Comparison of triangular rod implants and cylindrical threaded implants in patients undergoing sacroiliac joint fusion

Objective: Sacroiliac (SI) joint dysfunction is increasingly recognized as a major cause of low back pain. While multiple systems are available to achieve fixation and arthrodesis, few studies compare clinical outcomes between varying implant types. Methods: Retrospective analysis of adult patients who underwent SI joint fusion from November 2019 to November 2022 was performed. Patients were segregated into two cohorts who received fusion using either triangular rod (TR) implants or cylindrical threaded (CT) implant. Clinical outcomes were assessed by documenting visual analog scale (VAS) scores at clinical visit immediately prior to surgery and 4 months thereafter. Results: 24 patients met inclusion criteria. The average age was 59±13 yr. Men to women ratio was 1:1. In all patients, preoperative VAS score was 8±1 and postoperative VAS was 2±2. Twelve patients underwent fusion with TR implant while 12 underwent fusion with the CT device. Both cohorts were composed of 50% men and 50% women. There was no difference in preoperative VAS scores between the TR cohort and the CT cohort (8±1 vs. 8±1, respectively; P =0.609). Patients in both groups experienced significant improvement in their pain following surgery. There was no statistically significant difference in postoperative VAS scores between TR cohort and CT cohort (1±2 vs. 3±2, respectively; P =0.115). Conclusion: Sacroiliac joint fusion results in significant improvement in back pain scores for patients with sacroiliac joint dysfunction who fail or become refractory to conservative treatment. Triangular rod implants and cylindrical threaded implants result in similarly successful clinical outcomes with no significant adverse events.