Concave apical translation with simultaneous convex apical derotation technique in adolescent idiopathic scoliosis Surgery: A technical note and case series

Abstract

Objective: There is still a debate regarding the efficacy of pedicle screws in adolescent idiopathic scoliosis (AIS) surgery. As well as the implant being used, the surgeon factor and the correction technique are also important for correction quality. The purpose of this study was to introduce the concave apical translation with simultaneous convex apical derotation technique (CATCAD) using polyaxial pedicle screws and report the radiographical outcomes. Material and Methods: Consecutive AIS patients who had been scheduled for surgery were enrolled in the study. The preoperative and postoperative radiographic parameters included Cobb angle, apical vertebral translation (AVT), thoracic kyphosis (TK) and apical vertebral rotation (AVR). Coronal plane parameters were measured in plain radiography. Sagittal and axial plane parameters were measured in computed tomography scan (CT scan). Implant density was calculated. Results: Twenty patients were included in the study. All were female with a mean age of 14.9 years. Eighteen patients were either Lenke 1 (45.0 %) or Lenke 2 (45.0 %). The remaining patients were Lenke 3 and 4 (10.0 %). There was an improvement of postoperative radiographic parameters. The mean of AVR corrections were −1.8 ± 2.8° (10.0 %) and −4.5 ± 2.8° (24.0 %) for lower apical screw density (LAD) group and higher apical screw density (HAD) group, respectively (p-value = 0.024). Conclusion: CATCAD technique can achieve the 3D correction in AIS surgery. With this correction technique, the AVR correction seem higher if the high apical screw density implant is used.

Keywords

• Adolescent idiopathic scoliosis
• Apical vertebral rotation
• Implant density
• Translation
• Vertebral derotation