Application And Safety Analysis Of 3D-Printed Guide Plate In Pelvic Nail Placement With Cephalic Pelvic Ring Traction In Patients With Extremely Severe Spinal Deformity

Objective The aim of this study was to investigate the impact of 3D printed drill guide template on the effect of halo-pelvic traction and pelvic screw placement,traction effect and complications in patients with extremely severe spinal deformity,and discuss its application value and safety.Methods Totally,34 patients with extremely severe spinal deformity who were admitted to the Second Affiliated Hospital of Chengdu Medical College between January and June,2021 were selected as the research subjects,and they were divided into observation group(16 cases)and control group(18 cases).Both groups were treated with halo-pelvic traction,and the head ring was installed in a regular way.For the control group,the screw was placed by hand with 2-3 cm above the anterior superior iliac spine as the entry point and the posterior superior iliac spine as the withdrawal point.For the observation group,the pelvis model was made by 3D printing technology to analyzed the screw placement angle,and a guide template connected with the pelvis was made using 3D printing technology for pelvic screw placement during surgery.Then,halo-pelvic traction was carried out after the head ring and pelvic screw were installed.The overall operation time,pelvic screw adjustment times,screw placement time.CT scan was performed after screw placement.The pelvic data of preoperative planned screw canal and implemented screw canal were fitted.The distance between the initiating terminals of actual screw canal and planned screw canal,the included angles between planned screw canal and actual screw canal on cross section and coronal plane,and the narrowest ilium thickness of screw canal were calculated.The Visual Analogue Scale(VAS)was used to assess pain at 6h、1d、3d、1w 、 1m after screw placement.The maximum width(cm)and the anteroposternal diameter(cm)of the two groups before and after surgery were recorded.Cobb angle,height,and the predicted value of forced vital capacity were measured before and after operation.The incidence rates of complications during screw placement and during traction were counted.Results(1)For overall traction effect,the 34 patients were treated with halo-pelvic traction,soft tissue release,and thoracoplasty,with traction time of 59-152 days,an average of(112.59 ± 35.54)days.The Cobb angle of scoliosis decreased from(151.12±11.76)° before the traction to(104.44±5.81)° after traction,height increased from(133.47±9.66)cm to(140.47 ± 10.38)cm,and the predicted value of forced vital capacity increased from(44.09 ± 2.58)% to(59.85 ± 7.49)%.(2)For operation-related indicators,the overall operation time,pelvic screw placement times,and screw placement time of the observation group were significantly shorter/lower than those of the control group(P<0.05).(3)For pain after screw placement,the observation group had lower VAS score than the control group at 6h after operation(P<0.05),but there was no significant difference in VAS score between the 2 groups at 1d、3d、1w、1m after operation(P>0.05).(4)For the effect of screw placement,there was no statistically significant difference in the distance of entry point between the 2 groups(P>0.05).The cross-sectional screw canal angle and coronal screw canal angle of the observation group were smaller than those of the control group,and the narrowest ilium thickness of screw canal was larger than that of the control group(P<0.05).(5)The comparison of thoracic imaging indexes before and after surgery:there was no significant difference in the maximum thoracic width(cm)between the two groups((P>0.05);There was no significant difference in anterior and posterior thoracic diameter(cm)between the two groups((P>0.05).(6)For traction effect,Cobb angles of the 2 groups were significantly reduced after traction(P<0.05),and height and lung function indicators were significantly increased(P<0.05).There was no statistically significant difference between the 2 groups in Cobb angle,height,and predicted value of forced vital capacity(P>0.05).(7)For complications,there were 4 cases of skin infection at pelvic screw canal,and 1 case of pelvic screw loosening after traction in the control group.In the observation group,there was 1 case of screw canal infection,but no loosening or sinking of pelvic screw.Conclusion Compared with traditional screw placement by hand,3D printed drill guide template is more objective.When applied to halo-pelvic traction and pelvic screw placement,it can significantly shorten the screw placement time,reduce screw placement times,and improve the accuracy of screw placement.It is of high clinical application value in halo-pelvic traction and pelvic screw placement.