Biomechanical modeling of surgical reconstructive treatment variants of unilateral sacral fractures

A comparative analysis of two surgical treatment variants for a unilateral longitudinal sacral fracture was carried out in three possible localization of the fracture line: outside the zygapophysis, inside and directly on the zygapophysis. Two variants of implants were considered: cannulated sacroiliac screws and a similar variant in combination with a bilateral lumbar-pelvic transpedicular structure. Analysis and selection of the most rational surgical treatment variant was carried out with the help of biomechanical and computer modelling methods. Surgical treatment variants were evaluated on the basis of investigated succes criteria. Finite-element modelling of static loading of the vertebral-pelvic complex segment was carried out. Displacements and equivalent stresses in bone tissues and implants were analyzed. From the biomechanical point of view, the installation of a transpedicular screws in combination with sacroiliac screws was the most rational variant of surgical treatment. This conclusion is valid for all simulated cases of the fracture line localization. The most unstable fracture variant was a one-sided longitudinal fracture of the sacrum passing through the zygapophysis.