CF 175: Car Crashes And Awesome Research To Go Along With It Today we’re going to talk about car wreck research and it’s pretty cool. Especially if you treat PI patients and you ever find yourself testifying. I’m going to give you a couple of caveman clubs that you can use to figuratively bash a rabid attorney with.  But first, here’s that sweet sweet bumper music.

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OK, we are back and you have found the Chiropractic Forward Podcast where we are making evidence-based chiropractic fun, profitable, and accessible while we make you and your patients better all the way around.  We’re the fun kind of research. Not the stuffy, high-brow kind of research. We’re research talk over a couple of beers. I’m Dr. Jeff Williams and I’m your host for the Chiropractic Forward podcast.   If you haven’t yet I have a few things you should do. 

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You have found yourself smack dab in the middle of Episode #175 Now if you missed last week’s episode , we talked about ow back disability and osteoarthritis research. Make sure you don’t miss that info. Keep up with the class. 

On the personal end of things…..

We hired a nurse practitioner. I have to say that there are so many scary talented and scary smart people out there in the world, folks. We got to meet several of them while going through the interview process. If everyone comes out of school highly trained, it’s hard to use that as a measuring stick.  So, I fell back to my core need; which was to hire a good person. It wouldn’t be helpful to hire someone that would come in and feel superior to everyone else in the office. It wouldn’t be helpful to hire someone highly trained but they don’t treat my staff with respect and even love. That would kill office culture dead in its tracks and I like my office culture. 

I tease my staff. I tease my patients. They tease me back. I love the atmosphere. I don’t want to hire a stick in the mud. So I didn’t. When it comes down to it, you can train everything that needs to be trained. But you can’t make a miserable person a good person. You can’t make an introvert an extrovert. You can’t make someone that has a sense of entitlement into someone that is full of gratitude.  You just can’t do it. I think the one we hired is the closest of all that we interviewed to me and who I am and how I carry myself.

He’s new so there won’t be any bad habits. He’s eager to learn. I love that. I’m afraid I’m not the best teacher but we’re going to do it anyway! So, that’s my big news this week, the NP is on and this train is rolling down the tracks now.  Now, I’m going to tell you that here in Texas, masks are no longer mandated. Not even in the schools. So, as you might imagine, if COVID were still a huge concern here, there would be people piling up in the hospitals.

There aren’t. In fact, your hospital load just continues to dwindle. We are in an area of about 275,000 people or so. And the last number I saw last week was that we added 15 new cases that day.  That’s with kids going to school and interacting with each other. In BIG schools. When you go to a restaurant, the places are packed with people. I’m telling you, here in Texas, there is no ‘new normal’. There is the old normal.

You’d never even know that anything was ever different for a year, honestly.  Yet, numbers are continuing to go down. So, why are other states back on the rise? What does it all mean? Has Texas reached herd immunity through infections and vaccines? Maybe. Texas has been a problem state for COVID for months until more recently.  I don’t know all of the answers. But what I feel is that the states that are still on serious lockdown are doing their population an injustice when you compare them to Texas. If their kids aren’t in school, they should be. They’re doing more damage than good from what I can tell. At this point anyway. 

Trust me, I’ve been all about being safe and smart and taking care of each other. Especially those most at risk. But, at this point, everyone that wants to be vaccinated in my area is vaccinated. At this point, in my state, if you get sick, it’s because you chose to risk it. Plain and simple.  Alright, let’s dive in. But first, I want to drop in a word about our amazing sponsors and give you a way to save a little money. 


This podcast episode was inspired by a recent episode of the Chiropractic Science podcast hosted by Dean Smith. His guest was Dr. Michael Freeman who I’ll talk about here in just a minute. These papers are papers they talked about on that episode so, if you want it from the horse’s mouth, go over to Chiropractic Science and find the recent episode with Dr. Michael Freeman and hit play. Then come back here and get my take on it. 

Item #1

This one is called “Is Acceleration a Valid Proxy for Injury Risk in Minimal Damage Traffic Crashes? A Comparative Review of Volunteer, ADL and Real-World Studies” by Nolet, et. al. (Nolet PS 2021) published in International Journal of Environmental Research and Public Health in March of 2021 and I can’t even….wouldn’t even try to touch it…..

