Stress analysis of the thoracolumbar junction in the process of backward fall: An experimental study and finite element analysis

Abstract

The aim of the present study was to evaluate the biomechanical mechanism of injuries of the thoracolumbar junction by the methods of a backward fall simulation experiment and finite element (FE) analysis (FEA). In the backward fall simulation experiment, one volunteer was selected to obtain the contact force data of the sacrococcygeal region during a fall. Utilizing the fall data, the FEA simulation of the backward fall process was given to the trunk FE model to obtain the stress status of local bone structures of the thoracolumbar junction during the fall process. In the fall simulation test, the sacrococcygeal region of the volunteer landed first; the total impact time was 1.14±0.58 sec, and the impact force was up to 4,056±263 N. The stress of thoracic (T)11 was as high as 42 MPa, that of the posterior margin and the junction of T11 was as high as 70.67 MPa, and that of the inferior articular process and the superior articular process was as high as 128 MPa. The average stress of T12 and the anterior margin of lumbar 1 was 25 MPa, and that of the endplate was as high as 21.7 MPa, which was mostly distributed in the back of the endplate and the surrounding cortex. According to the data obtained from the fall experiment as the loading condition of the FE model, the backward fall process can be simulated to improve the accuracy of FEA results. In the process of backward fall, the front edge of the vertebral body and the root of vertebral arch in the thoracolumbar junction are stress concentration areas, which have a greater risk of injury.

Adjacent vertebral fractures in the lumbar and thoracic spine after balloon kyphoplasty: A finite element analysis

“…The form of a buttock fall was assumed as the boundary condition in this analysis; a total vertical compressive force of 4000 N (100 N/step × 40 steps [13] ) was applied to the upper surface of the model (85% vertebral body and 15% vertebral arch). Regarding stress during falls, a study [13] reported that the maximum impact force of instantaneous stress in vertebrae during a backward fall experiment (in the form of a buttock fall) was 4056 ± 263 N. Thus, standards (4000 N) were adopted. Complete fixation of the lower surface of the vertebral body was performed.…”