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Viano D.C.,ProBiomechanics LLC | Withnall C.,Biokinetics and Associates Ltd. | Wonnacott M.,Biokinetics and Associates Ltd.
Annals of Biomedical Engineering | Year: 2012

The potential for mouthguards to change the risk of concussion was studied in football helmet impacts. The Hybrid III head was modified with an articulating mandible, dentition, and compliant temporomandibular joints (TMJ). It was instrumented for triaxial head acceleration and triaxial force at the TMJs and upper dentition. Mandible force and displacement were validated against cadaver impacts to the chin. In phase 1, one of five mouthguards significantly lowered HIC in 6.7 m/s impacts (p = 0.025) from the no mouthguard condition but not in 9.5 m/s tests. In phase 2, eight mouthguards increased HIC from +1 to +17% in facemask impacts that loaded the chinstraps and mandible; one was statistically higher (p = 0.018). Peak head acceleration was +1 to +15% higher with six mouthguards and 2-3% lower with two others. The differences were not statistically significant. Five of eight mouthguards significantly reduced forces on the upper dentition by 40.8-63.9%. Mouthguards tested in this study with the Hybrid III articulating mandible lowered forces on the dentition and TMJ, but generally did not influence HIC or concussion risks. © 2011 Biomedical Engineering Society. Source

Viano D.C.,ProBiomechanics LLC | Halstead D.,University of Tennessee at Knoxville | Halstead D.,Southern Impact Research Center
Annals of Biomedical Engineering | Year: 2012

Linear impactor tests were conducted on football helmets from the 1970s-1980s to complement recently reported tests on 1990s and 2010s helmets. Helmets were placed on the Hybrid III head with an array of accelerometers to determine translational and rotational acceleration. Impacts were at four sites on the helmet shell at 3.6-11.2 m/s. The four generations of helmets show a continuous improvement in response from bare head impacts in terms of Head Injury Criterion (HIC), peak head acceleration and peak rotational acceleration. Helmets of 2010s weigh 1.95 ± 0.2 kg and are 2.7 times heavier than 1970s designs. They are also 4.3 cm longer, 7.6 cm higher, and 4.9 cm wider. The extra size and weight allow the use of energy absorbing padding that lowers forces in helmet impacts. For frontal impacts at 7.4 m/s, the four best performing 2010s helmets have HIC of 148 ± 23 compared to 179 ± 42 for the 1990s baseline, 231 ± 27 for the 1980s, 253 ± 22 for the 1970s helmets, and 354 ± 3 for the bare head. The additional size and padding of the best 2010s helmets provide superior attenuation of impact forces in normal play and in conditions associated with concussion than helmets of the 1970s-1990s. © 2011 Biomedical Engineering Society. Source

Viano D.C.,ProBiomechanics LLC
SAE Technical Papers | Year: 2011

Purpose: This study presents cases of fracture-dislocation of the thoracic spine in extension during severe rear impacts. The mechanism of injury was investigated. Methods: Four crashes were investigated where a lap-shoulder belted, front-seat occupant experienced fracture-dislocation of the thoracic spine and paraplegia in a severe rear impact. Police, investigator and medical records were reviewed, the vehicle was inspected and the seat detrimmed. Vehicle dynamics, occupant kinematics and injury mechanisms were determined in this case study. Results: Each case involved a lap-shoulder belted occupant in a high retention seat with >1,700 Nm moment or >5.5 kN strength for rearward loading. The crashes were offset rear impacts with 40-56 km/h delta V involving under-ride or over-ride by the impacting vehicle and yaw of the struck vehicle. In each case, the occupant's pelvis was restrained on the seat by the open perimeter frame of the seatback and lap belt. The rear loading caused the head, neck and upper body to displace off the side or top of the seatback. The seatback frame acted like a fulcrum as the unsupported head and upper body was accelerated forward causing extension of the spine around the seatback frame as the head and shoulders moved rearward of the frame. In each case, there was fracture-dislocation of the thoracic spine in extension with spinal cord injury resulting in paraplegia. Two occupants were overweight and two were obese, which increased inertial loads on the spine. Conclusions: High retention seats have improved safety of occupants in rear crashes, but there are situations where the upper body becomes unsupported in a severe rear crash. This can lead to extension loads on the spine causing fracture-dislocation, spinal cord injury and paraplegia. Injury is a result of the strong seat frame remaining upright, the lap belt holding the pelvis on the seat and the upper body moving off the seatback concentrating load on the thoracic spine. The seatback frame acts like a fulcrum resulting in fracture-dislocation of the spine in extension. Copyright © 2011 SAE International. Source

