Novel Technique for Sacral-Alar-Iliac Screw Placement Using Three-Dimensional Patient-Specific Template Guide

Area of Science:

• Spine surgery
• Orthopedic surgery
• Medical device technology

Background:

• Sacral-alar-iliac (SAI) screw placement is crucial for sacropelvic fixation but technically demanding.
• Narrow safe corridors and risk of neurovascular/visceral injuries complicate traditional SAI screw placement.
• Three-dimensional patient-specific template guides offer a promising approach to enhance accuracy and safety.

Purpose of the Study:

• To investigate the accuracy and feasibility of SAI screw placement using patient-specific template guides.
• To evaluate the safety and precision of this technique in both cadaveric and clinical settings.

Main Methods:

• 3D planning of SAI screw placement (entry point, trajectory, length, diameter) using simulation software.
• Creation of 3D-printed patient-specific template guides based on the surgical plan.
• Placement of 12 SAI screws in 6 cadavers and 20 SAI screws in 10 patients using the guides.
• Postoperative CT analysis for cortical breach and deviation measurements.

Main Results:

• No screw perforations were observed in any specimens or patients.
• Cadaveric study showed mean deviations of 1.40±1.21 mm (horizontal) and 1.34±1.09 mm (vertical) at the entry point.
• Mean angular deviations were 1.68°±1.24° (sagittal) and 1.53°±1.06° (transverse).
• Clinical study results demonstrated comparable accuracy to cadaveric findings, with a statistically significant difference only in vertical deviation (p=0.048).

Conclusions:

• This study demonstrates the feasibility and accuracy of patient-specific template guides for SAI screw placement.
• The technique provides an effective solution for achieving accurate and safe sacropelvic fixation.
• This method holds potential to improve outcomes in spinal fusion surgeries requiring sacropelvic fixation.