Study Of Intertransverse Lower Thoracic Interbody Fusion

Objective:To study the safy area of ITIF surgery and definite the feasibility and safety,based on 3D reconstruction CT examination and autopsy of Lower Thoracic intertransverse area anatomy. Methods:1.Study of the lower thoracic intertransverse area based on 3D reconstruction CT examination.Contrasted 3D reconstruction CT examination was performed in 20 volunteers without thoracic disease on the thoracic segment T8-T12,then the statistical analysis was made by measuring the length of transverse process,the distance of upper and lower transverse process, the remote distance of transverse process,the height of extraforminal intervertebral space,the oblique diameter of intervertebral space,observing the blood vessels of intertransverse lower thoracic,measuring th blood vessel internal diameter.2.Autopsy study of intertransverse lower thoracic interbody fusion.To observe the anatomic structure by necroscopy after the study of 3D reconstruction CT examination. To simulate operative procedure of ITIF with transpedicle screw fixation and evaluate its feasibility and safety. Results:1.There had no significant difference between the left side length and right of the thoracic transverse process.The order of the length of the different thoracic transverse process was T8 > T9 > T10 > T11 > T12.The order of the distance of upper and lower thoracic transverse process was T8-T9?T9-T10< T10-T11< T11-T12.The remote distance of thoracic transverse process was T8 > T9 > T10 > T11 > T12.The height of extraforminal interbertebral space was T8-T9 ? T9-T10< T10-T11< T11-T12.The order of oblique diameter of interbertebral space was T8-T9<T9-T10<T10-T11<T11-T12.The blood supply of lower thoracic intertransverse area was come from the posterior intercostal artery and dorsal branchs. Artery circuities could be seen in the lower thoracic intertransverse area. Variation in its own right of posterior intercostal artery dorsal branchs could also be found.The order of the blood vessels' inner diameter was T11-T12<T10-T11,and there was no significant different between T8-T9 and T11-T12.2. After bilateral posterior skin incisions approximately 10 cm lateral to the midline and separating of spinalis and longissimus muscles,we could observed the intertransverse area. The root could be retracted gently in T10-T11 and T11-T12, exposing the underlying intervertebral disc.There are enough space to implant the cage. And with this incision, transpedicle screws could be insert conveniently. The intertransverse area was too narrow to perform ITIF on T8-T9 and T9-T10.Conclusion:1.The contrasted enhancement and 3D reconstruction CT examination has good value for anatomy of bony and arteries structures in lower thoracic intertransverse area.The blood supply is adequate in the lower thoracic intertransverse area,and the distribution of blood vessels follows some regularities particularly the posterior intercostals arteries.To be familiar with the anatomy of the lower thoracic intertransverse area and to operate carefully can reduce artery bleeding.Intertransverse lower thoracic interbody fusion in segment T10-T11 and T11-T12 is feasible.2. There are enough operation space for ITIF in T10-T11 and T11-T12 with the root being retracted gently.And it is feasible to insert a couple unilateral transpedicle screws homolaterally.The intertransverse area was too narrow to perform ITIF on T8-T9 and T9-T10.