Influence of Different Vibration Loads and Body Postures on Sacroiliac Joints: Implications for Low Back Pain.

Sacroiliac joints (SIJ) injury has been recognised as a crucial cause of low back pain (LBP), but investigations on SIJ are insufficient. The aim of this study was to reveal the mechanism of SIJ injury induced by different vibration conditions and body inclinations and thus to analyse the relationship between vibration and LBP. Based on whole-body finite element models, eight load cases were analysed, where the multi-axis vibration loading cases were closer to the typical vehicle environment. In addition, three different body inclinations were involved to analyse the effect of body inclinations on vibration transmission of SIJ. The results showed that the vertical vibration would induce larger loads on SIJ than the fore-and-aft vibration. Single-axis vibrations tended to cause large fore-and-aft loads of SIJ, and multi-axis vibrations tended to cause large vertical loads. For the three body inclinations, static loads on SIJ were minimal at 100° and dynamic loads were minimal at 110°, which indicated that the 100° inclination was a recommended sitting posture for occupational drivers to reduce their incidence of LBP. These findings might be helpful for understanding the association between different vibration conditions and LBP, and provide reasonable ergonomics recommendations for occupational drivers to reduce the incidence of LBP.