stop would be a large time if I were to hit the trampoline and the increased time would decrease my injury potential.  Now compare this with jumping off of my roof and landing on concrete.  I would have the same final speed of zero and the same original speed, but the time it would take me to stop would be a lot smaller and my injury potential would be a lot higher.  We need more time in collisions to decrease injury potential. 

Energy that enters a collision has to be used.  If the energy is used in the collision to damage a bumper or the vehicle then this energy will not be used to injure the occupants.  Denting a bumper and destroying a vehicle takes a lot of energy and it takes time.  This energy loss and increase in time of the collision will decrease forces transferred into the occupants.  This will likely be overcome when there is just so much energy that the entire vehicle is destroyed.  Once the entire vehicle is destroyed the remaining energy will transfer to the occupants. 

This is exactly what they saw in the study we went over today.  When there was no damage to the vehicle there was more treatment needed.  Even low speed collisions often involve a lot of mass and a lot of speed which creates a lot of energy.  This energy was not used in damaging the vehicle and lack of damage correlates to shorter collision time and higher energy transfer to patients.  No time spent damaging the vehicle in the collision is similar to me jumping off the roof and landing on concrete.  Time spent damaging the bumper and the vehicle is similar to me jumping off of the roof and landing on a trampoline. 

Hopefully this helps today’s study make sense.  It should make sense when we consider the physics involved in MVCs.  Now keep in mind that this doesn’t mean that all collisions with no damage will cause injuries.  We still need to take each individual patient and do a work up to see if they have injuries and if they are causally related to the MVC.  The power in today’s study is to show that significant injuries are possible when there is no damage to a vehicle. 

Real world

I have a patient that reported never having any symptoms prior to her MVC.  She came in and x-rays showed she has alteration of motion segment integrity or AOMSI.  If you are unsure what AOMSI is please listen to my first few podcasts.  Her x-rays show no degenerative changes and it was clear that this injury was related to recent trauma.  Given the lack of prior symptoms and no prior injuries it was clear that the recent MVC caused the AOMSI injury. 

Her MVC caused very minimal if any damage to her vehicle.  The insurance company fought paying for her injuries for a long time.  They did not argue with the diagnosis.  They did not dispute the lack of degenerative changes seen in her spine.  They did not dispute that AOMSI would lead to degenerative changes in her spine.  They only argued that there is no way she could have been hurt given the lack of damage to her vehicle. 

This can be a scary argument for an attorney to fight.  A final report was written that explained her injuries and how they were new injuries.  They were causally related to the MVC.  I then spent a lot of time discussing research including today’s article.  Then I spent a lot of time discussing physics and how much energy could be transferred in a collision.  Especially a collision with no damage to the vehicle. 

Although this was still a fight with the insurance company the case was able to settle and she was able to get her bills paid and a substantial amount of money for future meds and pain and suffering.  Not everyone who is in a MVC with no damage to the vehicle will be hurt, but some will be.  Today’s study shows it is certainly possible. 

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