Sacroiliac Joint Stabilization Using Two Short Screws, A Mechanical Study

Introduction: Current recommendations for sacroiliac (SI) luxation fixation include lag screw insertion into and spanning at least 60% of sacral body width. Drill bit or implant deviation using this technique risks impingement on sensitive surrounding neurovascular structures. The purpose of this study was to assess the feasibility and compare the mechanical stability of SI stabilization using two cortical screws short enough not to impinge on these neurovascular structures.

Materials and Methods: In total, 24 canine cadaver pelvis specimens were prepared and randomly assigned to a long lag screw (LLS), short lag screw (SLS), or short positional screw (SPS) group using 3.5 mm cortical screws. CT imaging was obtained on each sample to determine standardized screw lengths for each testing group and repeated following screw insertion, prior to testing. Specimens were secured within a Servo-hydraulic test frame and load was applied through the acetabulum to simulate a weight bearing force under displacement control at 4 mm/min up to 20 mm displacement. Mechanical data was compared between groups with significance set at p <0.05.

Results: Peak load, yield load, and stiffness were significantly greater in both the SLS and SPS groups when compared with the LLS group. No significant differences were detected between the SLS or SPS groups.

Discussion/Conclusion: SI stabilization using two, short cortical screws creates a stronger, stiffer construct with potentially decreased chance of iatrogenic neurovascular injury when compared with fixation using a single lag screw spanning 60% of sacral body width.

Acknowledgement: Implants for this study were provided by VOI, St. Augustine, FL

Publication History

Article published online:
26 October 2022