Study of tractor side tilt operation on intervertebral disc injury between L4 and L5 in drivers

The tilting of the cab seat when the tractor is in deep ploughing operation changes the sitting position of the driver, which may accelerate lumbar spine injury. This paper adopts the musculoskeletal model and the finite element model of the lumbar L4–L5 segment to predict the maximum Von-Mises stress and maximum strain of the driver’s lumbar L4–L5 segment intervertebral disc. In this study, we used 3D motion capture to obtain the driver's spine position spatial data when the tractor tilted at different angles. A tractor-driver musculoskeletal model and a finite element model of the lumbar spine L4–L5 segments were created in AnyBody™ and Abaqus, respectively. The tractor-driver musculoskeletal model was used to calculate the load of the driver's lumbar spine L4–L5 segment at different angles of tractor tilt, which was used as the load condition of the finite element model of the lumbar spine L4–L5 segment, and then the influence of tractor tilt angle and vibration on the driver's lumbar spine L4–L5 disc was studied. The results show that the maximum Von-Mises stress and maximum strain of the driver’s lumbar L4–L5 intervertebral disc will increase due to the tilt. The maximum Von-Mises stress occurs in the annulus II, and the maximum strain occurs in the upper end plate of the intervertebral disc. With the occurrence of tilt, the position of the maximum Von-Mises stress changes, which can lead to disc injury to the driver, and vibration may exacerbate this injury.