The Measurement Of The Lag Screw Internal Fixation In The Anterior Column Of The Acetabulum By Three-dimensional Reconstruction Of CT

Objective:To investigate the feasibility of the three dimensional reconstruction of CT images. To create a new study method for the application research of the Lag Screw internal fixation in the anterior column of the acetabulum,and provide anatomical basis for the placement of lag screw in the anterior column of the acetabulum, To provide empirical method and evidence for the personal preoperative prepare of lag screw in the anterior column of the acetabulum。Methods: Obtained 40 adult patients randomly, who took complete CT scan of pelvis in our hospital between February 2008 and February 2010,without any bony and anatomy abnormality. Twenty-one males,Nineteen females,80 cadaveric hemipelves were collected. All the sequent tomoscan images of pelvis were imported into the Materialise's Interactive Medical Image Control System (Mimics 10.01) in personal computer, The 3-dimensonal models were reconstructed by the same calculated, Simulated the screws fixation of anterior column of acetabular,to get the best position,use the software of mimics to measure the optimal entry point and the inclination of the lag screw. Results: (1)the optimal entry point on Lag Screw internal fixation in the anterior column of the acetabulum is determined to be intersection of the greater sciatic notch was (29.15±1.85) mm and vertex of acetabulum were (28.47±2.15)mm. (2) The angle of the lag screw to the sagittal plane: males were: 37.47°±1.75°, females were: 47.44°±2.61°. (3) The angle of the lag screw to the coronal plane were: 38.83°±1.66°,(4)Average length of lag screw: males were: (113.87±2.37) mm; females were: (105.17.87±2.97) mm.(5)The mean diameter: males were: (9.68±0.77) mm; females were: (8.2±0.62) mm. The optimal entry point and the angle of the lag screw to the coronal plane of Males and females were same (P>0.01).The length;diameter of the lag screw and the angle of the lag screw to the sagittal plane of Males and females were different(P<0.01). Conclusion: We could obtain satisfactory morphous and dainty boundary in the three-dimension model of the pelvis. we can measure the optimal entry point and the inclination of the lag screw precision. The digital model of pelvis can not only provide a new method for the study of application basis research of lag screws fixation of anterior column fracture,but also offer an ideal preoperative prepare for the use of the technique.