Potential risk factors in development of the “halo sign” in patients performed transpedicular screw fixation through the posterior spinal approach.

Abstract

It has been shown in literature that a fibrous tissue called "halo sign" in the radiological terminology can develop around the transpedicular screws implanted incompletely and/or incorrectly, which appears after movement of the screw in the cancellous bone. In this retrospective clinical study, 141 patients who underwent posterior spinal instrumentation for thoracic, lumbar or thoracolumbar vertebrae were evaluated using computed tomography (CT) and direct X-rays images for "halo sign" formation which refers in probable failure of spinal instrumentation. Hospital records included in the year 2014-2018 were examined and adult patients who were performed lumbar, thoracal, and thoracolumbar spinal instrumentation via posterior approach due to reasons such as "spine fracture", "spondylosis", "spondylolisthesis" and "intervertebral disc hernia" were included and evaluated in this study. The age and sex of the patients were recorded. Spinal X-ray and spinal CT images obtained during the postoperative follow-up period were examined. Halo sign was seen in 13 patients. Age (p=0.013), number of instrumented vertebrae (p=0.001) and number of transpedicular screws (p<0.001) values were different between the patients with halo sign and patients without halo sign. As a result, it was observed in this study that the formation of the halo sign in posterior spinal instrumentation system could develop in proportion to the number of transpedicular screw and patients' age. It was thought that the halo sign formation was not connected with the parameters called performed laminectomy, gender, inserted intervertebral cage, or vertebral region which were inserted transpedicular screws.