The Effect of Fusion End-Levels on Sagittal Parameters and Quality of Life in Thoracic and Lumbar Adolescent Idiopathic Scoliosis Patients

Study design: Retrospective cohort study. Objectives: The study aimed to evaluate the effect of fusion end levels on sagittal parameters and quality of life. Methods: A total of 162 patients (72 Lenke-1 and 90 Lenke-5 who underwent Posterior Spinal Fusion (PSF) were included in the study. Of these, 57 patients underwent Cobb-to-Cobb (CC) fusion (18 patients in Lenke-1 and 39 in Lenke-5), and 105 patients underwent non-Cobb to Cobb (non-CC) fusion (54 patients in Lenke-1 and 51 in Lenke-5). Cervical lordosis, thoracic kyphosis, lumbar lordosis, and spinopelvic parameters were measured preoperatively, post-operative 6th months and at the final follow-up. Short Form-36 (SF-36) score, Scoliosis Research Society-22 (SRS-22) score, and radiographic measurement parameters were compared between the groups. Results: The post-operative 6th months cervical lordosis angle in Lenke-1 patients was significantly lower in the CC group than in the non-CC group (5.9 ± 4.4 vs. 12.1° ± 10.9°, p=0.022), and in Lenke-5 patients, the thoracic kyphosis angle was significantly higher in the CC group than in the non-CC group at 6 months and at the final follow-up visit. (46.8 ± 8.9 vs. 37.4 ± 11.0, p<0.001 and 43.6 ± 9.2 vs. 37.9 ± 10.6, p=0.009, respectively). Our results support the idea that instrumentation is limited to the main curve when proximal levels of the curve are instrumented. Conclusion: The choice of CC or non-CC surgery affects the parameters proximally rather than distally in both Lenke-1 and Lenke-5 patients. The effect of level selection on the parameters was mostly prominent in the early post-operative period.