1. 2026;29;83-94Minimally Invasive Sacroiliac Joint Fusion Using 3D Printed Implants and a Lateral Approach: Safety and Effectiveness Assessments of Fusion Performed by Interventional Physicians in a Prospective Multicenter Single-Arm Clinical Study (The FICS Study)
   Retrospective Study
   Douglas P. Beall, MD, Ty Ptacek, MD, Ashley M. Classen, CO, Michael Jung, MD, Matthew Skoblar, MD, John Hatheway, MD, Olivia A. Beall, MA, Matthew C. Shonnard, MD, and Reade DeLeacy, MBBS.

BACKGROUND: Low back pain (LBP) is a widespread and costly condition. Sacroiliac joint (SIJ) dysfunction accounts for 15–25% of chronic LBP cases and is especially common following lumbar spine fusion—affecting up to 75% of such patients within five years. Risk factors include prior spine surgery, pregnancy, obesity, trauma, and inflammatory diseases. For persistent cases, sacroiliac joint fusion (SIJF) is increasingly used, offering better outcomes than conservative treatments. Recent advancements in minimally invasive surgical (MIS) techniques and implant designs have improved the safety and effectiveness of SIJF, making it a reliable option for managing chronic SIJ dysfunction.

OBJECTIVES: To examine the effectiveness of a minimally invasive sacroiliac joint approach and fusion device by means of clinical patient reported outcomes (PROs) and radiological outcomes.

STUDY DESIGN: The design of this clinical trial is a multi-site, prospective, single arm feasibility study.

SETTING: The study was conducted in 7 sites located across the United States including both private practices and academic centers from September 19, 2022, to December 6, 2023. 

METHODS: This study enrolled 37 patients aged 21–80 with chronic SIJ pain or degenerative sacroiliitis unresponsive to conservative care. All underwent SIJF and were followed for six months. PROs on pain, function, opioid use, work status, adverse events, and quality of life were collected via email at 1, 3, and 6 months postoperatively. Diagnostic inclusion required SIJ pain localization, ? 3 of 6 positive physical exam tests, 75% pain relief after anesthetic injection, and confirmatory imaging. Exclusions included alternative causes of back pain, trauma, infection, or conditions that could interfere with recovery. Radiologic outcomes were evaluated by a six-month CT. PROs included pain reporting via the Numeric Rating Scale (NRS), function via the Oswestry Disability Index (ODI), and quality of life via PROMIS-10. 

RESULTS: The study measured outcomes using NRS, ODI, PROMIS-10, opioid use, pain interventions, work status, and SAEs. Pain scores (NRS) significantly decreased from 6.8 at baseline to 4.1, 4.8, and 4.2 at 1, 3, and 6 months (P < 0.01). Disability scores (ODI) also improved significantly from 50.3 to 41.7, 35.6, and 34.9 (P < 0.05). PROMIS-10 scores showed slight, non-significant improvements. Opioid use dropped from 26 to 13–16 patients over time, though not statistically significant. No SAEs occurred. CT scans at 6 months showed 96% implant bone apposition and no implant failures; 72% of patients had SIJ bridging.

LIMITATIONS: This study is limited by a small sample size, short follow-up, and lack of control group.

CONCLUSIONS: Laterally placed SIJ fusion titanium alloy implants are a safe and effective treatment for patients with refractory SIJ dysfunction, as evidenced by significant improvements in pain and function, high rates of radiological fusion, and a favorable safety profile. 

KEY WORDS: Low back pain, sacroiliac joint, SI joint dysfunction, SI joint fusion, chronic pain, patient reported outcome measures, radiological outcomes