PhD Scientific Days 2025

Surgical Medicine

Development of Intraoperative and Postoperative 3D Reconstruction Methods For The Follow-Up of Adolescent Idiopathic Scoliosis Correction Surgeries

Name of the presenter

Szőke András

Institute/workplace of the presenter

University of Pécs - 3D Printing and Visualisation Centre

Authors

András Szőke, MSc¹, Lauer Barnabás², Schlégl Ádám³, Maróti Péter⁴

1: University of Pécs - 3D Printing and Visualisation Centre
2: Fejér County Szent György University Teaching Hospital
3: University of Pecs - Department of Orthopaedics
4: Medical Skills Education and Innovation Centre, Medical School - University of Pecs

Text of the abstract

Introduction
Adolescent idiopathic scoliosis (AIS) is a prevalent three-dimensional spinal deformity often requiring surgical intervention using posterior pedicle screw and rod instrumentation. Although the correction achieved during surgery is generally stable, implant rod deformation due to intraoperative bending forces and postoperative biomechanical loads remains insufficiently studied.

Aims
This study aims to develop and apply intraoperative and postoperative 3D reconstruction methods for evaluating rod deformation in AIS surgery. The primary objective is to document the implant rods’ intraoperative geometry using handheld 3D scanning and track shape changes over a two-year follow-up period. A secondary aim is to explore correlations between rod deformation and postoperative postural adaptation and correction loss.

Methods
A prospective cohort study was conducted on ten AIS patients undergoing posterior segmental instrumentation. Intraoperative rod shapes were captured using a handheld 3D scanner after final in situ bending. Postoperative follow-up was performed at five timepoints (day 3, 3, 6, 12, and 24 months) using a stereoradiograph. 3D models of the rods were reconstructed from both intraoperative scans and radiograph data, and spatial alignment was performed in CAD. Rod shape evolution was analysed using second derivative calculations to identify localized deformation points.

Results
In nine patients, complete 3D data were acquired. Contrary to the initial hypothesis that rod geometry would stabilize after in-situ bending, several cases showed significant deformation even between the one- and two-year follow-ups. Preliminary results suggest that relevant deflection points often exceed the 5.5 mm threshold—equivalent to the rod diameter—indicating clinically meaningful geometric changes. Initial modelling reveals trends in cranial displacement over time with high spatial accuracy.

Conclusion
This study demonstrates the clinical applicability of handheld 3D scanning for radiation-free intraoperative rod geometry capture in AIS surgery. Ongoing analysis will establish correlations between deformation patterns and postural adaptation, potentially improving predictive capabilities for correction loss. Future results are expected to provide insights for personalized surgical planning and long-term outcome prediction in scoliosis treatment.