Periapical-dropout Screws Strategy For 3-Dimensional Correction of Lenke 1 Adolescent Idiopathic Scoliosis in Patients Treated by Posterior Spinal Fusion

Study Design: This was a single-center, retrospective study. Objective: The objective of this study was to compare periapical-dropout screws strategy (PDSS) with traditional-multilevel pedicle screws strategy (TMSS) for 3-plane correction of Lenke 1 adolescent idiopathic scoliosis deformity. Summary of Background Data: There are limited data in 3-plane correction and the optimal pedicle screw (PS) configuration for Lenke 1 adolescent idiopathic scoliosis surgery. Materials and Methods: Sixty-one consecutive patients with Lenke 1 curves (range: 50-80 degrees), undergoing single-stage posterior spinal fusion with PS fixation, were included. Patients with a minimum follow-up of 1 year were divided into 2 groups according to PS strategy. The PDSS group included 33 patients with PS placement bilaterally at both ends and apex of the construct. The TMSS group included 28 patients with conventional PS placement. Baseline, immediate, and last follow-up demographic, radiographic, and clinical outcomes were analyzed. Radiographic outcomes were assessed in axial (using rib index and apical vertebral rotation using Raimondi ruler and Upasani methods), coronal, and sagittal planes. The implant costs were also evaluated. Results: There were no differences in demographic, preoperative radiographic parameters and levels fused. The number of PSs per level fused was significantly lower in the PDSS group (1.3 vs. 1.4; P=0.0002). At last follow-up, major Cobb correction averaged 79% for the PDSS group and 69.5% for the TMSS group (P=0.001). T2-T12 kyphosis angle changes were 1 degree in the PDSS group and -2.5 degrees in the TMSS group (P=0.35). Rib index correction was 28.2% for the PDSS group and 17.7% for the TMSS group (P=0.02). Upasani grade apical vertebral rotation was significantly better in the PDSS group (0.7 vs. 1.4; P=0.0001). Clinical outcomes evaluated by Scoliosis Research Society-30 scores were similar in both groups. Total implant costs were significantly lower in the PDSS group ($16,852 vs. $18,926; P<0.001). Conclusion: The PDSS construct provides better deformity correction in all 3 planes and helps decrease implant costs compared with the TMSS construct. Thus, the PDSS construct can be considered as a rational strategy and cost-effective technique when treating moderate Lenke 1 curves with posterior spinal fusion.