Sacroiliac joint (SIJ) painful dysfunction is a common source of low back pain (LBP). Several surgical treatment options for SIJ fusion were described. A promising treatment option with demonstrated clinical improvement is the minimally-invasive SIJ fusion. The aim of this case study was to document the effectiveness and safety of the new SIJ system (Torpedo®) over a period of 6 months after the minimally invasive implantation. Patients with failed conservative treatment of painful SIJ dysfunction were enrolled successively in two centers. The Diagnosis was made by positive response to SIJ-injection with local anesthetic and at least by two positive SIJ provocation tests. The Torpedo® Implant system was used for the implantation. This workpiece made of titanium alloy is characterized by a helical profile geometry (CST: chronical spinal turn) with a hydrophilic surface. The evaluated endpoints LBP and grade of disability were assessed using a 0-10 numerical rating scale (NRS), and Oswestry Disability Index (ODI) preoperatively and at one, three and six months postoperatively. 15 patients (10 female, 5 male; mean age 59 ± 13 years) were operated on one after the other. The pain intensity decreased in all 15 patients. After 6 months, a decrease in the median values of 70% (quartiles 1-3: 65-79%) was calculated. The median values of the Oswestry Disability Index after 6 months were 62% (quartiles 1-3: 53-67) lower than before the operation. Before surgery, 13 patients (87%) were taking opioids for pain management. Six months after the operation, opioids were only needed by 3 patients (20%). Implant malpositioning was not detected on plain radiograph. No surgical site infections or perioperative complications occurred. The clinical improvement in early follow up and the absence of surgery related complications demonstrate a high grade of device-related safety and effectiveness of the treatment with a novel minimally-invasive SIJ fusion system.