Three-dimensional finite element analysis of lumbosacral reconstruction with a novel four-rod fixation system / 中华骨科杂志

ABSTRACT

Objective To analysis the biomechanical properties of four-rod fixation system for lumbosacral reconstruction after sacrectomy.Methods Two finite element models of lumbosacral area were established according to pelvic CT imagesa subtotal saerectomy model and a total sacrectomy model.The range of motion of L3 vertebral body and max yon Mise stress of instruments of a novel four-rod fixation system were evaluated and compared with those of modified Galveston technique(MGT)under conditions of veaebral body and max von Mise stress of instruments of the four-rod fixation system were evaluated and compared with those of MGT under vertical compression.Results In subtotal sacreetomy model,the range of motion of L3 vertebral body in the four-rod fixation system were 4.2 mm,0.49°,0.49°,0.24°and 0.26°compared to 5.5 mm.0.74°,0.74°,0.27°and 0.30°in the MGT.The max von Mise stress of instruments in the four-rod fixation system were 810.7,148.0,148.0,134.6 and 14.4 MPa,compared to 655.0,109.9,109.9,119.1 and 11.4 MPa in the MGT.In total sacrectomy model under veaical compression,the range of motion of L3 vertebral body and max van Mise stress of instruments in the four-rod fixation system were 10.9mm and 2172 MPa compared to 49.1 mm and 4325 MPa in the MGT.Conclnsion Comparing with the MGT.the four-rod fixation system was stiffer and showed a significant increase in the stability of lumbosacral area.When total sacrectomy without bone graft were performed,the max stress of the four-rod fixation system was much lower than that of the MGT,which means smaller risk of instrument failure.When subtotal sacrectomy or bone graft were performed,despite better stability,the higher stress shielding-effect of the four-rod fixation svstem might be unfavorable for bone fusion,which still need to be evaluated by clinical trials.