Dynamic Chiropractic – January 15, 2010, Vol. 28, Issue 02
Study Confirms Flaws in Standard MVC Defense Strategy
By Arthur Croft, DC, MS, MPH, FACO
The seemingly complex, or perhaps even inscrutable, calculus of what practitioners term personal injury is, in truth, deceptively simple. However, while it keeps getting simpler, many practitioners and lawyers feel hopelessly wrapped around the axle of this puzzling system. The net result is abandonment of needful patients and clients, with a corresponding loss of revenue stream. Consider just a few facts. Motor vehicle collisions are a leading cause of injury in the U.S. and constitute one of our most burdensome public health dilemmas. With 3 million such injuries each year, a total recovery proportion of only about 50 percent, a permanent disability proportion of 10-12 percent, coupled with the fact that many of the injured are young and have many quality life years to lose, the $43 billion annual price tag is hardly surprising.1
Auto insurers make every reasonable effort to insulate themselves from their liability. Some would argue that they engage in efforts most of us would consider unreasonable, if not downright unsavory or unethical. Regardless of your personal judgment, most would agree that over the past two decades, the insurers’ concerted and very expensive campaign to limit claims has been fairly successful.
With Allstate taking the vanguard position with their now-famous three Ds – delay, deny, and defend – most major auto insurers have since instituted similar policies, and the plaintiff persona-injury bar has more often withered than weathered. With a loss of potential legal representation, plaintiffs have had fewer alternatives for compensation. This often has meant that needed health care resources are simply not available to them, which contributes further to the doleful outcome statistics mentioned above. Since inaugurating its get-tough policy in the mid-1990s, which was described by its consulting firm as a transition “from good hands to boxing gloves,” Allstate has reportedly posted surprising high profits.2 Other insurers have not failed to notice.
The Standard Defense and the Importance of Delta V
How could any of this possibly be simple? One need look no further than the essential game plan of most defense lawyers: deception, dissimilation and obfuscation. It requires a team of experts from the fields of medicine (including chiropractic), accident reconstruction and biomechanics who have collectively developed what I consider to be the standard defense strategy. It continues to be the most successful and widely used strategy today, having become the world standard.
This has fostered a small research industry dedicated to the production of pro-defense literature to aid in the cause. Most is junk science. Make no mistake, insurers have the best researchers money can buy and they know how to get published. As a result, even many clinicians remain split on critical issues depending on which brand of literature they rely upon. I note, with all due respect to the Insurance Institute for Highways Safety (IIHS) and members of the International Insurance Whiplash Protection Group (IIWPG), that their research activities are quite laudatory and most welcome. However, there is just a bit of schizophrenia in this industry when it comes to research. While the valid research of the IIHS and the IIWPG is squarely aimed at reducing the industry payout problem by reducing the number of actual injuries, the “other” research seems to be aimed at providing verisimilitude for company experts to wield in courtrooms to sway jurors toward defense theories.
The standard defense has three parts and is based on the ultimate playing field: a court of law, and, in particular, the biases and naivete (i.e., the normal lack of specific factual information in the field of crash traumatology) of jurors. Polls suggest that Americans are also divided on the question of whiplash injuries. As many as 60-70 percent consider it either definitively or very likely a non-injury, but merely an opportunity to bilk insurers at the expense of the rest of us policy-holders who subsidize the system through the increasing premiums we must pay. Thus, jurors are easily misled by the standard defense strategy because it merely reinforces that which they already believe.
The first and most fundamental part of this strategy is to demonstrate that the forces of the collision would not have been of a sufficient magnitude to cause injury. The common currency for this discussion is the plaintiff vehicle’s delta V or change in velocity. For this, an accident reconstructionist is usually employed. Because reconstructionists are rarely allowed to provide opinions as to injury risk, they are often followed by a biomechanist, who is granted more latitude to venture into the discussion of injury risk. In some cases, they are allowed to consider medical records, MRIs, etc., in forming their opinions. Finally, the defense physician (DC, DO or MD) adds the icing to the cake, testifying that either there was no injury or that there was a minor straining-type injury that has long since resolved.
When pre-existing conditions are present, the plaintiff’s complaints are often attributed to them rather than the injury. Company doctors will typically also be of the opinion that a large portion of the medical expenses claimed by the plaintiff are unnecessary, unreasonable,and represent unwarranted treatment and diagnostics. Note that low back injuries are virtually never admitted to be causally related to low-velocity collisions. I have written a paper on this subject which is available upon e-mail request at email@example.com .3
As I have so many times implored readers – and this fact is never contested even by my small army of industry-affiliated detractors – the entire defense mechanism just described is nothing more than a series of interlocking nonsequiturs. The accident reconstructions and biomechanists provide a very polished and seemingly airtight argument based on what appear to be sound mathematical principles and classical Newtonian physics. This is all very interesting, and would be even more so if it had the additional virtue of being true.
