An Experimental Study On Internal Fixation Of Acetabular Fractures Based On Digital Design And 3D Printing Technology

Objective:(1)To investigate the way of virtual fracture model based on 3D editing.( 2) To investigate the optimization location design of Internal fixation with reconstruction plate for acetabular fractures based on the simplified multi planar three-dimensional measurement.(3)To design and 3D printing the reconstruction plate bending module according to the fixation position of reconstruction plate. Plates were bended based on the printing module. To verify the unique clamping position of reconstruction plate in the specimens.(4)To verify the real position of reconstruction is quite consistent with preoperative design.Methods:14 adult pelvic specimens were enrolled in this study. The data of lamellar CT scanning were imported into Mimics software. 3 type of acetabular fracture model were made based on 3D editing. According to Judet-Letournel classification, there were9 cases of associated transverse-posterior wall fractures, 9 cases of "T" type fracture, 10 cases of double column fractures. Then the position of plate and the screw channels in the 3D model of pelvis were optimized based on the simplified multi planar three-dimensional measurement, and the screw length measured. 3D printing technique was used to print the bone. Plates were contoured based on the printing bones. Then internal fixation implants were inserted into the specimens. After second CT scan, 3D model of the pelvis was imported into the 3D model of preoperative design.3D registration was performed between the postoperative pelvic and the preoperative designed to obtain the data of the three-dimensional coordinate values of screw entrance points. Taking the absolute value of the difference as the experimental precision index, the qualified screw points under various levels precision in preoperative design and postoperative were treated with chi square test.Results:(1)In the study, 64 plates were planted.The position of plates were in high accordance with the preoperative design.(2)In the study, 339 screws were planted. No screws into the joint cavity.(3)the absolute value of the difference of X, Y, Z axis were0.35±0.29,0.32±0.29,0.36±0.30 mm respectively. The chi square test χ2=2.26,p>0.05 when the precision level of entrance points ≥1.3mm.(4)The contouring module of reconstruction plate by 3D printing that can guide accurate contouring of preoperative reality plate.(5)3 type of acetabular fracture model were made based on3 D editing. there were 9 cases of associated transverse-posterior wall fractures, 9 cases of "T" type fracture, 10 cases of double column fractures.Conclusions:(1)Internal fixation plan of acetabular fracture was optimized based on the simplified multi planar three-dimensional measurement. 3D printing technology was able to realize the real fixation placement. Optimized placement position could be reproduced accurately in the reality fixation placement.(2)The contouring module of reconstruction plate by using 3D printing technology could guide accurate precontouring of reconstruction plate. The unique intraoperative clamping position could be realized by using reconstruction plate to get the desired fixation effect of morphology and biomechanics.( 3) The accuracy of the digitized placement of reconstruction plate for acetabular fracture could be judged by the absolute value of the difference of three-dimensional coordinate values of postoperative and the preoperative entrance points.