To investigate the changes of hipbone biomechanics after the resection of ischiopubic tumors and their relationships with the complications in the convalescent stage

and directing the postoperative pelvic reconstruction. Methods DICOM data were used to create an intact hipbone finite element model and postoperative model.The biomechanical indices on the same region in the two models under the same boundary condition were compared.The differences of displacement

stress

and strain of the two models were analyzed with statistical methods. Results The distribution areas of the hipbone nodes’ displacement

stress

and strain were similar before and after the simulated operation.The sacroiliac joint nodes’ displacement (P=0.040) and strain (P=0.000)

and the acetabular roof nodes’ stress (P=0.000) and strain (P=0.005) of two models had significant differences

respectively.But the sacroiliac joint nodes’ stress (P=0.076) and the greater sciatic notch nodes’ stress (P=0.825) and strain (P=0.506) did not have significant differences. Conclusions The resection of ischiopubic tumors mainly affect the biomechanical states of the homolateral sacroiliac joint and acetabular roof.The complications in the convalescent stage are due to the biomechanical changes of the sacroiliac joint and the acetabular roof and disappearances of the stabilization and connection functions of the pubic symphysis and superior ramus of pubis.