Minimally Invasive Sacroiliac Joint Fusion: 2-Year Radiographic and Clinical Outcomes with a Principles-Based SIJ Fusion System

Background Sacroiliac joint (SIJ) degeneration is a common source of low back pain (LBP). Minimally invasive (MI) SIJ fusion procedures have demonstrated meaningful clinical improvement. A recently developed MI SIJ fusion system incorporates decortication, placement of bone graft and fixation with threaded implants (DC/BG/TF). Patients and Methods Nineteen patients who had MI SIJ fusion with DC/BG/TF were enrolled at three centers. Fusion was assessed in CT images obtained 12 and 24 months postoperatively by an independent radiographic core laboratory. LBP was assessed using a 0-10 numerical pain scale (NPS) preoperatively and at 12 and 24 months postoperatively. Results At 12 months, 15/19 patients (79%) had bridging bone across the SIJ, and at 24 months 17/18 patients (94%) available for follow-up had SIJ fusion. Of the patients with bridging bone 88% had fusion within the decorticated area, with solid fusion in 83%. A significant reduction in NPS scores was demonstrated, representing a 73% reduction in average low back pain. Conclusion The patients in this series demonstrated significant improvement in LBP. Fusion rates at 24 months demonstrate promise for this system, which utilizes the established orthopedic principles of DC/BG/TF to achieve arthrodesis. Further study is warranted to demonstrate comparative fusion rates for different implant systems.