Free-hand placement of high thoracic pedicle screws with the aid of fluoroscopy: evaluation of positioning by CT scans in a four-year consecutive series

Abstract

Objective: To evaluate the feasibility, safety and accuracy of pedicle screw placement in the upper thoracic spine using the free-hand technique with the aid of fluoroscopy; to analyze the methods used to verify correct screw positioning intra and postoperatively. Method: All patients with instability of the cervicothoracic or upper thoracic spine and at least one screw placed in the segment T1-T6 as part of a posterior construct entered the study. Only C-arm intraoperative fluoroscopy was used to guide screw placement. Results: We obtained excellent positioning in 98.07% of the screws. CT scans precisely demonstrated pedicle wall and anterolateral body violations. There was no hardware failure, no neurological or vascular injury and no loss of alignment during the follow-up period. Conclusion: Pedicle screws can be safely placed in the upper thoracic spine when strict technical principles are followed. Only a CT scan can precisely demonstrate vertebral body and medial pedicle cortical violations. Key words: pedicle screws, transpedicular fixation, thoracic spine, cervicothoracic junction, spinal instability.Colocação de parafusos pediculares na coluna torácica alta utilizando fluoroscopia: avaliação do posicionamento dos parafusos por tomografia computadorizada em uma série de casos durante quatro anos RESUMO Objetivo: Avaliar a factibilidade, segurança e eficácia da colocação de parafusos pediculares na coluna torácia alta utilizando apenas a fluoroscopia; analisar os métodos intra e pós-operatórios de verficação do posicionamento de parafusos. Método: Todos os pacientes com instabilidade da coluna cervico-torácica ou torácica alta e pelo menos um parafuso colocado no segmento T1-T6 foram incluídos no estudo. Apenas fluoroscopia intra-operatória foi utilizada para guiar a colocação dos parafusos. Resultados: Obtivemos excelente posicionamento em 98,07% dos parafusos. TC axial mostrou precisamente violações pediculares e da parede anterolateral do corpo vertebral. Não houve falência do instrumental, lesões neurológicas ou vasculares, ou perda do alinhamento sagital no período de seguimento. Conclusão: Os parafusos pediculares podem ser colocados com segurança na coluna torácica alta desde que técnicas operatórias precisas sejam executadas. Somente a TC pode demonstrar precisamente violações do corpo vertebral e da parede pedicular. Palavras-chave: parafusos pediculares, fixação transpedicular, coluna torácica alta, junção cervico-torácica, instabilidade espinhal.

Surgical challenges in posterior cervicothoracic junction instrumentation

“…For Th1, as for other upper thoracic vertebrae, pedicle screws are the most stable posterior xation technique providing a three-columns support with improved rotational strength compared to techniques of xation involving only posterior columns [4,35]. From C7 to Th2 the entry point for pedicle screws becomes more medial and the trajectory less angulated toward the midline [29].…”

How to Optimize Pedicle Screw Parameters for the Thoracic Spine? A Biomechanical and Finite Element Method Study

“…[12][13][14]16 The selection of the screw parameters used involves the surgeon's analysis of the patient's anatomical landmarks and tactile examination 22 ; however, preoperative planning with CT and intraoperative imaging techniques such as intraoperative CT and fluoroscopy has been used more recently. [23][24][25][26] In addition, it has been noted that larger screw diameters increased the pullout strength. 27,28 Yet, there is minimal consensus on standardized guidelines for selecting screws and methods of assessment on the placement of the screws.…”