Radiological studies on anterior cervicothoracic transpedicular screw fixation

English Keywords:Cervicothoracic junction  Anterior transpedicular screw  Radiology

English Abstract:

  【abstract】 Objectives: To explore the entry point and trajectory of anterior transpedicular screws(ATPS) in the cervicothoracic junction, and to investigate its feasibility by radiological method. Methods: From January 2014 to June 2014, 50 patients with no signs of cervicothoracic misalignment and bone destruction were scanned by spiral CT on the cervical and upper thoracic spine, there were 29 males and 21 females with the age ranging from 22 to 60 years(average 36.4 years). Sequential raw cervicothoracic transaxial CT image data of each segment were processed by multiplanar reformation(MPR) in Advantage Workstation 4.2. The data of transverse pedicle angle(TPA), sagittal pedicle angle(SPA) and distance transverse intersection point(DTIP), distance sagittal intersection point(DSIP) and pedicle axis length(PAL) of each pedicle were measured. The cervicothoracic junction was devided into three different regions by two lines, and the distribution of the trajectory of sagittal pedicle axis in three regions was recorded. All the above data were processed by the software SPSS 13.0. Results: There was no statistical difference in gender regarding to the value of TPA and SPA, so the data of male and female patients were merged for analysis. From C6 to T2, the TPA decreased from 46.77° to 20.02°. The sagittal pedicle axis all tilted caudally. From C6 to T1, the SPA decreased from 18.10° to 14.54°. However, the SPA of T2(20.62°±5.04°) was the largest. The difference in different segments showed statistical significance(P＜0.05). The gender differences regarding to the DTIP, DSIP and PAL showed statistical significance(P＜0.05). From C6 to T2, the DTIP increased from -0.34 to 4.75mm. The DSIP of C6(5.18±1.02mm) was the minimum, and the maximal DSIP was at the level of T2(9.82±2.28mm). The PAL changed irregularly, from 31.01 to 34.21mm. The difference of the DTIP and DSIP under the same sex in different segments showed statistical significance(P＜0.05). The sagittal pedicle axis of C6 and C7 all located superior to the manubrium. The sagittal pedicle axis of T1 was mainly in manubrium region, but only 3 of them located over the line connecting the superior margin of both sternal ends of clavicle above the manubrium. The sagittal pedicle axis of T2 mainly located in manubrium region followed by the region below the manubrium. There was no statistical significance regarding to the regional distribution between sexes. Conclusions: The ATPS techniques at the level C6, C7 and few T1 is feasible through the anterior cervical approach, but unavailable for most T1 and T2 due to their bony obstacle.