Challenging a Biomechanical Expert’s Opinion
When it comes to being in an automobile accident that resulted in little to no damage to the cars involved, it is common practice for the defense attorney to argue that physical injuries are impossible. In these cases, the defense attorney will likely bring in a biomechanical “expert” to further their point.
The biomechanical expert will give their opinion on how the physical force of the car accident could not have caused the victim’s injuries.
The science used by the defense’s biomechanical “expert: ”
A biomechanical expert’s opinion will be based on analyzing the following three things.
1. The force that impacted the vehicles
2. The force that impacted the victim’s body
3. How much of an impact/force can the human body withstand without being injured?
The force of the impact on the vehicles involved in the accident:
Often referred to as “deltaV, ” this is the force of impact on the vehicles involved in the accident. When a stopped vehicle is hit from behind, rear-ended, the impact force accelerates the struck vehicle, going from 0 to “x” miles per hour. The accelerated speed, the velocity, of the struck vehicle is a positive deltaV, and the vehicle that struck the other vehicle loses speed, velocity, and a negative deltaV.
It is the biomechanics expert’s job to calculate the deltaV. They often use software such as CRASH III, a software that they put the accident information such as type of vehicles involved, accident site, and damage to the vehicle. After calculating the deltaV, the expert can calculate the G-force, which is a measurement of the force that impacted the body.
The force of impact to the victims’ body - human dynamics analysis
Once deltaV is calculated, the insurance company expert will then calculate the impact that the deltaV and the G-force had on the people inside the vehicles, the victim in particular.
This calculation is referred to as the analysis of human dynamics. There is also a software used to calculate this. By entering the deltaV and the G-force along with some other data of the accident, the software program will figure out if the accident was the cause of the victim’s injuries. Some of the other data needed for the software are the occupant’s height and weight, stiffness of occupant’s seat, headrest location, and data regarding how occupant was sitting in the vehicle.
Human tolerance values of the accident victim
There are two studies generally referred to by biomechanical experts when deciding if a victim’s injuries were caused by the accident.
“Low speed rear-end collision testing using human subjects” by D. H. West. This study used human volunteers who were exposed to a low-speed rear-end collision with up to and exceeding five mph. West concluded that if the equivalent fixed barrier speed (EBS) of the impact was less than 5 mph, then those forces would not cause injuries any more than everyday activities would cause.
and…
“acceleration Perturbations of a daily living-a comparison to whiplash” by Murray E. Allen.
This was conducted by studying repeated human head accelerations that happened during daily activities.
Consisting of eight volunteers, Allen compared thirteen daily activities with G-force to low-velocity rear-end auto accidents. This study also concludes that a force of low velocity and no damage on impact causes little to no injuries to victims.
When it comes to settlement negotiations and even trials, all that trash you just read is out the window. A lot of attorneys fall for this pseudoscience, and the defense attorneys keep regurgitating the same nonsense repeatedly. This is how I get around all their arguments and still settle minimal or no impact cases:
10 flaws to the biomechanical expert’s theory:
1. Is this a qualified expert in biomechanical engineering?
When an insurance company brings in an expert to determine if a victim’s injuries are as severe as claimed, sometimes the experts can be former police officers qualified to reconstruct an accident scene and calculate the deltaV and G-forces. However, these experts tend to venture outside of their lane of expertise and give their opinions on injuries from a low-impact accident without any credentials as a biomechanical engineer, knowledge of human anatomy, human dynamic, or human tolerance values.
2. Is the expert using the correct data?
A lot of experts will rely on data from the CRASH III software. According to the creator of this software, it was created with data from studying crash tests of over 20 mph deltaV and is made to study collisions of deltaV between 10 to 40 mph.
Making it an improper measuring tool for a low-impact crash which is 5mph.
3. Is the expert using Neptune engineering data software?
Some of the experts brought in by the defendant’s insurance company will rely on data collected by the Neptune engineering data. When deciding if someone’s injuries match the collision, the vehicle stiffness coefficient must be considered, meaning how hard or soft the vehicle is. Different parts of the vehicle being harder than others; the frame is much harder than the bumper.
The Neptune study was conducted on high-speed collisions with a high deltaV. Making its data useless and hold no clout when it comes to a low-speed auto accident.
