Abstract: ［Abstract］ Objective〖HTSS〗〓To compare the biomechanical stability of three kinds of internal fixation for sacroiliac joint dislocation by threedimensional finite element analysis.
〖HTH〗〖WTHZ〗Methods〖HTSS〗〓A healthy adult male was randomly seclected and the CT images of pelvis(1.0 mm thickness) were collected. Intact pelvis model and sacroiliac dislocation model were made using software of Mimics 10.01, Geomagic Studio 12, SolidWorks, Abaqus 6.111. Two iliosacral (IS) screws, the minimally invasive adjustable plate(MIAP) and the tension band plate(TBP) were used to fix the posterior pelvic ring respectively, and a loading of 500 N was put on the sacrum. Total displacement, strain value, stress distribution and the shift of dislocation gap of the whole model and internal fixator were compared.
〖HTH〗〖WTHZ〗Results〖HTSS〗〓The stress of upper body passed through sacral wing, bilateral sacroiliac joint, the large sciatic notch, arcuate line of the iliac bone to the bilateral acetabulum. Under 500 N load, displacements of the fixed models were two IS screws model(1.377 mm), the MIAP model(2.517 mm), and the TBP model(5.132 mm). The shifts of dislocation gap were two IS screws model(0.887 mm), MIAP model(2.502 mm) and TBP model(5.117 mm).
〖HTH〗〖WTHZ〗Conclusion〖HTSS〗〓The stability of sacroiliac dislocation fixed with the MIAP was less than that fixed with the two IS screws, and better than that fixed with the TBP.

Key words: sacroiliac joint, internal fixators, biomechanics