The sacroiliac joint (SIJ) is estimated to be the source of low mechanical back pain in 10-27% of patients. When conservative measures for treating SIJ pain fail (physiotherapy, exercise, analgesic medications, chiropractic manipulation, etc.) radiofrequency ablation (RFA) is a treatment option in carefully selected patients. RFA uses a radiofrequency generator to create a thermal lesion, with the aim of ablating the nerves that innervate the SIJ complex. Studies have confirmed that SIJ RFA can provide significant relief for patients with SIJ pain. The current gold standard is the use of fluoroscopic (x-ray guidance) to visualize bony landmarks in order to create an accurate thermal lesion along the lateral sacral crest; where the nerves that innervate the SIJ complex reside. Recent literature has proposed a technique for an ultrasound-guided approach to achieve an RFA lesion in patients with SIJ pain. It is proposed that with ultrasound-guidance, versus fluoroscopic-guidance, the interventionalist is able to perform fewer needle passes for the procedure, as well as fewer thermal lesions, thereby achieving shorter performance times. The proposed study serves as a non-inferiority randomized controlled trial to assess the effectiveness of ultrasound-guided versus fluoroscopy-guided RFA for the treatment of SIJ pain.