National Taiwan University of Science and Technology

Simulation details the spine-pelvis-femur complex with different pelvic fixation techniques and human postures using ANSYS software within the ANSYS Workbench environment. Structural simulation provides useful clinical suggestions and reliable mechanical evidence for healthcare professionals.

Problem:

Unstable pelvic fractures are often associated with high mortality and morbidity. Two different fixation devices have been used in fracture treatment. However, it is quite difficult to evaluate the in vivo biomechanical performances of the two devices because of frequent high variations in bone quality and geometry among patients. In addition, patients with different human postures may significantly affect the biomechanical performances of both fixation devices and human bones. NTUST believes that computer simulation can solve this problem fairly and efficiently.

Solution:

To analyze different pelvic fixation techniques and human postures, NTUST used ANSYS Workbench to develop the spine-pelvis-femur complex, comprising 23 human muscles and ligaments for structural simulation. Nonlinear contact conditions and 164 tension-only springs simulated bone-implant interfaces and human muscles and ligaments, respectively. Intact model, fractured model and fractured model implanted with three types of pelvic fixation devices (including posterior iliosacral screws, sacral bars and a locking compression plate) were simulated and studied. This provided data on the maximum stress of human bones, the maximum stress of different fixation devices and the fixation stability of different fixation techniques. The results showed that all fixation techniques could provide required fixation stability. Both the posterior iliosacral screws and the sacral bars revealed better biomechanical performances on the pelvic stress and the implant strength.

NTUST believes this is the first model to consider both the spine-pelvis-femur complex and real geometry of pelvic fixation devices. In addition, the numerical model also considers the effect of different human postures such as walking upstairs, walking downstairs, standing posture, etc.

Software used:

  • ANSYS Workbench