Intervertebral neck injury criterion for prediction of multiplanar cervical spine injury due to side impacts.
OBJECTIVE
Intervertebral Neck Injury Criterion (IV-NIC) is based on the hypothesis that dynamic three-dimensional intervertebral motion beyond physiological limits may cause multiplanar injury of cervical spine soft tissues. Goals of this study, using a biofidelic whole human cervical spine model with muscle force replication and surrogate head in simulated side impacts, were to correlate IV-NIC with multiplanar injury and determine IV-NIC injury threshold for each intervertebral level.


METHODS
Using a bench-top apparatus, side impacts were simulated at 3.5, 5, 6.5, and 8 g horizontal accelerations of the T1 vertebra. Pre- and post-impact flexibility testing in three-motion planes measured the soft tissue injury, i.e., significant increase (p < 0.05) in neutral zone (NZ) or range of motion (RoM) at any intervertebral level, above corresponding physiological limit.


RESULTS
IV-NIC in left lateral bending correlated well with total lateral bending RoM (R = 0.61, P < 0.001) and NZ (R = 0.55, P < 0.001). Additionally, the same IV-NIC correlated well with left axial rotation RoM (R = 0.50, P < 0.001). IV-NIC injury thresholds (95% confidence limits) varied among intervertebral levels and ranged between 1.5 (0.6-2.4) at C3-C4 and 4.0 (2.4-5.7) at C7-T1. IV-NIC injury threshold times were attained beginning at 84.5 ms following impact.


CONCLUSIONS
Present results suggest that IV-NIC is an effective tool for determining multiplanar soft tissue neck injuries by identifying the intervertebral level, mode, time, and severity of injury.
Panjabi
Manohar M
MM
Biomechanics Research Laboratory, Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, Connecticut 06520-8071, USA. manohar.panjabi@yale.edu
Ivancic
Paul C
PC
Tominaga
Yasuhiro
Y
Wang
Jaw-Lin
JL
D000054:Acceleration; D000063:Accidents, Traffic; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002102:Cadaver; D002574:Cervical Vertebrae / Q000293:injuries*; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000293:injuries*; D008297:Male; D008954:Models, Biological; D017695:Soft Tissue Injuries; D015599:Trauma Severity Indices