Optimizing Postoperative Sagittal Alignment: The Effect of Pedicle Screw Fixation in 540° Combined Surgery for Degenerative Cervical Disease

Abstract

Study design Retrospective cohort study. Objective To determine whether increased pedicle screw use in the lower subaxial cervical spine (C5-C7) improves sagittal alignment after posterior-anterior-posterior (PAP) surgery. Method A total of 108 patients who underwent posterior-anterior-posterior (PAP) surgery for multilevel cervical degenerative disease were retrospectively reviewed. Patients were divided into three groups according to the distal fixation level: Group 1, pedicle screw fixation limited to C7; Group 2, pedicle screw fixation limited to C6-7; and Group 3, pedicle screw fixation extending to C5-6-7. Cervical sagittal alignment and patient-reported outcomes were evaluated preoperatively, immediately postoperatively, at 3 months, and at 1 year. Results Baseline sagittal parameters were similar among groups. CL increased in all groups but was significantly greater in Groups 2 and 3 than in Group 1 postoperatively (21.8 degrees and 26.1 degrees vs 14.2 degrees) and at 1 year (22.3 degrees and 26.0 degrees vs 14.8 degrees; P < 0.05). T1S-CL decreased significantly in Groups 2 and 3 but not in Group 1 at 3 months (8.5 degrees and 3.4 degrees vs 16.6 degrees; P < 0.001) and at 1 year (7.7 degrees and 7.3 degrees vs 17.8 degrees; P < 0.001). Group 1 showed greater vertical height loss (3.9 vs 2.3 and 2.2 mm; P = 0.016) and higher subsidence rates. C2-7 SVA, C2 SVA, and clinical scores improved in all groups without between-group differences. Conclusions Greater use of pedicle screws at C5-C7 enhanced sagittal alignment correction compared with C7-only fixation, while clinical outcomes were similar across groups.