Application Of The 3D Printing Combined With Pedicle Guider Technology In Severe Congenital Scoliosis

Severe congenital scoliosis(CS)refers to a type of spinal deformity caused by an abnormal vertebral body,with a major curvature Cobb angle above 90°.Because it is often accompanied by high vertebral rotation,pedicle dysplasia,or even lack of,the use of traditional freehand pedicle screw placement technique is difficult and risky,and surgical neurological complications are much higher than adolescent idiopathic scoliosis(AIS).In recent years,some scholars have used pedicle cortical bone and cancellous bone width measured by CT to classify the pedicle as a preoperative assessment to guide the placement of pedicle screws.It was found that the probability of improper screw placement in abnormal pedicles was significantly higher than that of normal pedicles.At present,the classification criteria for pedicles under CT are different.There is no study comparing the incidence and distribution of abnormal pedicles of CS and AIS under the same criteria.At the same time,in order to improve the accuracy of nail placement,CT or O-arm navigation technology has been applied to spinal correction,but the disadvantages of expensive equipment,intraoperative radiation exposure,and complicated operation limit its clinical promotion.With the rise of 3D printing technology in orthopedics in recent years,pedicle screw guide(PG)assisted screw placement technology is still in the trial stage in the field of spinal deformity,and its safety and effectiveness for severe CS need to be further demonstrated.First,we used a retrospective study to compare the incidence and distribution of abnormal pedicles of CS and AIS without surgery under the same standard CT measurement method and classification system.The incidence of abnormal pedicles in CS was significantly higher than that in AIS,and the upper thoracic spine,the major Cobb angle greater than 70°,and the concave pedicles were risk factors for abnormal pedicles in CS.Then we used a prospective,non-randomized controlled study to compare the PG technology and freehand technology for severe CS surgery with the placement accuracy,imaging parameters,surgery-related indicators,and perioperative complications.The results show that 3D printing combined with PG technology can significantly improve the accuracy of nail placement,shorten the operation time and reduce intraoperative blood transfusion.This technique is safe and effective for severe CS surgery and is worthy of clinical promotion.Part 1 The comparison of incidence and distribution of abnormal vertebral pedicle between congenital scoliosis and adolescent idiopathic scoliosisObjective To compare the incidence and distribution of abnormal vertebral pedicle between congenital scoliosis(CS)and adolescent idiopathic scoliosis(AIS).Methods Retrospective comparative study of patients in our hospital were performed,from January 2012 to December 2016,with CT scan of thoracic and lumbar spine.Patients were divided into CS group or AIS group according to the diagnosis.The vertebral pedicles were divided into five types from type A to type E according to the narrowest distance of the widest plane of the pedicle.Type B,C,D and E were defined as abnormal pedicles.The incidence and distribution of abnormal pedicles were compared and analyzed.Results In the CS group,39 patients with1326 pedicles were measured,and the incidence of abnormal vertebral pedicle was 64%(843/1326).In the AIS group,24 patients with 816 pedicles were measured,and the incidence of abnormal vertebral pedicle was 56%(455/816).The incidence of abnormal pedicle in the CS group was significantly higher than that in the AIS group(P < 0.001).The abnormal vertebral pedicles were mainly distributed in the upper thoracic vertebra and thoracolumbar vertebra.For the subgroup analysis in the CS group,the upper thoracic vertebra,Cobb Angle of major carve more than 70° and concave side pedicle were the risk factors of abnormal pedicles.Conclusions The incidence of abnormal vertebral pedicle in CS patients is significantly higher than that of AIS,and it was more difficult in pedicle screw placement in severe CS patients.Part 2 The safety and effectiveness evaluation of the 3D printing combined with pedicle guider technology in severe congenital scoliosisObjective To evaluate the safety and clinical efficacy of the 3D printing combined with pedicle guide(PG)technology in the treatment of severe congenital scoliosis(CS).Methods A prospective non-randomized controlled study was conducted on patients with severe CS who were admitted to our hospital from January 2016 to December 2017.The patients were divided into the PG group and the control group based on the willingness of patients and their guardians to use 3D printing combined with pedicle guide technology.In the PG group,Mimics software was used to design the pedicle guide and the 3D printer was used to print the spine model and the pedicle guide.The guide was used to assist the pedicle screw placement.The control group used the free hand technology.Two groups of patients underwent CT examination after surgery,and the accuracy of pedicle screw placement was evaluated on the basis of the status of screws breaking through the pedicle cortex.The preoperative and postoperative imaging parameters,intraoperative data,and perioperative complications were compared between the two groups.Results The PG group included 11 CS patients(female 7;male 4)with an average age of 12.65 years.The preoperative Cobb angle was 117.52°.The control group included 15 CS patients(female 8;male 7)with an average age of 13.36 years.The preoperative Cobb angle was 104.46°.There was no statistical difference in preoperative imaging parameters between the two groups.A total of 193 screws were successfully implanted with the help of 198 pedicle guides during surgery,and the success rate of screw placement was 97.5%(193/198).Postoperative CT was used to evaluate the pedicle screw placement accuracy,PG group placement accuracy(grade 0 and 1)was 81.3%,significantly higher than the 68.4% of the conventional group(P=0.002).The operative time(P=0.025),placement time(P=0.001),single screw insertion time(P=0.013)and intraoperative blood transfusion(P=0.005)were all lower in the PG group than in the conventional group;The total time(P=0.008)and preoperative waiting time(P<0.001)were more than the control group.There was no significant difference in postoperative imaging parameters and the incidence of screw-related complications between the two groups.Conclusions The 3D printing and pedicle guide technology is safe and reliable for severe CS.It effectively solves the difficult and high risk of screw implanting during surgery,shortens the operation time,and reduces intraoperative blood transfusion.This technology is economical and practical,intuitive and easy to understand,and worthy of clinical promotion.