Evaluation of Fusion After Minimally Invasive Sacroiliac Joint Fusion Surgery with Decortication: 24-Month Results

Cross et al, (2017) Evaluation of Fusion After Minimally Invasive Sacroiliac Joint Fusion Surgery with Decortication: 24 – Month Results. Summary of Presentation at International Society for the Advancement of Spine Surgery Annual Meeting

Background
Time-to-fusion for the SI joint is not well reported. Previous literature examined SI joint fusion post-surgery at 5 years and a separate trial demonstrated only a small percentage of SI joints fuse within 1 year.^1,2 The purpose of this study was to evaluateradiological evidence of arthrodesis post SI joint fusion with decortication at 12 and 24 months.

Methods
This prospective, multi-center study enrolled patients after receiving SI joint fusion with decortication (SImmetry) prior to their 24-month visit. Thin-slice computerized tomography (CT) was collected and submitted to an independent core laboratory (Medical Metrics, Inc.) for evaluation. Non-biased radiologists experienced in evaluating the SI joint independently reviewed all CTs for fusion in relation to the joint and the area of decortication. Fusion was defined as presence of a continuous segment of solid bridging bone that extends from sacrum to ilium. Pain quantified by numeric pain scale and adverse events were also reported.

Results
19 patients at three institutions were enrolled and completed a 12-month visit and CT. From the original 19 patients, 18 patients completed a 24-month visit and CT. All patients received SIJ fixation with threaded implant(s) after undergoing decortication and bone graft insertion.

Primary Endpoint: Fusion

• 94% of subjects had solid or possible continuous bone across the SI joint at 24 month
• 88% of fused joints were fused within the area of decortication

Secondary Endpoint: Pain Reduction

• 70% pain reduction maintained through 24-months
  post-op
• 89% had greater than 50% reduction in pain

Smoking status, age, gender, body mass index, or implanting site did not appear to affect fusion of the SI joint.
Freedom from device- or procedure-related serious adverse events through 24 months was 100%.

Conclusion
Minimally invasive SIJ fusion surgery with decortication and bone graft material can result in arthrodesis as early as 12 months with continued positive clinical outcomes through 24 months. Decortication and bone grafting may contribute to earlier fusion than seen in other trials. Minimally invasive SIJ fusion surgery provides significant pain relief 2-years post-operatively.

^{1 Leonard Rudolf et al, (2014) Five-Year Clinical and Radiographic Outcomes After Minimally Invasive Sacroiliac Joint Fusion Using Triangular Implants. The Open Orthopeadics Journal; 8, 375-383
2 Bradley S. Duhon et al. (2016) Triangular Titanium Implants for Minimally Invasive Sacroiliac Joint Fusion: 2-Year Follow-Up from a Perspective Multicenter Trial. International Journal of Spine Surgery; Volume 10; Article 13:1-27}