CORRELATION BETWEEN THE SCHANZ SCREW INSERTION ANGLE AND THE LOSS OF KYPHOSIS CORRECTION IN THORACOLUMBAR FRACTURES

Fabio Antonio Vieira,André Sousa Garcia,Eduardo Barros Puertas,David Del Curto,Renato Hiroshi Salvioni Ueta,Fernando Tadashi Salvioni Ueta

doi:10.1590/s1808-185120201903179394

Fabio Antonio Vieira, André Sousa Garcia + Show 4 more

Open Access

https://doi.org/10.1590/s1808-185120201903179394

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Journal: Coluna/Columna	Publication Date: Jul 1, 2020
License type: CC BY 4.0

Affiliation: Universidade Federal de São Paulo

Abstract

ABSTRACT Objective To compare the Schanz screw insertion angle and the loss of the regional kyphosis correction in thoracolumbar burst fractures following posterior short instrumentation surgery. Methods Patients with a thoracolumbar burst fracture between levels T11-L2 were divided into two groups (parallel and divergent) according to the angle formed between the Schanz screw and the vertebral plateau. Regional kyphosis was evaluated in preoperative, immediate postoperative and last follow-up radiographs. Results Of the 58 patients evaluated, 31 had a parallel assembly and 27 had a divergent assembly. When we analyzed the angle of kyphosis, no statistical difference was observed between the pre- and postoperative radiographs. However, a statistical difference in the last follow-up radiographs and in the final loss of the kyphosis correction was confirmed. Conclusion The insertion of Schanz screws with a divergent assembly presents better radiographic results with less loss of kyphosis correction angle when compared with the parallel assembly technique. Level of Evidence III; Retrospective cohort study.

Highlights

A high incidence of spinal fractures occurs in the thoracic or lumbar region.[1]
Regional kyphosis was evaluated in preoperative, immediate postoperative and last follow-up radiographs
When we analyzed the angle of kyphosis, no statistical difference was observed between the pre- and postoperative radiographs

Summary

INTRODUCTION

A high incidence of spinal fractures occurs in the thoracic or lumbar region.[1]. Most of these injuries are between segments T10-L2, which comprise the thoracolumbar junction.[1]. Posterior instrumentation is often used in surgeries for unstable thoracolumbar fractures.[4,5,6,7,8] Transpedicular short segment fixation became popular after the introduction of pedicle screws by Roy-Camille et al and the internal fixator by Dick et al.[9,10] The internal fixator stands out for being an injury stabilization and reduction assembly system made up of screws, rods, and connectors that enables the correction of deformity in the different planes, acting as a tension band, a buttress, or a neutralization system.[11,12] With the use of the internal fixator, it became possible to achieve better correction of kyphotic deformity, greater initial stability, early painless mobilization, and indirect decompression of the vertebral canal, with decreases in interoperative bleeding and surgical time.[13,14,15] the correction obtained in the sagittal plane may be lost in long-term follow-up and in some cases reconstruction of the anterior spine is required to prevent collapse due to kyphosis.[16,17,18,19]. The objective of this study is to evaluate the correlation between the Schanz screw sagittal plane insertion angle in short instrumentations and the loss of kyphotic correction in the respective long-term follow-ups

METHODS

Findings

CONCLUSION