Identification of optimized rod shapes to guide anatomical spinal reconstruction for adolescent thoracic idiopathic scoliosis

Abstract

Adolescent idiopathic scoliosis (AIS), the most common pediatric musculoskeletal disorder, causes a three-dimensional deformity of the spine. Although rod curvature could play an important role in anatomical spinal reconstruction in patients with thoracic AIS, intraoperative contouring of the straight rod induces notches into the rod, leading to decreased fatigue strength. Here, we analyzed pre-bent rod geometries from 46 intraoperative tracings of the rod geometry, which can provide anatomical spinal reconstruction in patients with thoracic AIS. The center point clouds of the rod shapes were extracted and approximated as arcs and straight lines. The difference between the center point clouds were evaluated using the iterative closest point methods. When the rod shapes were divided into six groups based on length followed by hierarchical cluster analysis, 10 representative rod shapes were obtained with a difference value of 5 mm. Thus, we identified optimized rod shapes to guide anatomical spinal reconstruction for thoracic AIS, which will reduce not only the risk of rod breakage but also operation time, leading to decreased patient burden. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

In vivo deformation of anatomically pre-bent rods in thoracic adolescent idiopathic scoliosis

“…However, we currently use these rods for other Lenke 2–6 curves except for Lenke 5 curve. Eleven rods are regarded as appropriate for pre-bent rods 15 . Although the configurations were obtained from Japanese patients, the algorithm to identify anatomical rod configurations can be applied for other races 15 .…”

“…In this surgical strategy, two rods were bent identically to guide postoperative anatomical TK without reference to the intraoperative coronal alignment of the deformity 9 . Thus, pre-bent configurations were intraoperatively derived from tracings of the rod shapes applied to the technique, and optimized rod configurations were identified to guide the anatomical reconstruction 15 . These results suggest that anatomically designed rods could be provided as notch-free, pre-bent rods 15 .…”

“…Thus, pre-bent configurations were intraoperatively derived from tracings of the rod shapes applied to the technique, and optimized rod configurations were identified to guide the anatomical reconstruction 15 . These results suggest that anatomically designed rods could be provided as notch-free, pre-bent rods 15 . The anatomical notch-free rods are created using custom-made rigid bending fixtures, and 11 types of cobalt chrome (CoCr) alloy rods can be utilized based on the curve types and its lengths.…”

Use of the sagittal Cobb* angle to guide the rod bending in the treatment of thoracolumbar fractures: a retrospective clinical study

“…In a small number of studies on the bending angle of the connecting rod, the researchers thought that the angle should almost match the kyphosis angle [20]. A large number of studies have shown that the coronal Cobb angle is an important indicator of the balance of the coronal position of the spine [7,[19][20][21][22][23]. According to previous studies, the sagittal Cobb angle is also an important index used to evaluate the spine sagittal balance [8,[24][25][26].…”

Use of the Sagittal Cobb* Angle to Guide the Rod Bending in the Treatment of Thoracolumbar Fractures：A Retrospective Clinical Study

“…21 A large number of studies have shown that the coronal Cobb angle is an important indicator of the balance of the coronal position of the spine. 11,[20][21][22][23][24] According to previous studies, the sagittal Cobb angle is also an important index used to evaluate the spine sagittal balance. 8,[25][26][27] In this study, for the single thoracolumbar vertebra fracture, we rede ned the sagittal Cobb angle of a single fractured vertebra as the sagittal Cobb* angle, and its measurement method.…”