[Parameters of S1 screw fixation for percutaneous screw fixation of the sacroiliac joint using a targeting device: a...

To explore a new approach to determining the location of S1 screw for percutaneous screw fixation of the sacroiliac joint using a targeting device.

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.

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).

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.