The Study Of Thoracic Pedicle Morphometry And Its Related Factors

Objective1. To quantify the Thoracic Pedicle Morphometry by using reformatted Computed Tomography;2. to study the related factors to the thoracic pedicle parameters and further analyze the relationship between these related factors and thoracic pedicle parameters.Materials and MethodsThe study included 130 Chinese patients, who were sampled from the patients'registry. The population consisted of 70 males (age range, 19-59 years ;body-height range, 156-180 cm; body weight range, 42- 90 kg; body mass index range, 15.5-31.1 kg/m2 ), and 60 females (age range, 22-63 years ;body-height range, 150-171 cm; body weight range, 39- 75 kg; body mass index range, 15.6-28.2 kg/m2). Those who had thoracic spinal abnormalities (congenital or acquired deformity, trauma, infection, spinal tuberculosis, primary or secondary tumors), cancer, tuberculosis, or chronic kidney disease were excluded from this study. A Lightspeed VCT (General Electric) scanner system was used to obtain images from all the patients. The T1 to T12 vertebrae were scanned continuously with a slice thickness of 0.625 mm. Multiplanar reformation was applied to the original images to obtain the optimal sagittal, transverse and coronal section of the pedicles. The optimal images was chosen for measuring parameters as follow: outer pedicle width of the isthmus, outer pedicle height of the isthmus, pedicle length, transverse pedicle angle, superior cortical thickness of the isthmus, inferior cortical thickness of the isthmus, medial cortical thickness of the isthmus, lateral cortical thickness of the isthmus. Statistical analyses were performed the SPSS 16.0 software to perform the independent T-test. Means and standard deviations of every parameter were calculated for males and females. Using Pearson's correlation test to analyze the relationship between thoracic pedicle parameters and its related factors. A P value less than 0.05 was considered statistically significant.ResultsNo statistically significant differences were found between the right and left pedicles for all the measured parameters. The outer pedicle width, pedicle height and pedicle length were significantly smaller in females than in males (P <0.01) except for the transverse pedicle angles and the pedicle cortical thickness. No significant correlation was found between thoracic pedicle parameters and body-weight and body mass index range. The pedicle cortical thickness presented a significant negative correlation with the factor of age. The outer pedicle width, pedicle height and pedicle length presented a significant positive correlation with the factor of body-height. After further covariance analysis to removing the effects of body height, no statistically significant differences in outer pedicle width, pedicle height and pedicle length were found between males and females at most levels. The percentage of outer pedicle widths less than 4.5 mm was extremely high at T3–T9 in females and T3–T7 in males and the percentage in females was greater than males. There was a much higher percentage of pedicle width≤4.5 mm,≤4.0 mm and≤3.5 mm when body-height was less than 160 cm.Conclusions1. The detailed internal structure of the thoracic pedicle can be well shown and the accurate measurement of the thoracic pedicle parameters can be obtained by using reformatted CT before surgery .2. The pedicle cortical thickness presented a significant negative correlation with the factor of age.3. The outer pedicle width, pedicle height and pedicle length presented a significant positive correlation with the factor of body-height. After further covariance analysis to removing the effects of body height, no statistically significant differences in outer pedicle width, pedicle height and pedicle length were found between males and females at most levels. The results suggest that body-height is probably one of the main factors that contribute to the variation in pedicle size.4. The percentage of outer pedicle widths less than 4.5 mm was high at the upper and middle thoracic segments in Chinese population and there was a much higher percentage of pedicle width≤4.5 mm, 4.0 mm and 3.5 mm when body-height was less than 160 cm, which suggesting that a true transpedicular fixation might not be applicable for many Chinese patients at the upper and middle thoracic segments.