Development and Preliminary Clinical Application of a Novel Posterior Atlantoaxial auto Anti-Rotation Reduction Rod (PAAR)

Background: Atlantoaxial dislocation (AAD) is a common upper cervical spine disorder caused by various factors, including trauma, congenital anomalies, and inflammation, which can lead to spinal cord compression and neurological dysfunction. The posterior atlantoaxial screw-rod (PASR) system, though widely used for reduction and fixation, has limitations such as insufficient reduction force and potential spinal cord injury due to rod rotation. This study aimed to evaluate a novel posterior atlantoaxial reduction (PAAR) system with enhanced reduction capabilities and an auto anti-rotation feature. Methods: This was a retrospective study involving 11 patients who underwent posterior atlantoaxial surgery using the PAAR system. The patients' demographic data, dislocation types, surgical time, and blood loss were recorded. Pre- and post-operative measurements of the atlantodental interval (ADI), rotational angle (RA), neurological function, and occipital cervical pain were assessed. Statistical analysis was performed using paired t-test and Wilcoxon ranks test to evaluate significant differences between preoperative and postoperative outcomes. Results: The PAAR system demonstrated excellent reduction capabilities in all patients, with satisfactory outcomes for anterior, posterior, and rotational dislocations. The average surgical time was 110.5 minutes, and the average blood loss was 75 ml. Significant improvements were observed in the Japanese Orthopaedic Association (JOA) scores, Visual Analog Scale (VAS) scores for occipital cervical pain, ADI, and RA (P < 0.05). Additionally, MRI and CT scans showed complete decompression and stable fixation without complications. Conclusions: The novel PAAR system provides effective reduction and fixation for various types of atlantoaxial dislocations. Its auto anti-rotation function and versatile design overcome the limitations of traditional PASR systems, offering a safe and efficient treatment option for patients with atlantoaxial dislocation. This approach may help improve clinical outcomes and reduce surgical complications.