Why They Did It

Let me preface this by saying that Dr. Michael Freeman is an author on this paper and he’s just a phenomenal asset to chiropractic, health in general, and personal injury research. If you aren’t familiar with Dr. Freeman, we’re talking about the fact that he’s a DC, an MD, and Ph.D. and a whole bunch of other stuff one single person has any business being.  Also on this paper is Dr. Art Croft. I have the advanced certification through Dr. Croft’s SPINE Institute in San Diego and I have to tell you that he’s one of the most impressive individuals I’ve ever personally met.  In the paper, they say, “Injury claims associated with minimal damage rear impact traffic crashes are often defended using a “biomechanical approach,” in which the occupant forces of the crash are compared to the forces of activities of daily living (ADLs), resulting in the conclusion that the risk of injury from the crash is the same as for ADLs.” 

To put that in me and you talk…..what they’re saying is that it’s common in court for attorneys to say that being in a 5mph low-speed rear impact is similar in force to just stepping off of a sidewalk curb. Or some other ridiculous analogy like that.  They go on to say, “The purpose of the present investigation is to evaluate the scientific validity of the central operating premise of the biomechanical approach to injury causation; that occupant acceleration is a scientifically valid proxy for injury risk.”

To put that in me and you talk…..they just want to see if common every day events are truly like a low-speed rear impact car wreck. 

How They Did It

  • Data were abstracted, pooled, and compared from three categories of published literature: 
      1. Volunteer rear-impact crash testing studies, 
      2. ADL studies, and 
      3. Observational studies of real-world rear impacts. 
    • We compared the occupant accelerations of minimal or no damage (i.e., 3 to 11 kph speed change or “delta-V”) (2 mph up to 7 mph. ) rear-impact crash tests to the accelerations described in 6 of the most commonly reported ADLs in the reviewed studies. 
    • As a final step, the injury risk observed in real-world crashes was compared to the results of the pooled crash test and ADL analyses, controlling for delta-V.
    • OK in me and you speak, Delta V just means the change in speed that was experienced. Anytime you are in a wreck, you essentially go from one speed to another in a millisecond. That’s not conceptually, that’s literally. Delta V helps to describe that change in speed. 

What They Found

  • The results of the analyses indicated that average peak acceleration forces observed at the head during rear impact crash tests were typically at least several times greater than average forces observed during activities of daily living.
  • In contrast, the injury risk of real-world minimal damage rear impact crashes was estimated to be at least 2000 times greater than for any activities of daily living. So defense attorneys can stick that in their hat and smoke it up twice.

Wrap It Up

The results of our analysis indicate that the principle underlying the biomechanical injury causation approach, that occupant acceleration is a proxy for injury risk, is scientifically invalid. The biomechanical approach to injury causation in minimal damage crashes invariably results in the vast underestimation of the actual risk of such crashes and should be discontinued as it is a scientifically invalid practice. That also seems like a mic drop if the attorney pulls it out and uses it in a case. And should be appropriately accompanied by superhero comic noises like

Slap! Pow! Snap! Kazaam! Fwaaaap!! I love it.

Item #2

Item #2 is called “Estimating the number of traffic crash-related cervical spine injuries in the United States; An analysis and comparison of national crash and hospital data” by Michael Freeman and Wendy Leith (Freeman MD 2020) and published in Accident Analysis And Prevention in July of 2020 and that’s still got some steam to it. 

Why They Did It

In the intro, they say, “Cervical spine injury is a common result of traffic crashes, and such injuries range in severity from minor (i.e. sprain/strain) to moderate (intervertebral disk derangement) to serious and greater (fractures, dislocations, and spinal cord injuries). There are currently no reliable estimates of the number of crash-related spine injuries occurring in the US annually, although several publications have used national crash injury samples as a basis for estimating the frequency of both cervical and lumbar spinal disk injuries occurring in lower speed rear impact crashes.”

In me and you speak, they’re saying that many defense attorneys want to use estimates on neck injury and severity prevalence from national databases but it doesn’t make sense to do it that way and you can’t use these databases as a proper defense in a court case.  They say the purpose is, “To develop a reliable estimate of the number of various types of cervical spine injuries occurring in the US by comparing data from national crash injury to national hospital emergency departments and inpatient samples.”

Well, that makes sense to me….let’s see how it came out. 

How They Did It

Comparative cross-sectional METHODS: Cervical spine injury data were accessed, analyzed, and compared from 3 national databases; the 

    1. National Automotive Sampling System-Crashworthiness Data System (NASS-CDS), 
    2. Nationwide Emergency Department Sample (NEDS), and the 
    3. Nationwide Inpatient Sample (NIS).

