Robot-assisted lumbar facet joint infiltration improves accuracy and reduces radiation exposure compared to the manual technique in a comparative phantom study

Compact robotic systems offer new opportunities for spinal procedures outside the operating room, but their potential for small-scale interventions such as facet joint infiltrations remains underexplored. The objective of this study was to assess the feasibility, accuracy, radiation exposure, and user experience of a compact robotic assistance system (Micromate) for lumbar facet joint infiltrations compared to the manual technique using a standardized phantom model. The robot allows needle placement after a single registration with two orthogonal fluoroscopic images, enabling multiple punctures without repeat imaging. Twenty-two neurosurgeons (0-23 years of experience) performed bilateral infiltrations from L1/2 to L5/S1 both manually and with robotic assistance on an embedded synthetic lumbar spine model. Outcomes included fluoroscopy time, radiation dose, number of X-rays, needle repositioning, and accuracy (Euclidean distance to predefined targets on 3D scans). User experience was evaluated using the NASA-TLX and structured questionnaires. Robotic guidance significantly reduced fluoroscopy time (5.4 vs. 13.7 s), radiation dose (1.95 vs. 3.12 mGy), and X-ray count (6.4 vs. 15.3). Manual infiltrations required multiple needle repositionings (mean 22.2 per participant), whereas there were none in the robotic group (per protocol). Accuracy was higher with robotic assistance (5.9 vs. 7.3 mm deviation; p < 0.001), and placement was more consistent across spinal levels. Although total procedure time was longer robotically (27.4 vs. 11.6 min), a learning effect was observed and participants rated their performance higher with the robot. Compact robot-assisted facet joint infiltration is feasible and improves accuracy while reducing radiation exposure. Its potential for multi-level, low-radiation interventions combined with its lower infrastructural requirements may offer a practical and cost-effective alternative to CT-guided procedures, particularly in outpatient settings.