How Spinal Flexion Influences Fracture Morphology in the Porcine Spine

Acute injuries to the spine, including slips and falls and motor vehicle accidents, most commonly occur when the spine is positioned in flexion. Therefore, the purpose of this study was to investigate how spine position influences the morphology of vertebral fractures following rapid intervertebral disc pressurization. To investigate the effects of position on fracture morphology, 19 functional spine units (FSUs) (ten C3/4 and nine C5/6 specimens) dissected from porcine cervical spines underwent a rapid pressurization protocol. In this protocol, specimens were randomly assigned to undergo the protocol either in a neutral condition or in a 15 deg flexed condition. The rapid pressurization resulted in endplate fracture in eight of the ten specimens in the flexed condition and eight of the nine specimens in the neutral condition. When neutral and flexed specimens were compared, peak pressure, peak force, rate of pressurization, and size of fracture were not statistically different; however, flexed specimens had a significantly faster rate of depressurization, as well as a more anterior location of the fracture on the endplate. The findings of this study indicate that spine position, and specifically flexion, impacts fracture location in the anterior-posterior direction but does not appear to affect fracture likelihood or severity.