Anatomy of the Thoracic Pedicle

Thoracic pedicle anatomy (interpedicular distance, transverse and sagittal pedicle widths, transverse and sagittal pedicle angles, and the distance from the axis of the pedicle to the axis of the transverse process) was assessed in 11 cadavers of elderly people. The cadaveric spines were extensively dissected to augment the accuracy of the measurements via caliper and goniometer. The results were compared with those of previous studies that assessed pedicle anatomy with computed tomography, direct measurement, and three-dimensional morphometry. Between the studies, significant differences were found in transverse pedicle width and transverse and sagittal pedicle angles. These morphometric differences may reflect either the diversity of the techniques used to measure the pedicle anatomy or sampling variation. This article presents a previously unreported morphometric finding, the rostral-caudal distance from the thoracic pedicle to the midpoint of the base of the transverse process. At T1, the transverse process is 5.45 +/- 1.2 mm rostral to the pedicle. This relationship gradually changes as the thoracic spine is descended, so that at T12, the transverse process is 6.6 +/- 2.4 mm caudal to the pedicle. Crossover consistently occurs at the T6-T7 region. Although the transverse process is a reliable external landmark for the location of the pedicle in the lumbar spine, this relationship in the thoracic spine is variable and only moderately predictable.