The Evolving SI Fusion Landscape: Innovations and Outcomes in Focus
The field of SI joint fusion has undergone rapid growth and diversification in recent years. Today, minimally invasive surgical techniques are increasingly supplanting traditional open surgeries, and new medical devices, implant materials, and evaluation techniques gaining prominence in the literature.
To shed light on these advancements, we’re highlighting recent publications on SI fusion techniques, focusing on two key areas: radiographic parameter evaluation and patient outcomes.
New patient outcome studies in minimally invasive SI fusion
Minimally invasive surgical (MIS) approaches make up the majority of SI fusion procedures performed today (Federico et al. 2023). The lateral transiliac MIS approach using insertion of transfixing triangular titanium implants (TTI) represents the most extensively studied MIS technique, both in terms of study volume and patient follow-up duration.
Alternative MIS approaches, such as posterior oblique, posterior, and posterolateral, are gaining more attention in the literature, but these currently rest on a more limited body of clinical data. It appears that average follow-up periods for posterior SI fusion, for example, hover around 6 months in the literature, typically a maximum of 12 months.
Recent publications on patient outcomes in SI joint fusion include:
- Patel et al. 2024 found sustained improvements in ODI, EuroQOL-5D and EuroQOL scores at 5-year follow-up in 36 SI joint fusion patients receiving TTI, with no evidence of device breakage, migration, or subsidence. Additionally, patients using opioids for pain management decreased from 57% to 17% at 5 years.
- Davies et al. 2024 evaluated 6-month clinical outcomes and 12-month radiographic outcomes following SI fusion using minimally invasive inferior-posterior delivery of a fixation device in 33 patients. They found significant improvements in VAS scores from pre-op (80.9mm) to 6 weeks (25.2mm), 3 months (21.8mm), and 6 months (31.1mm), as well as mean ODI scores from pre-op (51.9%) to 6 months post-op (29.6%). These findings indicate positive trends in pain reduction and function improvement.
- Moghim et al. 2024found in their recently published monocentric study statistically significant reductions in VAS scores and morphine usage at 3, 6, 9, and 12 months following posterior SI fusion using allograft.
New studies on imaging endpoints, radiographic, and spinopelvic parameters in SI fusion
adiographic assessment is essential for both preoperative planning and postoperative monitoring in SI joint fusion. Computed tomography (CT) remains the gold standard due to its capacity to confirm fusion, identifying features such as bone bridging across the joint and the absence of radiolucent lines around the implant.
CT scans remain the standard for evaluating SI fusion. Spinopelvic parameters, as visualized in this radiograph of a patient with corrective equipment in the lumbosacral spine, are also of increasing interest in the literature.
Additionally, newer studies are examining additional radiographic parameters for pre- and post-op assessment, including range of motion and select spinopelvic parameters:
- Range of motion in flexion-extension, axial rotation, and lateral bending in Raji et al. 2024: In a recent cadaveric study, the authors found that a posterior transfixation cage system and lateral triangular rods effectively reduced motion in flexion-extension, axial rotation, and lateral bending. In contrast, a posterior cylindrical threaded implant showed less effectiveness for flexion-extension
- Changes in Post-Op Pelvic Incidence: Hirpara et al. 2024 suggest that pelvic incidence may be a mutable parameter in SI joint fusion, finding that pelvic incidence changed by >5 ° in 10.6% of patients after primary SIJF
New opportunities for research in SI fusion
At RAYLYTIC, we believe that collaborations aimed at developing novel techniques to evaluate both pre- and postoperative mobility of the SI joint will be crucial in the effort to advance the safety and efficacy of this procedure. Such partnerships could elevate our knowledge of the relationship between fusion and patient outcomes, potentially refining patient selection criteria and identifying more precise predictors of long-term success.
We are poised to support this growing field of research with our next-gen spinal and orthopedic research platform, UNITY, complete with automated analysis of spinopelvic parameters, including:
- Pelvic incidence
- Lumbar lordosis (LL)
- Pelvic tilt (PT)
- Sacral slope (SS)
Book a demo to learn how we can support your clinical strategy or research endeavors in the rapidly evolving field of SI joint fusion.