A biomechanical study of intervertebral foraminal narrowing during simulated automotive head-forward and head-turned rear impacts. The objective of this study was to quantify foraminal width, height and area narrowing during head-forward and head-turned rear impacts, and evaluate the potential for nerve root and ganglion impingement. Muscle weakness and paresthesias, documented in whiplash patients, have been associated with neural compression within the cervical intervertebral foramen. Rotated head posture at the time of rear impact has been correlated with increased frequency and severity of chronic radicular symptoms, as compared to facing forward. No studies have quantified dynamic changes in foramen dimensions during head-forward or head-turned rear impacts. Six whole cervical spine specimens with muscle force replication and surrogate head underwent simulated whiplash at 3.5, 5, 6.5 and 8 g, following non-injurious baseline 2 g acceleration. Continuous dynamic foraminal width, height and area narrowing were recorded, and the peaks were determined during each impact and statistically compared to baseline narrowing. During head-forward rear impacts, significant increases (P<0.05) in average peak foraminal width narrowing above baseline were observed at C5-C6 beginning with 3.5 g impact. No significant increases in average peak foraminal height narrowing were observed, while average peak foraminal areas were significantly narrower than baseline at C4-C5 at 3.5, 5 and 6.5 g. During head-turned rear impacts, significant increases (P<0.05) in average peak foraminal width narrowing above baseline of up to 1.8 mm in the left C5-C6 foramen at 8 g were observed. Average peak dynamic foraminal height was significantly narrower than baseline at right C2-C3 foramen at 5 g and 6.5 g, while no significant increases in foraminal area were observed. Extrapolation of the present head-forward rear impact results indicated that the greatest potential for ganglia compression injury was at the lower cervical spine, C5-C6 and C6-C7. The present head-turned rear impact results indicated that the greatest potential ganglia compression injury exists at C5-C6 and C6-C7. Greater potential for ganglia compression injury exists at C3-C4 and C4-C5 due to head-turned rear impact, as compared to head-forward rear impact. Acute ganglia compression may produce a sensitized neural response to repeat compression leading to chronic radiculopathy following head-forward and head-turned rear impacts. Dynamic ganglion or nerve root compression may also lead to chronic radiculopathy.

Whiplash is a neck injury caused by the sudden differential movement between the head and torso. Whiplash injuries are most commonly reported as a consequence of rear impacts in car accidents. They are regarded as minor injuries, but can still lead to long-term disablement and discomfort in the neck. Whiplash injuries can be mitigated by better car seat designs. For this purpose, head restraint geometry must be improved first, and then the dynamic performance of the whole seat must be assessed at all crash seventies. A biofidelic human-body model is a key requirement in designing whiplash mitigating car seats. This thesis presents the development of a 50th percentile male multi-body human model and several energy absorbing car seat designs. The human-body model is specifically designed for rear impact and validated using the responses of seven volunteers from Japanese Automobile Research Institute (JARI) sled tests, which were performed at an impact speed of 8 kph with a rigid seat and without head restraint and seat belt. A generic multi-body car seat model is also developed to implement various seatback and recliner properties, anti-whiplash devices (A WDs) and head restraints. Using the same driving posture and the rigid seat in the JARI sled tests as the basic configuration, several anti-whiplash seats are designed to allow different types of motion for the seatback and seat-pan. The major findings of this research are: -The human-body model simulates the effects of muscle contraction and its overall response is superior in comparison to the currently used models and dummies. -A criterion called the S-shape index (SSI) is developed based on the intervertebral angles of the upper and lower cervical spine. -The car seat design concepts are able to control and use crash energy effectively with the aid of anti-whiplash devices for a wide range of crash seventies. -In order to reduce whiplash injury risk, this study advocates energy absorbing car seats which can also provide head restraint contact as early as possible.

Orientador: Antonio Celso Fonseca de Arruda / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-13T03:10:22Z (GMT). No. of bitstreams: 1 Mariolani_JoseRicardoLenzi_D.pdf: 4176852 bytes, checksum: 167bdeef2aec084118559b01ce0a899c (MD5) Previous issue date: 2009 / Resumo: Milhares de pessoas morrem por ano em todo o mundo em conseqüência da falta de párachoques adequados nas traseiras dos caminhões. Na tentativa de reverter essa situação, iniciou-se um trabalho de cooperação entre UNICAMP, Mercedes-Benz do Brasil e General Motors do Brasil cujos objetivos principais foram os de denunciar a Resolução CONTRAN No. 805/95 como ineficaz, projetar, construir e testar pára-choques confiáveis e apresentar soluções às autoridades governamentais. Para isso sugeriram-se os requisitos mínimos necessários ao projeto de um pára-choque eficaz, o qual deveria idealmente resistir ao impacto de um hipotético veículo "médio" a 50 km/h, projetou-se e construiu-se um pára-choque articulado com base nos requisitos sugeridos e realizaram-se dois crash tests, com o novo pára-choque articulado e com um pára-choque construído de acordo com a Resolução CONTRAN No. 805/95. O pára-choque articulado foi capaz de evitar a penetração do automóvel sob o caminhão, o que não ocorreu com o outro. Os resultados obtidos e os requisitos de projeto sugeridos formaram a base de uma nova norma brasileira referente à matéria, a qual se tornou a Resolução CONTRAN No. 152/03 e introduziu, na data de sua publicação, avanços inéditos em relação à proteção dos ocupantes de passageiros em colisões contra a traseira de caminhões. / Abstract: Because of the lack of effective rear underride guards attached to trucks, trailers and semitrailers, rear underride crashes are responsible for thousands of deaths every year throughout the world. Trying to reverse this situation, cooperative work was started between University of Campinas, Mercedes-Benz do Brasil and General Motors do Brasil, whose main goals were to denounce the Brazilian regulation CONTRAN no. 805/95 as ineffective, to design, construct and test a reliable underride guard and to present solutions to government authorities. To meet these goals, design parameters considered being the minimum essential requirements for effective underride guards, which ideally should be able to resist an impact of a hypothetical "average" car at 50 km/h, have been proposed. A new retractile underride guard has been designed according to the proposed parameters and crash tests have been carried out with the retractile guard and with another constructed according to regulation CONTRAN no. 805/95. The retractile guard could avoid underride, but the other could not. Based on these results and on the proposed design parameters, a new Brazilian standard for rear underride guards has been elaborated. This standard became later the new regulation CONTRAN no. 152/03 and introduced, at the date of issuing, the utmost in safety requirements concerning protection against underride. / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica