Feasibility Studies Of Pedicle Screw Placement Using The Tangent Line Of Lateral Wall Of The Pedicle

Objective:To investigate the feasibility of thoracic pedicle screw placement using an laterl pedicle wall tangent.Methods:CT scans of the thoracic spine of 30 adolescent patients were reconstructed in three dimensions using Mimics Medical(21.0.0.406)software.The distance of the entry point from the lateral edge of the superior articular process,the maximum angle of inclination of the thoracic pedicle screw,the length of the nail path,and the distance of the paraspinal gap from the posterior midline of the spine were measured.The data were analysed using SPSS 23.0 statistical software,and the data were expressed as x±s.Mimics Medical(21.0.0.406)was used to simulate pedicle screw placement and to verify the feasibility and safety of tangent line of the lateral wall of pedicle approach to nailing.Results:There was a statistically significant difference in the maximum angle of inclination between males and females at each segment(except at T5),whereas there was no statistically significant difference in the distance from the entry point to the superior articular process,the length of the nail path and the distance from the paraspinal gap to the posterior midline of the spine at the same segment between males and females(p>0.05).The maximum inversion angle of the thoracic pedicle screw decreases from T3-T8 and increases from T9-T10.The distance from the entry point to the lateral margin of the superior articular process is less in the T3-T6 segment than in the T7-T10 segment.The distance from the posterior midline of the thoracic paravertebral space approach increases progressively from T3-T10.Simulated thoracic pedicle screw placement based on the maximum angle of inclination of the pedicle,the length of the nail path,and the distance from the entry point to the lateral margin of the superior articular process is safe.Conclusion:Thoracic pedicle screw placement using tangential approach to the lateral wall of pedicle is feasible.