Dynamic vertebral artery elongation during frontal and side impacts.
BACKGROUND
Elongation-induced vertebral artery (VA) injury has been hypothesized to occur during nonphysiological coupled head motions during automobile impacts. Although previous work has investigated VA elongation during head-turned and head-forward rear impacts, no studies have performed similar investigations for frontal or side impacts.


OBJECTIVE
The present study quantified dynamic VA elongations during simulated frontal and side automotive collisions, and compared these data with corresponding physiological limits.


METHODS
In vitro biomechanical study of dynamic VA elongation during simulated impacts.


METHODS
A biofidelic whole cervical spine model with muscle force replication and surrogate head underwent simulated frontal impacts (n=6) of 4, 6, 8, and 10 g or left side impacts (n=6) of 3.5, 5, 6.5, and 8 g.


RESULTS
Average (SD) maximum physiological VA elongation was 7.1 (3.2) mm, measured during intact flexibility testing. Average peak dynamic elongation of right VA during left side impact, up to 17.4 (2.6) mm, was significantly greater (p<.05) than physiological beginning at 6.5 g, whereas the highest average peak VA elongation during frontal impact was 2.5 (2.4) mm, which did not exceed the physiological limit. Side impact, as compared with frontal impact, caused earlier occurrence of average peak VA elongation, 113.8 (13.5) ms versus 155.0 (46.2) ms, and higher average peak VA elongation rate, 608.8 (99.0) mm/s versus 130.0 (62.9) mm/s.


CONCLUSIONS
Elongation-induced VA injury is more likely to occur during side impact as compared with frontal impact.
Carlson
Erik J
EJ
Biomechanics Research Laboratory, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520-8071, USA.
Tominaga
Yasuhiro
Y
Ivancic
Paul C
PC
Panjabi
Manohar M
MM
D002102:Cadaver; D002574:Cervical Vertebrae / Q000293:injuries*; D006801:Humans; D013124:Spinal Injuries; D014711:Vertebral Artery / Q000293:injuries* / Q000473:pathology*; D014911:Whiplash Injuries / Q000503:physiopathology