The Human Lumbar Spine During High-Rate Under Seat Loading: A Combined Metric Injury Criteria

Failure tolerance of the human lumbar spine in dynamic combined compression and flexion loading

“…However, the weighting factor dictated that the relative contribution from the moment component was substantially less than that from the force component. A similar finding was described previously 18 , who implemented an approach similar to the cervical spine and tibia to predict lumbar spine injury risk using a linear combination of force and moment divided by critical values. They found that the optimized critical value associated with moment (1155 Nm) was one to two degrees of magnitude larger than reported flexion moments, resulting in the minimization of its contribution in predicting injury risk.…”

“…For example, the 50% injury risk corresponds to L fx of 3.5 for the 65 year-old level and average CSA. For comparison, in Ortiz-Paparoni et al 18 50% injury risk corresponds to a κ of 1.0, and average donor age was 66 years old. After setting moment equal to the average failure moment from combined compression-flexion loading 30 in both equations (71 Nm), of which was within the range of flexion moments for both studies, forces of 5456 N and 3512 N were required to reach 50% injury risk probability using κ and L fx equations respectively.…”

“…This could be explained by the loading in each study. Ortiz-Paparoni et al 18 prescribed axial compression, while Tushak et al 30 prescribed combined compression and flexion. Therefore, when considering injury risk of the lumbar spine in motor vehicle crashes, it is critical to use injury risk prediction tools which represent the desired loading scenario (i.e.…”

DataSheet1.docx

“…Alternative risk functions addressing lumbar vertebra fractures have been proposed by Stemper et al (2018) and Ortiz-Paparoni et al (2021). The former's was based on compression forces at the lumbar spine measured in drop tower tests, from 23 PMHS lumbar specimens.…”

“…The flexion moment was found to have some (albeit small) influence on the fracture risk, so it was included in the risk function proposed by Tushak et al (2021). Ortiz-Paparoni et al (2021) carried out a combined analysis from tests with 75 PMHS lumbar spines. Based on the test results, they developed an injury risk function using a combined metric.…”