4. Is the expert relying on the proper measurement of G-force?
There is a point during a collision when the G-force is at its peak, usually at the moment of the impact, and then will recede as the vehicles come to a rest. Sometimes the expert will focus on the average G-force of the accident and entirely bypass the peak G-force, which makes downplaying the victim’s injuries easier.
5. Is the expert focusing on the right G-force?
Often the expert will focus on the G-force on the car that was struck rather than the occupants themselves. The G-force experienced by the people in the vehicle will be a lot higher than the vehicle’s G-force.
6. Has the expert taken the law of physics into account?
One of the laws of physics is that all energy must go somewhere. The defense attorney will say that because the accident did not cause damage to the vehicle, then the occupants in the vehicle must not have been affected by the impact. This is wrong and flawed on so many levels; for one, the energy during an accident can be transferred in more ways than damage to the vehicles, including transferring to the occupants of the vehicle.
7. Is the correct duration of the accident being used?
It is common practice to use a time range of 100-120 milliseconds when calculating the duration of a collision. This is not an accurate representation of the duration of the specific crash in question, which may have happened in a smaller time frame; the shorter the duration, the more significant the impact making an injury hard to calculate using a general range.
8. Is the expert using information from flawed studies?
The studies mentioned earlier done by West and Allen were limited because the subjects used were all reasonably similar. Allen used healthy men and women 4 of each gender between the ages of 19 to 50 years old. At the same time, West used all men from 25 to 43 years of age. Other experts have criticized these studies in the same field for not being broader with subjects and varying situations. Biomechanical engineer Michael Freeman’s study “A review and methodic critique of the literature refuting whiplash syndrome” criticizes the studies done by Allen, West, and other similar studies that defense experts use in settling personal injury cases.
Some of the flaws pointed out by Freeman are:
•An inadequate sample size of subjects
•Insufficient study designs
•Bias in the selection process
•Conclusions not supported by results
•Misquoted literature in studies
•Not representative of real-life crash victims or conditions
9. Is the expert using up-to-date federal bumper standards?
Sometimes the defense expert will rely on Title 49 of the code of federal regulations, part 581. This states that vehicles made from 1974 to 1982 have bumpers front and back that can withstand an impact of up to 5 mph. If there is no damage to the vehicle that was hit during the collision, the defense expert may conclude that deltaV was under 5 mph, and no injuries could have been sustained. This is a big problem since most people have more modern cars whose bumper systems have been designed to sustain an impact up to 10 mph and not receive any damage from the collision.
10. Is the expert using a one-size-fits-all analysis?
There are so many variables involved in an auto accident. Using the studies and software mentioned above do not take these variables into account and use a one-size-fits-all for the auto collision. The defense expert should be questioned when it comes to how they came up with the data that they are using as proof to discredit the victim.
Some things to investigate when it comes to the biomechanics expert opinion:
•The victim: was the victim’s body composition, age, gender, and pre-existing conditions considered?
•Victims body position: what was the victim doing during the point of impact? Were they twisting in their seat, have their head turned, was the victim braced for impact?
These are all factors that need to be considered; different positions could have left the victim more vulnerable to injury.
•What was the seat back and headrest position: the insurance institute for public safety states that slight differences in the vehicle’s adjustment headrest and seat back can make a significant difference during a collision regarding how forceful an impact is on the occupants?
•Seat belt: was the seat belt being appropriately worn based on the occupant’s weight and height?
•Angle and direction: not all rear-end collisions are textbook rear-ends and can occur at different angles and from different directions adding a new dynamic to collision and how the occupants in the vehicle would have been impacted.
•Ramping effect: what is referred to as “ramping effect” is if the occupant’s body moved up or backward during the collision and by doing so may have increased the odds of a cervical injury.
X: These are the X-Factors that always get the biomechanical experts to stop and think:
1.) Did they ever treat the patient?
2.) Do they know or understand the nature of the injuries?
There are so many dynamics and variables in automobile collisions that basing them on flawed studies and not on the facts of your collision is doing a disservice to your case. Do not let the defense biomechanics expert trip you up and second-guess your injuries based on their flawed information. If I had a dollar for every minimal or no impact case I have settled for good money, I would be a millionaire. I always manage to argue through their so-called pseudoscience.