Delta V Not a Valid Gauge of Injury Risk?
But figures don’t always add up, which brings me back to the headline of this article. A new study that provides further compelling evidence that delta V, the keystone in the standard defense strategy, is not a valid gauge of injury risk.4 The authors recruited a total of 57 people within 48 hours of their MVCs. The subjects were recruited either from an engineer’s office for vehicle damage assessment or an ER. The whiplash grades ranged from 0-4 (0 indicating no claimed injury and 4 indicating fracture). The collision types included 13 frontal, 21 rear, 19 side, three multiple crashes and one rollover. There were 25 males and 32 females with a median age of 33.
In all cases a trained engineer determined the delta V by examining both crash vehicles. The VAS and Neck Disability Indexes (NDI) scores were tabulated. The authors found no significant correlation between NDI and delta V, no correlation between whiplash grade and delta V, and only a moderate correlation between VAS reported pain and delta V. However, the R2 value (coefficient of determination) for that correlation was only 0.30, which means that 70 percent of the proportion of the variability of pain severity was not explained by differences in delta V.
There was no lower threshold below which a large proportion would predictably not be injured, nor was there an upper threshold above which most would predictably be injured. This was because some people were injured in very low velocity crashes while others were not injured despite fairly high velocity crashes. The authors commented, “It can be concluded that delta V is an irrelevant predictive value for cervical spine injury after MVA [motor vehicle accident].”
Some specific findings include the following: Cervical spine fractures in frontal crashes occurred in delta Vs of 9.3, 19.9 and 31.1 mph. Fractures in side impacts occurred in delta Vs of 6.2 (z-joint fracture of C4), 9.9 (C7 with dislocation of C6-7), 19.9 (z-joint fracture of C2), 31.1 (C5 fracture with C5-6 dislocation and paraplegia), 32.3 (rupture of alar ligaments), 36.0 (atlantoaxial dislocation) and 36.6 mph (rupture of alar ligaments). There was a dens fracture in the one rollover with the delta V reported as 9.3 mph. This article is available for free download at www.ncbi.nlm.nih.gov/pmc/articles/PMC2657117.
A related component of the standard defense strategy is the property damage issue. Specifically, the argument goes, when the property damage is minor, an injury is very unlikely. We addressed this issue earlier in a meta-analysis of medical and engineering literature dating back as far as 1970 that failed to provide a clear link between property damage and any of three outcomes: risk for acute injury, degree of injury severity and risk for long-term symptoms.5 As I always caution readers, this lack of correlation considers the genre of collisions producing property damage that would be described as minor or non-severe. Clearly, when crash severity increases beyond this, there is an increased risk for injury or death.
A related interesting paper by Viano and Parenteau demonstrated that more than 60 percent of the National Automotive Sampling System case database for rear impacts are for crashes with delta Vs of under 15 mph. They noted, “In very low speed crashes, advanced age, stenosis and degeneration of the cervical spinal canal can lead to spinal cord injury and paralysis in crashes otherwise not causing injury in normal adults.”6 I would also note that it has been demonstrated rather conclusively that human variables (i.e., risk factors) are more determinative vis-a-vis injury risk than crash metrics in the lower crash-severity range.
In the end, when essential parts of the foundation of the defense strategy are tested, they repeatedly fail to hold up to the scrutiny of hard science. In a court of law, however, if the plaintiff and their experts cannot effectively present the real facts and rebut the junk science, 12 impressionable jurors will decide the outcome of the case based on their perception of the soundness of the arguments they heard. The simple fact is that more often than not, the plaintiff and their witnesses are simply not adequately prepared. Knowledge is power and information is the currency of success.
Zaloshnja E, Miller T, Council F, Persaud B. Comprehensive and human capital crash costs by maximum police-reported injury severity within selected crash types. Annu Proc Assoc Adv Automot Med, 2004;48:251-63.
Berardinelli DJ. From Good Hands to Boxing Gloves: The Dark Side of Insurance. Portland: Trial Guides, LLC, 2008.
Croft AC. Low back injuries in low velocity rear impact collisions. Forum, 2009;39(4):33-7.
Elbel M, Kramer M, Huber-Lang M, et al. Deceleration during “real life” motor vehicle collisions: a sensitive predictor for the risk of sustaining a cervical spine injury? Patient Saf Surg, 2009;3(1):5.
Croft AC, Freeman MD. Correlating crash severity with injury risk, injury severity, and long-term symptoms in low velocity motor vehicle collisions. Medical Science Monitor, 2005;11(10):RA316-21.
Viano DC, Parenteau CS. Serious injury in very low and very high speed rear impacts. SAE, 2008;2008-01-1485.
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