Spinal injury (SPI) often causes death and disability in snow-sport accidents. SPIs often result from spinal compression and flexion, but the injury risks due to over flexion have not been studied. Back protectors are used to prevent SPIs but the testing standards do not evaluate the flexion-extension resistance. To investigate SPI risks and to better define back-protector specifications, this study quantified the flexion-extension range of motions (ROMs) of the thoracic-lumbar spine during typical snowboarding backward falls. A human facet-multibody model, which was calibrated against spinal flexion-extension responses and validated against vehicle-pedestrian impact and snowboarding backward fall, was used to reproduce typical snowboarding backward falls considering various initial conditions (initial velocity, slope steepness, body posture, angle of approach, anthropometry, and snow stiffness). The SPI risks were quantified by normalizing the numerical spinal flexion-extension ROMs against the corresponding ROM thresholds from literature. A high risk of SPI was found in most of the 324 accident scenarios. The thoracic segment T6-T7 had the highest injury risk and incidence. The thoracic spine was found more vulnerable than the lumbar spine. Larger anthropometries and higher initial velocities tended to increase SPI risks while bigger angles of approach helped to reduce the risks. SPIs can result from excessive spinal flexion-extension during snowboarding backward falls. Additional evaluation of back protector's flexion-extension resistance should be included in current testing standards. An ideal back protector should consider the vulnerable spinal segments, the snowboarder's skill level and anthropometry.
Keywords: back protector; injury risk; multi-body model; range of motion; snow sports.
© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.