Catamaran SI Joint Fusion System MAINSAIL Study: a prospective, single-arm, multi-center, post-market study of six-month clinical outcomes and twelve-month radiographic findings

Introduction: Sacroiliac joint (SIJ) dysfunction is a prevalent cause of LBP, significantly impacting the quality of life of affected patients. Recently, minimally invasive surgical (MIS) techniques for SIJ fixation have shown the potential to reduce risk and improve patient outcomes for surgical treatment when conservative care options have failed to provide relief; however, clinical evidence remains limited. This interim analysis presents early findings from an ongoing, prospective multi-center post-market study evaluating the safety and efficacy of the MIS inferior-posterior approach with the Catamaran SIJ Fusion System in patients with chronic SIJ pain.

Methods: The primary endpoint of success at 6 months was defined as a ≥20 mm improvement in SIJ pain (Visual Analog Scale, VAS), no neurologic worsening, absence of device-related serious adverse events (SAEs), and no surgical reintervention. Secondary endpoints included 6-month evaluation of the Oswestry Disability Index (ODI), patient satisfaction, and 12-month radiographic CT fusion performed by an independent radiologist.
Ethical approval was obtained through WCG IRB (Pr.No 20,225,058). All subjects provided informed consent to participate, and all collected patient data was de-identified to provide data confidentiality and compliance with HIPAA and the Declaration of Helsinki.

Results: Thirty-three consecutive patients (mean age: 58.9 years; 76%-females; Body Mass Index: 30.5) were treated across six U.S. clinical sites. At the primary endpoint of 6 months, 80% of patients met the criteria for success, with no device-related SAEs and no surgical reintervention reported. VAS SIJ-Pain significantly decreased from preoperative levels (mean: 80.9 mm) to 6 months postoperatively (31.1 mm; p < 0.001). Mean ODI scores also showed a significant improvement from preoperative values (51.9%) to 6 months postoperatively (29.6%, p < 0.01). Patients reported high satisfaction rates throughout all follow-ups, with 93.3% of patients being satisfied at 6 months.

Conclusion : In patients with chronic SIJ pain attributed to SIJ dysfunction, early findings indicate that the minimally invasive inferior-posterior approach for the delivery of an SIJ fixation device, utilizing the Catamaran System, is both safe and effective in significantly relieving pain and reducing disability, with high patient satisfaction. However, further research is needed to validate these findings, including comprehensive long-term data analysis.