Effectiveness of 'O'-Arm Navigation-Assisted In-Out-In Pedicle Screw Technique for the Treatment of Congenital Scoliosis: A Study of 17 Cases

Objective: To investigate the efficacy and safety of internal fixation of narrow varicose vertebrae using the lateral In-Out-In screw technique with the assistance of the "O" arm navigation system in 17 patients with congenital scoliosis. Methods: A retrospective analysis was conducted on the clinical data of 17 patients with congenital scoliosis who underwent internal fixation surgery at Luohe Central Hospital from January 2019 to January 2021. During the procedure, the "O"-arm navigation system was utilized to assist in the placement of pedicle screws for narrow and variant vertebrae using the In-Out-In technique. Pedicle screws were inserted into the normal pedicles with the assistance of the "O"-arm navigation system for internal fixation to correct lateral and posterior convex deformities. Post-screw placement, the accuracy of screw placement was evaluated using the "O"-arm machine scan. After satisfactory correction, residual gaps between vertebral bodies were filled with bone grafts, and the surfaces of transverse processes and other posterior structures within the fusion range were decorticated before bone grafting. Preoperative Cobb angles of lateral and posterior convexities, as well as intraoperative details and the success of single-stage screw placement, were recorded. Follow-up was conducted until December 2023, documenting occurrences of postoperative complications such as spinal cord injury, cerebrospinal fluid leakage, wound infection, screw and rod loosening or displacement, and fractures. Full-length anteroposterior and lateral X-rays of the spine were obtained at 1 week and 1 year postoperatively to record Cobb angles of lateral and posterior convexities and calculate the correction rate. Patient or caregiver satisfaction with surgical outcomes was assessed using the Scoliosis Research Society-22 (SRS-22) questionnaire. At the final follow-up, the bone fusion status was evaluated using the Eck fusion grading system. Results: (1) The mean operative time was (184.0±43.2) minutes, with an intraoperative blood loss of (632.0±192.7) ml. The highest instrumented vertebra was T5, and the lowest was S1. The mean number of fixed and fused segments was (9.0±2.7). A total of 216 pedicle screws were inserted, comprising 152 pedicle screws and 64 lateral pedicle screws, all successfully placed in a single attempt. Intraoperative "O"-arm scans revealed that all screws were positioned close to the inner wall of the pedicles and did not breach the vertebral canal. (2) Follow-up was conducted until December 2023, with a mean follow-up duration of (28.0±3.4) months. None of the 17 patients experienced complications such as spinal cord injury, cerebrospinal fluid leakage, wound infection, screw or rod loosening, displacement, or fracture. In 17 patients, the preoperative Cobb angle for lateral convexity was (57.8±6.6) °, and for posterior convexity was (44.0±9.6) °. At 1 week postoperatively, the Cobb angle for lateral convexity was (12.6±4.2) °, and for posterior convexity was (15.3±2.4) °. At 1 year postoperatively, the Cobb angle for lateral convexity was (15.3±2.4) °, and for posterior convexity was (15.4±2.3) °. The differences between preoperative and postoperative angles were statistically significant, while the differences between angles at 1 week and 1 year postoperatively were not statistically significant. At 1 week postoperatively, the correction rate for lateral convexity was (77.6±8.6) %, and for posterior convexity was (63.9±8.4) %. At 1 year postoperatively, the correction rate for lateral convexity was (76.8±7.1) %, and for posterior convexity was (63.6±8.6) %. There were no statistically significant differences in comparison between the two time points (t=0.272, P=0.789; t=0.123, P=0.904). The SRS scores of the 17 patients at baseline (71.8±4.2), 1 week postoperatively (83.1±4.4), and 1 year postoperatively (84.7±3.8) showed statistically significant differences (F=291.43, P<0.001). The baseline SRS score was lower than those at 1 week and 1 year postoperatively (P<0.05), but there was no significant difference between the scores at 1 week and 1 year postoperatively (P>0.05). At the final follow-up, all 17 patients achieved grade Ⅰ fusion. Conclusion: The In-Out-In screw technique for the treatment of congenital scoliosis using the "O"-arm navigation system for navigation-assisted internal fixation can safely insert the screws for the treatment of narrow variant lateral pedicles, which provides solid internal fixation, good orthopedic effect, and fewer complications.