Abstract: BACKGROUND: For thoracolumbar spine fractures with developmental stenosis of the vertebral arch, accurate nail placement is difficult using traditional fluoroscopy-assisted techniques. O-arm navigation assistance systems offer higher precision in general vertebral arch nail placement, but there is scarce literature on the application of O-arm navigation-assisted nail placement in thoracolumbar spine fractures with developmental stenosis of the vertebral arch both domestically and abroad. 
OBJECTIVE: To explore the accuracy of percutaneous vertebral arch nail placement assisted by O-arm navigation in patients with thoracolumbar spine fractures complicated by developmental stenosis of the vertebral arch.
METHODS: A retrospective analysis was conducted on 53 patients who underwent percutaneous vertebral arch screw fixation surgery at Department of Orthopedics, General Hospital of Central Theater Command of PLA for thoracolumbar spine fractures complicated by developmental stenosis of the vertebral arch from January 2021 to March 2023. Totally 208 cases of vertebral arch developmental stenosis were found (cases with multiple vertebral arch developmental stenosis were counted separately). Based on the surgical approach, the patients were divided into two groups: O-arm navigation group (n=98) and C-arm fluoroscopy group (n=110). Postoperative imaging data were compared between the two groups, including anatomical perforation score, functional perforation score, actual vs. expected nail trajectory in the horizontal plane, and sagittal plane angle differences.

RESULTS AND CONCLUSION: (1) There was no significant difference in the narrowest width of the pedicle isthmus (pow) between the two groups of patients (P > 0.05). The proportions of different degrees of narrowing (mild: 6 mm≤pow<7 mm, moderate: 5 mm≤pow<6 mm, severe: pow<5 mm) were also not significantly different between the two groups (P > 0.05). (2) The overall grade and scores of anatomical perforation and functional perforation were lower in the O-arm group compared to the C-arm group, and these differences were statistically significant (P < 0.001). In terms of the angular deviation between the actual and planned screw trajectories, the O-arm group had smaller deviations, and these differences were statistically significant (P < 0.05). (3) In the mild and moderate narrowing groups, the O-arm group showed significant advantages in anatomical perforation, functional perforation, and angular deviation between actual and planned screw trajectories, and these differences were statistically significant (P < 0.001). (4) The O-arm group demonstrated better performance in anatomical perforation and functional perforation, especially in the T12-L2 segment, with more significant advantages. Additionally, the O-arm group had better angular deviations in actual and planned screw trajectories in all segments compared to the C-arm group. (5) Therefore, the use of O-arm navigation-assisted percutaneous screw placement for the treatment of thoracolumbar fractures with developmental pedicle isthmal narrowing provides higher accuracy and safer surgery. 

中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程

Key words: developmental stenosis of vertebral pedicle, O-arm navigation system, pedicle screw, screw placement accuracy, percutaneous screw placement, internal fixation, pedicle rupture, thoracolumbar fractures