Percutaneous Magic screw Fixation for acetabular posterior column fracture: An imaging anatomical study / 解剖学报

ABSTRACT

Objective To investigate the entry point, direction and fixation range of Magic screw for acetabular posterior column fracture. Methods The 3D models of 100 pelvis were reconstructed by Mimics 19. 0 software based on CT data, and the virtual magic screw were placed in acetabular posterior column, then the screw' s entry point were determined, and the direction, length, diameter and safe range were measured respectively. Acetabular posterior column with magic screw was osteotomy modeling by Mimics 19.0 and imported the Geomagic Wrap 2017 software, after that anatomical parameters of the screw path were measured. Results The entry point of Magic screw on bone surface was located at (33. 37±5. 53) mm of the anterior inferior iliac spine moving posteriorly, and ( 13. 40±3. 70) mm of the apex of the upper margin of acetabular moving celphalad in male, which were (33. 97±5. 46) mm and (9. 01±3. 86)mm in female. The posterior inclination angle, interior inclination angle of magic screw and the angle between screw and iliac wing were (57.40±6.57)°, (52. 09±5. 65)° and (15. 21 ±3.42)° in male, which were (55. 64±8. 01)°, ( 51. 55±5. 58)° and (9. 85±3. 68)°in female. The maximum diameter of male screw was (6. 97±0. 98) mm, which was (6. 39±0. 85) mm in female. The length of male screw was (76. 73±9. 20) mm, which was (63. 64±8. 37) mm in female. The safe range of posterior inclination and interior inclination of were ( 7. 19 ± 3. 30)° and (9. 41 ±3. 95)° in male screw with 5.5 mm diameter, which were (8. 37±2. 82)° and ( 10. 32±3. 93)° in female screw with 5. 2 mm diameter. In the direction of the screw, the length range of the posterior column which is fixed by screw was (56. 87±7. 60) mm, and the proportion of fractures fixed with screws which were located on the top of the acetabular was 20/50 in male, which were (41. 71±7. 97) mm and 8/50 in female. Conclusion Percutaneous Magic screw is a minimally invasive treatment for acetabular posterior column fracture, which is difficult to operate. The screw can fix the fracture which is located at the middle and upper part of the acetabular posterior column.