Imaging Study Of Three-dimension Reconstruction Model Tosimulate Lag Screw Internal Fixation For The Sacroiliac Joint

Objective To provide anatomic basis for operation of placing lag screw internal fixation for the sacroiliac joint through the line from posterior inferior iliac spine to tubercle of iliac crest.Methods CT scanning data from 60 adults pelvis(30 males and 30 females)were collected clinically and then imported into Mimics15.01 for 3D image reconstruction. Place screws from the intersection of the long axis of sacrum articular surface and the pedicle axis of S1, S2, S3.The distances from screw entry points to posterior inferior iliac spine(OA,OB,OC); the length of screws trajectory(M1,M2,M3),as well as the angle between the screws and coronal plane(α),and horizontal plane(β) were measured,then compared with results between sides and sexual.Results(1)Three penetrated points that the screws through the outside of iliac wing on the line from posterior inferior iliac spine to tubercle of iliac crest.(2)The results of each screw related diameters and angles were measured as follows: Male OA(47.7±5.2)mm,OB(33.7±7.2)mm,OC(16.1±4.5)mm;M1(75.9±4.3)mm,M2(64.4±4.0)mm,M3(55.9±4.3);α1(13.6±3.7)°,α2(4.3±1.8)°,α3(10.0±4.4)°;β1(19.1±5.3)°,β2(9.5±4.1)°,β3(4.0±1.5)°. Female OA(42.9±3.7)mm,OB(30.1±5.0)mm,OC(15.0±4.6)mm;M1(77.2±4.0)mm,M2(66.2±4.8)mm,M3(57.3±5.5)mm;α1(12.4±3.4)°,α2(4.5±2.1)°,α3(10.7±4.0)°;β1(17.5±4.6)°,β2(10.0±4.1)°,β3(3.7±1.5)°.(3)There were significant statical differences between male and female in the M2,D1,D2( P<0.05).Conclusions It is safe and convenient for placing lag screws through the entry point in the line from posterior inferior iliac spine to iliac tubercle internal fixation for the sacroiliac joint.