Assessing whiplash injury potential

When asked to investigate a rear-end crash, MEA Forensic relied on knowledge drawn from research and testing to assess whether a specific neck injury could have been caused by the crash.

The Event:

A Toyota Corolla stopped at an intersection was rear-ended by a flat deck truck. The female driver was looking left at the time of the impact and experienced headaches and neck, shoulder, and back pain in the days following the crash. The neck and shoulder pain did not resolve and, after undergoing diagnostic medial branch blocks, she was diagnosed with facet joint injuries at multiple levels of her cervical spine. MEA Forensic was asked whether these injuries were caused by the collision.

Our Analysis:

First, our collision reconstruction engineers determined the severity of the crash based on numerous photographs of damage sustained to the rear of the Toyota and to the front of the truck. They compared this damage to that sustained by the same model of vehicle during crash tests we had previously published. This analysis indicated that the Toyota experienced a speed change between 11 and 17 km/h (7 to 11 mph) and peak acceleration between 8 and 17 g during the crash.

Based on this crash severity, our biomechanical engineers assessed how the driver responded and whether the resulting forces could have caused her injuries. Our biomechanical analysis first compared the collision exposure to published field data with known injury outcomes. These field data showed that some individuals reported similar symptoms following a comparable level of crash exposure.

We then quantified the occupant exposure using crash test dummy data from tests we had previously completed and published using the same vehicle. Recognizing that the plaintiff was slightly shorter and lighter than the crash test dummy, we estimated that she experienced a peak forward acceleration at the base of her neck of about 7 to 12 g, a peak head acceleration of 19 to 29 g, and a Neck Injury Criterion (NIC) value—a parameter that evaluates the potential for neck injury—of 11 to 26 m²/s².

The proposed injury threshold for NIC is 15 m²/s², and other published data show that injuries to the cervical spine ligaments begin to appear when the base of the neck is accelerated at more than 5 g. Other MEA Forensic research has also shown that facet joint injuries can occur in some female necks following exposures generated during an 8 km/h speed change.
This comparison between the plaintiff’s exposure and the available tolerance data indicated that her facet joint injury was consistent with her crash exposure. Other factors, including a higher risk of whiplash injury in females and in occupants with their heads turned, further supported the causal relationship between the crash and the injury.

The Results:

Our reconstruction and biomechanical work helped show that the crash experienced by the plaintiff could generate the forces and accelerations associated with her diagnosed injuries. Assuming no other intervening event, we could conclude that the crash probably caused her facet joint injury.

The vehicle in this case matched one of the many vehicles we have previously tested, and allowed us to rely on dummy exposure data from the same vehicle over a range of crash severities that spanned the plaintiff’s exposure. In cases involving vehicles we have not tested, we are often able to find useful data from crash tests performed by others. Also, key in this case was the diagnosis of facet joint injury. In many whiplash injury cases, there is no specific tissue-level diagnosis, and as a result our conclusions may be less specific.

MEA Forensic has conducted numerous industry-leading studies into the biomechanics of whiplash injuries. If you have questions about a case that may involve a whiplash injury, our experts are ready to investigate.

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