Finite element analysis of lumbar spine with different backpack positions in parachuting landing.

The purpose of this study was to investigate the lumbar spine stress with different backpack positions in parachuting landing using a finite element model of lumbar vertebra 1-5. The backpack gravity center was set at three positions (posterior-high (case PH), posterior-low (case PL), and anterior-low (case AL)) respectively. In results, the peak Von-Mises stresses of the matrix, nucleus, fibers, endplate and ligament in case AL were 2.765 MPa, 0.534 MPa, 6.561 MPa, 4.045 MPa and 1.790 MPa respectively, lower than those in case PL (6.913 MPa, 1.316 MPa, 20.716 MPa, 10.917 MPa and 5.147 MPa respectively) and case PH (7.328 MPa, 1.394 MPa, 22.147 MPa, 11.617 MPa and 5.464 MPa respectively). In conclusion, setting the gravity center of backpack at anterior-low position would reduce lumbar spine stress and reduce lumbar spine injuries.