Biomechanical Comparison of Intact Ankylosing Spondylitis and Normal Vertebra

In order to compare the range of motion (ROM) of intact AS model with the ROM of normal vertebra in biomechanical experiment, a 7.5 Nm moment and a compression 150N force [22 (link), 23 (link)] were applied at the center of the superior surface of T9. The inferior surface of L5 was immobilized. The ROM of T9-L5 was calculated and the ROM of the corresponding segment was compared with the previous experiment studies (Table 2). For testing the fixation capacity, a compressive load of 400 N force and a 10 Nm moment were applied in all fixation patterns [23 (link)–25 (link)]. Six loading conditions including flexion, extension, left bending, right bending, left axial rotation, and right rotation were simulated. Ansys workbench 17 (ANSYS Inc., PA, USA) was used to set the material properties and simulate the loading conditions.