The potential risk of left subclavian artery injury from excessively long thoracic pedicle screws placed in the proximal thoracic regions of Lenke type 2 adolescent idiopathic scoliosis patients and normal teenagers: an anatomical study.

PURPOSE: The altered anatomic positions of important structures adjacent to the vertebrae in adolescent idiopathic scoliosis (AIS) patients have been comprehensively investigated by previous radiographic studies. However, no study has evaluated the altered position of left subclavian artery (SA) in these patients. The purpose of this study is to evaluate the altered position of left subclavian artery in AIS patients with a double thoracic curve pattern.

METHODS: Nineteen Lenke type 2 AIS patients and thirteen normal teenagers were included in this study. Axial computed tomography images at T2 and T3 levels were obtained in all these subjects to evaluate the subclavian artery-vertebral angle (SAVA, defined as 0° when the artery was located directly lateral to the left and 180° when directly lateral to the right) and subclavian artery-vertebral distance (SAVD, the shortest distance between the artery and vertebral body). The percentage of left subclavian arteries at potential risk of injury from excessively long pedicle screws was calculated.

RESULTS: The SAVA was significantly larger in AIS patients than that in normal teenagers at both T2 and T3 levels (P < 0.05) while the SAVD was significantly smaller in AIS patients compared with normal teenagers at both T2 and T3 levels (P < 0.05). The left SA was at potential risk of injury from excessively long left pedicle screws in 6 (31.6 %) AIS patients at T2 level and in 10 (52.6 %) patients at T3 level. The patients with risk of left SA injury had larger proximal thoracic (PT) and larger AVT of PT curve when compared with those without. No left SA was at potential risk of injury from excessively long left pedicle screws in normal teenagers.

CONCLUSIONS: The left SA is located much closer to the vertebrae in the proximal thoracic curve of Lenke type 2 AIS patients when compared with normal teenagers. The spine surgeons should be aware of such altered position of left SA and choose appropriate pedicle length to avoid anterior cortical penetration in Lenke type 2 AIS patients.