Comparison of the Incidence of Sacroiliac Pain in Spinal Deformity Patients with Single and Multipoint Fixation to Pelvis

Introduction: Adult spinal deformity patients often undergo spinal fusion with pelvic fixation to protect against hardware failure and provide a solid foundation. Multiple different techniques are used for pelvic fixation, each characterized by different entry points and trajectories in the pelvis. More recently, multipoint fixation has emerged, which functions to provide further stability and less strain to yield lower rates of hardware failure. However, the effect of multipoint fixation on the incidence of post-surgical sacroiliac pain has not been well explored.

Methods: We conducted a retrospective chart review on spinal deformity patients who underwent long fusion with pelvic fixation. The variables collected included patient demographics, pelvic fixation technique, post-operative and long-term complications, and patient outcomes, including incidence of post-surgical sacroiliac pain, as measured with the visual analogue scale (VAS), obtained from patients using chart review and phone calls. The number of pelvic fixation points for each patient was obtained using post-operative imaging.

Results: A total of 268 patients were included (42.9% female, 57.1% male) with an average age at surgery of 64 years. The proportion of patients with one (3.0%), two (42.5%), three (14.2%), four (23.5%), five (2.6%), and six (0.37%) points of fixation in the pelvis. Pearson correlation between the number of fixation points and the incidence of sacroiliac pain after surgery yielded a weak and not statistically significant Pearson coefficient (-0.075, p= 0.259). The incidence of pain with two-point pelvic fixation was compared to higher and lower numbers of points of fixation, and no significant difference was observed.

Conclusion : There is no significant difference in the incidence of sacroiliac pain as the number of pelvic fixation points increases. Additionally, the traditional two-point fixation does not significantly differ in pain incidence compared to fixations with a higher or a lower number of fixation points. In the study, individual patients often had different types of pelvic screw techniques between iliac, S2AI, and modified iliac screws, which may explain variability within the groups themselves. More studies are warranted to characterize this relationship further.