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Fluoroscopy-guided pedicle screw accuracy with a mini-open approach: a tomographic evaluation of 470 screws in 125 patients

José Antonio Soriano-Sánchez, MD,1 Luis Alberto Ortega-Porcayo, MD,1,2 Carlos Francisco Gutiérrez-Partida, MD,1 Luis Rodolfo Ramírez-Barrios, MD,1 Ramses Uriel Ortíz-Leyva, MD,1 Manuel Rodríguez-García, MD,1 Oscar Sánchez-Escandón, MD1

1 Neurological Center, American British Cowdray Medical Center, Mexico City, Mexico, 2 Department of Neurosurgery, National Institute of Neurology and Neurosurgery "Manuel Velasco Suárez," Mexico City, Mexico.

Abstract

Background

Transpedicular screws are currently placed with open free hand and minimally invasive techniques assisted with either fluoroscopy or navigation. Screw placement accuracy had been investigated with several methods reaching accuracy rates from 71.9% to 98.8%. The objective of this study was to assess the accuracy and safety for 2-D fluoroscopy-guided screw placement assisted with electrophysiological monitoring and the inter-observer agreement for the breach classification.

Methods

A retrospective review was performed on 125 consecutive patients who underwent minimally invasive transforaminal lumbar interbody fusion and transpedicular screws placement between the levels of T-12 and S-1. Screw accuracy was evaluated using a postoperative computed tomography by three independent observers. Pedicle breach was documented when there was a violation in any direction of the pedicle. Inter-observer agreement was assessed with the Kappa coefficient.

Results

A total of 470 transpedicular screws were evaluated between the levels of T-12 and S-1. In 57 patients the instrumentation was bilateral and in 68 unilateral. A substantial degree of agreement was found between the observers A-B (κ=0.769) and A-C (κ=0.784) and almost perfect agreement between observers B-C (κ=0.928). There were a total of 427.33 (90.92%) screws without breach, 39.33 (8.37%) minor breach pedicles and 3.33 (0.71%) major breach pedicles. The pedicle breach rate was 9.08% Trajectory pedicle breach percentages were as follows: minor medial pedicle breach 4.68%, minor lateral pedicle breach 3.47%, minor inferior pedicle breach 0.22%, and major medial breach 0.70%. No intraoperative instrumentation-related or postoperative clinical complications were encountered and no surgical revision was needed.

Conclusions

Our study demonstrated a high accuracy (90.2%) for 2-D fluoroscopy-guided pedicle screw using electromonitoring. Only 0.71% of the 470 screws had a major breach. Knowing the radiological spine pedicle anatomy and the correct interpretation of EMG are the key factors for this technique.

keywords: 
Accuracy, Computed tomography, electromonitoring, fluoroscopy, minimally invasive, mini-open, pedicle screw.
Volume 9 Article 54
doi: 
10.14444/2054