Biomechanical comparison of three kinds of fixation in fracture-dislocation of the sacroiliac joint

BACKGROUND: Although there are several different kinds of fixation techniques for the sacroiliac fracture-dislocation, the treatment remains a challenge for orthopedic surgeons. OBJECTIVE: The purpose of this study was to compare the stability of sacroiliac fracture-dislocation fixed with two ilios acral (IS) screws, tension band plate (TBP), and minimally invasive adjustable plate (MIAP). METHODS: Five human cadavers (L4-pelvic-femora) were used to compare biomechanical stability. The pubic symphysis separation and left sacroiliac dislocation were created. The symphysis pubis was stabilized with a five-hole plate. The sacroiliac joint dislocation fracture was fixed with three kinds of internal fixation in a randomized design. The specimens were fastened in a biomechanical machine with a cycle vertical load. Displacements of the whole specimen and shifts in the fracture gap were recorded. RESULTS: Under different vertical loads, the shifts in the fracture gap and the displacements of the pelvis fixed with MIAP were similar to those in fractures fixed with two IS screws. However, the shifts in the fracture gap and the displacements of the pelvis fixed with MIAP were significantly smaller than those fixed with TBP. CONCLUSIONS:The stability of the sacroiliac joint dislocation fixed with MIAP was similar to that of dislocation fixed with two IS screws, and MIAP performed better than the TBP under vertical load.