Posterior spinal fusion using dual rod translation: impact on kyphosis restoration in AIS

To describe the surgical technique of Dual Rod Translation (DRT) and evaluate its radiographic and patient-reported outcomes in thoracic adolescent idiopathic scoliosis (AIS), with a focus on sagittal alignment restoration.

A retrospective review was conducted on patients with AIS who underwent posterior spinal fusion using the DRT technique between July 2020 and December 2023. DRT employs asymmetrically contoured rods and reduction screws with extended tabs. After both rods are positioned, posterior translation is performed on the concave side. The convex rod, fully seated in the screw heads, functions as a mechanical axis for vertebral rotation and hump reduction, enabling simultaneous three-dimensional correction. Radiographic parameters and SRS-22 scores were assessed preoperatively and at follow-up. Mixed-effects models and Pearson's correlation coefficient were used for analysis.

Sixty patients (mean age 16.5 ± 3.9 years; 88% female) were included. The mean follow-up period was 20.5 ± 6.3 months. The main thoracic curve improved from 58° ± 9° to 16° ± 5° (mean correction 76%). Thoracic kyphosis increased by 18° in all, with greater gains (22°) in hypokyphotic patients. Cervical and lumbar lordosis increased significantly, correlating with changes in thoracic kyphosis (r = 0.442 and r = 0.428, respectively). SRS-22 self-image and subtotal scores improved significantly. No intraoperative complications occurred.

The DRT technique may represent a safe and reproducible method for thoracic AIS, achieving favorable coronal correction with notable improvement in sagittal alignment.