Mild traumatic brain injury (more commonly known as concussion) presents a growing concern both within sports and throughout society. Forensic biomechanics experts are often asked to determine the likelihood that a specific head impact could have resulted in concussion. In a great number of cases, the main concern focuses on whether or not the likelihood of injury would have been sufficiently reduced if the injured person had been wearing a helmet at the time of the incident.
Research has demonstrated that helmets are effective at reducing the biomechanical severity of a head impact. Helmets reduce the severity of an impact primarily by absorbing force in its outer shell and other materials that are between the impact surface and the head of the person wearing the helmet. By absorbing the impact, the helmet increases the duration over which the impact occurs, and subsequently decreases the maximum force and acceleration imparted to the head of the person wearing the helmet. Recent biomechanical research has been able to relate the magnitude of acceleration experienced during an impact to the probability that a person could sustain a concussion from that impact.
Do all helmets have similar performance?
There are several standards (e.g. CSA Z262.1-15 for hockey helmets, CSA Z263.1-14 for recreational alpine skiing and snowboarding helmets) that describe the testing and minimum performance capabilities of helmets during impact. However, findings from several biomechanical studies have demonstrated that no two helmets perform in a similar manner when it comes to protecting the head. A report from a recent study conducted on hockey helmets by researchers at Virginia Tech in the United States found that there was no relationship between a hockey helmet’s cost and its protective capabilities.
How is an assessment of helmet efficacy conducted?
First, the biomechanics expert must determine the severity of the impact in the subject incident. Often this will require a reconstruction of the incident, and include a review of medical documentation to identify specific trauma endured by the injured person. Once the reconstruction has been completed, the biomechanics expert would be able to use either published data or their own data collected from a mock scenario of the subject incident using exemplar helmets to determine the difference in severity if a helmet had been worn by the injured person. In these cases, it is important to obtain a range for the difference in severity from multiple tests or sources. The reduction in biomechanical severity should be compared against published injury thresholds to determine if the helmet would have provided sufficient protection if worn during the incident.
The Snell Memorial Foundation website is a useful resource for those wishing to obtain tips for selecting a helmet and more information on helmet testing, safety standards, and certification.
| Dr. Samuel Howarth is a biomechanics expert for Pario Engineering and Environmental Science. He uses the latest knowledge in biomechanics to assess human dynamics, injury mechanisms, and injury thresholds for injuries resulting from sporting activities, occupational activities, motor vehicle accidents, and slip/trip and fall incidents. Pario is also able to conduct lab-based biomechanical testing for specific claims. For more information, or to arrange for a presentation or demonstration please contact Dr. Samuel Howarth (T: 289 795-3655, E: samuel.howarth@pariosciences.ca). |