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UBC Theses and Dissertations

A fluoroscopy-based intraoperative tool for measuring alignments in spinal deformity correction surgery Amini, Mohammad


Spinal deformity is any abnormal formation, alignment, or shape of the vertebral column which can lead to pain and disability. In severe cases, corrective surgery is recommended for improving the spinal alignment with the goal of reducing pain and improving patient mobility. Although accurate intraoperative assessments of spinal alignments can highly influence patient outcomes, it still remains a technically challenging task due to the limited field of view or poor image quality of existing intraoperative tools. Therefore, the objective of this thesis is to develop a new intraoperative tool for radiographic assessment of long anatomies with a focus on spinal deformity correction surgery. An image-based technique is developed to produce long calibrated images on the surgical table. The system was validated by performing experiments on phantom objects and four cadaveric specimens. The sagittal and coronal radiographic parameters were measured on the generated long views and compared against the ground-truth data collected from computed tomography. The usability of the system, in terms of radiation exposure and the required time for image acquisition and processing, was compared against a long radiographic plain film method. Tests on the phantoms demonstrated localization accuracies of 3.9±2.3mm, and 0.6±0.7°, and stitching accuracies of 0.6±0.6mm and 2.5±1mm for coronal and sagittal views. From in-vitro experiments, on the coronal plane, the accuracies of radiographic measurements for spinal alignment angles and global spinal balance measurements were 1.1±0.7° and 0.9±0.7mm, respectively. On the sagittal plane, the Cobb angle measurement accuracy was 2.3±1.2°. The calculated radiation exposure and required time for image acquisition and processing were 2616mR and 12 minutes, which were 46% and 60% of the corresponding estimated values of long radiographic plain film method. The introduced technique showed promising results for monitoring the spinopelvic alignments in both coronal and sagittal planes with accuracies within the clinically acceptable range of <5mm and <5°, while the radiation exposure and time of image acquisition are kept lower than the corresponding values from competing methods. The proposed solution can potentially assist improve the outcomes of spinal deformity correction surgeries and similar surgical interventions where accurate assessment of long anatomies is critically important.

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