Viano D.C.,ProBiomechanics LLC | Parenteau C.S.,ProBiomechanics LLC
Traffic Injury Prevention | Year: 2010

Purpose: This study investigated injury risks in frontal crashes by belt use and crash severity (delta V) with a focus on studying whether there is a pattern to the crashes causing serious head injuries in low-speed frontal collisions. Methods: 1996-2007 National Automotive Sample System-Crashworthiness Data System (NASS-CDS) was analyzed for frontal crashes involving front-outboard occupants. Light vehicles were included with model year 1997+. Injuries of maximum severity MAIS 0-6 and fatalities were determined by crash severity and belt. Body region injury (AIS 0-6) was also determined. NASS-CDS electronic cases involving lt;15 mph crashes were evaluated to determine the crash circumstances causing serious head injury (AIS 3+) in occupants with overall severe injuries (MAIS 4+F). Results: More than half (51.3%) of belted occupants in 10-15 mph delta V crashes were uninjured compared with 30.2 percent for unbelted occupants. The ratio of the fraction (relative risk) of belted occupants who were uninjured to the fraction of unbelted, uninjured occupants was highest at 3.74 in the 30-35 mph delta V. For 10-15 mph crashes, 0.40 ± 0.15 percent of unbelted occupants were severely injured (MAIS 4+F) compared to 0.033 ± 0.009 percent for belted occupants. For 30-35 mph crashes, 8.51 ± 2.20 percent of unbelted and 5.83 ± 1.93 percent of belted occupants were severely injured. Overall, seat belt use was 87.4 percent effective in preventing severe injury (MAIS 4+F). The effectiveness decreased with increasing crash severity. The highest relative risk for severe injury of unbelted compared to belted occupants was 12.3 in crashes of 10-15 mph delta V. The relative risk was 8.8 in lt;10 mph crashes. Overall, the relative risk was 8.0 for severe injury (MAIS 4+F) in frontal crashes. 16.5 ± 0.98 percent of unbelted occupants experienced serious (AIS 3-6) injury. This risk was 6.49 times greater than the 2.53 ± 0.10 percent risk with belted occupants. The largest relative risk for serious injury (AIS 3-6) was to the neck (367 times), face (15.5 times) and head (10.2 times). Conclusions: The highest relative risk for severe injury of unbelted occupants was in frontal crashes <15 mph. Most of the crashes involved multiple impacts and air bag deployment in the accident sequence. The use of long fill-time side curtains, additional curtain deployment logic, limited deflation front air bags and broader curtain coverage of the front interior may address these injuries. © 2010 Taylor & Francis Group, LLC. Source

Viano D.C.,ProBiomechanics LLC | Parenteau C.S.,ProBiomechanics LLC
Traffic Injury Prevention | Year: 2010

Purpose: This study investigates the risk of severe-to-fatal injury (Maximum Abbreviated Injury Score, MAIS 4+F) in crashes with two front-seat occupants. It determines the relative risk of injury in the same crash by belt use and seating position. Methods: 1993-2008 NASS-CDS was analyzed for crashes with occupants in both front-outboard seats. The effect of belt use was investigated for the driver and passenger. Light vehicles were included with model year 1990+. Injury severity was subdivided into MAIS 0-2 and 4+F in NASS-CDS to compare no-to-moderate injury with severe-to-fatal injury. Standard errors were calculated in SAS and the z-test was used to determine the significance of differences in risk. Relative risks were determined by seat belt use and seating position; odds ratios were determined for one or both occupants being severely injured. Results: In 76.7 percent of the MAIS 4+F crashes, either the driver (32.4%) or passenger (44.3%) was severely injured, rather than both occupants (23.3%). When both were belted, one occupant was severely injured in 86.5 percent of crashes. When both were unbelted, both occupants were severely injured in 68.9 percent of the crashes. Both occupants were belted in 74.7 percent of the cases and unbelted in 18.6 percent. In 6.7 percent of crashes, either the driver (4.4%) or passenger (2.3%) was unbelted when the other was belted. The highest risk occurred with an unbelted driver and belted passenger (4.98 ± 0.73% vs. 1.97 ± 0.38%, z = 3.65, p <.05). When both occupants were belted, the driver and passenger injury risk was similar (0.459 ± 0.098% vs. 0.449 ± 0.047%, z = 0.10, ns). Conclusions: In crashes with two front occupants, typically one occupant was severely injured, not both. Overall, the odds ratio was 3.28 for one compared to two occupants being severely injured; and, risks vary by seat belt use and seating position. The highest relative risk for unbelted versus belted occupants was 9.22 when both occupants were severely injured in the same crash. © 2010 Taylor & Francis Group, LLC. Source

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