Feasibility study of navigational template for antegrade lag screw fixation of the fractures in the posterior column of acetabulum / 中华骨科杂志

ABSTRACT

Objective To analyze the feasibility and practicality of the navigational template for antegrade lag screw fixation of the fractures in the posterior column of acetabulum.Methods Spiral CT scan data of 40 normal adult pelvis was collected.3D CT scans of pelvics were performed.Virtual 3D pelvic models were reconstructed with software Mimics 10.01.Virtual cylindrical implants were placed along the longitudinal axis of the acetabular posterior column via the ischial tuberosity among the ipsilateral hemipelvis and some anatomical parameters were measured.To adjust cylinder position to determine the best projection point,the shortest distance of the point to the linea terminalis and the anterior border of the auricular surface,the angle between the cylindrical and the coronal plane (α),and the angle between the quadrilateral district and iliac fossa plane (β) were measured respectively.The 3D models were imported into software UG 6.0.The models of navigational templates were designed according to the anatomic features of the acetabulums and the measured parameters.16 cases of dry left side of pelvis specimens were collected.Simulate acetabular posterior column screw fixation from different screw holes and verify the accuracy of navigation template assisted in the nail.Results The navigational templates was designed and manufactured successfully which was more consistent with the anatomical features of the quadrilateral plane.Placement of lag screw from the first hole:6.3％ achieved accurate positioning,75％ well positioning,and 18.7％ loose.From the second hole:81.3％ had accurate positioning,18.7％ well positioning.From the third hole:37.5％ had accurate positioning,62.5％ loose.Conclusion The navigational template designed according to the anatomic features of acetabulum and the measured parameters can accurately assist lag screw placement.