title: An investigation into axial impacts of the cervical spine using digital image correlation.
abstract: BACKGROUND
  High-energy impacts are commonly encountered during sports such as rugby union. Although catastrophic injuries resulting from such impacts are rare, the consequences can be devastating for all those involved. A greater level of understanding of cervical spine injury mechanisms is required, with the ultimate aim of minimizing such injuries.
  
  
  OBJECTIVE
  The present study aimed to provide a greater understanding of cervical spine injury mechanisms, by subjecting porcine spinal specimens to impact conditions based on those measured in vivo. The impacts were investigated using high-speed digital image correlation (DIC), a method not previously adopted for spinal impact research.
  
  
  METHODS
  This was an in vitro biomechanical study.
  
  
  METHODS
  Eight porcine specimens were impacted using a custom-made rig. The cranial and caudal axial loads were measured at 1 MHz. Video data were captured with two cameras at 4 kHz, providing measurements of the three-dimensional deformation and surface strain field of the specimens using DIC.
  
  
  RESULTS
  The injuries induced on the specimens were similar to those observed clinically. The mean±standard deviation peak caudal load was 6.0±2.1 kN, which occurred 5.6±1.1 ms after impact. Damage observable with the video data occurred in six specimens, 5.4±1.1 ms after impact, and the peak surface strain at fracture initiation was 4.6±0.5%.
  
  
  CONCLUSIONS
  This study has provided an unprecedented insight into the injury mechanisms of the cervical spine during impact loading. The posture represents a key factor in injury initiation, with lordosis of the spine increasing the likelihood of injury.
authors: Department of Mechanical Engineering, Centre for Orthopaedic Biomechanics, University of Bath, Bath, BA2 7AY, UK. Electronic address: thols@seas.upenn.edu.
authors: Timothy Patrick
authors: TP
authors: Holsgrove
authors: Department for Health, Sport, Health & Exercise Science, University of Bath, Bath, BA2 7AY, UK.
authors: Dario
authors: D
authors: Cazzola
authors: Department for Health, Sport, Health & Exercise Science, University of Bath, Bath, BA2 7AY, UK.
authors: Ezio
authors: E
authors: Preatoni
authors: Department for Health, Sport, Health & Exercise Science, University of Bath, Bath, BA2 7AY, UK.
authors: Grant
authors: G
authors: Trewartha
authors: Department of Mechanical Engineering, Centre for Orthopaedic Biomechanics, University of Bath, Bath, BA2 7AY, UK.
authors: Anthony W
authors: AW
authors: Miles
authors: Department of Mechanical Engineering, Centre for Orthopaedic Biomechanics, University of Bath, Bath, BA2 7AY, UK.
authors: Harinderjit Singh
authors: HS
authors: Gill
authors: Department of Mechanical Engineering, Centre for Orthopaedic Biomechanics, University of Bath, Bath, BA2 7AY, UK.
authors: Sabina
authors: S
authors: Gheduzzi
mesh_terms: D000818:Animals; D001265:Athletic Injuries / Q000503:physiopathology*; D001696:Biomechanical Phenomena; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000293:injuries* / Q000503:physiopathology*; D004195:Disease Models, Animal; D005538:Football / Q000293:injuries*; D011187:Posture / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D013124:Spinal Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology*; D013552:Swine; D014741:Video Recording; D055114:X-Ray Microtomography
keywords: Axial; DIC; Digital image correlation; Impact; Injury; Spine