Neck Injuries in Rear-End Car Collisions: Sites and Biomechanical Causes of the Injuries, Test Methods and Preventive Measures

This work addresses the problem of neck injuries following rear-end car collisions. Biomechanics and sites of the injuries have been investigated. A new dummy neck has been developed and used to study the influence of different seat properties on occupant kinematics.

Anaesthetised pigs were exposed to swift extension-flexion motions of the cervical spine. Pressure pulses in the central nervous system with magnitudes of up to about 150 mmHg (20 kPa) were registered during these neck motions. These pressure magnitudes seem to depend on the velocity and direction of the angular motion between adjacent vertebrae. Injuries to the spinal ganglia, particularly in the lower cervical region were found at histopathological examination. These injuries could explain many of the symptoms that are typical for patients with an AIS 1 neck injury sustained in rear-end collisions. The measured pressures are believed to be a possible cause of these injuries.

In order to enable better assessment of the neck motion during staged rear-end collisions at low impact-velocities (<20 km/h), a new dummy-neck was developed. It consists of seven cervical and two thoracic vertebrae connected by pin-joints. Data from volunteer tests found in the literature were used for validation.

A Hybrid III-dummy equipped with the new dummy-neck was used in two series of rear-end collision sled tests at 5 km/h and 12.5 km/h pre-impact sled-velocity. The horizontal head to head-restraint gap proved to have the largest influence on the head-neck motion during the impact. The maximum head-torso displacement increased with increasing head to head-restraint gap. An increased stiffness of the seat-back frame resulted in slightly increased maximum head-torso displacement, but in combination with a stiffening of the lower seat-back cushion and deeper upper seat-back cushion, the result was a clear reduction of the head-torso displacement. The results indicate that minor changes to existing car-seats might radically improve the protection against neck injuries in rear-end collisions.

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Year	Entry
1998	Lundell B, Jakobsson L, Alfredsson B, Jernström C, Isaksson-Hellman I. Guidelines for and the design of a car seat concept for improved protection against neck injuries in rear end car impacts. In: Proceedings of the SAE International Congress & Exposition. February 23-26, 1998; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 980301.
1998	Wiklund K, Larsson H. Saab active head restraint (SAHR): seat design to reduce the risk of neck injuries in rear impacts. In: Proceedings of the SAE International Congress & Exposition. February 23-26, 1998; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 980297.
2001	Linder A, Olsson T, Truedsson N, Morris A, Fildes B, Sparke L. Dynamic performances of different seat designs for low to medium velocity rear impact. In: 45th Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). September 24-26, 2001; San Antonio, TX.
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1996	Thunnissen JGM, van Ratingen MR, Beusenberg MC, Janssen EG. A dummy neck for low severity rear impacts. In: Proceedings of the 15th International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 13-16, 1996; Melbourne, Australia.1665-1678.
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Year

Entry

1998

Lundell B, Jakobsson L, Alfredsson B, Jernström C, Isaksson-Hellman I. Guidelines for and the design of a car seat concept for improved protection against neck injuries in rear end car impacts. In: Proceedings of the SAE International Congress & Exposition. February 23-26, 1998; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 980301.

1998

Wiklund K, Larsson H. Saab active head restraint (SAHR): seat design to reduce the risk of neck injuries in rear impacts. In: Proceedings of the SAE International Congress & Exposition. February 23-26, 1998; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 980297.

2001

Linder A, Olsson T, Truedsson N, Morris A, Fildes B, Sparke L. Dynamic performances of different seat designs for low to medium velocity rear impact. In: 45th Annual Proceedings, Association for the Advancement of Automotive Medicine (AAAM). September 24-26, 2001; San Antonio, TX.

1994

Nilson G, Svensson MY, Lövsund P, Häland Y, Wiklund K. Rear-end collisions: the effect of the seat-belt and the crash pulse on occupant motion. In: Proceedings of the 14th International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 23-26, 1994; Munich, Germany.1630-1639.

1996

Thunnissen JGM, van Ratingen MR, Beusenberg MC, Janssen EG. A dummy neck for low severity rear impacts. In: Proceedings of the 15th International Technical Conference on the Enhanced Safety of Vehicles (ESV). May 13-16, 1996; Melbourne, Australia.1665-1678.