Effect of seat tilting on biomechanics of L4 in tractor drivers

The tilting of the tractors' seat during deep tillage operations affects the drivers' sitting position, which can lead to lumbar spine injuries. To investigate the effect of seat tilting on the driver's L4 biomechanics, we built a tractor-driver musculoskeletal model in AnyBody™. The maximum activity of the driver's erector spinae at different tilted angles were measured by sEMG and compared with the simulation results to validate the model. The spatial position of the driver's spine at different tilted angles were obtained by 3 D motion capture. The model simulated the driver's spine posture during the actual tilt and investigated the effects of different tilted angles and vibration on the biomechanics of the driver's L4 . The results showed that as the tilt angle of the tractor increased, the load on the driver's L4 also increased, especially the shear force increased at a faster rate than the axial and normal forces, with the shear force on the driver's L4 increasing from 0 N to 138.7 N when the tractor was tilted from 0° to 15°. When vibration was applied to the musculoskeletal model, the maximum value of the shear force on the driver became progressively greater as the angle of tilt of the tractor increased. Overall, tilting the tractor can have a large impact on the biomechanics of the driver's L4, and tilting the tractor may be an important cause of lumbar spine injuries for tractor drivers.