Study Design. A computed tomography (CT) study.
Objective. To evaluate the changed relative positions of esophagus in proximal thoracic (PT) curves of adolescent idiopathic scoliosis (AIS) patients and analyze the potential risks of esophageal injuries from thoracic pedicle screw (TPS) insertion.
Summary of Background Data. Translation and rotation of the vertebrae could lead to altered relative positions of surrounding vital structures in AIS patients. The changed positions of aorta and spinal cord in main thoracic (MT) curve have been comprehensively investigated; however, no studies have analyzed the relative position of esophagus in PT curve.
Methods. Twenty patients with complete proximal thoracic (CPT group) curve, 22 patients with fractional proximal thoracic (FPT group) curve, and 14 normal patients with a straight spine (normal group) were included. Axial CT images from T2 to T5 at the midvertebral body level were obtained to evaluate esophagus-vertebral angle (EVA, defined as 0° when the esophagus was located directly lateral to the left, 90° when strictly anterior, and 180° when directly lateral to the right). The percentages of esophagus in the direction of screw passage were calculated to analyze potential risks of esophageal injuries during TPS insertion.
Results. EVA in the FPT group was significantly smaller than that in the normal group (P < 0.05), whereas EVA in the CPT group was significantly greater than that in the normal group (P < 0.05) at each level. The esophagus was located approximately anterior to the vertebral body in the normal group but shifted anterolaterally to the right in the CPT group and anterolaterally to the left in the FPT group. The esophagus was at a high risk of injury with right anterior penetrated TPS in the CPT group and was at a high risk of injury with left anterior penetrated TPS in the FPT group.
Conclusion. Different anatomic patterns of PT curves could cause different altered positions of esophagus relative to spine and result in different potential risks of esophageal injuries during TPS insertion. Spine surgeons should choose appropriate pedicle screw length to avoid anterior cortical perforation in the PT region of AIS patients.
This study demonstrated that the esophagus was located approximately anteriorly to vertebral body in normal patients but shifted anterolaterally to the right in patients with complete proximal thoracic (CPT) curve and anterolaterally to the left in patients with fractional proximal thoracic (FPT) curve. The esophagus was at a potential high risk of injury with right anterior penetrated thoracic pedicle screw (TPS) in patients with CPT curve and was at a potential high risk of injury with left anterior penetrated TPS in patients with FPT curve.
From the Department of Spine Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, China.
Address correspondence and reprint requests to Yong Qiu, MD, Spine Surgery, Affiliated Drum Tower Hospital of Nanjing University Medical School, Zhongshan Road 321, Nanjing 210008, China; E-mail: firstname.lastname@example.org
Acknowledgment date: September 21, 2010. First revision date: January 11, 2011. Acceptance date: February 23, 2011.
The manuscript submitted does not contain information about medical device(s)/drug(s).
Foundation funds were received to support this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.