Morphometric evaluation of subaxial cervical vertebrae for surgical application of transpedicular screw fixation

Study Design. A morphometric evaluation of pedicle projections in 29 cervical spinal columns (C3-C7) for three-dimensional surgical anatomy for safe surgery was proposed. Objective. In this study, pedicles and intimate structures of the subaxial vertebrae from C3 to C7 were evaluated to provide some morphometric data for cervical transpedicular screw fixation. Summary of Background Data. Detailed knowledge of surgical anatomy and variation of the subaxial vertebrae is a must for safe and effective surgery of the region. Although there are several clinical studies of transpedicular fixation, few studies have been performed on cervical pedicle measurements and their projection. Methods. In 29 dried bone cervical spinal columns (C3-C7), pedicle dimensions ( pedicle height, width, length), measurements of lateral mass and pedicle length distance and pedicle axis length, investigation of distances of superior facet-midpedicle axis and inferior facet-midpedicle axis, and transverse and sagittal angles of the pedicles were performed in linear and angular measurements. Results. The obtained data from the series revealed that the mean values were approximately ranging from 6.7 to 7.2 mm for pedicle height, 4.4 to 4.9 mm for pedicle width, 5.3 to 6.2 mm for pedicle length, 15.3 to 16.0 mm for lateral mass and pedicle length, 22.2 to 27.7 mm for pedicle axis length, 3.8 to 5.3 mm for superior facet-midpedicle axis distance, 9.9 to 12.0 mm for inferior facet-midpedicle axis distance, 42.3 to 51.5 for transverse angle, and 5.2 to 14.1 for sagittal angle. Conclusions. Linear measurements of pedicle dimensions and also axial angles from horizontal and vertical planes may provide some anatomic limitations for subaxial cervical transpedicular screw fixation, and also contribute to the safety of the surgical procedure. One should also rely on tomographic data and computer-assisted guidance systems.