Development And Mechanical Testing Of 3D Printing Cervical Porous Metal Mesh Cage Vertebra

ObjectiveAccording to the radiological measurement of the cervical spine,a new porous metal mesh cage based on 3D printing technology is designed and developed and its safety and effectiveness are verified by the mechanical testing.Method:1.A total of 104 cases of cervical vertebral imaging data of Chinese are collected,a three-dimensional model based on cervical vertebra CT data is established,the anterior and posterior diameters,the left and right diameters,the tilt angle and the height of vertebral segments are measured,and the anatomical characteristics of the cervical vertebra and the range of different measurement values are analyzed.Based on summarizing the defects of the current mesh cage(titanium mesh),a new porous metal mesh cage is designed in accordance with the anatomy measurement data,and the experiment testing is also conducted to the cadaveric specimen.2.Taking the conventional mesh cage as the control group,the mechanical properties of the new porous(metal)mesh cage are tested to verify its mechanical safety and effectiveness as a cervical vertebral implant.Results:1.Through analyzing 104 cases of cervical vertebral imaging data of Chinese,it is found:the inclination angle of the upper endplate of the vertebral segments??(4.50°±3.82°)was larger than that of the lower endplate of the fusion segment??(3.96°±3.35°)(P<0.05);the average height of the anterior and posterior edges of the vertebral segments is(21.26mm±1.87mm);and the width and depth of the endplate of the cervical vertebra,(24.70mm±3.09mm)and(15.24mm±1.39mm)respectively,demonstrate a gradual upward trend(P_w<0.05 and P_d<0.05)and there are statistical significance of the differences between men and women(P_w<0.05 and P_d<0.05).2.According to the differences between the structure design of the current titanium mesh and the anatomical structure of the human cervical vertebra,the mesh cage is improved and the porous metal mesh cage of the cervical vertebra is developed in this study.Based on the measurement parameters of cervical vertebra anatomy,different gradient specifications are set in this cage in order to make the cage match with the anatomical structure of human cervical vertebra.Meanwhile,the mechanical properties of the cage are improved through combining the unique trabecular truss of the bone trabecula and the mismatch of structure design and mechanical properties are reduced with 3D printing technology,avoiding implant subsidence and bone graft non-fusion.3.In the static mechanics experiment,the compression stiffness(12799.55N/mm±823.23 N/mm)of the experimental group(the group of the 3D printed cervical vertebra porous(metal)mesh cage)is higher than that of the control group(the ordinary mesh cage)(10733.43N/mm±1516.71N/mm),with better anti-axial compression performances.Meanwhile,the simulated bone stiffness K_P value of the experimental group(269.96 N/mm±16.65 N/mm)was higher than that of the experimental group(174.92 N/mm±14.21 N/mm),which indicates that there is better anti-subsidence performance in the cage of the experimental group.In the dynamic mechanic's experiment,the anti-fatigue of the experimental group is slightly lower than that of the control group and the cages of both groups can meet the mechanical requirements of the intervertebral support under normal physiological load.Conclusion:1.The 3D printed cervical vertebra porous(metal)mesh cage designed on the basis of cervical vertebral anatomical data can effectively reconstruct cervical vertebra structure through matching with the anatomical structure of cervical vertebra.2.Compared with the conventional mesh cage,the 3D printed cervical vertebra porous(metal)mesh cage not only meets the demands of clinical mechanics but also has better performances of anti-axial compression and anti-subsidence.