Computer simulation of three-dimensional modeling for the best screw direction in atlas pedicle / 中国组织工程研究

ABSTRACT

BACKGROUND:Atlantoaxial anatomical structures were special. Compared with thoracolumbar vertebrae, there is no fixed anatomical marker for screw implantation. Moreover, pedicle structural variation is great. The current consensus view is to suggest an individualized program of pedicle screws. The development of orthopedic digital software technology provides a novel manner for preoperative design. OBJECTIVE:To original y design 3D matrix model, to observe atlas pedicle channel, pedicle screw safety zone, to measure optimal program for screw fixation, and to simplify preoperative design of entering pedicle screw. METHODS:Continuous atlas CT data of 12 healthy adults in picture archiving and communication system of People’s Hospital, Three Gorges University were imported into Mimics 10.01 software. There were seven males and five females, at the age of 30-65 years old, averagely 45 years. After three-dimensional reconstruction, the three-dimensional reconstruction models were imported into 3Dmax 2009 as .dwg format. The reference three-dimensional planes and the sites of nail insertion were determined by the atlas modeling. The modeling consisted of 17×17×2 elements and the transverse section angles ranged from 0° to 40° and the sagittal section angles ranged from 0° to 40° with a space of 2.5°. 578 elements were used to simulate pedicle screw array model. Perspective observation showed that the diameter was 3.5 mm, and length was 22 mm in pedicle channel. Thus, safety area, best screw channel and screw angle were analyzed. RESULTS AND CONCLUSION:The total number of elements in the matrix study was 17×17×2×12 in 12 subjects. 175 screws in total of 6 936 units could safely meet the operative standard. No significant difference in the number of pedicle screw between left and right sides (P>0.05). Results indicated that the digital three-dimensional modeling technology is an effective, simple, accurate way in the preoperative design and measurement for atlas pedicle surgery.