Neck injuries in car collisions — a review covering a possible injury mechanism and the development of a new rear-impact dummy Mats Y. Svensson a,*, Ola Bostrom b, Johan Davidsson a, Hans-Arne Hansson c, ¨ b Yngve Haland , Per Lovsund a, Anders Suneson d, Anette Saljo c ˚ ¨ ¨ ¨ Crash Safety Di6ision, Chalmers Uni6ersity of Technology, SE-412 96 Goteborg, Sweden ¨ b Autoli6, Research, SE-447 83 Vargarda, Sweden ˚ ˚ c Department of Anatomy and Cell Biology, Uni6ersity of Gothenburg, SE-413 90 Goteborg, Sweden ¨ d Di6ision of Human Sciences, FOA Defence Research Establishment, SE-172 90 Sundbyberg, Sweden Accepted 21 July 1999 a
Abstract A review of a few Swedish research projects on soft tissue neck injuries in car collisions is presented together with some new results. Efforts to determine neck injury mechanisms was based on a hypothesis stating that injuries to the nerve root region in the cervical spine are a result of transient pressure gradients in the spinal canal during rapid neck bending. In experimental neck trauma research on animals, pressure gradients were observed and indications of nerve cell membrane dysfunction were found in the cervical spinal ganglia. The experiments covered neck extension, ﬂexion and lateral bending. A theoretical model in which ﬂuid ﬂow was predicted to cause the transient pressure gradients was developed and a neck injury criterion based on Navier-Stokes Equations was applied on the ﬂow model. The theory behind the Neck Injury Criterion indicates that the neck injury occurs early on in the rearward motion of the head relative to the torso in a rear-end collision. Thus the relative horizontal acceleration and velocity between the head and the torso should be restricted during the early head-neck motion to avoid neck injury. A Bio-ﬁdelic Rear Impact Dummy (BioRID) was developed in several steps and validated against volunteer test results. The new dummy was partly based on the Hybrid III dummy. It had a new articulated spine with curvature and range of motion resembling that of a human being. A new crash dummy and a neck injury criterion will be very important components in a future rear-impact crash test procedure. © 2000 Elsevier Science Ltd. All rights reserved. Keywords: Whiplash; Neck injury; Rear impact; Crash dummy; Spinal ganglia; Pig
1. Introduction The symptoms of injury following neck trauma in rear-end collisions include pain, weakness or abnormal responses in the parts of the body (mainly the neck, shoulders and upper back) that are connected to the central nervous system via the cervical nerve-roots. Vision disorder, dizziness, headaches, unconsciousness, and neurological symptoms in the upper extremities are other symptoms that have been reported (Deans et al., 1987; Hildingsson, 1991; Nygren et al., 1985; Spitzer et * Corresponding author. Tel.: + 46-31-7723644; fax: + 46-317723660. E-mail address: email@example.com (M.Y. Svensson)
al., 1995; Watkinson et al., 1991). The symptoms associated with soft-tissue neck injuries in frontal and side collisions appear to be very similar to those of rear-end collisions (Hildingsson, 1991). During a rear-end car collision the struck vehicle is subjected to a forceful forward acceleration and the car occupant is pushed forward by the seat-back. The head lags behind due to its inertia, forcing the neck into a swift extension motion. In a later phase, the head moves forward relative to the torso and may stop with a somewhat ﬂexed neck posture. This head and neck motion, commonly called ‘whiplash motion’, has been described by Ono and Kanno (1993) among others. The term ‘whiplash’ has also been used in the literature for the neck motion in frontal and side collisions.
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