Study On The Feasibility Of Anterior Transpedicular Screw And Anterior Trans Pedicle-RIB Unit Screw At Upper Thoracic Spine

Part Ⅰ:Radiographic Anatomy Study of the Anterior Transpedicular Screw Fixation Techniques at Upper Thoracic SpineObjective:To provide a theoretical basis of the ATPS techniques at upper thoracic spine (T1～T4) by means of radiographic anatomy study.Methods:The thin-section CT scan data(which thickness is0.6mm) of the upper thoracic spine were reconstructed, select the transverse and sagittal sections on the axis of each pedicle. Observe and measure the OPW, OPH, PAL, TPA, SPA, DTIP and DSIP of each pedicle of the upper thoracic vertebrae. Then, the relevant data was obtained by means of statistical processing.Results:From T1to T4, the OPW decrease gradually, from3.47mm to8.14mm; the OPH increase gradually from6.89mm to10.29mm; the TPA decrease gradually, from32.96°to11.64°; the DTIP increase gradually from1.80mm to5.50mm; the SPA increase gradually from104.95°to115.74°; the DSIP increase gradually from5.95to8.76mm; the PAL changes irregularly, from32.95to35.96mm.Conclusion:The diameter of ATPS of the upper thoracic vertebrae depends on the OPW; at T1and T2, the ATPS whose diameter is about4.0mm can be implanted successfully. The ATPS isn’t fit for T3and T4, but the ATPRS whose diameter is about5.0mm can be implanted successfully at T3and T4. In order to achieve the bicortical fixed purpose, the length of screw can be so long that it can through out the rear bone cortex. Part Ⅱ:The Safety and Feasibility Study of the Anterior Transpedicular Screw and Anterior Trans Pedicle-rib Unit Screw Implementation at Upper Thoracic Spine by Free HandPurpose:To investigate the safety and feasibility of the ATPS and ATPRS fixation techniques by means of free hand analog operation on cadaveric specimens in the guidance of result in part I.Methods:In the guidance of result in part I, using adult antiseptic cadaveric upper thoracic specimens, ATPS were implanted at T1and T2, ATPRS were implanted at T3and T4by free hand. After that the specimens accepted X-ray fluoroscopy and CT scans. At last, the screws were removed, the specimens were sawed along the transaction and sagittal section of the screw channel. The success rate of the screws’implantation was evaluated by means of X-ray fluoroscopy, CT scans and observation and measurement at transaction and sagittal section.Results:There were40vertebraes and80pedicles, according to the criteria for this experiment,33ATPS were implanted at T1and T2successfully,7ATPS were failed, the success rate was82.5%.32ATPRS were implanted at T1and T2successfully,8ATPRS were failed, the success rate was80%.Conclusion:At T1and T2, the ATPS can be implanted safely. At T3and T4, the ATPRS can be implanted safely. The DTIP was too narrow at T1and T2, that the ATPS can be implanted only at one side. Part Ⅲ:The Safety and Feasibility Study of the Anterior Transpedicular Screw and Anterior Trans Pedicle-rib Unit Screw Implantation at Upper Thoracic Spine in the Guidance of CT3D NavigationPurpose:To investigate the safety and feasibility of the ATPS and ATPRS fixation techniques at upper thoracic spine by means of analog operation on cadaveric specimens in the guidance of CT3D navigation.Methods:In the guidance of CT3D navigation, using adult antiseptic cadaveric upper thoracic specimens, ATPS were implanted at T1and T2, ATPRS were implanted at T3and T4. After that the specimens accepted X-ray fluoroscopy and CT scans. At last, the screws were removed, the specimens were sawed along the transaction and sagittal section of the screw channel. The success rate of the screws’implantation was evaluated by means of X-ray fluoroscopy, CT scans and observation and measurement at transaction and sagittal section.Results:There were40vertebraes and80pedicles, according to the criteria for this experiment,39ATPS were implanted at T1and T2successfully,1ATPS were failed, the success rate was97.5%.38ATPRS were implanted at T3and T4successfully,2ATPRS were failed, the success rate was95%. The accuracy of screw placement is significantly improved compared to the free-hand operation, the statistical difference is significant.Conclusion:CT3D navigation technology can be used for the implantation of ATPS and ATPRS at upper thoracic spine. It can significantly improve the accuracy of screw placement compared to the free-hand operation.