title: The effect of lateral eccentricity on failure loads, kinematics, and canal occlusions of the cervical spine in axial loading.
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<0.05 for all comparisons). These results provide new insights to develop prevention, recognition, and treatment strategies for compressive cervical spine injuries with lateral eccentricities.
authors.affiliation: Orthopaedic and Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics, University of British Columbia, 818 West 10th Ave, Vancouver, BC, Canada V5Z 1M9; International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
authors.forename: C
authors.initials: C
authors.lastname: Van Toen
authors.affiliation: Orthopaedic and Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics, University of British Columbia, 818 West 10th Ave, Vancouver, BC, Canada V5Z 1M9; International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
authors.forename: A D
authors.initials: AD
authors.lastname: Melnyk
authors.affiliation: Combined Neurosurgical and Orthopaedic Spine Program, Department of Orthopaedics, University of British Columbia, Vancouver, BC, Canada V6T 1Z4; International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
authors.forename: J
authors.initials: J
authors.lastname: Street
authors.affiliation: Orthopaedic and Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics, University of British Columbia, 818 West 10th Ave, Vancouver, BC, Canada V5Z 1M9; International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
authors.forename: T R
authors.initials: TR
authors.lastname: Oxland
authors.affiliation: Orthopaedic and Injury Biomechanics Group, Departments of Mechanical Engineering and Orthopaedics, University of British Columbia, 818 West 10th Ave, Vancouver, BC, Canada V5Z 1M9; International Collaboration on Repair Discoveries (ICORD), University of British Columbia, Vancouver, BC, Canada V6T 1Z4. Electronic address: cripton@mech.ubc.ca.
authors.forename: P A
authors.initials: PA
authors.lastname: Cripton
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000293:injuries* / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011312:Pressure; D013115:Spinal Canal; D013124:Spinal Injuries / Q000209:etiology*; D013131:Spine / Q000502:physiology*; D016474:Weight-Bearing
keywords: Acoustic emission; Biomechanics; Cervical spine; Lateral bending; Spinal canal occlusion