Abstract: Objective To explore a new approach to determining the location of S1 screw for percutaneous screw fixation of the
sacroiliac joint using a targeting device. Methods Virtual three-dimensional pelvic models were reconstructed using the
computed tomography (CT) scan data obtained from 100 adult subjects without any bony abnormalities. Mimics software was
used to determine the ideal operating plane for S1 sacroiliac screw fixation based on the osseous marks. The parameters for
screw fixation on the plane were measured, including the entry point, the needle angle (γ) and the safety range, and the
accuracy of these parameters was verified using the digital models. Results The ideal operating plane could be determined by
the osseous prominences of ASIS (A) and PSIS (B) and the midpoint of S1 vertebral spines. The point at the posterior 1/3 of the
line connecting points A and B could be defined as the entry point on the plane. The range of the needle angle γ was
101.4-117.2° for male and 109.5-120.78° for female patients, showing a significant sexual difference. Simulation results based on
these parameters resulted in a total success rate of 91.25% (92.5% in male and 90% in female). Conclusion These parameters of
the S1 screw can ensure a high success rate for percutaneous screw fixation of the sacroiliac joint and provide anatomical
evidence for the development of a targeting device for the procedure.