Different potential risk of injury from thoracic pedicle screw insertion between left and right main-stem bronchus in Lenke 1 type adolescent idiopathic scoliosis.

Abstract

The changed relative anatomic position of trachea with increased potential risk of injury from thoracic pedicle screw (TPS) has been reported in Lenke 1 type adolescent idiopathic scoliosis (AIS) patients. However, such change of main-stem bronchus has not been investigated. The purposes of this study were to evaluate the altered positions of both left and right main-stem bronchus in Lenke 1 type patients and to assess the potential risks of main-stem bronchus injuries from TPS screw insertion in these patients. A total of 19 Lenke 1 type AIS patients and 15 normal teenagers were included. Axial computed tomography (CT) images at T5 level were obtained in all these subjects to evaluate the main-stem bronchus-vertebral distance (MVD, the closet distance between the main-stem bronchus and vertebral body) and main-stem bronchus-vertebral angle (MVA, defined as 0° when the main-stem bronchus was located directly lateral to the left and 180° when directly lateral to the right) on both left and right sides. The percentage of main-stem bronchus located adjacent to vertebrae and in the direction of screw passage was calculated to analyze potential risks of injuries from pedicle screw placement. Both the average left and right MVD were significantly smaller in AIS patients when compared with normal teenagers at T5 level (P<0.05). Both the mean left and right MVA were lower in AIS patients than those in normal teenagers at T5 level (P<0.05). All the AIS patients (100%) had the right main-stem bronchus with high risk of injury from right TPS placement and only five AIS patients (26.3%) had left main-stem bronchus with high risk of injury from left TPS placement at T5 level. No main-stem bronchus was found to be at risk of injury from TPS placement on both two sides in normal teenagers at this level. Both the right and left main-stem bronchus were located much closer to the vertebrae in Lenke 1 type AIS patients when compared with normal teenagers. However, the potential risk of injury of main-stem bronchus from TPS placement was higher on the right side than that on the left side.