The Morphometric Study Of The Thoracic Pedicles In Chinese Adolescent Idiopathic Scoliosis Patients And A Preliminary Study Of Strategies In Thoracic Pedicle Screw Placement

Objective:(1) To analyze the morphometry of thoracic pedicles of Chinesepatients with adolescent idiopathic scoliosis by utilizing3-Dimensionalreconstruction measurement.(2) To analyze the morphometry of thoracicpedicles of normal patients in Chinese population by utilizing3-Dimensional reconstruction measurement.(3)Comparing the morphologyof thoracic pedicles of AIS patients with normal population, to find if thedifference existed and conclude the features of variation tendency ofthoracic pedicles in Chinese AIS patients.(4) Retrospective study on thethoracic pedicle morphology of Chinese patients with adolescent idiopathicscoliosis, to find if the differences existed compared with other races and toprovide a reference for the pedicle screw placement in Chinese population.Methods:(1) After3-Dimensional CT reconstruction of thoracic pedicles in56AIS patients, we chose the ideal plane to conduct the measurements,including pedicle width and pedicle angle in sagittal plane, minimal pediclediameter in coronal plane, chord length、 pedicle width and pedicle angle intransverse plane.(2) The same measurements were also conducted in54normal teenagers utilizing3-Dimensional CT reconstruction.(3)Wecompared the data of thoracic pedicles in AIS with the normal teenagers, tofind if the statistical difference existed between two groups. Furthermore,the statistical analysis was also conducted between the current study andthe previous studies on different population.Results:（1） In normal teenagers, the transverse pedicle width decreased from T1to T4, then increased in the caudal direction, the left pedicles werethicker in the upper thoracic spines. The sagittal pedicle width increased inthe caudal direction.(2) The asymmetry existed in the apical region in AISpatients, the pedicle width was smaller and the chord length was greater inthe concavity. In sagittal plane, the pedicle width increases in the caudaldirection, with the smallest width of0.68cm at T1R and the greatest widthof1.36cm at T12L. The mean smallest transverse pedicle width was foundat T4R with a value of0.30cm and the largest transverse pedicle width wasfound at T11R with a value of0.70cm. No difference was found in thetransverse pedicle angle measurement.（3）19.94%pedicles were foundsmaller than3.2mm, which could cause the penetration of medial or lateralcortex in the placement of4.0mm diameter screw. These diminutivepedicles were commonly found at T3-T6and apical region.（4）Comparedwith the previous studies, the pedicle width in Chinese population with AISwas relatively smaller than Caucasian population, similar with the Japanesepopulation.Conclusion:（1） The current measurements could provide a basic referencefor pedicle screw placement in Chinese AIS patients. The data of pediclemorphology can help the beginners in learning the screw placement.(2) Themorphology of the Chinese patients with adolescent idiopathic scoliosiswas different from other races but with the nearly same variation tendency.The width of the pedicle was relatively smaller in Chinese population. Thedifference existed in individual and level must be paid attention.(3)4.0mmmight be inappropriate in some pedicles, in-out-in technique wasrecommended in some small pedicles smaller than3.2mm, more attentionshould be paid when placing the pedicle in the apical region.