Pedicle Morphology of the Lower Thoracic, Lumbar, and S1 Vertebrae: An Indian Perspective

Abstract

Analysis of morphometric data obtained from computed tomography scans in relation to the lower thoracic, lumbar, and S1 pedicle in patients from the Indian subcontinent. To record the surgically relevant parameters of transverse pedicle isthmus width, transverse pedicle angle, and depth to anterior cortex along the midline axis and the pedicle axis and to compare the results with those of similar studies in literature. Most studies reported are for white populations. Considerable differences are documented in the few reports in Oriental populations compared with Western populations. To the authors' knowledge, no similar study has been published for patients from the Indian subcontinent. Computed tomography scans of the lower thoracic and lumbosacral spine of patients from the Indian subcontinent were reviewed. We selected and analyzed 86 vertebrae in 31 patients. Parameters recorded were transverse pedicle isthmus width, transverse pedicle angle, and depth to anterior cortex along the midline axis and the pedicle axis. The mean transverse pedicle isthmus width was least at the T9 level (5.02 mm). Of the pedicles at T9, 46.15% had a diameter of less than 5 mm, followed by T10 (12.5%), T11 (11.11%), and L1 (11.11%). Of the pedicles at T9, 76.92% had a diameter of less than 6 mm, followed by T11 (33.33%), L1 (33.33%), T10 (25%), T12 (25%), L2 (20%), and L3 (5.56%). The mean transverse pedicle angle faced laterally at T11 (-2.97 degrees ) and T12 (-3.00 degrees ), being least at T12. The depth to the anterior cortex was more along the pedicle axis at all levels except T11 and T12, consistent with the laterally facing pedicles at these levels. Significant differences exist between the pedicles of Indian and white populations. It is suggested that preoperative computed tomography scans of the patients must be evaluated to choose the appropriately sized implant and avoid inadvertent complications. Preparation of the pedicle intraoperatively should take into account the orientation of the transverse pedicle angle.