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Shaw Chiropractic New Low Velocity Biomechanics Video Several months ago Tom Szabo and Judd Welcher released a video demonstrating the effects of low speed rear end collisions (LOSRIC). You may recall that Tom Szabo is one of the leading researchers in the field of injury biomechanics and spoke at our Hartford seminar in December 1998. The new video is designed for courtroom presentations and demonstrates the effects of LOSRIC on human occupant exposed to ÎVs from 1-5 mph. The data from the crash tests were recorded using accelerometers placed on the vehicle and several parts of the occupant including head, neck and torso. G forces were recorded in the X, Y and Z axis. Below you will find the crash data in graphic format and my interpretation of the findings.
The above graph demonstrates the delay in acceleration between different body parts. Note that the vehicle accelerates before the occupant. This is followed by the lumbar spine, thorax and head. The significance of this is that the different onsets of acceleration result in shearing forces known to cause injury.
This representation of a Î5mph crash graphs the X (front and back) and Y (up and down) accelerations. The data reveals that at the same time as shear (X) occurs in the cervical spine at 8Gs the compression force (Z) of the spine is taking place at 16Gs. Under compression, the discs narrow allowing for laxity of the spinal motor unit and greater shear damage to the disc and facet joints.
This graph represents the head accelerations as it relates to ÎV. At a ÎV of 4mph there is are 8Gs and at ÎV of 5mph there are 17Gs. These accelerations are certainly far above injury thresholds contrary to insurance industry arguments. It also shows that the ÎV to G relationship is not linear. In other words, a ÎV of 5mph is far more that 5 times the acceleration of a ÎV of 1 (1.5G vs 18G)
This graph clearly demonstrates that the head and neck are moving in opposite directions within the same plane at the same time compounding both compression and shear forces. Much more can be extrapolated from this
data but suffice to say that it clearly
demonstrates the injury potential of LOSRIC.
It is important to keep in mind that this
data is collected in a controlled environment
with a properly positioned aware occupant
who is belted and otherwise healthy. If
any of these controls are changed one
could reasonably expect far greater injury
potential. Since it is rare that our patients/clients
are representative the Aperfect@ subject
we should discuss these variable subsequent
to presenting the video. |
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