Purpose <p>To evaluate the efficacy and safety of robotic-arm-assisted [¹⁸F]NaF-PET/CT-guided intra-articular block for lumbar facet joint (LFJ) or sacroiliac joint (SIJ) arthropathy.</p> Materials and methods <p>In this single-centre, non-randomized, prospective phase 2 clinical-trial, participants with chronic low back pain (CLBP) were recruited from August 2022 to June 2024. Participants having NaF-avid LFJ or SIJ on [¹⁸F]NaF-PET/CT underwent robotic-arm-assisted intra-articular block with steroids and local anaesthesia. Baseline, immediate post-procedural, and 3-month follow-up visual analog score (VAS), Low-Back Outcome Scale (LBOS), Oswestry Disability Index (ODI), and change in SUV values of target joints were documented. The primary end-point of the trial was ≥ 50% improvement in VAS at 3 months, and secondary end-points were improvements in ODI, LBOS by at least one grade and change in SUV. Descriptive statistics were applied. Qualitative variables were reported in percentages.</p> Results <p>Out of 85 enrolled participants, 79 (92.9%) underwent [¹⁸F]NaF-PET/CT. Among them, 61 (77.2%) had NaF-avid joints, and 55(69.6%) underwent PET/CT-guided robotic-arm-assisted intra-articular blocks. The primary end-point was met in 84% (46/55) participants, and secondary end-points in 96% (53/55) and 89% (49/55), respectively. The procedure was technically successful in all the target joints. A significant change in pre- and post-procedural median SUVmax and SUVpeak of the treated joints was noticed. No major adverse effects were noticed in the participants.</p> Conclusion <p>Robotic-arm-assisted [¹⁸F]NaF-PET/CT guided intra-articular blocks of LFJ and SIJ in CLBP appear to be safe and feasible in NaF-avid arthropathy. However, lack of comparison with the standard of care, small sample size, selection bias and radiation exposure limit its generalizability.</p>