The Design And Finite Element Analysis Of The Anatomical Plate Of Axis Anterior Ifxation

Objective:To observe and measure linear and angular parameters of C2-3for obtaining parameters of morphology in Chinese people via imageology, based on which the anatomical plate of axis anterior fixation could be designed. To investigate the stress distributions the C2and C3bone of the simulation of models with the anatomical plate of axis anterior fixation under quasistatic loading in Compression、 extension、lateral bending and rotation.Methods:One hundred sets of normal Chinese adults’radiography on lateral neck CT and3DCT images of the upper cervical spine were measured to obtain the relative anatomic parameters. The parameters include C2CA (∠α)、C2APP (EF)、 C2API (AP)、C3BALA (AO)、C3BALU (OB)、C2ATD (WAIL)、HAIL The superior inclination of the posterior edge of the anteroinferior lip (AIL) on sagittal plane (∠β)、C2/3IDAH (BC)、C3BAH (CD)、C3APC (XY) and so on. To investigate the stress distributions the C2and C3bone of the simulation of models with the anatomical plate of axis anterior fixation under quasistatic loading in compression、extension、lateral bending and rotation. The results were compared with that obtained from the common restricted anterior cervical spine plate.Results:Measurement results showed that C2CA (∠α) was for(19.32±3.07)°、 C2APP (EF) for(14.75±1.17)mm、C2API (AP) for(11.54±1.17)mm、C3BALA (AO) for(6.86±0.90)mm、C3BALU (OB) for(7.34±1.08)mm、C2ATD (WAIL) for(16.11±0.99)mm、HAIL for(3.26±0.81)mm、The superior inclination of the posterior edge of the anteroinferior lip (AIL) on sagittal plane (∠β) for(31.99±5.37)°、C2/3IDAH(BC)for(3.66±0.83)mm、C3BAH(CD)for(13.09±1.11)mm、 C3APC (XY) for(14.63±1.59)mm. The inclination measured on CT skill which was formed by the two lateral boundary lines of the axis vertebra anterior border transverse on coronal plane increases gradually. The finite element model predicted that the stress/strain mainly distributes on the connection part between bone screw and the anatomical plate of axis anterior fixation, and on the centre of the anatomical plate of axis anterior fixation; When the top of the anatomical plate of axis anterior fixation screw was not implanted, the stress of the anatomical plate of axis anterior fixation increased in extension and decreased in compression、lateral bending and rotation,compared with the common restricted anterior cervical spine plate. The stress of the anatomical plate of axis anterior fixation was bigger,when the top of anterior fixation and anatomical axis vertebra of plate screw was implanted.Conclusion:The anatomical plate system of axis anterior fixation provides the best biomechanical stability for Chinese people. When the top of the anatomical plate of axis anterior fixation screw was not implanted, the stress of it is better or similar in extension、compression、lateral bending and rotation,compared with the restricted anterior cervical spine plate. Meeting C2vertebra anterior border transverse fracture or implanting screw difficultly because of it and dislocation of the C2, the top of the anatomical plate of axis anterior fixation screw can be implanted in order to increase stability after reduction.