What They Found

  • It is estimated that there are approximately 869,000 traffic crash-related cervical spine injuries seen in hospitals in the US annually, including around 
      • 841,000 sprain/strain (whiplash) injuries, 
      • 2800 spinal disk injuries, 
      • 23,500 fractures, 
      • 2800 spinal cord injuries, and 
      • 1500 dislocations.
  • Because of highly restrictive inclusion criteria for both crash and injury types, as well as a very small sample size, the NASS-CDS underestimated all types of crash-related cervical spine injuries seen in US hospital emergency departments by 84 %
  • The injury type with the largest degree of underestimation in the NASS-CDS was cervical disk injuries, which were estimated at an 88 % lower frequency than in the Nationwide Emergency Department Sample
  • National insurance claim data, which include cases of cervical disk injury diagnosed both in and outside of the ED, indicate that the Nationwide Emergency Department Sample likely undercounts cervical disk injuries by 92 %, and thus the NASS-CDS correspondingly undercounts such injuries by 99 % or more.

Do you see why it’s so good to have people like Dr. Michael Freeman and Dr. Art Croft on our side? Holy smokes. Who else is out there putting attorneys in their place like these folks have done for years?

Wrap It Up

They end it by saying “Because of a limited sample size and restrictive criteria for both crash and injury inclusion, the NASS-CDS cannot be used to estimate the number of crash-related spinal injuries of any type or severity in the US. The most inappropriate use of the database is for estimating the number of spinal injuries resulting from low-speed rear impact collisions, as the NASS-CDS samples fewer than 1 in 100,000 of the cervical spine injuries of any type occurring in low-speed rear impact collisions.” Smack, Kowapow, Thunk! As I said, I love this kind of research. I remember Dr. Croft speaking about being an expert and attorneys starting to come at him and how he was able to just draw them out into deeper water before putting ‘em under!! I love it. 

Alright, that’s it. Y’all be safe. Keep changing our profession from your little corner of the world. Keep taking care of yourselves and everyone around you. Tough times are upon us but, the sun will shine again. Trust it, believe it, count on it.

Let’s get to the message. Same as it is every week. 

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The Message

I want you to know with absolute certainty that when Chiropractic is at its best, you can’t beat the risk vs reward ratio because spinal pain is primarily a movement-related pain and typically responds better to movement-related treatment rather than chemical treatments like pills and shots. When compared to the traditional medical model, research and clinical experience show us patients can get good to excellent results for headaches, neck pain, back pain, and joint pain to name just a few. It’s safe and cost-effective can decrease surgeries & disability and we do it through conservative, non-surgical means with minimal hassle to the patient. And, if the patient treats preventatively after initial recovery, we can usually keep it that way while raising the overall level of health!

Key Point: At the end of the day, patients should have the guarantee of having the best treatment that offers the least harm. When it comes to non-complicated musculoskeletal complaints…. That’s Chiropractic! Contact Send us an email at dr dot williams at and let us know what you think of our show and tell us your suggestions for future episodes.  Feedback and constructive criticism is a blessing and so are subscribes and excellent reviews on podcast platforms.  We know how this works by now. If you value something, you have to share it, interact with it, review it, talk about it from time to time, and actively hit a few buttons to support it here and there when asked. It really does make a big difference. 

Connect We can’t wait to connect with you again next week. From the Chiropractic Forward Podcast flight deck, this is Dr. Jeff Williams saying upward, onward, and forward.


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About the Author & Host Dr. Jeff Williams – Fellow of the International Academy of Neuromusculoskeletal Medicine – Chiropractor in Amarillo, TX, Chiropractic Advocate, Author, Entrepreneur, Educator, Businessman, Marketer, and Healthcare Blogger & Vlogger    


Freeman MD, L. W. (2020). “Estimating the number of traffic crash-related cervical spine injuries in the United States; An analysis and comparison of national crash and hospital data.” Accid Anal Prev 142(105571).  

Nolet PS, N. L., Kristman VL, Croft AC, Zeegers MP, Freeman MD, (2021). “Is Acceleration a Valid Proxy for Injury Risk in Minimal Damage Traffic Crashes? A Comparative Review of Volunteer, ADL and Real-World Studies.” Int J Environ Res Public Health 18(6): 2901.      

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