Analysis of Sagittal Thoracic Inlet Measures in Relation to Anterior Access to the Cervicothoracic Junction.

Abstract

Retrospective radiographic study. The aim of this study was to define the association between thoracic inlet measures in relation to anterior access to the cervicothoracic junction. Trauma CT scans in patients >16 years were analyzed. The projection angle (PA), defined as the angle subtended by a line along the superior endplate of the vertebral body and the line from the anterosuperior corner of the vertebral body to the manubrium, was measured at C7, T1 and T2; angles were positive if the projection was above the manubrium. Thoracic inlet angle (TIA), thoracic inlet distance (TID) and pelvic incidence (PI) were measured. 65 scans were assessed (33 males; mean age 47.7 years (s.d. 8.7)). The mean TIA 79.9° (s.d. 13.4°; range 52.6° - 112.2°), mean TID 66.1 mm (s.d. 6.6 mm) and mean PI was 50.5° (s.d. 10.2°). Mean values for the projection angles at C7, T1 and T2 were 24.2°, 7.6° and -8.3° respectively. PA were positive in 95% at C7, 73% at T1 and 30% at T2. PA at each level correlated significantly with age (mean r=-0.371; <i>P</i> = .015) and TIA (mean r=-0.916; <i>P</i> < .001) but neither TID nor PI. TIA correlated with age (r = 0.328; <i>P</i> = .008). The projection angles of the CTJ vertebrae are influenced by thoracic inlet angle and a lesser degree age. Understanding sagittal spinal parameters in the CTJ can aid in planning surgical strategy and approach.