Session VIII - Pediatrics/Spine

*Presentation of a New Type of Side-Airbag System to Prevent Head and Neck Injuries

Oliver Pieske, MD; Günter Lob, MD; Wolfgang Lange, Dipl.-Ing.; Georg Messner, Dipl.-Ing.; Peter Bauer, MD; Josef Haberl, Dipl.-Physiker, Ludwig Maximilians University, Munich, Germany (all authors - a-BMW Group)

Purpose: Seventy-seven percent of all severe traumatic brain injuries (GCS < 8 for more than 6 hours) are caused by traffic accidents. Our analysis of more than 1,000 real world car accidents over more than a decade has determined a head injury occurence of approximately 60% in side impacts (SI) compared to 35% in frontal collisions. Severe cervical spine injuries occur in SI because of hyperlateral flexion and/or axial spinal compression. To provide meaningful head and spine protection especially in SI, a new type of head-side airbag, the Head Protection System (HPS), was developed with our medical support by an automotive manufacturer.

Methods: In order to achieve head restraint without any form of reaction support being available, the airbag must be highly stable. This stability is lacking in conventional airbag systems unless the force-input vector coincides precisely with the mounting point. In the HPS system the structural factor is achieved by clamping the unit with a force of up to 5 kN diagonally between its 2 attachment points: the lower part of the a-pillar and behind the top of the b-pillar. This high axial force is easily able to withstand the resulting lateral forces. The ideal cushion thickness has proved to be a diameter of 120 to 150 mm. When inflated, it fills the gap between the shoulder and head.

To evaluate the effectiveness of HPS, worst-case SI tests with dummy occupants were carried out both with and without HPS. Test vehicles were impacted into a rigid pole (diameter, 250 mm) with a speed of 20 MPH in accordance with a draft test procedure developed by ISO (ISO/CC22/SC10/WG3/N121). The centerline of the rigid pole was aligned with the center of gravity of the dummy's head.

Results: The tests demonstrated that the HPS reduces the Head Injury Criterion (HIC) from 4,700 to 650, significantly far below the critical HIC of 1000. High-speed videos of the crash configuration documented an effective reduction of hyperlateral flexion of the cervical spine. The cervical axial compression force could be reduced from 6.5 kN to 1.6 kN.

Discussion: The unique HPS reduces loading on the dummy´head and cervical spine in a worst-case SI test configuration. In real-world SI, we can also expect a reduction of injuries in these anatomical regions.

Conclusion: The interdisciplinary cooperation of trauma surgeons and automotive manufacturer can result in effective injury prevention to fulfill our basic rule: to prevent is better than to cure.