Novel approach to sacroiliac joint pain: Preliminary cadaveric and in-silico analysis of safety and feasibility of X-ray-guided high-intensity focused ultrasound ablation

Current treatment modalities for chronic sacroiliac joint (SIJ) pain each have advantages and limitations. High-intensity focused ultrasound (HIFU) is a novel, non-invasive tool which produces highly localized thermal ablation using common imaging platforms such as magnetic resonance imaging (MRI), ultrasound, and fluoroscopy. Regulators have approved Fluoroscopy- or X-ray-guided HIFU (XRgHIFU) in the USA, EU, UK, and Canada. This study evaluates XRgHIFU's initial safety and feasibility as a non-invasive alternative to RFA for chronic SIJ pain. In a cadaveric model, thermocouples were implanted in targets along the lateral sacral crest and 1 cm into the foramen. The targets were then sonicated and temperature was recorded. In an in-silico model, 10 adult computed tomography scans were simulated using a 3D, k-Wave -based acoustic and thermal simulation pipeline. Target and foraminal temperatures corresponding to the cadaveric model were recorded, and the resultant lesions were analyzed. The cadaveric and in-silico models showed agreement. Neither model indicated ablation of the intra-foraminal nerve root. The ratio of heating at target vs. foraminal test point was 15.7 ± 4.6 (N = 6) in the cadaveric model, whereas the ratio in the in-silico model was 17.3 ± 9.3 (N = 20). Contiguous strip lesions ≥15 mm in width were produced in the in-silico model. This study supports the safety and feasibility of XRgHIFU for SIJ pain. • Previously demonstrated: x-ray guided focused ultrasound safely ablates lumbar medial branch nerves. • Focused ultrasound principles apply to sacroiliac joint pain treatment. • Study measures heat exposure near spinal nerve roots during treatment. • No harmful heating detected in critical nerve root structures. • Results support future research using focused ultrasound for sacroiliac pain.