Individualized 3D printing model-assisted posterior screw fixation for the treatment of craniovertebral junction abnormality

Objective To study the method and effect of individualized 3 D printing model-assisted posterior screw fixation for the treatment of craniovertebral junction abnormality.Methods 31 patients with craniovertebral junction abnormalities diagnosed by CT and MRI were retrospectively analyzed in neurosurgical department of Guizhou Provincial People's Hospital.First,made a 3D printing model of craniovertebral junction by 31 printing technology,then simulated screw insertion and fixation operation on the model to obtain the individual screw insertion data to assist the real operation,at last implemented one-stage posterior decompression operation combined with internal fixation.Results 25 of 31 patients with craniovertebral junction abnormalities successfully underwent the posterior screw fixation operation assisted by individual 3D printing models.Preoperative CT evaluation suggested that the operations of axial pedicle screw placement were planned for 2 cases,but 3D printing models revealed the operations could not be implemented; and 3 cases were unsuitable for axial pedicle screw placement,but 3D printing models revealed the operation could be accomplished by an isthmus part screw insertion of axial pedicle.Postoperative follow-up time was 3-28 months,with an average of 13.9 months.Postoperative JOA scores of the patients underwent posterior screw fixation treatment were significantly increased,with significant differences (P =0.000).Postoperative MRI and CT scanning of 24 cases with craniovertebral junction abnormalities combined with atlantoaxial dislocation revealed that the dislocations were completely reduced in 19 cases and incompletely reduced in 5 cases.Postoperative ADI was significantly reduced,CMA was significantly increased,medullary ventral compression obviously alleviated or disappeared and there was a significant statistical difference (P =0.000).There were no deaths during operation,but dyspnea occurred in 2 cases.Conclusion Posterior screw fixation operation assisted by individualized 3D printing model can improve the success rate and safety of screw insertion,and effectively protect the vertebral artery avoiding damage,which suggests this technique is very useful for the new comer and worth popularizing; there is a good short-term efficacy for direct posterior distraction reduction treatment of atlantoaxial dislocation. Key words: 3D printing models;  Craniovertebral junction abnormality;  Atlantoaxial dislocation;  Internal fixation