Fracture-Dislocation of the Thoracic Spine in Extension by Upright Seats in Severe Rear Crashes ProBiomechanics LLC

Format:

Conference/Event

Author/Creator:

Viano, Viano, author.

Conference Name:

SAE 2011 World Congress & Exhibition (2011-04-12 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2011

Summary:

Purpose: This study presents cases of fracture-dislocation ofthe thoracic spine in extension during severe rear impacts. Themechanism of injury was investigated.Methods: Four crashes were investigated where alap-shoulder-belted, front-seat occupant experiencedfracture-dislocation of the thoracic spine and paraplegia in asevere rear impact. Police, investigator and medical records werereviewed, the vehicle was inspected and the seat detrimmed. Vehicledynamics, occupant kinematics and injury mechanisms were determinedin this case study.Results: Each case involved a lap-shoulder-belted occupant in ahigh retention seat with 1,700 Nm moment or 5.5 kN strength forrearward loading. The crashes were offset rear impacts with 40-56km/h delta V involving under-ride or override by the impactingvehicle and yaw of the struck vehicle. In each case, theoccupant's pelvis was restrained on the seat by the openperimeter frame of the seatback and lap belt. The rear loadingcaused the head, neck and upper body to displace off the side ortop of the seatback. The seatback frame acted like a fulcrum as theunsupported head and upper body was accelerated forward causingextension of the spine around the seatback frame as the head andshoulders moved rearward of the frame. In each case, there wasfracture-dislocation of the thoracic spine in extension with spinalcord injury resulting in paraplegia. Two occupants were overweightand two were obese, which increased inertial loads on thespine.Conclusions: High retention seats have improved safety ofoccupants in rear crashes, but there are situations where the upperbody becomes unsupported in a severe rear crash. This can lead toextension loads on the spine causing fracture-dislocation, spinalcord injury and paraplegia. Injury is a result of the strong seatframe remaining upright, the lap belt holding the pelvis on theseat and the upper body moving off the seatback concentrating loadon the thoracic spine. The seatback frame acts like a fulcrumresulting in fracture-dislocation of the spine in extension

Notes:

Vendor supplied data

Publisher Number:

2011-01-0274

Access Restriction:

Restricted for use by site license