The effect of lateral eccentricity on failure loads, kinematics, and canal occlusions of the cervical spine in axial loading

• Published in: Journal of biomechanics 2014-03, Vol.47 (5), p.1164-1172
• Main Authors: Van Toen, C, Melnyk, A.D, Street, J, Oxland, T.R, Cripton, P.A
• Format: Article
• Language: English
• Subjects: Acoustic emission; Aged; Arthritis; Bending; Biomechanical Phenomena; Biomechanics; Bone density; Canals; Cervical spine; Cervical Vertebrae - injuries; Cervical Vertebrae - physiology; Eccentricity; Female; Fractures; Humans; Injuries; Kinematics; Lateral bending; Ligaments; Loads (forces); Male; Middle Aged; Occlusion; Peak load; Physical Medicine and Rehabilitation; Pressure; Spinal Canal; Spinal canal occlusion; Spinal Injuries - etiology; Spine; Spine - physiology; Sports injuries; Studies; Test systems; Vertebrae; Weight-Bearing
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2013.12.001

Abstract Current neck injury criteria do not include limits for lateral bending combined with axial compression and this has been observed as a clinically relevant mechanism, particularly for rollover motor vehicle crashes. The primary objectives of this study were to evaluate the effects of lateral eccentricity (the perpendicular distance from the axial force to the centre of the spine) on peak loads, kinematics, and spinal canal occlusions of subaxial cervical spine specimens tested in dynamic axial compression (0.5 m/s). Twelve 3-vertebra human cadaver cervical spine specimens were tested in two groups: low and high eccentricity with initial eccentricities of 1 and 150% of the lateral diameter of the vertebral body. Six-axis loads inferior to the specimen, kinematics of the superior-most vertebra, and spinal canal occlusions were measured. High speed video was collected and acoustic emission (AE) sensors were used to define the time of injury. The effects of eccentricity on peak loads, kinematics, and canal occlusions were evaluated using unpaired Student t -tests. The high eccentricity group had lower peak axial forces (1544±629 vs. 4296±1693 N), inferior displacements (0.2±1.0 vs. 6.6±2.0 mm), and canal occlusions (27±5 vs. 53±15%) and higher peak ipsilateral bending moments (53±17 vs. 3±18 Nm), ipsilateral bending rotations (22±3 vs. 1±2°), and ipsilateral displacements (4.5±1.4 vs. −1.0±1.3 mm, p