Anthropometry of the Vertebral Pedicles of the Thoracic Spine without Pathology in Mexican Patients of a Public Institution in the Metropolitan Area

Abstract

Introduction The anatomy of the pedicles is complex and vary according to the region valued. For proper placement of a transpedicular screw requires a high knowledge of the anatomy of the pedicle and the different surgical techniques for placement. Tomography is the best radiological tool for measuring various parameters of the pedicles. The purpose of this study was to determine, through tomography, thoracic pedicle anthropometry of the Mexican population and its variations according to sex, with the aim of providing irrefutable anatomical information for the development of techniques, materials, and tools more specific to our population pedicle fixation. Methods This study is a descriptive, retrospective, and observational study. The source collection and measurement were performed on CT chest scan of Unit Trauma Hospital “Dr. Victorio de la Fuente Narv·ez,” between January 2012 and June 2013, on computer tomographic Siemens Somatom and General Electric of 16 cuts, which were made in Mexican patients without lesions in the thoracic spine, with an age range of 18 and 60 years, who had axial, sagittal, and coronal to no more than 3 mm in T1 to T12 levels in the left and right pedicles. The sample size was calculated using tables Hulley, given a universe of 1,620 thoracic CT, with a confidence level of 95% amplitude interval 0.15, an expected ratio of 0.15, and a β 0.20, determined a sample of 122 scans. Measurements (axial and sagittal diameter, coronal morphology, axial, and sagittal angulation) were performed by two observers and the involvement of a third when discordance of more than 10% between the first two was found. Data analysis was performed with SPSS version XVII, using descriptive statistics and weighted Kappa. Results The pedicles were of smaller diameter T5, with 2.03 ± 0.94 mm in men and 1.66 ± 0.77 mm in women. The smallest sagittal diameter was found in T2, with 1.95 and 10.15 ± 9.27 ± 2.60 mm, respectively. The angle was increased axial T1, averaging 32.70 ± 4.37ʃ. The sagittal angle of thoracic pedicle showed greater angles from T4 to T10. Predominated teardrop at T1–T3, the elongated drop in T4–T5 and T11–T12, and kidney-shaped in T6–T10. Conclusions Women may be less than the male population values. From T3 to T9 pedicles are smaller than the diameter of the screws that are included in the market. Therefore, anteroposterior, lateral, and axial assessment of each vertebral body to the pedicle screws placement necessary; we also seek new screw placement techniques as described in-out-in, and use technology such as neuronavigation, to continue to benefit from the biomechanical properties of transpedicular instrumentation both to the surgeon and the patient.