Development And Preliminary Feasibility Analysis Of Cervical Percutaneous Pedicle Cannulated Screw

Objective: To design a cervical posterior percutaneous pedicle internal fixation and evaluate the feasibility and reliability under the monitor of the navigational system.Method: 1.Design of cervical percutaneous pedicle cannulated screw: according to the specifications of traditional cervical pedicle screws,we have developed the cervical percutaneous pedicle cannulated screw which is based on the clinical experience of the thoracolumbar percutaneous pedicle screw technique.The Shitaibao Medical Equipment Limited Company was authorized to manufacture and process the sample screws and its matching instruments.The screws were divided into 2 groups,the experimental group was made up of the cervical percutaneous pedicle cannulated screws and the control group was consist of traditional cervical pedicle solid screws.The static torsion test was completed by a microcomputer-controlled electronic torsion machine,and the static bending test was completed by a microcomputer-controlled electronic universal testing machine(Shitaibao Medical Equipment Limited Company).In the static torsion test,we measured the maximum torque,yield torque and break torsion angle of two groups and made comparison between them.In the static bending test,the maximum load of two groups should be measured and compared as well.The SPSS25.0 statistical software was used to analyze the corresponding data in the experiment,and the independent-samples T test was used to compare the mechanical properties of the two groups(When P<0.05,there was statistic difference the two groups).2.Implanting the cannulated screws with the navigational system: Four normal human fresh cadaver cervical spine specimens(C1-T1)with the intact skin were chosen.The cervical front-lateral radiographs and three-dimensional CT were taken before surgery to exclude deformity.The specimens were fixed on the wooden operating platform to prevent sliding,and then 32 cannulated screws were inserted percutaneously through the bilateral pedicles of C4-C7 by the monitor of the navigational system(Huaihua Hospital of Traditional Chinese Medicine).Every specimen was performed three-dimensional CT scan after operation.The location of screws was evaluated by Mobbs-Raley standard(Grade 0~3),and the implanting accuracy rate could be calculated.Results: 1.This new type of cannulated screw makes the posterior cervical percutaneous operation come true.In the static torsion test.the maximum torque and yield torque of experimental group were smaller than control group(P<0.05).There was no statistic significant difference between two groups in comparison of break torsion angle.In the static bending test,the maximum load of experimental group was smaller than control group(P<0.05).2.There were 22 Grade 0 screws,6 Grade 1 screws,3 Grade 2 screws and 1 Grade 3 screws in the experimental group.The nailing accuracy rate was 87.5%.Conclusion: The design of cervical percutaneous hollow pedicle screws makes it come true which the posterior cervical percutaneous pedicle screw placement under the monitor of the navigational system;the new type of screw still has space to improve in the aspect of anti-torsion and anti-bending through this mechanical test.